Materiały źródłowe

• #1 Klinefelter Syndrome | Treatment & Management | Point of Care

  https://www.statpearls.com/point-of-care/23907

  Klinefelter syndrome is the most common form of aneuploidy, characterized by an abnormal number of chromosomes in the affected individual’s cells. The estimated prevalence is between 1 in 500 and 1 in 1000 males. Diagnosis often occurs in adulthood, as many cases remain unidentified until later in life. Recognition often begins during evaluation for specific clinical features across different life stages, such as in the following: […] Up to two-thirds of individuals with Klinefelter syndrome remain undiagnosed. Comparative studies suggest that Klinefelter syndrome may occur more frequently with advancing parental age, environmentally derived errors in meiosis I, or a decrease in elective terminations for prenatally diagnosed cases. Underdiagnosis is likely due to the variable phenotype, with many cases presenting with only subtle features.

• #2 How many people are affected by or at risk for Klinefelter syndrome (KS)? | NICHD – Eunice Kennedy Shriver National Institute of Child Health and Human Development

  http://www.nichd.nih.gov/health/topics/klinefelter/conditioninfo/risk

  Researchers estimate that 1 in about 500-1,000 newborn males has an extra X chromosome, making KS among the most common chromosomal disorders found in all newborns. […] Scientists are not sure what factors increase the risk of KS. […] Research suggests that women who have pregnancies after age 35 might be slightly more likely to have a son with KS. However, the extra X chromosome in KS comes from the father about half the time.

• #3 Clinical features, diagnosis, and management of Klinefelter syndrome – UpToDate

  https://www.uptodate.com/contents/clinical-features-diagnosis-and-management-of-klinefelter-syndrome

  Klinefelter syndrome is the most common cause of primary hypogonadism. The prevalence of Klinefelter syndrome is approximately 1 to 2.5 per 1000 boys and adult males (0.1 to 0.25 percent). Only 25 to 50 percent of patients with Klinefelter syndrome are diagnosed during their lifetimes. This underdiagnosis is likely due to clinicians’ lack of awareness of the variable clinical features of Klinefelter syndrome, as well as inexperience assessing testicular volumes.

• #4 Klinefelter Syndrome: Practice Essentials, Pathophysiology, Epidemiology

  https://emedicine.medscape.com/article/945649-overview

  Klinefelter syndrome (XXY aneuploidy) is the most common human sex chromosome disorder. Approximately 1 in 500-600 males is born with an extra X chromosome. The prevalence rate is 5-20 times higher in males who are mentally challenged than in the general male population. Approximately 250,000 men in the United States have Klinefelter syndrome. […] About 40% of concepti with Klinefelter syndrome survive in utero to the postnatal period. In general, the severity of somatic malformations in Klinefelter syndrome is proportional to the number of supernumerary X chromosomes; intellectual disability and hypogonadism are more severe in patients with 49,XXXXY than in those with 48,XXXY. The mortality rate is not significantly higher than in healthy individuals. […] Klinefelter syndrome does not have any racial predilection. Klinefelter syndrome (47,XXY) results from an additional X chromosome on an XY background; therefore, this condition affects only males. Klinefelter syndrome is often undiagnosed in young males. Diagnosis frequently occurs in adulthood; however about 75% of sex chromosome aneuploidies are never diagnosed. For suspected 47,XXY males, common indicators for karyotype analysis on peripheral blood are hypogonadism and infertility.

• #5 Klinefelter Syndrome: Practice Essentials, Pathophysiology, Epidemiology

  https://emedicine.medscape.com/article/945649-overview

  Klinefelter syndrome (XXY aneuploidy) is the most common human sex chromosome disorder. Approximately 1 in 500-600 males is born with an extra X chromosome. The prevalence rate is 5-20 times higher in males who are mentally challenged than in the general male population. Approximately 250,000 men in the United States have Klinefelter syndrome. […] About 40% of concepti with Klinefelter syndrome survive in utero to the postnatal period. In general, the severity of somatic malformations in Klinefelter syndrome is proportional to the number of supernumerary X chromosomes; intellectual disability and hypogonadism are more severe in patients with 49,XXXXY than in those with 48,XXXY. The mortality rate is not significantly higher than in healthy individuals. […] Klinefelter syndrome does not have any racial predilection. Klinefelter syndrome (47,XXY) results from an additional X chromosome on an XY background; therefore, this condition affects only males. Klinefelter syndrome is often undiagnosed in young males. Diagnosis frequently occurs in adulthood; however about 75% of sex chromosome aneuploidies are never diagnosed. For suspected 47,XXY males, common indicators for karyotype analysis on peripheral blood are hypogonadism and infertility.

• #6 Is the prevalence of Klinefelter syndrome increasing? | European Journal of Human Genetics

  https://www.nature.com/articles/5201956

  The birth prevalence of sex chromosome trisomies (SCT), that is individuals with an XYY, XXY or XXX sex chromosome constitution, is traditionally based on six surveys of unselected newborns carried out in the 1960s and early 1970s. […] The more recent newborn surveys suggest there has been an increase in the prevalence of XXYs, but not of the other two SCTs since the original newborn series. The prevalence of XXYs has risen from 1.09 to 1.72 per 1000 male births (P=0.023). […] Recent data from the UK Chromosome Abnormality Database showed a much greater number of prenatal diagnosis of XXY (Klinefelter’s syndrome) than either XXX (Triple X) or XYY. […] The greater number of prenatal diagnoses of XXY than either XXX or XYY reported in the UK Chromosome Abnormality Database is consistent with their prevalence at birth in the later newborn surveys and the data on spontaneous abortions and perinatal deaths. […] A comparison of the later newborn surveys with the original newborn surveys carried out in the late 1960s and early 1970s demonstrated an increased birth prevalence of XXYs, but not of XYYs nor of XXXs.

• #7 Is the prevalence of Klinefelter syndrome increasing? | European Journal of Human Genetics

  https://www.nature.com/articles/5201956

  The birth prevalence of sex chromosome trisomies (SCT), that is individuals with an XYY, XXY or XXX sex chromosome constitution, is traditionally based on six surveys of unselected newborns carried out in the 1960s and early 1970s. […] The more recent newborn surveys suggest there has been an increase in the prevalence of XXYs, but not of the other two SCTs since the original newborn series. The prevalence of XXYs has risen from 1.09 to 1.72 per 1000 male births (P=0.023). […] Recent data from the UK Chromosome Abnormality Database showed a much greater number of prenatal diagnosis of XXY (Klinefelter’s syndrome) than either XXX (Triple X) or XYY. […] The greater number of prenatal diagnoses of XXY than either XXX or XYY reported in the UK Chromosome Abnormality Database is consistent with their prevalence at birth in the later newborn surveys and the data on spontaneous abortions and perinatal deaths. […] A comparison of the later newborn surveys with the original newborn surveys carried out in the late 1960s and early 1970s demonstrated an increased birth prevalence of XXYs, but not of XYYs nor of XXXs.

• #8 Klinefelter Syndrome: Practice Essentials, Pathophysiology, Epidemiology

  https://emedicine.medscape.com/article/945649-overview

  Klinefelter syndrome (XXY aneuploidy) is the most common human sex chromosome disorder. Approximately 1 in 500-600 males is born with an extra X chromosome. The prevalence rate is 5-20 times higher in males who are mentally challenged than in the general male population. Approximately 250,000 men in the United States have Klinefelter syndrome. […] About 40% of concepti with Klinefelter syndrome survive in utero to the postnatal period. In general, the severity of somatic malformations in Klinefelter syndrome is proportional to the number of supernumerary X chromosomes; intellectual disability and hypogonadism are more severe in patients with 49,XXXXY than in those with 48,XXXY. The mortality rate is not significantly higher than in healthy individuals. […] Klinefelter syndrome does not have any racial predilection. Klinefelter syndrome (47,XXY) results from an additional X chromosome on an XY background; therefore, this condition affects only males. Klinefelter syndrome is often undiagnosed in young males. Diagnosis frequently occurs in adulthood; however about 75% of sex chromosome aneuploidies are never diagnosed. For suspected 47,XXY males, common indicators for karyotype analysis on peripheral blood are hypogonadism and infertility.

• #9 Klinefelter syndrome – Wikipedia

  https://en.wikipedia.org/wiki/Klinefelter_syndrome

  This syndrome, evenly distributed in all ethnic groups, has a prevalence of approximately four subjects per every 10,000 (0.04%) males in the general population. However, it is estimated that only 25% of the individuals with Klinefelter syndrome are diagnosed throughout their lives. The rate of Klinefelter syndrome among infertile males is 3.1%. The syndrome is the main cause of male hypogonadism. One survey in the United Kingdom found that the majority of people with KS identify as male, however, a significant number have a different gender identity. The prevalence of KS is higher than expected in transgender women.

• #10 Klinefelter Syndrome | AAFP

  https://www.aafp.org/pubs/afp/issues/2005/1201/p2259.html

  Approximately one in 1,000 boys is born with an additional X chromosome47,XXY, the karyotype that causes Klinefelter syndrome. This karyotype is detected at or before birth in 10 percent of affected boys, and it is found during adulthood in 25 percent of affected men. Almost all men with a 47,XXY karyotype will be infertile; Klinefelter syndrome accounts for 3 percent of male infertility. Klinefelter syndrome is common in infertile men with oligospermia or azoospermia (5 to 10 percent). […] Because most boys with Klinefelter syndrome appear similar to boys with normal karyotypes, the disorder typically is identified in adulthood, when infertility or gynecomastia are common presentations. However, by this time, a therapeutic window during adolescence for treatment of hypogonadism, cognitive impairments, and psychosocial factors has been missed. […] Clinical suspicion warrants diagnostic investigation to ensure appropriate surveillance for testosterone deficit.

• #11 Klinefelter Syndrome – The Oncofertility Consortium

  https://oncofertility.msu.edu/non-malignant-conditions/klinefelter-syndrome/

  Between 1 in 500 and 1 in 1000 males have Klinefelter syndrome. Variants of Klinefelter syndrome occur more infrequently; approximately 1 in 50,000 or fewer newborns has a variant of Klinefelter syndrome. […] Most men are diagnosed as adults in the context of male infertility. Only 10% of males with Klinefelter syndrome are diagnosed before age 14 years. Klinefelter syndrome is underdiagnosed because the condition is often not identified in men with mild signs and symptoms. Additionally, features can vary and overlap with other conditions. […] Klinefelter syndrome is one of the leading causes of male infertility. Approximately 3% of all infertile men have Klinefelter syndrome and 14% of non-obstructive azoospermic men have Klinefelter syndrome.

• #12 Klinefelter Syndrome | AAFP

  https://www.aafp.org/pubs/afp/issues/2005/1201/p2259.html

  Approximately one in 1,000 boys is born with an additional X chromosome47,XXY, the karyotype that causes Klinefelter syndrome. This karyotype is detected at or before birth in 10 percent of affected boys, and it is found during adulthood in 25 percent of affected men. Almost all men with a 47,XXY karyotype will be infertile; Klinefelter syndrome accounts for 3 percent of male infertility. Klinefelter syndrome is common in infertile men with oligospermia or azoospermia (5 to 10 percent). […] Because most boys with Klinefelter syndrome appear similar to boys with normal karyotypes, the disorder typically is identified in adulthood, when infertility or gynecomastia are common presentations. However, by this time, a therapeutic window during adolescence for treatment of hypogonadism, cognitive impairments, and psychosocial factors has been missed. […] Clinical suspicion warrants diagnostic investigation to ensure appropriate surveillance for testosterone deficit.

• #13 Klinefelter Syndrome – The Oncofertility Consortium

  https://oncofertility.msu.edu/non-malignant-conditions/klinefelter-syndrome/

  Between 1 in 500 and 1 in 1000 males have Klinefelter syndrome. Variants of Klinefelter syndrome occur more infrequently; approximately 1 in 50,000 or fewer newborns has a variant of Klinefelter syndrome. […] Most men are diagnosed as adults in the context of male infertility. Only 10% of males with Klinefelter syndrome are diagnosed before age 14 years. Klinefelter syndrome is underdiagnosed because the condition is often not identified in men with mild signs and symptoms. Additionally, features can vary and overlap with other conditions. […] Klinefelter syndrome is one of the leading causes of male infertility. Approximately 3% of all infertile men have Klinefelter syndrome and 14% of non-obstructive azoospermic men have Klinefelter syndrome.

• #14 Klinefelter Syndrome: Practice Essentials, Pathophysiology, Epidemiology

  https://emedicine.medscape.com/article/945649-overview

  Klinefelter syndrome (XXY aneuploidy) is the most common human sex chromosome disorder. Approximately 1 in 500-600 males is born with an extra X chromosome. The prevalence rate is 5-20 times higher in males who are mentally challenged than in the general male population. Approximately 250,000 men in the United States have Klinefelter syndrome. […] About 40% of concepti with Klinefelter syndrome survive in utero to the postnatal period. In general, the severity of somatic malformations in Klinefelter syndrome is proportional to the number of supernumerary X chromosomes; intellectual disability and hypogonadism are more severe in patients with 49,XXXXY than in those with 48,XXXY. The mortality rate is not significantly higher than in healthy individuals. […] Klinefelter syndrome does not have any racial predilection. Klinefelter syndrome (47,XXY) results from an additional X chromosome on an XY background; therefore, this condition affects only males. Klinefelter syndrome is often undiagnosed in young males. Diagnosis frequently occurs in adulthood; however about 75% of sex chromosome aneuploidies are never diagnosed. For suspected 47,XXY males, common indicators for karyotype analysis on peripheral blood are hypogonadism and infertility.

• #15 Azthena logo with the word Azthena

  https://www.news-medical.net/health/Klinefelter-Syndrome.aspx

  Klinefelter syndrome is estimated to affect approximately 1 in 500 male babies and is, therefore, one of the most common chromosomal variations. However, only about 25% of these cases are diagnosed with Klinefelter syndrome and the majority do not have an impact on sexual characteristics. The prevalence of the condition is considerably higher (5-20 times) in individuals with mental retardation than in the general newborn population. […] An individual usually presents with symptoms of Klinefelter syndrome during childhood, puberty or adulthood when infertility becomes an issue.

• #16 Klinefelter syndrome – Wikipedia

  https://en.wikipedia.org/wiki/Klinefelter_syndrome

  This syndrome, evenly distributed in all ethnic groups, has a prevalence of approximately four subjects per every 10,000 (0.04%) males in the general population. However, it is estimated that only 25% of the individuals with Klinefelter syndrome are diagnosed throughout their lives. The rate of Klinefelter syndrome among infertile males is 3.1%. The syndrome is the main cause of male hypogonadism. One survey in the United Kingdom found that the majority of people with KS identify as male, however, a significant number have a different gender identity. The prevalence of KS is higher than expected in transgender women.

• #17 Clinical features, diagnosis, and management of Klinefelter syndrome – UpToDate

  https://www.uptodate.com/contents/clinical-features-diagnosis-and-management-of-klinefelter-syndrome/print

  Klinefelter syndrome is the most common cause of primary hypogonadism. The majority of males with Klinefelter syndrome are not diagnosed. Many of these missed diagnoses are likely due to the failure of clinicians to recognize the symptoms and signs of hypogonadism and the distinctive phenotype (eg, small, very firm testes) of classic Klinefelter syndrome. Recognition and treatment of Klinefelter syndrome is important for prevention or treatment of its consequences, such as micropenis, learning disabilities, delayed puberty, infertility, and osteoporosis. […] The epidemiology, pathogenesis, clinical features, diagnosis, and management of Klinefelter syndrome are reviewed here. […] The prevalence of Klinefelter syndrome is approximately 1 to 2.5 per 1000 boys and adult males (0.1 to 0.25 percent). Only 25 to 50 percent of patients with Klinefelter syndrome are diagnosed during their lifetimes. […] This underdiagnosis is likely due to clinicians’ lack of awareness of the variable clinical features of Klinefelter syndrome, as well as inexperience assessing testicular volumes.

• #18 Klinefelter syndrome – Wikipedia

  https://en.wikipedia.org/wiki/Klinefelter_syndrome

  This syndrome, evenly distributed in all ethnic groups, has a prevalence of approximately four subjects per every 10,000 (0.04%) males in the general population. However, it is estimated that only 25% of the individuals with Klinefelter syndrome are diagnosed throughout their lives. The rate of Klinefelter syndrome among infertile males is 3.1%. The syndrome is the main cause of male hypogonadism. One survey in the United Kingdom found that the majority of people with KS identify as male, however, a significant number have a different gender identity. The prevalence of KS is higher than expected in transgender women.

• #19 How many people are affected by or at risk for Klinefelter syndrome (KS)? | NICHD – Eunice Kennedy Shriver National Institute of Child Health and Human Development

  http://www.nichd.nih.gov/health/topics/klinefelter/conditioninfo/risk

  Researchers estimate that 1 in about 500-1,000 newborn males has an extra X chromosome, making KS among the most common chromosomal disorders found in all newborns. […] Scientists are not sure what factors increase the risk of KS. […] Research suggests that women who have pregnancies after age 35 might be slightly more likely to have a son with KS. However, the extra X chromosome in KS comes from the father about half the time.

• #20 How many people are affected by or at risk for Klinefelter syndrome (KS)? | NICHD – Eunice Kennedy Shriver National Institute of Child Health and Human Development

  http://www.nichd.nih.gov/health/topics/klinefelter/conditioninfo/risk

  Researchers estimate that 1 in about 500-1,000 newborn males has an extra X chromosome, making KS among the most common chromosomal disorders found in all newborns. […] Scientists are not sure what factors increase the risk of KS. […] Research suggests that women who have pregnancies after age 35 might be slightly more likely to have a son with KS. However, the extra X chromosome in KS comes from the father about half the time.

• #21 Klinefelter Syndrome: Symptoms, Causes, Treatments, and More

  https://www.healthline.com/health/klinefelter-syndrome

  Klinefelter syndrome is one of the most common chromosome conditions in newborns. It affects between 1 in 500 and 1 in 1,000 newborn males. […] Its possible that Klinefelter syndrome affects even more male children and adults than statistics suggest. Sometimes symptoms are so mild that they go unnoticed. Or symptoms can be misdiagnosed as being caused by other similar conditions. […] Females who have pregnancies after age 35 are slightly more likely to give birth to a baby with Klinefelter syndrome. […] A small number of males with Klinefelter syndrome receive a diagnosis before birth when their mother has one of these tests: Amniocentesis. During an amniocentesis, a technician removes a small amount of amniotic fluid from the sac surrounding the baby. The fluid is then examined in a lab for chromosome problems.

• #22

  https://step2.medbullets.com/pediatrics/120570/klinefelter-syndrome

  Klinefelter syndrome is a sex chromosome disorder that is a common underlying cause of hypogonadism in men. […] Incidence: 1-2.5 per 1000 men; only 25-50% of Klinefelter syndrome patients are diagnosed during their lifetimes. […] Risk factors: advanced maternal age.

• #23 How many people are affected by or at risk for Klinefelter syndrome (KS)? | NICHD – Eunice Kennedy Shriver National Institute of Child Health and Human Development

  http://www.nichd.nih.gov/health/topics/klinefelter/conditioninfo/risk

  Researchers estimate that 1 in about 500-1,000 newborn males has an extra X chromosome, making KS among the most common chromosomal disorders found in all newborns. […] Scientists are not sure what factors increase the risk of KS. […] Research suggests that women who have pregnancies after age 35 might be slightly more likely to have a son with KS. However, the extra X chromosome in KS comes from the father about half the time.

• #24 Klinefelter Syndrome | GLOWM

  https://www.glowm.com/section-view/heading/Klinefelter%20Syndrome/item/360

  X-chromatin surveys of unselected newborn boys have revealed an incidence of X-chromatinpositive males ranging from 1.1:1000 to 1.9:1000. Jacobs tabulated data from various centers and found that 37 (0.09%) of 37,557 male newborns had 47,XXY complements. Because some males with X chromatin are 46,XX or 46,XY/47,XXY, X-chromatin surveys and chromosomal surveys are not necessarily comparable. […] Increased maternal age is associated with an additional X chromosome in both males and females. In a series of 45 cases of 47,XXY patients, Ferguson-Smith and colleagues found an average maternal age of 32.5 years, compared with 28.7 years for controls and 36.1 years for mothers of children with Downs syndrome. Hamerton reviewed the parental age distribution for two separate series of 47,XXY patients and found a far higher proportion of both mothers and fathers over age 35 than would be expected in the general population of either Sweden or Great Britain. Patil and colleagues calculated that the highest risk of having 47,XXY offspring is to mothers over age 40; Carothers and Filippi reported that at age 40, the risk is two to three times that of a mother at age 30.

• #25 Klinefelter Syndrome | GLOWM

  https://www.glowm.com/section-view/heading/Klinefelter%20Syndrome/item/360

  X-chromatin surveys of unselected newborn boys have revealed an incidence of X-chromatinpositive males ranging from 1.1:1000 to 1.9:1000. Jacobs tabulated data from various centers and found that 37 (0.09%) of 37,557 male newborns had 47,XXY complements. Because some males with X chromatin are 46,XX or 46,XY/47,XXY, X-chromatin surveys and chromosomal surveys are not necessarily comparable. […] Increased maternal age is associated with an additional X chromosome in both males and females. In a series of 45 cases of 47,XXY patients, Ferguson-Smith and colleagues found an average maternal age of 32.5 years, compared with 28.7 years for controls and 36.1 years for mothers of children with Downs syndrome. Hamerton reviewed the parental age distribution for two separate series of 47,XXY patients and found a far higher proportion of both mothers and fathers over age 35 than would be expected in the general population of either Sweden or Great Britain. Patil and colleagues calculated that the highest risk of having 47,XXY offspring is to mothers over age 40; Carothers and Filippi reported that at age 40, the risk is two to three times that of a mother at age 30.

• #26 Clinical features, diagnosis, and management of Klinefelter syndrome – UpToDate

  https://www.uptodate.com/contents/clinical-features-diagnosis-and-management-of-klinefelter-syndrome

  Klinefelter syndrome is the most common cause of primary hypogonadism. The prevalence of Klinefelter syndrome is approximately 1 to 2.5 per 1000 boys and adult males (0.1 to 0.25 percent). Only 25 to 50 percent of patients with Klinefelter syndrome are diagnosed during their lifetimes. This underdiagnosis is likely due to clinicians’ lack of awareness of the variable clinical features of Klinefelter syndrome, as well as inexperience assessing testicular volumes.

• #27 Klinefelter Syndrome | Treatment & Management | Point of Care

  https://www.statpearls.com/point-of-care/23907

  Klinefelter syndrome is the most common form of aneuploidy, characterized by an abnormal number of chromosomes in the affected individual’s cells. The estimated prevalence is between 1 in 500 and 1 in 1000 males. Diagnosis often occurs in adulthood, as many cases remain unidentified until later in life. Recognition often begins during evaluation for specific clinical features across different life stages, such as in the following: […] Up to two-thirds of individuals with Klinefelter syndrome remain undiagnosed. Comparative studies suggest that Klinefelter syndrome may occur more frequently with advancing parental age, environmentally derived errors in meiosis I, or a decrease in elective terminations for prenatally diagnosed cases. Underdiagnosis is likely due to the variable phenotype, with many cases presenting with only subtle features.

• #28 Klinefelter syndrome: MedlinePlus GeneticsLock

  https://medlineplus.gov/genetics/condition/klinefelter-syndrome/

  Klinefelter syndrome affects about 1 in 650 male newborns. It is the most common sex chromosome disorder, which is a group of conditions caused by changes in the number of sex chromosomes (the X chromosome and the Y chromosome). […] Researchers believe that up to 65 percent of people with Klinefelter syndrome are never diagnosed.

• #29 Klinefelter Syndrome: What It Is, Symptoms & Treatment

  https://my.clevelandclinic.org/health/diseases/21116-klinefelter-syndrome

  Klinefelter syndrome is fairly common, occurring in about 1 in 600 males. But many people (some experts say 70% to 80%) likely dont know they have this condition. […] People with mild cases of Klinefelter syndrome those without symptoms may never even know they have the condition. For others, their providers only discover it during infertility testing. […] You cant prevent Klinefelter syndrome because its a random change in your genetic code and it happens before birth. You cant pass this condition down to your child. And theres nothing a parent can do to keep their child from developing Klinefelter syndrome. […] People who have Klinefelter syndrome have a normal life expectancy. Treatment can help people with this condition live full, happy, healthy lives.

• #30 Klinefelter Syndrome | Treatment & Management | Point of Care

  https://www.statpearls.com/point-of-care/23907

  Klinefelter syndrome is the most common form of aneuploidy, characterized by an abnormal number of chromosomes in the affected individual’s cells. The estimated prevalence is between 1 in 500 and 1 in 1000 males. Diagnosis often occurs in adulthood, as many cases remain unidentified until later in life. Recognition often begins during evaluation for specific clinical features across different life stages, such as in the following: […] Up to two-thirds of individuals with Klinefelter syndrome remain undiagnosed. Comparative studies suggest that Klinefelter syndrome may occur more frequently with advancing parental age, environmentally derived errors in meiosis I, or a decrease in elective terminations for prenatally diagnosed cases. Underdiagnosis is likely due to the variable phenotype, with many cases presenting with only subtle features.

• #31 Clinical features, diagnosis, and management of Klinefelter syndrome – UpToDate

  https://www.uptodate.com/contents/clinical-features-diagnosis-and-management-of-klinefelter-syndrome

  Klinefelter syndrome is the most common cause of primary hypogonadism. The prevalence of Klinefelter syndrome is approximately 1 to 2.5 per 1000 boys and adult males (0.1 to 0.25 percent). Only 25 to 50 percent of patients with Klinefelter syndrome are diagnosed during their lifetimes. This underdiagnosis is likely due to clinicians’ lack of awareness of the variable clinical features of Klinefelter syndrome, as well as inexperience assessing testicular volumes.

• #32 Clinical features, diagnosis, and management of Klinefelter syndrome – UpToDate

  https://www.uptodate.com/contents/clinical-features-diagnosis-and-management-of-klinefelter-syndrome

  Klinefelter syndrome is the most common cause of primary hypogonadism. The prevalence of Klinefelter syndrome is approximately 1 to 2.5 per 1000 boys and adult males (0.1 to 0.25 percent). Only 25 to 50 percent of patients with Klinefelter syndrome are diagnosed during their lifetimes. This underdiagnosis is likely due to clinicians’ lack of awareness of the variable clinical features of Klinefelter syndrome, as well as inexperience assessing testicular volumes.

• #33 Klinefelter Syndrome | Treatment & Management | Point of Care

  https://www.statpearls.com/point-of-care/23907

  An estimated quarter of individuals with Klinefelter syndrome show no discernible diagnostic features based on history or examination. With the increased use of noninvasive prenatal testing, the frequency of prenatal diagnosis is expected to rise, enabling early management by pediatricians. […] Fewer than 10% of cases are detected before puberty, and only 26% to 37% are identified overall, with most remaining undiagnosed. The average age of diagnosis is 30 years, and the median lifespan is reduced by 5 or 6 years compared to the general male population.

• #34 Klinefelter Syndrome | Children’s Hospital of Philadelphia

  https://www.chop.edu/conditions-diseases/klinefelter-syndrome

  Klinefelter syndrome affects 1 in 500-1,000 newborn males, making it is one of the most common chromosomal disorders. […] About 10 percent of cases are diagnosed prenatally during routine prenatal testing such as amniocentesis. […] Boys with Klinefelter syndrome should follow up with the endocrinologist to monitor progression in puberty, hormone levels and adjust medication as needed. […] Depending on your child’s condition, long-term care may be needed. […] With proper diagnosis and treatment, some of the symptoms of Klinefelter syndrome, such as low testosterone levels, can be resolved or well-controlled.

• #35 Perinatal presentation of Klinefelter syndrome and variants: take-home lessons for the urologist | African Journal of Urology | Full Text

  https://afju.springeropen.com/articles/10.1186/s12301-024-00462-x

  Klinefelter syndrome (KS) is a sex chromosome disorder usually diagnosed in adulthood during work-up for infertility or hypogonadism. Perinatal diagnoses are uncommon. […] Klinefelter syndrome can be suspected prenatally in patients with increased nuchal translucency or ambiguous genitalia. Cell-free DNA can establish prenatal diagnosis with good sensitivity and specificity. Early diagnosis allows for early initiation of multidisciplinary care, focused counseling, lifestyle modification, early androgen replacement, and cryopreservation during late puberty or early adulthood. Testosterone treatment during infancy was linked to improved phenotypic features of KS and better cognitive and behavioral outcomes. […] Klinefelter syndrome (KS) is the most prevalent sex chromosome abnormality affecting 1 in 650 live male births. The condition is poorly diagnosed in childhood due to subtle and underrecognized phenotypic features. It has been reported that 65-75% of KS remain undiagnosed, 10% of diagnoses are made prenatally, 6% in childhood or adolescence, and 19% in adulthood.

• #36 The Klinefelter Syndrome and Testicular Sperm Retrieval Outcomes

  https://www.mdpi.com/2073-4425/14/3/647

  Klinefelter syndrome (KS), caused by the presence of an extra X chromosome, is the most prevalent chromosomal sexual anomaly, with an estimated incidence of 1:500/1000 per male live birth (karyotype 47,XXY). […] In a Danish population study of more than 2 million live births, the prevalence (existing cases) of KS was estimated to be about 0.15% (150:100,000 males), varying with region and ethnicity, and the incidence (new cases) of KS was estimated to be around 1:500–1:1000 (0.1%–0.2%) male live births. […] Patients with KS are diagnosed throughout their lives. Findings from a national survey of 200 patients with KS in Denmark showed that 20% were diagnosed prenatally, 35% were diagnosed during childhood, due to excessive growth and/or behavioral problems, and the remaining 45% were diagnosed in adulthood, typically as part of infertility evaluation.

• #37 Klinefelter Syndrome | Treatment & Management | Point of Care

  https://www.statpearls.com/point-of-care/23907

  An estimated quarter of individuals with Klinefelter syndrome show no discernible diagnostic features based on history or examination. With the increased use of noninvasive prenatal testing, the frequency of prenatal diagnosis is expected to rise, enabling early management by pediatricians. […] Fewer than 10% of cases are detected before puberty, and only 26% to 37% are identified overall, with most remaining undiagnosed. The average age of diagnosis is 30 years, and the median lifespan is reduced by 5 or 6 years compared to the general male population.

• #38 Klinefelter syndrome A general practice perspective

  https://www.racgp.org.au/afp/2014/january-february/klinefelter-syndrome

  Klinefelter syndrome (KS) is a common genetic condition affecting one in 450 men, but is only diagnosed in fewer than half of those affected. […] Currently, KS is significantly under-diagnosed: only 39% of men with KS receive a diagnosis postnatally. Even for those who are diagnosed, only 10% will receive their diagnosis before puberty. This can be attributed to the difficulty in diagnosing KS, due to the heterogeneous phenotypic presentation and the lack of awareness of KS. […] General practitioners can play a major part in improving health outcomes for men with KS through improved detection amongst their male patients. Ongoing care and management can then be provided in the general practice setting and through the use of appropriate referral pathways. […] General practitioners have a role in monitoring men with KS for comorbidities, which are outlined in Table 2. A full blood examination, thyroid function test, cholesterol and fasting blood glucose levels should be performed every two years. […] Referral to a clinical geneticist should be considered, particularly for men who have questions about the genetics of KS. Referral to a psychiatrist should also be considered where psychiatric comorbidities exist.

• #39 Klinefelter Syndrome | AAFP

  https://www.aafp.org/pubs/afp/issues/2005/1201/p2259.html

  Approximately one in 1,000 boys is born with an additional X chromosome47,XXY, the karyotype that causes Klinefelter syndrome. This karyotype is detected at or before birth in 10 percent of affected boys, and it is found during adulthood in 25 percent of affected men. Almost all men with a 47,XXY karyotype will be infertile; Klinefelter syndrome accounts for 3 percent of male infertility. Klinefelter syndrome is common in infertile men with oligospermia or azoospermia (5 to 10 percent). […] Because most boys with Klinefelter syndrome appear similar to boys with normal karyotypes, the disorder typically is identified in adulthood, when infertility or gynecomastia are common presentations. However, by this time, a therapeutic window during adolescence for treatment of hypogonadism, cognitive impairments, and psychosocial factors has been missed. […] Clinical suspicion warrants diagnostic investigation to ensure appropriate surveillance for testosterone deficit.

• #40 Klinefelter Syndrome: Practice Essentials, Pathophysiology, Epidemiology

  https://emedicine.medscape.com/article/945649-overview

  Klinefelter syndrome (XXY aneuploidy) is the most common human sex chromosome disorder. Approximately 1 in 500-600 males is born with an extra X chromosome. The prevalence rate is 5-20 times higher in males who are mentally challenged than in the general male population. Approximately 250,000 men in the United States have Klinefelter syndrome. […] About 40% of concepti with Klinefelter syndrome survive in utero to the postnatal period. In general, the severity of somatic malformations in Klinefelter syndrome is proportional to the number of supernumerary X chromosomes; intellectual disability and hypogonadism are more severe in patients with 49,XXXXY than in those with 48,XXXY. The mortality rate is not significantly higher than in healthy individuals. […] Klinefelter syndrome does not have any racial predilection. Klinefelter syndrome (47,XXY) results from an additional X chromosome on an XY background; therefore, this condition affects only males. Klinefelter syndrome is often undiagnosed in young males. Diagnosis frequently occurs in adulthood; however about 75% of sex chromosome aneuploidies are never diagnosed. For suspected 47,XXY males, common indicators for karyotype analysis on peripheral blood are hypogonadism and infertility.

• #41 The Klinefelter Syndrome and Testicular Sperm Retrieval Outcomes

  https://www.mdpi.com/2073-4425/14/3/647

  Klinefelter syndrome (KS), caused by the presence of an extra X chromosome, is the most prevalent chromosomal sexual anomaly, with an estimated incidence of 1:500/1000 per male live birth (karyotype 47,XXY). […] In a Danish population study of more than 2 million live births, the prevalence (existing cases) of KS was estimated to be about 0.15% (150:100,000 males), varying with region and ethnicity, and the incidence (new cases) of KS was estimated to be around 1:500–1:1000 (0.1%–0.2%) male live births. […] Patients with KS are diagnosed throughout their lives. Findings from a national survey of 200 patients with KS in Denmark showed that 20% were diagnosed prenatally, 35% were diagnosed during childhood, due to excessive growth and/or behavioral problems, and the remaining 45% were diagnosed in adulthood, typically as part of infertility evaluation.

• #42 Klinefelter Syndrome | Treatment & Management | Point of Care

  https://www.statpearls.com/point-of-care/23907

  An estimated quarter of individuals with Klinefelter syndrome show no discernible diagnostic features based on history or examination. With the increased use of noninvasive prenatal testing, the frequency of prenatal diagnosis is expected to rise, enabling early management by pediatricians. […] Fewer than 10% of cases are detected before puberty, and only 26% to 37% are identified overall, with most remaining undiagnosed. The average age of diagnosis is 30 years, and the median lifespan is reduced by 5 or 6 years compared to the general male population.

• #43

  https://www.healthychildren.org/English/ages-stages/gradeschool/puberty/Pages/Klinefelter-Syndrome.aspx

  It is relatively common, occurring in about 1 of every 500 baby boys. […] Many cases are not diagnosed until adulthood. […] The syndrome is diagnosed by a special genetic blood test called a karyotype or chromosome analysis that shows the presence of an extra X chromosome. […] At the time of puberty, blood levels of the pituitary hormones follicle-stimulating hormone (called FSH) and luteinizing hormone (LH) increase as a result of decrease in testicular function, and measurement of these hormones aids in making the correct diagnosis. […] Overall, the predictions for long-term health and life expectancy are excellent.

• #44 Klinefelter Syndrome: Symptoms, Causes, Treatments, and More

  https://www.healthline.com/health/klinefelter-syndrome

  Klinefelter syndrome is one of the most common chromosome conditions in newborns. It affects between 1 in 500 and 1 in 1,000 newborn males. […] Its possible that Klinefelter syndrome affects even more male children and adults than statistics suggest. Sometimes symptoms are so mild that they go unnoticed. Or symptoms can be misdiagnosed as being caused by other similar conditions. […] Females who have pregnancies after age 35 are slightly more likely to give birth to a baby with Klinefelter syndrome. […] A small number of males with Klinefelter syndrome receive a diagnosis before birth when their mother has one of these tests: Amniocentesis. During an amniocentesis, a technician removes a small amount of amniotic fluid from the sac surrounding the baby. The fluid is then examined in a lab for chromosome problems.

• #45 Perinatal presentation of Klinefelter syndrome and variants: take-home lessons for the urologist | African Journal of Urology | Full Text

  https://afju.springeropen.com/articles/10.1186/s12301-024-00462-x

  Klinefelter syndrome (KS) is a sex chromosome disorder usually diagnosed in adulthood during work-up for infertility or hypogonadism. Perinatal diagnoses are uncommon. […] Klinefelter syndrome can be suspected prenatally in patients with increased nuchal translucency or ambiguous genitalia. Cell-free DNA can establish prenatal diagnosis with good sensitivity and specificity. Early diagnosis allows for early initiation of multidisciplinary care, focused counseling, lifestyle modification, early androgen replacement, and cryopreservation during late puberty or early adulthood. Testosterone treatment during infancy was linked to improved phenotypic features of KS and better cognitive and behavioral outcomes. […] Klinefelter syndrome (KS) is the most prevalent sex chromosome abnormality affecting 1 in 650 live male births. The condition is poorly diagnosed in childhood due to subtle and underrecognized phenotypic features. It has been reported that 65-75% of KS remain undiagnosed, 10% of diagnoses are made prenatally, 6% in childhood or adolescence, and 19% in adulthood.

• #46 Klinefelter Syndrome: Symptoms, Causes, Treatments, and More

  https://www.healthline.com/health/klinefelter-syndrome

  Because these tests can increase the risk for a miscarriage, they usually arent done unless the baby is at risk for a chromosome problem. Often, Klinefelter syndrome isnt discovered until a child reaches puberty or later. […] The main test used to diagnose Klinefelter syndrome is: Chromosome analysis. Also called karyotyping, this blood test checks for abnormal chromosomes, such as an extra X chromosome. […] Most people with Klinefelter syndrome dont produce much or any sperm. A lack of sperm can make it harder to biologically have a child, but its not impossible. […] While having a biological child is not the only way to become a parent, fertility treatments can help some people who are interested in that method. […] Many people living with Klinefelter syndrome either dont know they have it or arent adversely affected by it. However, in some cases, living with this syndrome can create stress. […] Most people with Klinefelter syndrome live long, healthy lives. If you or your child requires treatment, the earlier its received, the better. This is because treating Klinefelter syndrome during puberty can lessen some of the symptoms.

• #47

  https://www.healthychildren.org/English/ages-stages/gradeschool/puberty/Pages/Klinefelter-Syndrome.aspx

  It is relatively common, occurring in about 1 of every 500 baby boys. […] Many cases are not diagnosed until adulthood. […] The syndrome is diagnosed by a special genetic blood test called a karyotype or chromosome analysis that shows the presence of an extra X chromosome. […] At the time of puberty, blood levels of the pituitary hormones follicle-stimulating hormone (called FSH) and luteinizing hormone (LH) increase as a result of decrease in testicular function, and measurement of these hormones aids in making the correct diagnosis. […] Overall, the predictions for long-term health and life expectancy are excellent.

• #48 Klinefelter’s syndrome | Endocrine Conditions

  https://www.yourhormones.info/endocrine-conditions/klinefelters-syndrome/

  Klinefelter syndrome is a genetic condition that can only affect boys / men and occurs due to the presence of one (or more) extra X chromosomes. […] Klinefelter syndrome is one of the most common chromosome abnormalities in men. About 1 of every 650 live male births has an extra X chromosome, but many do not have any symptoms. Importantly, up to 3% of infertile men have Klinefelter syndrome and many cases go undiagnosed. It can often be diagnosed if a man is undergoing infertility testing. […] Klinefelter syndrome is a genetic condition but it is not inherited from the parents. In the vast majority of boys, there are no other affected family members; it occurs sporadically (i.e. without a family history). […] Where Klinefelter syndrome is suspected, blood tests will be carried out to assess levels of testosterone and gonadotrophins – LH (luteinising hormone) and FSH (follicle stimulating hormone).

• #49 Klinefelter Syndrome | Treatment & Management | Point of Care

  https://www.statpearls.com/point-of-care/23907

  An estimated quarter of individuals with Klinefelter syndrome show no discernible diagnostic features based on history or examination. With the increased use of noninvasive prenatal testing, the frequency of prenatal diagnosis is expected to rise, enabling early management by pediatricians. […] Fewer than 10% of cases are detected before puberty, and only 26% to 37% are identified overall, with most remaining undiagnosed. The average age of diagnosis is 30 years, and the median lifespan is reduced by 5 or 6 years compared to the general male population.

• #50 Frontiers | Klinefelter Syndrome and the Need for a Multi-Disciplinary Approach

  https://www.frontiersin.org/journals/reproductive-health/articles/10.3389/frph.2021.622144/full

  Klinefelter’s syndrome (KS) occurs as a de novo event in 1 in 600 males. While 80% of cases of KS have the 47 XXY Karyotype, it is known that some patients may have more than one extra X chromosome or express mosaicism 46XY/47XXY. It is the most frequently occurring chromosome abnormality in infertile men. […] As these patients are predisposed to developing secondary diseases mentioned earlier, they require long term monitoring of their blood pressure, glucose controls, bone health, and lipid levels. […] The clinic aims to increase awareness and education of KS in the healthcare community. One of the main reasons for the long waiting time for patients in primary care could be attributed to the lack of awareness of the possibility of KS as a diagnosis for these patients. Through education, we hope that more men with KS can be diagnosed earlier and spend less time in primary care before they see a specialist in their condition.

• #51 About Klinefelter Syndrome

  https://www.genome.gov/Genetic-Disorders/Klinefelter-Syndrome

  Klinefelter syndrome is found in about 1 out of every 500-1,000 newborn males. The additional sex chromosome results from a random error during the formation of the egg or sperm. About half of the time the error occurs in the formation of sperm, while the remainder are due to errors in egg development. Women who have pregnancies after age 35 have a slightly increased chance of having a boy with this syndrome. […] Klinefelter syndrome is associated with an increased risk for breast cancer, a rare tumor called extragonadal germ cell tumor, lung disease, varicose veins and osteoporosis. Men who have Klinefelter syndrome also have an increased risk for autoimmune disorders such as lupus, rheumatoid arthritis and Sjogren’s syndrome.

• #52 Klinefelter syndrome – Symptoms, diagnosis and treatment | BMJ Best Practice

  https://bestpractice.bmj.com/topics/en-gb/3000332

  Klinefelter syndrome (KS) is a chromosome variation affecting around 1 in 660 males in which an extra X chromosome is present, resulting in a genetic karyotype of 47,XXY. Karyotype analysis is required for definitive diagnosis. […] Symptoms and signs of KS may be subtle and the majority of affected individuals function fairly normally and are never diagnosed. Among those who are diagnosed, this most commonly happens following evaluation for male infertility, although antenatal diagnosis is becoming increasingly common. […] Men with KS have a significantly increased risk of many long-term health conditions, including diabetes, cardiovascular disease, osteoporosis, and breast cancer.

• #53 About Klinefelter Syndrome

  https://www.genome.gov/Genetic-Disorders/Klinefelter-Syndrome

  Klinefelter syndrome is found in about 1 out of every 500-1,000 newborn males. The additional sex chromosome results from a random error during the formation of the egg or sperm. About half of the time the error occurs in the formation of sperm, while the remainder are due to errors in egg development. Women who have pregnancies after age 35 have a slightly increased chance of having a boy with this syndrome. […] Klinefelter syndrome is associated with an increased risk for breast cancer, a rare tumor called extragonadal germ cell tumor, lung disease, varicose veins and osteoporosis. Men who have Klinefelter syndrome also have an increased risk for autoimmune disorders such as lupus, rheumatoid arthritis and Sjogren’s syndrome.

• #54 Klinefelter syndrome – Symptoms, diagnosis and treatment | BMJ Best Practice

  https://bestpractice.bmj.com/topics/en-gb/3000332

  Klinefelter syndrome (KS) is a chromosome variation affecting around 1 in 660 males in which an extra X chromosome is present, resulting in a genetic karyotype of 47,XXY. Karyotype analysis is required for definitive diagnosis. […] Symptoms and signs of KS may be subtle and the majority of affected individuals function fairly normally and are never diagnosed. Among those who are diagnosed, this most commonly happens following evaluation for male infertility, although antenatal diagnosis is becoming increasingly common. […] Men with KS have a significantly increased risk of many long-term health conditions, including diabetes, cardiovascular disease, osteoporosis, and breast cancer.

• #55 About Klinefelter Syndrome

  https://www.genome.gov/Genetic-Disorders/Klinefelter-Syndrome

  Klinefelter syndrome is found in about 1 out of every 500-1,000 newborn males. The additional sex chromosome results from a random error during the formation of the egg or sperm. About half of the time the error occurs in the formation of sperm, while the remainder are due to errors in egg development. Women who have pregnancies after age 35 have a slightly increased chance of having a boy with this syndrome. […] Klinefelter syndrome is associated with an increased risk for breast cancer, a rare tumor called extragonadal germ cell tumor, lung disease, varicose veins and osteoporosis. Men who have Klinefelter syndrome also have an increased risk for autoimmune disorders such as lupus, rheumatoid arthritis and Sjogren’s syndrome.

• #56 Klinefelter syndrome – Symptoms, diagnosis and treatment | BMJ Best Practice

  https://bestpractice.bmj.com/topics/en-gb/3000332

  Klinefelter syndrome (KS) is a chromosome variation affecting around 1 in 660 males in which an extra X chromosome is present, resulting in a genetic karyotype of 47,XXY. Karyotype analysis is required for definitive diagnosis. […] Symptoms and signs of KS may be subtle and the majority of affected individuals function fairly normally and are never diagnosed. Among those who are diagnosed, this most commonly happens following evaluation for male infertility, although antenatal diagnosis is becoming increasingly common. […] Men with KS have a significantly increased risk of many long-term health conditions, including diabetes, cardiovascular disease, osteoporosis, and breast cancer.

• #57 About Klinefelter Syndrome

  https://www.genome.gov/Genetic-Disorders/Klinefelter-Syndrome

  Klinefelter syndrome is found in about 1 out of every 500-1,000 newborn males. The additional sex chromosome results from a random error during the formation of the egg or sperm. About half of the time the error occurs in the formation of sperm, while the remainder are due to errors in egg development. Women who have pregnancies after age 35 have a slightly increased chance of having a boy with this syndrome. […] Klinefelter syndrome is associated with an increased risk for breast cancer, a rare tumor called extragonadal germ cell tumor, lung disease, varicose veins and osteoporosis. Men who have Klinefelter syndrome also have an increased risk for autoimmune disorders such as lupus, rheumatoid arthritis and Sjogren’s syndrome.

• #58 Klinefelter Syndrome

  https://fpnotebook.com/Endo/Sex/KlnfltrSyndrm.htm

  Most common major sexual differentiation abnormality […] Incidence of Klinefelter Syndrome in specific cohorts: Newborn males: 1 in 500 to 1000 […] Male Breast Cancer: 7.5% […] Infertile males: 3% […] Mild Mental Retardation: 1% […] Breast Cancer surveillance.

• #59 About Klinefelter Syndrome

  https://www.genome.gov/Genetic-Disorders/Klinefelter-Syndrome

  Klinefelter syndrome is found in about 1 out of every 500-1,000 newborn males. The additional sex chromosome results from a random error during the formation of the egg or sperm. About half of the time the error occurs in the formation of sperm, while the remainder are due to errors in egg development. Women who have pregnancies after age 35 have a slightly increased chance of having a boy with this syndrome. […] Klinefelter syndrome is associated with an increased risk for breast cancer, a rare tumor called extragonadal germ cell tumor, lung disease, varicose veins and osteoporosis. Men who have Klinefelter syndrome also have an increased risk for autoimmune disorders such as lupus, rheumatoid arthritis and Sjogren’s syndrome.

• #60 Klinefelter’s syndrome | Endocrine Conditions

  https://www.yourhormones.info/endocrine-conditions/klinefelters-syndrome/

  The diagnosis of Klinefelter syndrome is confirmed by chromosomal analysis (karyotype), which is done using a blood test. […] Adults with Klinefelter syndrome are more likely to have a number of health issues such as osteoporosis; obesity; varicose veins and leg ulcers; development of autoimmune conditions (diabetes mellitus, systemic lupus erythematosus and thyroid problems); chest conditions (bronchitis and emphysema); and there may be an increase in some cancers (breast cancer, germ cell tumours, non-Hodgkins lymphoma). Men with Klinefelter syndrome are also thought to be at an increased risk of developing chronic health problems such as cardiovascular, respiratory and gastrointestinal disease. […] Fertility problems are common in men with Klinefelter syndrome. However, more recent specialised fertility techniques, such as microsurgical testicular sperm extraction and intracytoplasmic sperm injection have helped some men with Klinefelter syndrome to father children.

• #61 About Klinefelter Syndrome

  https://www.genome.gov/Genetic-Disorders/Klinefelter-Syndrome

  Klinefelter syndrome is found in about 1 out of every 500-1,000 newborn males. The additional sex chromosome results from a random error during the formation of the egg or sperm. About half of the time the error occurs in the formation of sperm, while the remainder are due to errors in egg development. Women who have pregnancies after age 35 have a slightly increased chance of having a boy with this syndrome. […] Klinefelter syndrome is associated with an increased risk for breast cancer, a rare tumor called extragonadal germ cell tumor, lung disease, varicose veins and osteoporosis. Men who have Klinefelter syndrome also have an increased risk for autoimmune disorders such as lupus, rheumatoid arthritis and Sjogren’s syndrome.

• #62 Klinefelter syndrome and germ cell tumors: review of the literature | International Journal of Pediatric Endocrinology | Full Text

  https://ijpeonline.biomedcentral.com/articles/10.1186/s13633-020-00088-0

  The most common presentation of Klinefelter syndrome (KS) is infertility and features of hypogonadism. Currently no consensus exists on the risk of malignancy in this syndrome. Several case reports show an incidence of extragonadal germ cells tumors (eGCT) of 1.5 per 1000 KS patients (OR 50 against healthy population). […] KS has been associated with conditions like venous disease, auto-immune disorders, mild neurobehavioral deficit, diabetes mellitus, sexual precocity and osteoporosis. […] KS has been described earlier in correlation with an increased risk of developing extragonadal germ cell tumors, though routine screening in the KS population is not standard of care. […] The most common primary site for an extragonadal germ cell tumor (eGCT) is the mediastinum, followed by the peritoneum.

• #63 Klinefelter syndrome and germ cell tumors: review of the literature | International Journal of Pediatric Endocrinology | Full Text

  https://ijpeonline.biomedcentral.com/articles/10.1186/s13633-020-00088-0

  A large number of eGCT have been described in association with KS, most often located in the mediastinum with a relative risk of at least 50. […] The overall incidence of cancer in men with KS seems to be similar to that of the general population but some malignancies show a significantly higher prevalence. […] By reviewing all cases of KS and GCT reported in the medical case reports, we show the relationship between KS and eGCT, and thereby emphasizing the need for genetic analysis in all cases of a male with a mediastinal GCT for the underdiagnosed KS. […] The reported incidence of eGCT in KS patients is 1.5/1.000, a fifty-fold increase over the general population. […] Although it has been estimated that 12% of KS patients develop a neoplasm, previous data demonstrated that young males with KS have a relative risk of around 66.7 for developing extra-gonadal germ cell tumors.

• #64 Non-alcoholic fatty liver disease prevalence in Klinefelter syndrome | ECE2022 | European Congress of Endocrinology 2022 | Endocrine Abstracts

  https://www.endocrine-abstracts.org/ea/0081/ea0081p702

  Non-alcoholic fatty liver disease prevalence in Klinefelter syndrome […] No data are available regarding Klinefelter syndrome (KS), the most common chromosomal condition associated with hypogonadism and NAFLD. […] Prevalence of steatosis in KS was 51%. […] These data are consistent with our preliminary findings in KS patients in whom the prevalence of steatosis was relevant in 51% of cases.

• #65 Klinefelter Syndrome (17.05.2013)

  https://di.aerzteblatt.de/int/archive/article/138490

  Klinefelter syndrome (KS) with the karyotype 47,XXY is one of the commonest types of congenital chromosomal disorder in males, with an incidence of 0.1% to 0.2% of newborn male infants. […] On the basis of patient registries in Denmark, it is suspected that only 25% of all Klinefelter syndrome patients are diagnosed during their lifetimes. […] Klinefelter syndrome is associated with a significantly higher morbidity rate compared to the male population as a whole. […] This leads to a life expectancy 11.5 years below that of the male population as a whole. […] However, a survey completed by 290 practising primary care physicians, internal medicine specialists, and urologists showed that two-thirds of primary care physicians and internal medicine specialists had had not knowingly seen any cases of Klinefelter syndrome in recent years, although their theoretical knowledge of it was good; urologists fared a little better regarding diagnosis of Klinefelter syndrome. […] The diagnosis of KS would be less frequently missed if doctors were more aware of, and attentive to, its key manifestations, particularly the small, firm testes, erectile dysfunction, and the comorbidities mentioned above.

• #66 What is the significance of diagnosis in Klinefelter’s Syndrome? – Health Research Authority

  https://www.hra.nhs.uk/planning-and-improving-research/application-summaries/research-summaries/what-is-the-significance-of-diagnosis-in-klinefelters-syndrome/

  Klinefelters Syndrome is a sporadic, non-inherited genetic condition in males where there is the presence of an additional X chromosome. […] Klinefelters Syndrome is relatively common with an estimated incidence of approximately 1/650 males, compared to 1/250 incidence of autism in males and females. […] Few males are diagnosed, with only an estimated one quarter receiving a diagnosis and approximately 4-10% diagnosed before puberty. […] Klinefelters Syndrome is associated with a significant number of increased health risks which cause a reduction in life expectancy of approximately 2-6 years. […] Low diagnosis rates are attributed in the literature to two factors: low awareness among general practitioners and variability in presentation of the syndrome making diagnosis difficult or incorrect. […] This research will examine if there is any evidence for these assertions by exploring perceptions of diagnosis from three different groups with different perspectives using qualitative interviews and questionnaires.

• #67 Klinefelter Syndrome | Treatment & Management | Point of Care

  https://www.statpearls.com/point-of-care/23907

  An estimated quarter of individuals with Klinefelter syndrome show no discernible diagnostic features based on history or examination. With the increased use of noninvasive prenatal testing, the frequency of prenatal diagnosis is expected to rise, enabling early management by pediatricians. […] Fewer than 10% of cases are detected before puberty, and only 26% to 37% are identified overall, with most remaining undiagnosed. The average age of diagnosis is 30 years, and the median lifespan is reduced by 5 or 6 years compared to the general male population.

• #68 Klinefelter Syndrome (17.05.2013)

  https://di.aerzteblatt.de/int/archive/article/138490

  Klinefelter syndrome (KS) with the karyotype 47,XXY is one of the commonest types of congenital chromosomal disorder in males, with an incidence of 0.1% to 0.2% of newborn male infants. […] On the basis of patient registries in Denmark, it is suspected that only 25% of all Klinefelter syndrome patients are diagnosed during their lifetimes. […] Klinefelter syndrome is associated with a significantly higher morbidity rate compared to the male population as a whole. […] This leads to a life expectancy 11.5 years below that of the male population as a whole. […] However, a survey completed by 290 practising primary care physicians, internal medicine specialists, and urologists showed that two-thirds of primary care physicians and internal medicine specialists had had not knowingly seen any cases of Klinefelter syndrome in recent years, although their theoretical knowledge of it was good; urologists fared a little better regarding diagnosis of Klinefelter syndrome. […] The diagnosis of KS would be less frequently missed if doctors were more aware of, and attentive to, its key manifestations, particularly the small, firm testes, erectile dysfunction, and the comorbidities mentioned above.

• #69 Klinefelter syndrome A general practice perspective

  https://www.racgp.org.au/afp/2014/january-february/klinefelter-syndrome

  Klinefelter syndrome (KS) is a common genetic condition affecting one in 450 men, but is only diagnosed in fewer than half of those affected. […] Currently, KS is significantly under-diagnosed: only 39% of men with KS receive a diagnosis postnatally. Even for those who are diagnosed, only 10% will receive their diagnosis before puberty. This can be attributed to the difficulty in diagnosing KS, due to the heterogeneous phenotypic presentation and the lack of awareness of KS. […] General practitioners can play a major part in improving health outcomes for men with KS through improved detection amongst their male patients. Ongoing care and management can then be provided in the general practice setting and through the use of appropriate referral pathways. […] General practitioners have a role in monitoring men with KS for comorbidities, which are outlined in Table 2. A full blood examination, thyroid function test, cholesterol and fasting blood glucose levels should be performed every two years. […] Referral to a clinical geneticist should be considered, particularly for men who have questions about the genetics of KS. Referral to a psychiatrist should also be considered where psychiatric comorbidities exist.

• #70 Klinefelter syndrome A general practice perspective

  https://www.racgp.org.au/afp/2014/january-february/klinefelter-syndrome

  Klinefelter syndrome (KS) is a common genetic condition affecting one in 450 men, but is only diagnosed in fewer than half of those affected. […] Currently, KS is significantly under-diagnosed: only 39% of men with KS receive a diagnosis postnatally. Even for those who are diagnosed, only 10% will receive their diagnosis before puberty. This can be attributed to the difficulty in diagnosing KS, due to the heterogeneous phenotypic presentation and the lack of awareness of KS. […] General practitioners can play a major part in improving health outcomes for men with KS through improved detection amongst their male patients. Ongoing care and management can then be provided in the general practice setting and through the use of appropriate referral pathways. […] General practitioners have a role in monitoring men with KS for comorbidities, which are outlined in Table 2. A full blood examination, thyroid function test, cholesterol and fasting blood glucose levels should be performed every two years. […] Referral to a clinical geneticist should be considered, particularly for men who have questions about the genetics of KS. Referral to a psychiatrist should also be considered where psychiatric comorbidities exist.

• #71 Klinefelter syndrome A general practice perspective

  https://www.racgp.org.au/afp/2014/january-february/klinefelter-syndrome

  Klinefelter syndrome (KS) is a common genetic condition affecting one in 450 men, but is only diagnosed in fewer than half of those affected. […] Currently, KS is significantly under-diagnosed: only 39% of men with KS receive a diagnosis postnatally. Even for those who are diagnosed, only 10% will receive their diagnosis before puberty. This can be attributed to the difficulty in diagnosing KS, due to the heterogeneous phenotypic presentation and the lack of awareness of KS. […] General practitioners can play a major part in improving health outcomes for men with KS through improved detection amongst their male patients. Ongoing care and management can then be provided in the general practice setting and through the use of appropriate referral pathways. […] General practitioners have a role in monitoring men with KS for comorbidities, which are outlined in Table 2. A full blood examination, thyroid function test, cholesterol and fasting blood glucose levels should be performed every two years. […] Referral to a clinical geneticist should be considered, particularly for men who have questions about the genetics of KS. Referral to a psychiatrist should also be considered where psychiatric comorbidities exist.

• #72 Klinefelter syndrome A general practice perspective

  https://www.racgp.org.au/afp/2014/january-february/klinefelter-syndrome

  Klinefelter syndrome (KS) is a common genetic condition affecting one in 450 men, but is only diagnosed in fewer than half of those affected. […] Currently, KS is significantly under-diagnosed: only 39% of men with KS receive a diagnosis postnatally. Even for those who are diagnosed, only 10% will receive their diagnosis before puberty. This can be attributed to the difficulty in diagnosing KS, due to the heterogeneous phenotypic presentation and the lack of awareness of KS. […] General practitioners can play a major part in improving health outcomes for men with KS through improved detection amongst their male patients. Ongoing care and management can then be provided in the general practice setting and through the use of appropriate referral pathways. […] General practitioners have a role in monitoring men with KS for comorbidities, which are outlined in Table 2. A full blood examination, thyroid function test, cholesterol and fasting blood glucose levels should be performed every two years. […] Referral to a clinical geneticist should be considered, particularly for men who have questions about the genetics of KS. Referral to a psychiatrist should also be considered where psychiatric comorbidities exist.

• #73 Klinefelter syndrome A general practice perspective

  https://www.racgp.org.au/afp/2014/january-february/klinefelter-syndrome

  Klinefelter syndrome (KS) is a common genetic condition affecting one in 450 men, but is only diagnosed in fewer than half of those affected. […] Currently, KS is significantly under-diagnosed: only 39% of men with KS receive a diagnosis postnatally. Even for those who are diagnosed, only 10% will receive their diagnosis before puberty. This can be attributed to the difficulty in diagnosing KS, due to the heterogeneous phenotypic presentation and the lack of awareness of KS. […] General practitioners can play a major part in improving health outcomes for men with KS through improved detection amongst their male patients. Ongoing care and management can then be provided in the general practice setting and through the use of appropriate referral pathways. […] General practitioners have a role in monitoring men with KS for comorbidities, which are outlined in Table 2. A full blood examination, thyroid function test, cholesterol and fasting blood glucose levels should be performed every two years. […] Referral to a clinical geneticist should be considered, particularly for men who have questions about the genetics of KS. Referral to a psychiatrist should also be considered where psychiatric comorbidities exist.

• #74 Frontiers | Klinefelter Syndrome and the Need for a Multi-Disciplinary Approach

  https://www.frontiersin.org/journals/reproductive-health/articles/10.3389/frph.2021.622144/full

  Klinefelter’s syndrome (KS) occurs as a de novo event in 1 in 600 males. While 80% of cases of KS have the 47 XXY Karyotype, it is known that some patients may have more than one extra X chromosome or express mosaicism 46XY/47XXY. It is the most frequently occurring chromosome abnormality in infertile men. […] As these patients are predisposed to developing secondary diseases mentioned earlier, they require long term monitoring of their blood pressure, glucose controls, bone health, and lipid levels. […] The clinic aims to increase awareness and education of KS in the healthcare community. One of the main reasons for the long waiting time for patients in primary care could be attributed to the lack of awareness of the possibility of KS as a diagnosis for these patients. Through education, we hope that more men with KS can be diagnosed earlier and spend less time in primary care before they see a specialist in their condition.

• #75 Frontiers | Klinefelter Syndrome and the Need for a Multi-Disciplinary Approach

  https://www.frontiersin.org/journals/reproductive-health/articles/10.3389/frph.2021.622144/full

  Klinefelter’s syndrome (KS) occurs as a de novo event in 1 in 600 males. While 80% of cases of KS have the 47 XXY Karyotype, it is known that some patients may have more than one extra X chromosome or express mosaicism 46XY/47XXY. It is the most frequently occurring chromosome abnormality in infertile men. […] As these patients are predisposed to developing secondary diseases mentioned earlier, they require long term monitoring of their blood pressure, glucose controls, bone health, and lipid levels. […] The clinic aims to increase awareness and education of KS in the healthcare community. One of the main reasons for the long waiting time for patients in primary care could be attributed to the lack of awareness of the possibility of KS as a diagnosis for these patients. Through education, we hope that more men with KS can be diagnosed earlier and spend less time in primary care before they see a specialist in their condition.

• #76 Frontiers | Klinefelter Syndrome and the Need for a Multi-Disciplinary Approach

  https://www.frontiersin.org/journals/reproductive-health/articles/10.3389/frph.2021.622144/full

  Klinefelter’s syndrome (KS) occurs as a de novo event in 1 in 600 males. While 80% of cases of KS have the 47 XXY Karyotype, it is known that some patients may have more than one extra X chromosome or express mosaicism 46XY/47XXY. It is the most frequently occurring chromosome abnormality in infertile men. […] As these patients are predisposed to developing secondary diseases mentioned earlier, they require long term monitoring of their blood pressure, glucose controls, bone health, and lipid levels. […] The clinic aims to increase awareness and education of KS in the healthcare community. One of the main reasons for the long waiting time for patients in primary care could be attributed to the lack of awareness of the possibility of KS as a diagnosis for these patients. Through education, we hope that more men with KS can be diagnosed earlier and spend less time in primary care before they see a specialist in their condition.

• #77 Klinefelter Syndrome

  https://fpnotebook.com/Endo/Sex/KlnfltrSyndrm.htm

  Most common major sexual differentiation abnormality […] Incidence of Klinefelter Syndrome in specific cohorts: Newborn males: 1 in 500 to 1000 […] Male Breast Cancer: 7.5% […] Infertile males: 3% […] Mild Mental Retardation: 1% […] Breast Cancer surveillance.

• #78 Klinefelter syndrome and cancer | EBSCO Research Starters

  https://www.ebsco.com/research-starters/health-and-medicine/klinefelter-syndrome-and-cancer

  Klinefelter syndrome occurs in 1 in 500 to 1 in 1,000 newborn male children. The overall incidence of all malignancies in patients with Klinefelter’s syndrome is not significantly different from the incidence among men with normal male chromosomes. However, certain types of cancer are more common among Klinefelter patients than 46,XY (so-called normal) men. These include male breast cancer, non-Hodgkin lymphoma, extragonadal (often mediastinal) teratomas, germ-cell tumors of the testes, and possibly lung cancer, gallbladder cancer, and extrahepatic bile duct tumors. […] Surveillance for cancers that are more common in men with Klinefelter’s syndrome should be instituted.

• #79 Klinefelter syndrome A general practice perspective

  https://www.racgp.org.au/afp/2014/january-february/klinefelter-syndrome

  Klinefelter syndrome (KS) is a common genetic condition affecting one in 450 men, but is only diagnosed in fewer than half of those affected. […] Currently, KS is significantly under-diagnosed: only 39% of men with KS receive a diagnosis postnatally. Even for those who are diagnosed, only 10% will receive their diagnosis before puberty. This can be attributed to the difficulty in diagnosing KS, due to the heterogeneous phenotypic presentation and the lack of awareness of KS. […] General practitioners can play a major part in improving health outcomes for men with KS through improved detection amongst their male patients. Ongoing care and management can then be provided in the general practice setting and through the use of appropriate referral pathways. […] General practitioners have a role in monitoring men with KS for comorbidities, which are outlined in Table 2. A full blood examination, thyroid function test, cholesterol and fasting blood glucose levels should be performed every two years. […] Referral to a clinical geneticist should be considered, particularly for men who have questions about the genetics of KS. Referral to a psychiatrist should also be considered where psychiatric comorbidities exist.

• #80 Klinefelter Syndrome | Children’s Hospital of Philadelphia

  https://www.chop.edu/conditions-diseases/klinefelter-syndrome

  Klinefelter syndrome affects 1 in 500-1,000 newborn males, making it is one of the most common chromosomal disorders. […] About 10 percent of cases are diagnosed prenatally during routine prenatal testing such as amniocentesis. […] Boys with Klinefelter syndrome should follow up with the endocrinologist to monitor progression in puberty, hormone levels and adjust medication as needed. […] Depending on your child’s condition, long-term care may be needed. […] With proper diagnosis and treatment, some of the symptoms of Klinefelter syndrome, such as low testosterone levels, can be resolved or well-controlled.

• #81 Klinefelter syndrome: Symptoms & treatment | Healthy Male

  https://healthymale.org.au/mens-health/klinefelter-syndrome

  The number of males with Klinefelter syndrome is not known. About 1 in 100 male human embryos are 47,XXY, and 1-2 in 1000 newborn baby boys are diagnosed with the condition. […] Infants and children with Klinefelter syndrome should be examined by their doctor at least every two years to monitor their physical development. […] Testosterone treatment to achieve levels like those in men without Klinefelter syndrome minimises the risk of health problems.

• #82 Frontiers | Klinefelter Syndrome and the Need for a Multi-Disciplinary Approach

  https://www.frontiersin.org/journals/reproductive-health/articles/10.3389/frph.2021.622144/full

  Klinefelter’s syndrome (KS) occurs as a de novo event in 1 in 600 males. While 80% of cases of KS have the 47 XXY Karyotype, it is known that some patients may have more than one extra X chromosome or express mosaicism 46XY/47XXY. It is the most frequently occurring chromosome abnormality in infertile men. […] As these patients are predisposed to developing secondary diseases mentioned earlier, they require long term monitoring of their blood pressure, glucose controls, bone health, and lipid levels. […] The clinic aims to increase awareness and education of KS in the healthcare community. One of the main reasons for the long waiting time for patients in primary care could be attributed to the lack of awareness of the possibility of KS as a diagnosis for these patients. Through education, we hope that more men with KS can be diagnosed earlier and spend less time in primary care before they see a specialist in their condition.

• #83 UNDERSTANDING KLINEFELTER SYNDROME AN OVERVIEW AND NURSING CONSIDERATIONS | Society for Endocrinology

  https://www.endocrinology.org/endocrinologist/143-spring-22/features/understanding-klinefelter-syndrome-an-overview-and-nursing-considerations/

  Klinefelter syndrome (KS) is a common aneuploidy in men, clinically characterised by small testes, gonadal failure (hypergonadotrophic hypogonadism), disrupted spermatogenesis (infertility), gynaecomastia and eunuchoid proportions (arm span exceeds height by 7cm). It affects 1 in 600 men, but 50-75% of men with KS go undiagnosed in their lifetime. Almost 90% of men with KS have an XXY karyotype, and the remaining 10% have mosaicism (46,XY/47,XXY), higher grade aneuploidy (48,XXXY/49,XXXXY), or structurally abnormal X chromosomes. […] Effective management of patients with KS undergoing fertility treatment requires a multidisciplinary approach, including endocrinology, andrology, genetic counselling, psychology and nursing. […] The extent of mosaicism in KS causes an array of cognitive, psychosocial and physical symptoms which can affect men with varied degrees of severity. These include hypogonadism, gynaecomastia, tall stature, small phallus, reduced level of intelligence, depression, autism traits, schizotypal traits and social anxiety, which lead to impaired quality of life.

• #84 UNDERSTANDING KLINEFELTER SYNDROME AN OVERVIEW AND NURSING CONSIDERATIONS | Society for Endocrinology

  https://www.endocrinology.org/endocrinologist/143-spring-22/features/understanding-klinefelter-syndrome-an-overview-and-nursing-considerations/

  KS is characterised by primary testicular failure resulting in hypergonadotrophic hypogonadism with elevated luteinising hormone and follicle-stimulating hormone levels, and low testosterone. Testosterone replacement therapy is recommended for patients with KS once serum gonadotrophins begin to rise in early puberty, or when serum testosterone levels become hypogonadal. […] For many adult patients, presentation with infertility while trying for a family leads to diagnosis of KS. A detailed semen analysis determines whether sperm collection may be feasible if healthy spermatozoa are present in the ejaculate. […] Effective management of patients with KS undergoing fertility treatment requires a multidisciplinary approach, including endocrinology, andrology, genetic counselling, psychology and nursing. Infertility can put couples under significant psychological, physical and financial stress, and the endocrine nurse plays a vital role in supporting patients with their treatment management and suggesting psychological referral as appropriate.

• #85 UNDERSTANDING KLINEFELTER SYNDROME AN OVERVIEW AND NURSING CONSIDERATIONS | Society for Endocrinology

  https://www.endocrinology.org/endocrinologist/143-spring-22/features/understanding-klinefelter-syndrome-an-overview-and-nursing-considerations/

  KS is characterised by primary testicular failure resulting in hypergonadotrophic hypogonadism with elevated luteinising hormone and follicle-stimulating hormone levels, and low testosterone. Testosterone replacement therapy is recommended for patients with KS once serum gonadotrophins begin to rise in early puberty, or when serum testosterone levels become hypogonadal. […] For many adult patients, presentation with infertility while trying for a family leads to diagnosis of KS. A detailed semen analysis determines whether sperm collection may be feasible if healthy spermatozoa are present in the ejaculate. […] Effective management of patients with KS undergoing fertility treatment requires a multidisciplinary approach, including endocrinology, andrology, genetic counselling, psychology and nursing. Infertility can put couples under significant psychological, physical and financial stress, and the endocrine nurse plays a vital role in supporting patients with their treatment management and suggesting psychological referral as appropriate.

• #86 Klinefelter syndrome A general practice perspective

  https://www.racgp.org.au/afp/2014/january-february/klinefelter-syndrome

  Klinefelter syndrome (KS) is a common genetic condition affecting one in 450 men, but is only diagnosed in fewer than half of those affected. […] Currently, KS is significantly under-diagnosed: only 39% of men with KS receive a diagnosis postnatally. Even for those who are diagnosed, only 10% will receive their diagnosis before puberty. This can be attributed to the difficulty in diagnosing KS, due to the heterogeneous phenotypic presentation and the lack of awareness of KS. […] General practitioners can play a major part in improving health outcomes for men with KS through improved detection amongst their male patients. Ongoing care and management can then be provided in the general practice setting and through the use of appropriate referral pathways. […] General practitioners have a role in monitoring men with KS for comorbidities, which are outlined in Table 2. A full blood examination, thyroid function test, cholesterol and fasting blood glucose levels should be performed every two years. […] Referral to a clinical geneticist should be considered, particularly for men who have questions about the genetics of KS. Referral to a psychiatrist should also be considered where psychiatric comorbidities exist.

• #87 UNDERSTANDING KLINEFELTER SYNDROME AN OVERVIEW AND NURSING CONSIDERATIONS | Society for Endocrinology

  https://www.endocrinology.org/endocrinologist/143-spring-22/features/understanding-klinefelter-syndrome-an-overview-and-nursing-considerations/

  KS is characterised by primary testicular failure resulting in hypergonadotrophic hypogonadism with elevated luteinising hormone and follicle-stimulating hormone levels, and low testosterone. Testosterone replacement therapy is recommended for patients with KS once serum gonadotrophins begin to rise in early puberty, or when serum testosterone levels become hypogonadal. […] For many adult patients, presentation with infertility while trying for a family leads to diagnosis of KS. A detailed semen analysis determines whether sperm collection may be feasible if healthy spermatozoa are present in the ejaculate. […] Effective management of patients with KS undergoing fertility treatment requires a multidisciplinary approach, including endocrinology, andrology, genetic counselling, psychology and nursing. Infertility can put couples under significant psychological, physical and financial stress, and the endocrine nurse plays a vital role in supporting patients with their treatment management and suggesting psychological referral as appropriate.

• #88 UNDERSTANDING KLINEFELTER SYNDROME AN OVERVIEW AND NURSING CONSIDERATIONS | Society for Endocrinology

  https://www.endocrinology.org/endocrinologist/143-spring-22/features/understanding-klinefelter-syndrome-an-overview-and-nursing-considerations/

  KS is characterised by primary testicular failure resulting in hypergonadotrophic hypogonadism with elevated luteinising hormone and follicle-stimulating hormone levels, and low testosterone. Testosterone replacement therapy is recommended for patients with KS once serum gonadotrophins begin to rise in early puberty, or when serum testosterone levels become hypogonadal. […] For many adult patients, presentation with infertility while trying for a family leads to diagnosis of KS. A detailed semen analysis determines whether sperm collection may be feasible if healthy spermatozoa are present in the ejaculate. […] Effective management of patients with KS undergoing fertility treatment requires a multidisciplinary approach, including endocrinology, andrology, genetic counselling, psychology and nursing. Infertility can put couples under significant psychological, physical and financial stress, and the endocrine nurse plays a vital role in supporting patients with their treatment management and suggesting psychological referral as appropriate.

• #89 Klinefelter syndrome A general practice perspective

  https://www.racgp.org.au/afp/2014/january-february/klinefelter-syndrome

  Klinefelter syndrome (KS) is a common genetic condition affecting one in 450 men, but is only diagnosed in fewer than half of those affected. […] Currently, KS is significantly under-diagnosed: only 39% of men with KS receive a diagnosis postnatally. Even for those who are diagnosed, only 10% will receive their diagnosis before puberty. This can be attributed to the difficulty in diagnosing KS, due to the heterogeneous phenotypic presentation and the lack of awareness of KS. […] General practitioners can play a major part in improving health outcomes for men with KS through improved detection amongst their male patients. Ongoing care and management can then be provided in the general practice setting and through the use of appropriate referral pathways. […] General practitioners have a role in monitoring men with KS for comorbidities, which are outlined in Table 2. A full blood examination, thyroid function test, cholesterol and fasting blood glucose levels should be performed every two years. […] Referral to a clinical geneticist should be considered, particularly for men who have questions about the genetics of KS. Referral to a psychiatrist should also be considered where psychiatric comorbidities exist.

• #90 UNDERSTANDING KLINEFELTER SYNDROME AN OVERVIEW AND NURSING CONSIDERATIONS | Society for Endocrinology

  https://www.endocrinology.org/endocrinologist/143-spring-22/features/understanding-klinefelter-syndrome-an-overview-and-nursing-considerations/

  KS is characterised by primary testicular failure resulting in hypergonadotrophic hypogonadism with elevated luteinising hormone and follicle-stimulating hormone levels, and low testosterone. Testosterone replacement therapy is recommended for patients with KS once serum gonadotrophins begin to rise in early puberty, or when serum testosterone levels become hypogonadal. […] For many adult patients, presentation with infertility while trying for a family leads to diagnosis of KS. A detailed semen analysis determines whether sperm collection may be feasible if healthy spermatozoa are present in the ejaculate. […] Effective management of patients with KS undergoing fertility treatment requires a multidisciplinary approach, including endocrinology, andrology, genetic counselling, psychology and nursing. Infertility can put couples under significant psychological, physical and financial stress, and the endocrine nurse plays a vital role in supporting patients with their treatment management and suggesting psychological referral as appropriate.

• #91 Perinatal presentation of Klinefelter syndrome and variants: take-home lessons for the urologist | African Journal of Urology | Full Text

  https://afju.springeropen.com/articles/10.1186/s12301-024-00462-x

  An increasing number of genetic and congenital conditions are diagnosed in utero. Prenatal diagnosis of KS is associated with a less severe phenotype than cases diagnosed postnatally. Prenatally diagnosed cases can benefit from early developmental and speech interventions and subsequently have less severe phenotypes. […] Only 10-13% of KS patients are diagnosed prenatally due to the lack of knowledge of the prenatal ultrasound features characteristic of KS. […] Early diagnosis of KS represents an opportunity for parental education, focused counseling, early characterization of the neuropsychological and developmental profile, establishment of multidisciplinary care, and hopefully ameliorating some of the known complications. […] Early diagnosis provides an opportunity for early initiation of multidisciplinary care, focused parental counseling, institution of lifestyle modification, early androgen replacement, and cryopreservation during late adolescence or early childhood.

• #92 The prevalence and diagnosis rates of Klinefelter syndrome: an Australian comparison | The Medical Journal of Australia

  https://www.mja.com.au/journal/2011/194/1/prevalence-and-diagnosis-rates-klinefelter-syndrome-australian-comparison

  The birth prevalence of KS in Victoria is estimated to be 223 per 100 000 males (95% CI, 195254), with about 50% of cases remaining undiagnosed. […] Our results highlight the need for increased awareness leading to timely detection. […] The low diagnosis rate suggests most males with KS will not receive potentially beneficial treatments, especially androgen therapy. […] Detection in childhood and timely intervention may be essential for optimal medical and psychosocial outcomes in adulthood. […] The cumulative postnatal diagnosis rate of KS to age 84 was estimated at 87 per 100 000 males (95% CI, 70107). […] Therefore, the addition of prenatal and postnatal diagnosis rates gives an estimated 49% of all expected cases of KS being diagnosed, with around 51% of males who have KS remaining undiagnosed in Victoria.

• #93 Klinefelter Syndrome: Symptoms, Causes, Treatments, and More

  https://www.healthline.com/health/klinefelter-syndrome

  Because these tests can increase the risk for a miscarriage, they usually arent done unless the baby is at risk for a chromosome problem. Often, Klinefelter syndrome isnt discovered until a child reaches puberty or later. […] The main test used to diagnose Klinefelter syndrome is: Chromosome analysis. Also called karyotyping, this blood test checks for abnormal chromosomes, such as an extra X chromosome. […] Most people with Klinefelter syndrome dont produce much or any sperm. A lack of sperm can make it harder to biologically have a child, but its not impossible. […] While having a biological child is not the only way to become a parent, fertility treatments can help some people who are interested in that method. […] Many people living with Klinefelter syndrome either dont know they have it or arent adversely affected by it. However, in some cases, living with this syndrome can create stress. […] Most people with Klinefelter syndrome live long, healthy lives. If you or your child requires treatment, the earlier its received, the better. This is because treating Klinefelter syndrome during puberty can lessen some of the symptoms.

• #94 Klinefelter Syndrome | AAFP

  https://www.aafp.org/pubs/afp/issues/2005/1201/p2259.html

  Approximately one in 1,000 boys is born with an additional X chromosome47,XXY, the karyotype that causes Klinefelter syndrome. This karyotype is detected at or before birth in 10 percent of affected boys, and it is found during adulthood in 25 percent of affected men. Almost all men with a 47,XXY karyotype will be infertile; Klinefelter syndrome accounts for 3 percent of male infertility. Klinefelter syndrome is common in infertile men with oligospermia or azoospermia (5 to 10 percent). […] Because most boys with Klinefelter syndrome appear similar to boys with normal karyotypes, the disorder typically is identified in adulthood, when infertility or gynecomastia are common presentations. However, by this time, a therapeutic window during adolescence for treatment of hypogonadism, cognitive impairments, and psychosocial factors has been missed. […] Clinical suspicion warrants diagnostic investigation to ensure appropriate surveillance for testosterone deficit.

• #95 Perinatal presentation of Klinefelter syndrome and variants: take-home lessons for the urologist | African Journal of Urology | Full Text

  https://afju.springeropen.com/articles/10.1186/s12301-024-00462-x

  Klinefelter syndrome (KS) is a sex chromosome disorder usually diagnosed in adulthood during work-up for infertility or hypogonadism. Perinatal diagnoses are uncommon. […] Klinefelter syndrome can be suspected prenatally in patients with increased nuchal translucency or ambiguous genitalia. Cell-free DNA can establish prenatal diagnosis with good sensitivity and specificity. Early diagnosis allows for early initiation of multidisciplinary care, focused counseling, lifestyle modification, early androgen replacement, and cryopreservation during late puberty or early adulthood. Testosterone treatment during infancy was linked to improved phenotypic features of KS and better cognitive and behavioral outcomes. […] Klinefelter syndrome (KS) is the most prevalent sex chromosome abnormality affecting 1 in 650 live male births. The condition is poorly diagnosed in childhood due to subtle and underrecognized phenotypic features. It has been reported that 65-75% of KS remain undiagnosed, 10% of diagnoses are made prenatally, 6% in childhood or adolescence, and 19% in adulthood.

• #96 Perinatal presentation of Klinefelter syndrome and variants: take-home lessons for the urologist | African Journal of Urology | Full Text

  https://afju.springeropen.com/articles/10.1186/s12301-024-00462-x

  An increasing number of genetic and congenital conditions are diagnosed in utero. Prenatal diagnosis of KS is associated with a less severe phenotype than cases diagnosed postnatally. Prenatally diagnosed cases can benefit from early developmental and speech interventions and subsequently have less severe phenotypes. […] Only 10-13% of KS patients are diagnosed prenatally due to the lack of knowledge of the prenatal ultrasound features characteristic of KS. […] Early diagnosis of KS represents an opportunity for parental education, focused counseling, early characterization of the neuropsychological and developmental profile, establishment of multidisciplinary care, and hopefully ameliorating some of the known complications. […] Early diagnosis provides an opportunity for early initiation of multidisciplinary care, focused parental counseling, institution of lifestyle modification, early androgen replacement, and cryopreservation during late adolescence or early childhood.

• #97 Perinatal presentation of Klinefelter syndrome and variants: take-home lessons for the urologist | African Journal of Urology | Full Text

  https://afju.springeropen.com/articles/10.1186/s12301-024-00462-x

  An increasing number of genetic and congenital conditions are diagnosed in utero. Prenatal diagnosis of KS is associated with a less severe phenotype than cases diagnosed postnatally. Prenatally diagnosed cases can benefit from early developmental and speech interventions and subsequently have less severe phenotypes. […] Only 10-13% of KS patients are diagnosed prenatally due to the lack of knowledge of the prenatal ultrasound features characteristic of KS. […] Early diagnosis of KS represents an opportunity for parental education, focused counseling, early characterization of the neuropsychological and developmental profile, establishment of multidisciplinary care, and hopefully ameliorating some of the known complications. […] Early diagnosis provides an opportunity for early initiation of multidisciplinary care, focused parental counseling, institution of lifestyle modification, early androgen replacement, and cryopreservation during late adolescence or early childhood.

• #98 Perinatal presentation of Klinefelter syndrome and variants: take-home lessons for the urologist | African Journal of Urology | Full Text

  https://afju.springeropen.com/articles/10.1186/s12301-024-00462-x

  Klinefelter syndrome (KS) is a sex chromosome disorder usually diagnosed in adulthood during work-up for infertility or hypogonadism. Perinatal diagnoses are uncommon. […] Klinefelter syndrome can be suspected prenatally in patients with increased nuchal translucency or ambiguous genitalia. Cell-free DNA can establish prenatal diagnosis with good sensitivity and specificity. Early diagnosis allows for early initiation of multidisciplinary care, focused counseling, lifestyle modification, early androgen replacement, and cryopreservation during late puberty or early adulthood. Testosterone treatment during infancy was linked to improved phenotypic features of KS and better cognitive and behavioral outcomes. […] Klinefelter syndrome (KS) is the most prevalent sex chromosome abnormality affecting 1 in 650 live male births. The condition is poorly diagnosed in childhood due to subtle and underrecognized phenotypic features. It has been reported that 65-75% of KS remain undiagnosed, 10% of diagnoses are made prenatally, 6% in childhood or adolescence, and 19% in adulthood.

• #99 Klinefelter Syndrome – Diagnosis & Treatment | Atrium Health Wake Forest Baptist

  https://www.wakehealth.edu/condition/k/klinefelter-syndrome

  Klinefelter syndrome is when a boy is born with an extra chromosome. It occurs in one out of every 500 to 750 male births. […] Men with Klinefelter syndrome have a high chance (70-90 percent) of being infertile (a reduced ability to father children) or sterile (unable to father children.) […] Wake Forest Baptist is one of the few centers in the world that focuses on preserving fertility in boys with Klinefelter syndrome. […] Experimental services include spermatogonial stem cell banking for fertility preservation.

• #100 Perinatal presentation of Klinefelter syndrome and variants: take-home lessons for the urologist | African Journal of Urology | Full Text

  https://afju.springeropen.com/articles/10.1186/s12301-024-00462-x

  An increasing number of genetic and congenital conditions are diagnosed in utero. Prenatal diagnosis of KS is associated with a less severe phenotype than cases diagnosed postnatally. Prenatally diagnosed cases can benefit from early developmental and speech interventions and subsequently have less severe phenotypes. […] Only 10-13% of KS patients are diagnosed prenatally due to the lack of knowledge of the prenatal ultrasound features characteristic of KS. […] Early diagnosis of KS represents an opportunity for parental education, focused counseling, early characterization of the neuropsychological and developmental profile, establishment of multidisciplinary care, and hopefully ameliorating some of the known complications. […] Early diagnosis provides an opportunity for early initiation of multidisciplinary care, focused parental counseling, institution of lifestyle modification, early androgen replacement, and cryopreservation during late adolescence or early childhood.

• #101 Perinatal presentation of Klinefelter syndrome and variants: take-home lessons for the urologist | African Journal of Urology | Full Text

  https://afju.springeropen.com/articles/10.1186/s12301-024-00462-x

  An increasing number of genetic and congenital conditions are diagnosed in utero. Prenatal diagnosis of KS is associated with a less severe phenotype than cases diagnosed postnatally. Prenatally diagnosed cases can benefit from early developmental and speech interventions and subsequently have less severe phenotypes. […] Only 10-13% of KS patients are diagnosed prenatally due to the lack of knowledge of the prenatal ultrasound features characteristic of KS. […] Early diagnosis of KS represents an opportunity for parental education, focused counseling, early characterization of the neuropsychological and developmental profile, establishment of multidisciplinary care, and hopefully ameliorating some of the known complications. […] Early diagnosis provides an opportunity for early initiation of multidisciplinary care, focused parental counseling, institution of lifestyle modification, early androgen replacement, and cryopreservation during late adolescence or early childhood.

• #102 Perinatal presentation of Klinefelter syndrome and variants: take-home lessons for the urologist | African Journal of Urology | Full Text

  https://afju.springeropen.com/articles/10.1186/s12301-024-00462-x

  Klinefelter syndrome (KS) is a sex chromosome disorder usually diagnosed in adulthood during work-up for infertility or hypogonadism. Perinatal diagnoses are uncommon. […] Klinefelter syndrome can be suspected prenatally in patients with increased nuchal translucency or ambiguous genitalia. Cell-free DNA can establish prenatal diagnosis with good sensitivity and specificity. Early diagnosis allows for early initiation of multidisciplinary care, focused counseling, lifestyle modification, early androgen replacement, and cryopreservation during late puberty or early adulthood. Testosterone treatment during infancy was linked to improved phenotypic features of KS and better cognitive and behavioral outcomes. […] Klinefelter syndrome (KS) is the most prevalent sex chromosome abnormality affecting 1 in 650 live male births. The condition is poorly diagnosed in childhood due to subtle and underrecognized phenotypic features. It has been reported that 65-75% of KS remain undiagnosed, 10% of diagnoses are made prenatally, 6% in childhood or adolescence, and 19% in adulthood.

• #103 Frontiers | Klinefelter Syndrome and the Need for a Multi-Disciplinary Approach

  https://www.frontiersin.org/journals/reproductive-health/articles/10.3389/frph.2021.622144/full

  Klinefelter’s syndrome (KS) occurs as a de novo event in 1 in 600 males. While 80% of cases of KS have the 47 XXY Karyotype, it is known that some patients may have more than one extra X chromosome or express mosaicism 46XY/47XXY. It is the most frequently occurring chromosome abnormality in infertile men. […] As these patients are predisposed to developing secondary diseases mentioned earlier, they require long term monitoring of their blood pressure, glucose controls, bone health, and lipid levels. […] The clinic aims to increase awareness and education of KS in the healthcare community. One of the main reasons for the long waiting time for patients in primary care could be attributed to the lack of awareness of the possibility of KS as a diagnosis for these patients. Through education, we hope that more men with KS can be diagnosed earlier and spend less time in primary care before they see a specialist in their condition.

• #104 Klinefelter Syndrome (17.05.2013)

  https://di.aerzteblatt.de/int/archive/article/138490

  Klinefelter syndrome (KS) with the karyotype 47,XXY is one of the commonest types of congenital chromosomal disorder in males, with an incidence of 0.1% to 0.2% of newborn male infants. […] On the basis of patient registries in Denmark, it is suspected that only 25% of all Klinefelter syndrome patients are diagnosed during their lifetimes. […] Klinefelter syndrome is associated with a significantly higher morbidity rate compared to the male population as a whole. […] This leads to a life expectancy 11.5 years below that of the male population as a whole. […] However, a survey completed by 290 practising primary care physicians, internal medicine specialists, and urologists showed that two-thirds of primary care physicians and internal medicine specialists had had not knowingly seen any cases of Klinefelter syndrome in recent years, although their theoretical knowledge of it was good; urologists fared a little better regarding diagnosis of Klinefelter syndrome. […] The diagnosis of KS would be less frequently missed if doctors were more aware of, and attentive to, its key manifestations, particularly the small, firm testes, erectile dysfunction, and the comorbidities mentioned above.

• #105 Klinefelter syndrome A general practice perspective

  https://www.racgp.org.au/afp/2014/january-february/klinefelter-syndrome

  Klinefelter syndrome (KS) is a common genetic condition affecting one in 450 men, but is only diagnosed in fewer than half of those affected. […] Currently, KS is significantly under-diagnosed: only 39% of men with KS receive a diagnosis postnatally. Even for those who are diagnosed, only 10% will receive their diagnosis before puberty. This can be attributed to the difficulty in diagnosing KS, due to the heterogeneous phenotypic presentation and the lack of awareness of KS. […] General practitioners can play a major part in improving health outcomes for men with KS through improved detection amongst their male patients. Ongoing care and management can then be provided in the general practice setting and through the use of appropriate referral pathways. […] General practitioners have a role in monitoring men with KS for comorbidities, which are outlined in Table 2. A full blood examination, thyroid function test, cholesterol and fasting blood glucose levels should be performed every two years. […] Referral to a clinical geneticist should be considered, particularly for men who have questions about the genetics of KS. Referral to a psychiatrist should also be considered where psychiatric comorbidities exist.

• #106 The prevalence and diagnosis rates of Klinefelter syndrome: an Australian comparison | The Medical Journal of Australia

  https://www.mja.com.au/journal/2011/194/1/prevalence-and-diagnosis-rates-klinefelter-syndrome-australian-comparison

  Our estimates of the birth prevalence of KS in Victoria for the period 19862006 and the proportion of expected cases of KS that were diagnosed indicate that KS is both common and underdiagnosed. […] Given that all are infertile, why aren’t a greater proportion detected with infertility? […] In addition, both the risks and benefits of diagnosis through postnatal, population-based genetic screening for KS should be considered.

• #107 Klinefelter Syndrome | Treatment & Management | Point of Care

  https://www.statpearls.com/point-of-care/23907

  An estimated quarter of individuals with Klinefelter syndrome show no discernible diagnostic features based on history or examination. With the increased use of noninvasive prenatal testing, the frequency of prenatal diagnosis is expected to rise, enabling early management by pediatricians. […] Fewer than 10% of cases are detected before puberty, and only 26% to 37% are identified overall, with most remaining undiagnosed. The average age of diagnosis is 30 years, and the median lifespan is reduced by 5 or 6 years compared to the general male population.

• #108 Klinefelter Syndrome (17.05.2013)

  https://di.aerzteblatt.de/int/archive/article/138490

  Klinefelter syndrome (KS) with the karyotype 47,XXY is one of the commonest types of congenital chromosomal disorder in males, with an incidence of 0.1% to 0.2% of newborn male infants. […] On the basis of patient registries in Denmark, it is suspected that only 25% of all Klinefelter syndrome patients are diagnosed during their lifetimes. […] Klinefelter syndrome is associated with a significantly higher morbidity rate compared to the male population as a whole. […] This leads to a life expectancy 11.5 years below that of the male population as a whole. […] However, a survey completed by 290 practising primary care physicians, internal medicine specialists, and urologists showed that two-thirds of primary care physicians and internal medicine specialists had had not knowingly seen any cases of Klinefelter syndrome in recent years, although their theoretical knowledge of it was good; urologists fared a little better regarding diagnosis of Klinefelter syndrome. […] The diagnosis of KS would be less frequently missed if doctors were more aware of, and attentive to, its key manifestations, particularly the small, firm testes, erectile dysfunction, and the comorbidities mentioned above.

• #109 Klinefelter Syndrome | Treatment & Management | Point of Care

  https://www.statpearls.com/point-of-care/23907

  An estimated quarter of individuals with Klinefelter syndrome show no discernible diagnostic features based on history or examination. With the increased use of noninvasive prenatal testing, the frequency of prenatal diagnosis is expected to rise, enabling early management by pediatricians. […] Fewer than 10% of cases are detected before puberty, and only 26% to 37% are identified overall, with most remaining undiagnosed. The average age of diagnosis is 30 years, and the median lifespan is reduced by 5 or 6 years compared to the general male population.

• #110 Klinefelter Syndrome: Symptoms, Causes, Treatments, and More

  https://www.healthline.com/health/klinefelter-syndrome

  Klinefelter syndrome is one of the most common chromosome conditions in newborns. It affects between 1 in 500 and 1 in 1,000 newborn males. […] Its possible that Klinefelter syndrome affects even more male children and adults than statistics suggest. Sometimes symptoms are so mild that they go unnoticed. Or symptoms can be misdiagnosed as being caused by other similar conditions. […] Females who have pregnancies after age 35 are slightly more likely to give birth to a baby with Klinefelter syndrome. […] A small number of males with Klinefelter syndrome receive a diagnosis before birth when their mother has one of these tests: Amniocentesis. During an amniocentesis, a technician removes a small amount of amniotic fluid from the sac surrounding the baby. The fluid is then examined in a lab for chromosome problems.

• #111 Perinatal presentation of Klinefelter syndrome and variants: take-home lessons for the urologist | African Journal of Urology | Full Text

  https://afju.springeropen.com/articles/10.1186/s12301-024-00462-x

  An increasing number of genetic and congenital conditions are diagnosed in utero. Prenatal diagnosis of KS is associated with a less severe phenotype than cases diagnosed postnatally. Prenatally diagnosed cases can benefit from early developmental and speech interventions and subsequently have less severe phenotypes. […] Only 10-13% of KS patients are diagnosed prenatally due to the lack of knowledge of the prenatal ultrasound features characteristic of KS. […] Early diagnosis of KS represents an opportunity for parental education, focused counseling, early characterization of the neuropsychological and developmental profile, establishment of multidisciplinary care, and hopefully ameliorating some of the known complications. […] Early diagnosis provides an opportunity for early initiation of multidisciplinary care, focused parental counseling, institution of lifestyle modification, early androgen replacement, and cryopreservation during late adolescence or early childhood.

• #112 Top Published Expert Doctors for Klinefelter Syndrome

  https://findexpertmd.com/d/Klinefelter_Syndrome

  388 top medical experts on Klinefelter Syndrome across 55 countries and 36 U.S. states, including 223 MDs (Physicians). This is based on an objective analysis of their Scientific Publications, Clinical Trials, Medicare, and NIH Grants. […] Clinical Trials ClinicalTrials.gov: at least 32 including 1 Active, 22 Completed, 4 Recruiting.

• #113 Klinefelter Syndrome Market Size and Forecast 2024-2034

  https://www.imarcgroup.com/klinefelter-syndrome-market

  The 7 major Klinefelter syndrome markets are expected to exhibit a CAGR of 3.39% during 2024-2034. […] The Klinefelter syndrome market has been comprehensively analyzed in IMARC’s new report titled „Klinefelter Syndrome Market: Epidemiology, Industry Trends, Share, Size, Growth, Opportunity, and Forecast 2024-2034”. […] IMARC Group’s new report provides an exhaustive analysis of the Klinefelter syndrome market in the United States, EU5 (Germany, Spain, Italy, France, and United Kingdom) and Japan. This includes treatment practices, in-market, and pipeline drugs, share of individual therapies, market performance across the seven major markets, market performance of key companies and their drugs, etc. […] According to the report the United States has the largest patient pool for Klinefelter syndrome and also represents the largest market for its treatment.

• #114 Klinefelter Syndrome Market Size and Forecast 2024-2034

  https://www.imarcgroup.com/klinefelter-syndrome-market

  The 7 major Klinefelter syndrome markets are expected to exhibit a CAGR of 3.39% during 2024-2034. […] The Klinefelter syndrome market has been comprehensively analyzed in IMARC’s new report titled „Klinefelter Syndrome Market: Epidemiology, Industry Trends, Share, Size, Growth, Opportunity, and Forecast 2024-2034”. […] IMARC Group’s new report provides an exhaustive analysis of the Klinefelter syndrome market in the United States, EU5 (Germany, Spain, Italy, France, and United Kingdom) and Japan. This includes treatment practices, in-market, and pipeline drugs, share of individual therapies, market performance across the seven major markets, market performance of key companies and their drugs, etc. […] According to the report the United States has the largest patient pool for Klinefelter syndrome and also represents the largest market for its treatment.

• #115 Klinefelter Syndrome Market Size and Forecast 2024-2034

  https://www.imarcgroup.com/klinefelter-syndrome-market

  Historical, current, and future epidemiology scenario […] What is the number of prevalent cases (2018-2034) of Klinefelter syndrome across the seven major markets? […] What is the size of the Klinefelter syndrome patient pool (2018-2023) across the seven major markets? […] What would be the forecasted patient pool (2024-2034) across the seven major markets? […] What are the key factors driving the epidemiological trend of Klinefelter syndrome? […] What will be the growth rate of patients across the seven major markets?

• #116 KF-Xtra Clinic – Klinefelter syndrome (KS) : University College London Hospitals NHS Foundation Trust

  https://www.uclh.nhs.uk/our-services/find-service/medical-specialties-1/endocrinology/kf-xtra-clinic-klinefelter-syndrome-ks

  Klinefelter Syndrome (KS) is a common congenital condition affecting boys and men. It occurs in 1 in 500 live male births. […] Early diagnosis and intervention improves outcomes but the vast majority of affected individuals remain undiagnosed. […] Traditional NHS care for KS has predominately focused on the medical aspects of the condition (testosterone replacement and bone health) with a more recent interest in fertility potential. […] In response to feedback from patients and families we have set-up the KF-Xtra clinic in an attempt to address all of these needs in an integrated fashion.

• #117 Klinefelter Syndrome – Diagnosis & Treatment | Atrium Health Wake Forest Baptist

  https://www.wakehealth.edu/condition/k/klinefelter-syndrome

  Klinefelter syndrome is when a boy is born with an extra chromosome. It occurs in one out of every 500 to 750 male births. […] Men with Klinefelter syndrome have a high chance (70-90 percent) of being infertile (a reduced ability to father children) or sterile (unable to father children.) […] Wake Forest Baptist is one of the few centers in the world that focuses on preserving fertility in boys with Klinefelter syndrome. […] Experimental services include spermatogonial stem cell banking for fertility preservation.

• #118 Clinical features, diagnosis, and management of Klinefelter syndrome – UpToDate

  https://www.uptodate.com/contents/clinical-features-diagnosis-and-management-of-klinefelter-syndrome

  Klinefelter syndrome is the most common cause of primary hypogonadism. The prevalence of Klinefelter syndrome is approximately 1 to 2.5 per 1000 boys and adult males (0.1 to 0.25 percent). Only 25 to 50 percent of patients with Klinefelter syndrome are diagnosed during their lifetimes. This underdiagnosis is likely due to clinicians’ lack of awareness of the variable clinical features of Klinefelter syndrome, as well as inexperience assessing testicular volumes.

• #119 Klinefelter Syndrome (17.05.2013)

  https://di.aerzteblatt.de/int/archive/article/138490

  Klinefelter syndrome (KS) with the karyotype 47,XXY is one of the commonest types of congenital chromosomal disorder in males, with an incidence of 0.1% to 0.2% of newborn male infants. […] On the basis of patient registries in Denmark, it is suspected that only 25% of all Klinefelter syndrome patients are diagnosed during their lifetimes. […] Klinefelter syndrome is associated with a significantly higher morbidity rate compared to the male population as a whole. […] This leads to a life expectancy 11.5 years below that of the male population as a whole. […] However, a survey completed by 290 practising primary care physicians, internal medicine specialists, and urologists showed that two-thirds of primary care physicians and internal medicine specialists had had not knowingly seen any cases of Klinefelter syndrome in recent years, although their theoretical knowledge of it was good; urologists fared a little better regarding diagnosis of Klinefelter syndrome. […] The diagnosis of KS would be less frequently missed if doctors were more aware of, and attentive to, its key manifestations, particularly the small, firm testes, erectile dysfunction, and the comorbidities mentioned above.

• #120 The prevalence and diagnosis rates of Klinefelter syndrome: an Australian comparison | The Medical Journal of Australia

  https://www.mja.com.au/journal/2011/194/1/prevalence-and-diagnosis-rates-klinefelter-syndrome-australian-comparison

  The birth prevalence of KS in Victoria is estimated to be 223 per 100 000 males (95% CI, 195254), with about 50% of cases remaining undiagnosed. […] Our results highlight the need for increased awareness leading to timely detection. […] The low diagnosis rate suggests most males with KS will not receive potentially beneficial treatments, especially androgen therapy. […] Detection in childhood and timely intervention may be essential for optimal medical and psychosocial outcomes in adulthood. […] The cumulative postnatal diagnosis rate of KS to age 84 was estimated at 87 per 100 000 males (95% CI, 70107). […] Therefore, the addition of prenatal and postnatal diagnosis rates gives an estimated 49% of all expected cases of KS being diagnosed, with around 51% of males who have KS remaining undiagnosed in Victoria.

• #121 The prevalence and diagnosis rates of Klinefelter syndrome: an Australian comparison | The Medical Journal of Australia

  https://www.mja.com.au/journal/2011/194/1/prevalence-and-diagnosis-rates-klinefelter-syndrome-australian-comparison

  The birth prevalence of KS in Victoria is estimated to be 223 per 100 000 males (95% CI, 195254), with about 50% of cases remaining undiagnosed. […] Our results highlight the need for increased awareness leading to timely detection. […] The low diagnosis rate suggests most males with KS will not receive potentially beneficial treatments, especially androgen therapy. […] Detection in childhood and timely intervention may be essential for optimal medical and psychosocial outcomes in adulthood. […] The cumulative postnatal diagnosis rate of KS to age 84 was estimated at 87 per 100 000 males (95% CI, 70107). […] Therefore, the addition of prenatal and postnatal diagnosis rates gives an estimated 49% of all expected cases of KS being diagnosed, with around 51% of males who have KS remaining undiagnosed in Victoria.

• #122 Klinefelter syndrome A general practice perspective

  https://www.racgp.org.au/afp/2014/january-february/klinefelter-syndrome

  Klinefelter syndrome (KS) is a common genetic condition affecting one in 450 men, but is only diagnosed in fewer than half of those affected. […] Currently, KS is significantly under-diagnosed: only 39% of men with KS receive a diagnosis postnatally. Even for those who are diagnosed, only 10% will receive their diagnosis before puberty. This can be attributed to the difficulty in diagnosing KS, due to the heterogeneous phenotypic presentation and the lack of awareness of KS. […] General practitioners can play a major part in improving health outcomes for men with KS through improved detection amongst their male patients. Ongoing care and management can then be provided in the general practice setting and through the use of appropriate referral pathways. […] General practitioners have a role in monitoring men with KS for comorbidities, which are outlined in Table 2. A full blood examination, thyroid function test, cholesterol and fasting blood glucose levels should be performed every two years. […] Referral to a clinical geneticist should be considered, particularly for men who have questions about the genetics of KS. Referral to a psychiatrist should also be considered where psychiatric comorbidities exist.

• #123 Klinefelter Syndrome: Symptoms, Causes, Treatments, and More

  https://www.healthline.com/health/klinefelter-syndrome

  Klinefelter syndrome is one of the most common chromosome conditions in newborns. It affects between 1 in 500 and 1 in 1,000 newborn males. […] Its possible that Klinefelter syndrome affects even more male children and adults than statistics suggest. Sometimes symptoms are so mild that they go unnoticed. Or symptoms can be misdiagnosed as being caused by other similar conditions. […] Females who have pregnancies after age 35 are slightly more likely to give birth to a baby with Klinefelter syndrome. […] A small number of males with Klinefelter syndrome receive a diagnosis before birth when their mother has one of these tests: Amniocentesis. During an amniocentesis, a technician removes a small amount of amniotic fluid from the sac surrounding the baby. The fluid is then examined in a lab for chromosome problems.

• #124 Klinefelter Syndrome | Treatment & Management | Point of Care

  https://www.statpearls.com/point-of-care/23907

  An estimated quarter of individuals with Klinefelter syndrome show no discernible diagnostic features based on history or examination. With the increased use of noninvasive prenatal testing, the frequency of prenatal diagnosis is expected to rise, enabling early management by pediatricians. […] Fewer than 10% of cases are detected before puberty, and only 26% to 37% are identified overall, with most remaining undiagnosed. The average age of diagnosis is 30 years, and the median lifespan is reduced by 5 or 6 years compared to the general male population.

• #125 UNDERSTANDING KLINEFELTER SYNDROME AN OVERVIEW AND NURSING CONSIDERATIONS | Society for Endocrinology

  https://www.endocrinology.org/endocrinologist/143-spring-22/features/understanding-klinefelter-syndrome-an-overview-and-nursing-considerations/

  Klinefelter syndrome (KS) is a common aneuploidy in men, clinically characterised by small testes, gonadal failure (hypergonadotrophic hypogonadism), disrupted spermatogenesis (infertility), gynaecomastia and eunuchoid proportions (arm span exceeds height by 7cm). It affects 1 in 600 men, but 50-75% of men with KS go undiagnosed in their lifetime. Almost 90% of men with KS have an XXY karyotype, and the remaining 10% have mosaicism (46,XY/47,XXY), higher grade aneuploidy (48,XXXY/49,XXXXY), or structurally abnormal X chromosomes. […] Effective management of patients with KS undergoing fertility treatment requires a multidisciplinary approach, including endocrinology, andrology, genetic counselling, psychology and nursing. […] The extent of mosaicism in KS causes an array of cognitive, psychosocial and physical symptoms which can affect men with varied degrees of severity. These include hypogonadism, gynaecomastia, tall stature, small phallus, reduced level of intelligence, depression, autism traits, schizotypal traits and social anxiety, which lead to impaired quality of life.

• #126 Klinefelter Syndrome | Treatment & Management | Point of Care

  https://www.statpearls.com/point-of-care/23907

  An estimated quarter of individuals with Klinefelter syndrome show no discernible diagnostic features based on history or examination. With the increased use of noninvasive prenatal testing, the frequency of prenatal diagnosis is expected to rise, enabling early management by pediatricians. […] Fewer than 10% of cases are detected before puberty, and only 26% to 37% are identified overall, with most remaining undiagnosed. The average age of diagnosis is 30 years, and the median lifespan is reduced by 5 or 6 years compared to the general male population.

• #127 Klinefelter Syndrome | AAFP

  https://www.aafp.org/pubs/afp/issues/2005/1201/p2259.html

  Approximately one in 1,000 boys is born with an additional X chromosome47,XXY, the karyotype that causes Klinefelter syndrome. This karyotype is detected at or before birth in 10 percent of affected boys, and it is found during adulthood in 25 percent of affected men. Almost all men with a 47,XXY karyotype will be infertile; Klinefelter syndrome accounts for 3 percent of male infertility. Klinefelter syndrome is common in infertile men with oligospermia or azoospermia (5 to 10 percent). […] Because most boys with Klinefelter syndrome appear similar to boys with normal karyotypes, the disorder typically is identified in adulthood, when infertility or gynecomastia are common presentations. However, by this time, a therapeutic window during adolescence for treatment of hypogonadism, cognitive impairments, and psychosocial factors has been missed. […] Clinical suspicion warrants diagnostic investigation to ensure appropriate surveillance for testosterone deficit.

• #128

  https://www.theguardian.com/lifeandstyle/2019/aug/26/klinefelter-syndrome-many-men-have-an-extra-x-chromosome-but-it-is-rarely-diagnosed

  Affecting about one in 600 men, it is one of the most common genetic conditions in the UK, yet most people have never heard of it including many who have it. […] With only one in six men who have Klinefelters ever diagnosed, even though symptoms often emerge during puberty, it may be one of the leading unexplored causes of infertility. […] Most men are only diagnosed when they struggle to conceive, Yap says. This will be when they are in their 30s or older. […] GPs think its rarer than it is, but its not rare its just rarely diagnosed, she says. […] Clinicians emphasise that early intervention is key if men with Klinefelters want to reduce their symptoms and increase their chances of fertility. If we can retrieve sperm at an early age, these men wouldnt have to go down the path of surgery and infertility later, when there is more pressure on them, says Yap.

• #129 Frontiers | Klinefelter Syndrome and the Need for a Multi-Disciplinary Approach

  https://www.frontiersin.org/journals/reproductive-health/articles/10.3389/frph.2021.622144/full

  Klinefelter’s syndrome (KS) occurs as a de novo event in 1 in 600 males. While 80% of cases of KS have the 47 XXY Karyotype, it is known that some patients may have more than one extra X chromosome or express mosaicism 46XY/47XXY. It is the most frequently occurring chromosome abnormality in infertile men. […] As these patients are predisposed to developing secondary diseases mentioned earlier, they require long term monitoring of their blood pressure, glucose controls, bone health, and lipid levels. […] The clinic aims to increase awareness and education of KS in the healthcare community. One of the main reasons for the long waiting time for patients in primary care could be attributed to the lack of awareness of the possibility of KS as a diagnosis for these patients. Through education, we hope that more men with KS can be diagnosed earlier and spend less time in primary care before they see a specialist in their condition.

• #130 Klinefelter syndrome A general practice perspective

  https://www.racgp.org.au/afp/2014/january-february/klinefelter-syndrome

  Klinefelter syndrome (KS) is a common genetic condition affecting one in 450 men, but is only diagnosed in fewer than half of those affected. […] Currently, KS is significantly under-diagnosed: only 39% of men with KS receive a diagnosis postnatally. Even for those who are diagnosed, only 10% will receive their diagnosis before puberty. This can be attributed to the difficulty in diagnosing KS, due to the heterogeneous phenotypic presentation and the lack of awareness of KS. […] General practitioners can play a major part in improving health outcomes for men with KS through improved detection amongst their male patients. Ongoing care and management can then be provided in the general practice setting and through the use of appropriate referral pathways. […] General practitioners have a role in monitoring men with KS for comorbidities, which are outlined in Table 2. A full blood examination, thyroid function test, cholesterol and fasting blood glucose levels should be performed every two years. […] Referral to a clinical geneticist should be considered, particularly for men who have questions about the genetics of KS. Referral to a psychiatrist should also be considered where psychiatric comorbidities exist.

• #131 Frontiers | Klinefelter Syndrome and the Need for a Multi-Disciplinary Approach

  https://www.frontiersin.org/journals/reproductive-health/articles/10.3389/frph.2021.622144/full

  Klinefelter’s syndrome (KS) occurs as a de novo event in 1 in 600 males. While 80% of cases of KS have the 47 XXY Karyotype, it is known that some patients may have more than one extra X chromosome or express mosaicism 46XY/47XXY. It is the most frequently occurring chromosome abnormality in infertile men. […] As these patients are predisposed to developing secondary diseases mentioned earlier, they require long term monitoring of their blood pressure, glucose controls, bone health, and lipid levels. […] The clinic aims to increase awareness and education of KS in the healthcare community. One of the main reasons for the long waiting time for patients in primary care could be attributed to the lack of awareness of the possibility of KS as a diagnosis for these patients. Through education, we hope that more men with KS can be diagnosed earlier and spend less time in primary care before they see a specialist in their condition.

• #132

  https://www.theguardian.com/lifeandstyle/2019/aug/26/klinefelter-syndrome-many-men-have-an-extra-x-chromosome-but-it-is-rarely-diagnosed

  Affecting about one in 600 men, it is one of the most common genetic conditions in the UK, yet most people have never heard of it including many who have it. […] With only one in six men who have Klinefelters ever diagnosed, even though symptoms often emerge during puberty, it may be one of the leading unexplored causes of infertility. […] Most men are only diagnosed when they struggle to conceive, Yap says. This will be when they are in their 30s or older. […] GPs think its rarer than it is, but its not rare its just rarely diagnosed, she says. […] Clinicians emphasise that early intervention is key if men with Klinefelters want to reduce their symptoms and increase their chances of fertility. If we can retrieve sperm at an early age, these men wouldnt have to go down the path of surgery and infertility later, when there is more pressure on them, says Yap.

• #133 Frontiers | Klinefelter Syndrome and the Need for a Multi-Disciplinary Approach

  https://www.frontiersin.org/journals/reproductive-health/articles/10.3389/frph.2021.622144/full

  Klinefelter’s syndrome (KS) occurs as a de novo event in 1 in 600 males. While 80% of cases of KS have the 47 XXY Karyotype, it is known that some patients may have more than one extra X chromosome or express mosaicism 46XY/47XXY. It is the most frequently occurring chromosome abnormality in infertile men. […] As these patients are predisposed to developing secondary diseases mentioned earlier, they require long term monitoring of their blood pressure, glucose controls, bone health, and lipid levels. […] The clinic aims to increase awareness and education of KS in the healthcare community. One of the main reasons for the long waiting time for patients in primary care could be attributed to the lack of awareness of the possibility of KS as a diagnosis for these patients. Through education, we hope that more men with KS can be diagnosed earlier and spend less time in primary care before they see a specialist in their condition.

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