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• #1 Hereditary hemorrhagic telangiectasia – Symptoms and causes – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/hht/symptoms-causes/syc-20351135

  Hereditary hemorrhagic telangiectasia (tuh-lan-jee-uk-TAY-zhuh) is a condition that’s passed through families, called inherited. […] HHT is a condition of gene changes, called genetic, that you get from your parents. It is an autosomal dominant disorder. That means if one of your parents has HHT, you have a 50% chance of getting it. If you have HHT, each of your children has a 50% chance of getting it from you. […] The major risk factor for hereditary hemorrhagic telangiectasia is having a parent with the condition.

• #2 Hereditary haemorrhagic telangiectasia (HHT)

  https://www.nhs.uk/conditions/hereditary-haemorrahagic-telangiectasia/

  Hereditary haemorrhagic telangiectasia (HHT) is an inherited genetic disorder that affects the blood vessels. […] People with HHT have a faulty gene, which is usually inherited from one of their parents. […] This gene normally provides instructions for making certain proteins found in the lining of the blood vessels. In HHT, the gene cannot produce this protein, or the protein it produces is abnormal. […] You only need to have 1 copy of the faulty gene to develop HHT.

• #3

  https://111.wales.nhs.uk/encyclopaedia/h/article/hereditaryhaemorrhagictelangiectasia(hht)

  Hereditary haemorrhagic telangiectasia (HHT) is an inherited genetic disorder that affects the blood vessels. It’s known as Osler-Weber-Rendu syndrome. […] People with HHT have a faulty gene, which is usually inherited from 1 of their parents. This gene normally provides instructions for making certain proteins found in the lining of the blood vessels. In HHT, the gene cannot produce this protein, or the protein it produces is abnormal. […] You only need to have 1 copy of the faulty gene to develop HHT.

• #4 Hereditary haemorrhagic telangiectasia

  https://dermnetnz.org/topics/hereditary-haemorrhagic-telangiectasia

  HHT is a rare autosomal dominant condition, which means that only one abnormal gene needs to be inherited from one affected parent to express the disease. HHT is often passed from generation to generation as each child of a person with HHT has a 50% chance of getting the disease. However, the signs and symptoms of HHT within a single family can vary considerably. […] In addition to visible telangiectases, abnormal blood vessel formation may occur in many other organs. Telangiectases can be found anywhere in the gastrointestinal (GI) system, including the oesophagus, stomach, and small and large intestines. GI bleeding occurs in about 25% of patients with HHT and the risk is increased in patients older than 50 years. […] HHT cannot be prevented but most cases can be treated symptomatically. One third of the cases of HHT are mild, one third are moderate, and one third are severe. Mild cases usually require no treatment. HHT should be treated if it is causing significant problems, such as severe and/or frequent nosebleeds, or if there is a high risk of causing other problems, such as a stroke from a lung AVM.

• #5 Hereditary Hemorrhagic Telangiectasia (HHT) – Seattle Children’s

  https://www.seattlechildrens.org/conditions/hereditary-hemorrhagic-telangiectasia/

  HHT is a genetic condition that causes blood vessels in part of the body to develop abnormally. […] An abnormal gene causes HHT. Most often, it is passed down (inherited) from 1 parent who has HHT. Each child of a parent with an HHT gene has a 50% chance of getting this gene from their parent. […] HHT is a dominant disorder. This means it only takes 1 abnormal copy of the gene, from only 1 parent, to cause HHT.

• #6 Hereditary hemorrhagic telangiectasia | Beacon Health System

  https://www.beaconhealthsystem.org/library/diseases-and-conditions/hereditary-hemorrhagic-telangiectasia?content_id=CON-20155449

  This inherited blood vessel condition can cause bad nosebleeds, strokes, bleeding in the digestive tract and anemia. […] Hereditary hemorrhagic telangiectasia (tuh-lan-jee-uk-TAY-zhuh) is a condition that’s passed through families, called inherited. […] Also called Osler-Weber-Rendu disease and HHT, hereditary hemorrhagic telangiectasia passes from parents to children. […] HHT is a condition of gene changes, called genetic, that you get from your parents. It is an autosomal dominant disorder. That means if one of your parents has HHT, you have a 50% chance of getting it. If you have HHT, each of your children has a 50% chance of getting it from you. […] The major risk factor for hereditary hemorrhagic telangiectasia is having a parent with the condition.

• #7 Hereditary Hemorrhagic Telangiectasia (HHT)

  https://my.clevelandclinic.org/health/diseases/15618-hereditary-hemorrhagic-telangiectasia-hht

  Hereditary hemorrhagic telangiectasia (HHT) is a genetic disorder that affects blood vessel formation. […] HHT is genetic, meaning it’s passed down from parents to children. It’s a dominant disorder, caused by one copy of one abnormal gene from one parent. Hundreds of possible mutations in six different genes have been linked to HHT, but the vast majority of cases are due to mutations in two genes, ENG and ACVRL1. Scientists are still studying the mutations and genes involved.

• #8 Hereditary hemorrhagic telangiectasia: MedlinePlus GeneticsLock

  https://medlineplus.gov/genetics/condition/hereditary-hemorrhagic-telangiectasia/

  Hereditary hemorrhagic telangiectasia is a disorder that results in the development of multiple abnormalities in the blood vessels. […] Mutations in several genes, including the ACVRL1, ENG, and SMAD4 genes, cause hereditary hemorrhagic telangiectasia. […] Hereditary hemorrhagic telangiectasia type 1 is caused by mutations in the ENG gene. Type 2 is caused by mutations in the ACVRL1 gene. Juvenile polyposis/hereditary hemorrhagic telangiectasia syndrome is caused by mutations in the SMAD4 gene. […] Mutations in these genes generally prevent the production of the associated protein or result in the production of a defective protein that cannot fulfill its function. An individual with a mutated gene will therefore have a reduced amount of the functional protein available in the tissue lining the blood vessels. This shortage is believed to result in the signs and symptoms of hereditary hemorrhagic telangiectasia.

• #9 Hereditary hemorrhagic telangiectasia – Wikipedia

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

  Hereditary hemorrhagic telangiectasia (HHT), also known as Osler-Weber-Rendu disease and Osler-Weber-Rendu syndrome, is a rare autosomal dominant genetic disorder that leads to abnormal blood vessel formation in the skin, mucous membranes, and often in organs such as the lungs, liver, and brain. […] HHT is transmitted in an autosomal dominant fashion, and occurs in one in 5,000-8,000 people in North America. […] Five genetic types of HHT are recognized. Of these, three have been linked to particular genes, while the two remaining have currently only been associated with a particular locus. More than 80% of all cases of HHT are due to mutations in either ENG or ACVRL1. […] Both ENG and ACVRL1 mutations lead predominantly to underproduction of the related proteins, rather than misfunctioning of the proteins.

• #10 Hereditary Hemorrhagic Telangiectasia (HHT) – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK578186/

  Hereditary hemorrhagic telangiectasias (HHT) is an autosomal dominant bleeding disorder caused by malformed vessels. […] HHT is an autosomal dominant disorder affecting blood vessels within multiple organ systems. The condition is suspected of haploinsufficiency, where 1 functional gene copy cannot produce the required protein to preserve function. […] In 97% of patients with a definite clinical HHT diagnosis, a causative mutation is identified in 1 of 3 genes described below. […] These mutations disrupt signaling by transforming growth factor-beta (TGF-B), essential for maintaining vascular integrity. […] HHT1 stems from mutations in the gene ENG, which codes for endoglin on chromosome 9. […] HHT2 results from Activin A receptor-like type I (ACVRL1) mutations, which codes for the protein activin receptor-like kinase 1 (ALK1) on chromosome 12.

• #11 Hereditary Hemorrhagic Telangiectasia (HHT) (Osler-Weber-Rendu) – MD Searchlight

  https://mdsearchlight.com/genetic-disorders/hereditary-hemorrhagic-telangiectasia-hht-osler-weber-rendu/?utm_source=pubmedlink&utm_campaign=MDS&utm_content=141559

  Hereditary hemorrhagic telangiectasia (HHT), also known as Osler-Weber-Rendu syndrome, is a genetic disease where the blood vessels form incorrectly. […] HHT, or Hereditary Hemorrhagic Telangiectasia, is a condition that affects the blood vessels in various parts of the body. This condition happens when one copy of a specific gene isn’t able to make enough of a needed protein. […] Investigators have found that nearly all people with a confirmed diagnosis of HHT have mutations or changes in one of three specific genes. These mutations disturb the function of a molecule called transforming growth factor-beta (TGF-B), which is important for keeping blood vessels healthy. […] HHT Type 1, or HHT1, is caused by mutations in a gene called ENG, located on chromosome 9. […] HHT Type 2, or HHT2, is due to mutations in a gene called Activin A Receptor-Like Type I (ACVRL1).

• #12 Orphanet: Hereditary hemorrhagic telangiectasia

  https://www.orpha.net/en/disease/detail/774

  An inherited disorder of angiogenesis characterized by mucocutaneous telangiectases and visceral arteriovenous malformations. […] This genetic disorder is due to pathogenic variants primarily in ENG(9q34.11) or ACVRL1(12q13.13), encoding proteins involved in vascular development and angiogenic homeostasis of capillaries. Mutations in SMAD4 (18q21.2) occur in rare cases (1-3%) and result in HHT associated with juvenile polyposis. In a small proportion of HHT families, the pathogenic gene variant has not yet been identified.

• #13 Hereditary Hemorrhagic Telangiectasia (HHT) – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK578186/

  Hereditary hemorrhagic telangiectasias (HHT) is an autosomal dominant bleeding disorder caused by malformed vessels. […] HHT is an autosomal dominant disorder affecting blood vessels within multiple organ systems. The condition is suspected of haploinsufficiency, where 1 functional gene copy cannot produce the required protein to preserve function. […] In 97% of patients with a definite clinical HHT diagnosis, a causative mutation is identified in 1 of 3 genes described below. […] These mutations disrupt signaling by transforming growth factor-beta (TGF-B), essential for maintaining vascular integrity. […] HHT1 stems from mutations in the gene ENG, which codes for endoglin on chromosome 9. […] HHT2 results from Activin A receptor-like type I (ACVRL1) mutations, which codes for the protein activin receptor-like kinase 1 (ALK1) on chromosome 12.

• #14 Hereditary Hemorrhagic Telangiectasia (HHT)/Osler-Weber-Rendu Syndrome: A Review on Contemporary Knowledge, Its Accompanying Clinical Manifestations, Diagnostics, and Oro-Dental Management Plan | IntechOpen

  https://www.intechopen.com/chapters/1188856

  HHT is classified into four types, though more types may exist: HHT types I and II (account for approximately 85% of cases); HHT type III; and HHT-juvenile polyposis overlap syndrome (JPS-HHT). […] Briefly, HHT1 involves a mutation (61%) in the ENG gene (endoglin, in chromosome 9, 9q3334), wherein patients, especially women, are at a higher risk of developing pulmonary and cerebral AVMs. […] On the other hand, the HHT2 type involves a mutation (37%) in ACVRL1 (activin A receptor-like type 1, in chromosome 12, 12q13) also known as ALK1. […] OWRs, therefore, it has been stated, for decades, to be caused by genetic mutations involving the signaling of TGF-, with defects in at least four genes implicated (ENG, ALK1, mutations of chromosome 5, and mutations of SMAD4/MADH4). […] Today, OWRS/HHT is considered as a disease of the BMP9/10 pathway rather than a disease of the TGF- pathway. […] In about 80% of OWRS patients, a family history is realized.

• #15 Hereditary Hemorrhagic Telangiectasia » Department of Radiology » College of Medicine » University of Florida

  https://xray.ufl.edu/patient-care/divisions/interventional-radiology/therapies/hereditary-hemorrhagic-telangiectasia/

  Hereditary Hemorrhagic Telangiectasia (HHT) is a genetic disorder which affects about one in 5,000 people and causes arterial blood to flow directly into the veins, creating weakened ballooned vessels that can rupture. […] A person with HHT lacks capillaries in a few blood vessels in critical locations. Arteries connect directly into veins, creating a fragile site that can rupture and bleed. These abnormal blood vessels are called telangiectasis (tel-AN-jee-eck-TAZE-ee-ya) if they involve small blood vessels (nose, stomach and small bowel) and arterioveneous malformations (AVM) if it involves a larger blood vessel (lung, brain and liver). […] Telangiectases often occur near the surface of the skin like the mucous membrane in the nose while AVMs appear in the internal organs of the body.

• #16 Hereditary Hemorrhagic Telangiectasia (HHT) – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK578186/

  JPHT is due to a mutation in the gene Mothers Against Decapentaplegic homolog 4 (MADH4) that codes for the transcription factor SMAD4, a critical downstream effector of TGF-B signaling. […] The distribution in gene mutations among HHT patients is predominantly ENG (61%), followed by ACVRL1 (37%), and then MADH4 (2%). Over 600 mutations, including deletions, missense, nonsense, and insertions, have also been identified in ENG or ACVR genes.

• #17 Hereditary Hemorrhagic Telangiectasia (HHT) (Osler-Weber-Rendu) – MD Searchlight

  https://mdsearchlight.com/genetic-disorders/hereditary-hemorrhagic-telangiectasia-hht-osler-weber-rendu/?utm_source=pubmedlink&utm_campaign=MDS&utm_content=141559

  Another type of HHT, known as HHT associated with Juvenile Polyposis or JPHT, happens due to mutations in a gene called MADH4. […] The distribution of these gene mutations among HHT patients is mostly ENG (61%), followed by ACVRL1 (37%), and then MADH4 (2%). More than 600 different mutations, including deletions, substitutions, and insertions, have been identified in the ENG or ACVRL1 genes.

• #18 Hereditary Hemorrhagic Telangiectasia – HHT | Choose the Right Test

  https://arupconsult.com/content/hereditary-hemorrhagic-telangiectasia

  Hereditary hemorrhagic telangiectasia (HHT) is a rare autosomal dominant disorder characterized by multiple telangiectases in the skin and mucous membranes. […] Pathogenic variants of the ACVRL1 (also known as ALK1) and ENG genes are the most common causes of HHT. […] The diagnosis of hereditary hemorrhagic telangiectasia (HHT) is based on specific established clinical criteria. […] HHT is considered confirmed in individuals who meet three or more criteria, suspected in those who meet two criteria, and unlikely in those who meet a single criterion. […] For this reason, establishing a diagnosis by genetic testing is recommended in children born to a parent with confirmed HHT and a known causative variant. […] Identification of a heterozygous pathogenic variant in ACVRL1, ENG, or SMAD4 establishes the diagnosis of HHT.

• #19 Hereditary Hemorrhagic Telangiectasia – HHT | Choose the Right Test

  https://arupconsult.com/content/hereditary-hemorrhagic-telangiectasia

  Identification of a heterozygous pathogenic variant in GDF2 (also known as BMP9) establishes the diagnosis of an HHT-like telangiectasia syndrome. […] Identification of pathogenic variants in RASA1 and EPHB4 can be used to rule out the diagnosis of HHT and establish the diagnosis of capillary malformation-arteriovenous malformation syndrome (CM-AVM). […] A multigene panel that includes analysis of genes that cause either HHT (ACVRL1 and ENG) or a disorder with clinical overlap (SMAD4, GDF2, and genes that cause CM-AVM) can be used if clinical findings are inconclusive. […] Genetic testing should be offered to children of parents with HHT, even in the absence of symptoms.

• #20

  https://www.jci.org/articles/view/176379

  Hereditary hemorrhagic telangiectasia (HHT) is an inherited vascular disorder with highly variable expressivity, affecting up to 1 in 5,000 individuals. […] HHT is caused by loss-of-function mutations in the BMP9-10/ENG/ALK1/SMAD4 signaling pathway. […] Hereditary hemorrhagic telangiectasia (HHT) or Osler-Weber-Rendu syndrome is a hereditary disease that is transmitted in an autosomal dominant manner and is caused by loss-of-function (LOF) mutations in certain components of the predominantly endothelial BMP9-10/ENG/ALK1/SMAD4 signaling pathway, which is an important mediator of vascular quiescence. […] Specifically, mutations in ENG (chromosomal locus 9q34.11, encoding the coreceptor endoglin) and ACVRL1 (chromosomal locus 12q13.13, encoding the type I receptor ALK1) are nearly equally responsible for the majority of HHT cases and give rise to the two major forms of the disease, HHT1 (OMIM 187300) and HHT2 (OMIM 600376), respectively.

• #21 New Research Highlights Advances In Understanding And Managing Hereditary Haemorrhagic Telangiectasia (HHT) | VASCERN

  https://vascern.eu/news/new-research-highlights-advances-in-understanding-and-managing-hereditary-haemorrhagic-telangiectasia-hht/

  Hereditary haemorrhagic telangiectasia (HHT), also known as Osler-Weber-Rendu syndrome, is a genetic vascular disorder inherited in an autosomal dominant pattern. […] It is caused by mutations in genes involved in the BMP (bone morphogenetic protein) signalling pathway, which plays a critical role in vascular development. […] According to the study, 90% of HHT cases are linked to mutations in the ENG and ACVRL1 genes, while rarer cases involve SMAD4 and GDF2. These genetic abnormalities lead to fragile blood vessels and the formation of abnormal vascular structures known as telangiectases and arteriovenous malformations (AVMs).

• #22

  https://haematologica.org/article/view/8582

  Hereditary hemorrhagic telangiectasia (HHT), also known as Osler-Weber-Rendu syndrome, is an autosomal dominant disorder that causes abnormal blood vessel formation. […] Genetic mutations that have been identified include ENG, ACVRL1/ALK1, and MADH4/SMAD4, among others. […] There is considerable inter- and intra-family variation in disease onset and clinical severity, even in cases resulting from an identical mutation. […] Over 80% of HHT patients have identifiable mutations, leaving approximately 20% who meet clinical diagnostic criteria but do not have definitive mutations. […] Additional loci associated with HHT have been identified on chromosomes 5q31 (HHT3) and 7q14 (HHT4), but have not been completely characterized. […] All three identified causative genes are involved in cell signaling via the TGF-/BMP signaling pathway, which has roles in cell growth, apoptosis, smooth muscle cell differentiation, and vascular remodeling and maintenance.

• #23 Updates on diagnostic criteria for hereditary haemorrhagic telangiectasia in the light of whole genome sequencing of ‘gene-negative’ individuals recruited to the 100 000 Genomes Project | Journal of Medical Genetics

  https://jmg.bmj.com/content/61/2/182

  Different causal genes are now shown to distinguish individuals with HHT from HHT-like vasculopathies that overlap phenotypically with HHT. […] Restricting to the major HHT causal genes of ENG and ACVRL1, recent studies emphasise that even in adults, genetically confirmed HHT may result in few Curaao Criteria, while HHT bleeding severity may be modified by HHT-independent DNA variants. […] The important conclusion for the scientific field is that there is now no evidence for an independent HHT3 locus. […] The data support use of a likely HHT designation even if three criteria are present for a relative of a patient with known HHT.

• #24 Hemorrhagic Telangiectasia | Children’s Hospital Colorado

  https://www.childrenscolorado.org/conditions-and-advice/conditions-and-symptoms/conditions/hereditary-hemorrhagic-telangiectasia/

  Hereditary hemorrhagic telangiectasia (HHT), also called Osler-Weber-Rendu disease, is a vascular condition that causes malformed blood vessels. […] HHT is caused by genetic changes (mutations) that most often occur in one of three genes (ACVRL1, ENG and SMAD4). […] Three other genes have recently been reported to cause HHT-like disorders (GDF2, RASA1 and EPH4). […] HHT is a dominant condition, which means that if a person has HHT, they have a 50% chance of passing it on to each of their children.

• #25 Hereditary Hemorrhagic Telangiectasia – GeneReviews® – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK1351/

  Hereditary hemorrhagic telangiectasia (HHT) is characterized by the presence of multiple arteriovenous malformations (AVMs) that lack intervening capillaries and result in direct connections between arteries and veins. […] Identification of a heterozygous pathogenic variant in ACVRL1, ENG, or SMAD4 establishes the diagnosis if clinical features are inconclusive. […] HHT is inherited in an autosomal dominant manner with considerable intrafamilial variability. […] The clinical diagnosis of HHT can be established in a proband using criteria referred to as the Curaao criteria, which require three or more of the above suggestive findings. […] Molecular genetic testing approaches can include a combination of concurrent gene or serial single-gene testing, use of a multigene panel, and more comprehensive genomic testing. […] Currently, all known genetic defects that cause HHT are in genes that encode proteins within the transforming growth factor beta (TGF-) signaling pathway. […] Loss of function.

• #26

  https://haematologica.org/article/view/8582

  Hereditary hemorrhagic telangiectasia (HHT), also known as Osler-Weber-Rendu syndrome, is an autosomal dominant disorder that causes abnormal blood vessel formation. […] Genetic mutations that have been identified include ENG, ACVRL1/ALK1, and MADH4/SMAD4, among others. […] There is considerable inter- and intra-family variation in disease onset and clinical severity, even in cases resulting from an identical mutation. […] Over 80% of HHT patients have identifiable mutations, leaving approximately 20% who meet clinical diagnostic criteria but do not have definitive mutations. […] Additional loci associated with HHT have been identified on chromosomes 5q31 (HHT3) and 7q14 (HHT4), but have not been completely characterized. […] All three identified causative genes are involved in cell signaling via the TGF-/BMP signaling pathway, which has roles in cell growth, apoptosis, smooth muscle cell differentiation, and vascular remodeling and maintenance.

• #27 Hereditary Hemorrhagic Telangiectasia: Genetics, Pathophysiology, Diagnosis, and Management

  https://www.mdpi.com/2077-0383/11/17/5245

  Hereditary hemorrhagic telangiectasia (HHT), also known as Rendu–Osler–Weber Syndrome, is a rare disease characterized by multisystemic vascular dysplasia. This disease is caused, in approximately 90% of cases, by a heterozygous mutation of the endoglin gene (ENG) or the activin-like receptor kinase 1, called ALK1 (also known as ACVRL1), characterized by an autosomal dominant inheritance pattern. Disruption of the ENG gene, located on chromosome 9 (9q3.3-q3.4), causes HHT type 1 (HHT1), while mutation of the ACVRL1 gene, located on chromosome 12 (12q13), causes HHT type 2 (HHT2). The haploinsufficiency model in HHT is the most accepted theory for the pathogenesis of disease development. It is explained by the fact that mutations in ENG and ACVRL1 genes generate altered proteins that fail to be expressed in the cell membranes of endothelial cells. There have been more than 900 mutations described on the ENG and ACVRL1 genes including deletions, insertions, nonsense, missense, and splice site mutations. This lack of protein expression results in impairment on routes via ENG or ACVRL1 that normally enhances endothelial migration and proliferation. Importantly, animal models show that involvement of the endoglin and ALK1 pathways will also lead to a decrease in ALK5 pathway activity as a possible adaptation response to compensate the reduced expression of endoglin and ALK1.

• #28 Hereditary Hemorrhagic Telangiectasia (HHT) – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK578186/

  Hereditary hemorrhagic telangiectasias (HHT) is an autosomal dominant bleeding disorder caused by malformed vessels. […] HHT is an autosomal dominant disorder affecting blood vessels within multiple organ systems. The condition is suspected of haploinsufficiency, where 1 functional gene copy cannot produce the required protein to preserve function. […] In 97% of patients with a definite clinical HHT diagnosis, a causative mutation is identified in 1 of 3 genes described below. […] These mutations disrupt signaling by transforming growth factor-beta (TGF-B), essential for maintaining vascular integrity. […] HHT1 stems from mutations in the gene ENG, which codes for endoglin on chromosome 9. […] HHT2 results from Activin A receptor-like type I (ACVRL1) mutations, which codes for the protein activin receptor-like kinase 1 (ALK1) on chromosome 12.

• #29 Hereditary Hemorrhagic Telangiectasia: Genetics, Pathophysiology, Diagnosis, and Management

  https://www.mdpi.com/2077-0383/11/17/5245

  Hereditary hemorrhagic telangiectasia (HHT), also known as Rendu–Osler–Weber Syndrome, is a rare disease characterized by multisystemic vascular dysplasia. This disease is caused, in approximately 90% of cases, by a heterozygous mutation of the endoglin gene (ENG) or the activin-like receptor kinase 1, called ALK1 (also known as ACVRL1), characterized by an autosomal dominant inheritance pattern. Disruption of the ENG gene, located on chromosome 9 (9q3.3-q3.4), causes HHT type 1 (HHT1), while mutation of the ACVRL1 gene, located on chromosome 12 (12q13), causes HHT type 2 (HHT2). The haploinsufficiency model in HHT is the most accepted theory for the pathogenesis of disease development. It is explained by the fact that mutations in ENG and ACVRL1 genes generate altered proteins that fail to be expressed in the cell membranes of endothelial cells. There have been more than 900 mutations described on the ENG and ACVRL1 genes including deletions, insertions, nonsense, missense, and splice site mutations. This lack of protein expression results in impairment on routes via ENG or ACVRL1 that normally enhances endothelial migration and proliferation. Importantly, animal models show that involvement of the endoglin and ALK1 pathways will also lead to a decrease in ALK5 pathway activity as a possible adaptation response to compensate the reduced expression of endoglin and ALK1.

• #30

  https://www.jci.org/articles/view/176379

  Together, mutations in ENG, ACVRL1, and SMAD4 are responsible for more than 90% of HHT cases, leaving a minority of clinically diagnosed individuals with an unknown genetic basis. […] In some cases, this can be attributed to limitations of current sequencing technologies in detecting certain variants in the previously identified loci or to the exclusion of testing noncoding regions; however, additional chromosomal loci could also be implicated in HHT development. […] The LOF nature of HHT causal mutations and the autosomal dominant inheritance of the disease led to the longstanding belief that HHT is caused by haploinsufficiency of the mutated gene product. […] However, the haploinsufficiency model does not explain why HHT vascular lesions develop focally in characteristic vascular beds despite the presence of the germline HHT causal mutation in all endothelial cells of the body.

• #31 Hereditary Hemorrhagic Telangiectasia: Genetics, Pathophysiology, Diagnosis, and Management

  https://www.mdpi.com/2077-0383/11/17/5245

  […] […] Two other less recognized theories about the development of HHT are the dominant negativity theory and the double knockout hypothesis. The first searches to explain the development of the disease in patients with nonsense mutations in the ENG and ACVRL1 genes. These truncated proteins could inhibit endoglin protein expression on the vascular endothelium. On the other hand, somatic mutations in telangiectases of the skin have driven to propose a double hit hypotheses. In this scenario, more localized lesions (such as cutaneous telangiectasias) would be explained by somatic mutations that are caused by environmental stress (sun exposure). […] […] […] The relationship between the endothelium and affected genes in HHT is based on the positive regulation of angiogenesis by ENG and ACVRL1, a process in which the pathways of endothelial cell migration and proliferation are central. All affected genes encode proteins that participate in the transforming growth factor β (TGF-β) signaling pathway. The TGF-β family is a large and continuously expanding group of regulatory polypeptides. They are subdivided into two functional groups, the first includes the activins, inhibins, and the nodal growth differentiation factor; and the second includes the bone morphogenetic proteins (BMPs), most of the growth differentiation factors (GDFs), and antimullerian hormone (AMH), among others.

• #32 The Signs and Symptoms of Hereditary Hemorrhagic Telangiectasia–HHT

  https://dimensionsofdentalhygiene.com/article/the-signs-and-symptoms-of-hereditary-hemorrhagic-telangiectasia/

  Proposed mechanisms by which mutations to the endoglin gene might cause HHT 1 include a dominant negative effect, a two-hit model, and haploinsufficiency (when an individual with a gene mutation has a single copy of the normal gene and, thus, is incapable of generating enough protein to enable normal function). The most recent data seem to support haploinsufficiency as the most likely cause. […] Mutations in the gene for ALK-1 have been mapped to locus 12q and are referred to as the gene for HHT 2. ALK-1 is a type I serin-theronine kinase receptor that can bind TGF-? in the presence of its type II receptor and is expressed predominantly on endothelial cells. […] Each of the 12 mutations has affected the cytoplasmic kinase region, suggesting that the resulting protein has decreased kinase activity. As with the endoglin gene, there is evidence to support the dominant negative, two-hit, and haploinsufficiency mechanisms. Preliminary data suggest a third locus for HHT at 3q22, where the TGF-? II receptor gene is located.

• #33 Hereditary Hemorrhagic Telangiectasia: Genetics, Pathophysiology, Diagnosis, and Management

  https://www.mdpi.com/2077-0383/11/17/5245

  […] […] Two other less recognized theories about the development of HHT are the dominant negativity theory and the double knockout hypothesis. The first searches to explain the development of the disease in patients with nonsense mutations in the ENG and ACVRL1 genes. These truncated proteins could inhibit endoglin protein expression on the vascular endothelium. On the other hand, somatic mutations in telangiectases of the skin have driven to propose a double hit hypotheses. In this scenario, more localized lesions (such as cutaneous telangiectasias) would be explained by somatic mutations that are caused by environmental stress (sun exposure). […] […] […] The relationship between the endothelium and affected genes in HHT is based on the positive regulation of angiogenesis by ENG and ACVRL1, a process in which the pathways of endothelial cell migration and proliferation are central. All affected genes encode proteins that participate in the transforming growth factor β (TGF-β) signaling pathway. The TGF-β family is a large and continuously expanding group of regulatory polypeptides. They are subdivided into two functional groups, the first includes the activins, inhibins, and the nodal growth differentiation factor; and the second includes the bone morphogenetic proteins (BMPs), most of the growth differentiation factors (GDFs), and antimullerian hormone (AMH), among others.

• #34

  https://www.jci.org/articles/view/176379

  These disparities put forth the second-hit hypothesis in HHT, which is becoming more and more accepted by the HHT scientific community. […] This hypothesis implies that the germline mutation (first hit) predisposes the endothelium to vascular defects that strictly develop in the presence of additional, local factors (second hit) that could be either environmental or genetic. […] Several preclinical studies have demonstrated the role of proangiogenic and proinflammatory triggers in driving HHT pathogenesis. […] In addition to the well-documented HHT symptoms, i.e., epistaxis, telangiectases, and AVMs, HHT patients exhibit a heightened infectious risk in soft tissues, bones, and joints involving Staphylococcus aureus as well as cerebral infections involving bacteria from the orodigestive flora. […] HHT is also associated with immunological abnormalities, mainly characterized by a T-helper lymphopenia, although these abnormalities lack clear correlation with the aforementioned infectious risks.

• #35 Pediatric hereditary hemorrhagic telangiectasia (HHT) or Osler-Weber-Rendu syndrome – Children’s Health

  https://www.childrens.com/specialties-services/conditions/hht

  Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant genetic disorder. If a parent has HHT, his or her children have a 50 percent chance of being diagnosed with it. […] HHT affects blood vessels and can lead to bleeding when abnormally structured blood vessels rupture. […] HHT can affect many organs. However, the first sign is often unpredictable, severe nosebleeds. […] Arteriovenous malformations (AVMs) are large vascular malformations that can occur elsewhere in the body, including the lungs, liver, brain and spine. […] The types are differentiated primarily by the genetic cause, signs and symptoms. […] Symptoms develop earlier in Type 1, which has a higher risk of blood vessel malformation in lungs and brain. […] Symptoms develop later than type 1 in Type 2, which has a higher risk of blood vessel malformation in the liver.

• #36 The Signs and Symptoms of Hereditary Hemorrhagic Telangiectasia–HHT

  https://dimensionsofdentalhygiene.com/article/the-signs-and-symptoms-of-hereditary-hemorrhagic-telangiectasia/

  Hereditary hemorrhagic telangiectasia (HHT) is a relatively uncommon autosomal dominant genetic disorder that causes multiple arteriovenous malformations (AVMs) of the nose, skin, lung, brain, liver, and gastrointestinal (GI) tract, which can significantly impede blood circulation. […] The genetic aspect of HHT has been studied extensively for the past several years. The condition is part of a family of disorders caused by mutations in multiple genes. An abnormal gene on either chromosome 9 (endoglin) or 12 (active-like kinase, or ALK-1) causes most cases of HHT. […] Genetic linkages to HHT have found mutations to chromosome 9q33-q34 in some families and to chromosome 12q in others. This might explain the vast differences in clinical appearances among individuals affected by HHT. Currently, HHT is divided into two subgroups: HHT type 1 (HHT 1) and HHT type 2 (HHT 2). Some references state, however, that there is a possible third type. The chromosomal involvement determines the HHT type. In HHT type 1, mutations at chromosome 9 alter the coding sequence of endoglin. In HHT type 2, mutations at chromosome 12 alter the coding sequence of ALK-1.

• #37 Predictors of mortality in patients with hereditary hemorrhagic telangiectasia | Orphanet Journal of Rare Diseases | Full Text

  https://ojrd.biomedcentral.com/articles/10.1186/s13023-020-01579-2

  Retrospective questionnaire and healthcare administrative data suggest reduced life expectancy in untreated hereditary hemorrhagic telangiectasia (HHT). […] HHT is characterized by the presence of vascular malformations (VMs), including arteriovenous malformations (AVMs) of the lung, liver, brain, spinal cord and smaller mucosal lesions (telangiectasia) of the nose, mouth and gastro-intestinal (GI) tract. […] These lesions lead to acute life-threatening bleeding, stroke, heart failure and death, as well as chronic bleeding from the nose and GI tract. […] Mortality and its predictors remain poorly understood in HHT to date. […] One group reported no difference in life-expectancy by HHT gene mutated, the other reporting worse life-expectancy in patients with ENG mutation, with the largest difference in women.

• #38 Pediatric hereditary hemorrhagic telangiectasia (HHT) or Osler-Weber-Rendu syndrome – Children’s Health

  https://www.childrens.com/specialties-services/conditions/hht

  Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant genetic disorder. If a parent has HHT, his or her children have a 50 percent chance of being diagnosed with it. […] HHT affects blood vessels and can lead to bleeding when abnormally structured blood vessels rupture. […] HHT can affect many organs. However, the first sign is often unpredictable, severe nosebleeds. […] Arteriovenous malformations (AVMs) are large vascular malformations that can occur elsewhere in the body, including the lungs, liver, brain and spine. […] The types are differentiated primarily by the genetic cause, signs and symptoms. […] Symptoms develop earlier in Type 1, which has a higher risk of blood vessel malformation in lungs and brain. […] Symptoms develop later than type 1 in Type 2, which has a higher risk of blood vessel malformation in the liver.

• #39 Predictors of mortality in patients with hereditary hemorrhagic telangiectasia | Orphanet Journal of Rare Diseases | Full Text

  https://ojrd.biomedcentral.com/articles/10.1186/s13023-020-01579-2

  Retrospective questionnaire and healthcare administrative data suggest reduced life expectancy in untreated hereditary hemorrhagic telangiectasia (HHT). […] HHT is characterized by the presence of vascular malformations (VMs), including arteriovenous malformations (AVMs) of the lung, liver, brain, spinal cord and smaller mucosal lesions (telangiectasia) of the nose, mouth and gastro-intestinal (GI) tract. […] These lesions lead to acute life-threatening bleeding, stroke, heart failure and death, as well as chronic bleeding from the nose and GI tract. […] Mortality and its predictors remain poorly understood in HHT to date. […] One group reported no difference in life-expectancy by HHT gene mutated, the other reporting worse life-expectancy in patients with ENG mutation, with the largest difference in women.

• #40 Hereditary Hemorrhagic Telangiectasia – UChicago Medicine

  https://www.uchicagomedicine.org/conditions-services/neurology-neurosurgery/hht

  Hereditary hemorrhagic telangiectasia (HHT), also known as Osler-Weber-Rendu syndrome, is a rare genetic condition that causes bleeding due to blood vessels that did not develop correctly. HHT causes arteriovenous malformations (AVMs) tangled connections between arteries and veins. […] HHT is an autosomal dominant genetic disorder, meaning it takes only one parent with the gene to pass it on to a child. If a parent has HHT, there is a 50 percent chance that any of his or her children will inherit the disease. Multiple genes have been identified as having involvement in this disease, including a gene that also causes polyps in the colon or, potentially, colon cancer.

• #41 Pediatric hereditary hemorrhagic telangiectasia (HHT) or Osler-Weber-Rendu syndrome – Children’s Health

  https://www.childrens.com/specialties-services/conditions/hht

  HHT types 1, 2 and 3 don’t increase the likelihood of polyps. […] HHT is sometimes referred to as the „great masquerader” because children may not exhibit any symptoms. […] If children screen positive for vascular abnormalities, further testing will be ordered. […] Three out of four of the following criteria must be met before doctors will make a clinical diagnosis of HHT: Family history of a parent, sibling or child with HHT, recurrent nosebleeds, visible telangiectases on the mouth, lips, fingers and nose, AVMs in the lungs, spine, brain, digestive tract or liver.

• #42

  https://haematologica.org/article/view/8582

  Hereditary hemorrhagic telangiectasia (HHT), also known as Osler-Weber-Rendu syndrome, is an autosomal dominant disorder that causes abnormal blood vessel formation. […] Genetic mutations that have been identified include ENG, ACVRL1/ALK1, and MADH4/SMAD4, among others. […] There is considerable inter- and intra-family variation in disease onset and clinical severity, even in cases resulting from an identical mutation. […] Over 80% of HHT patients have identifiable mutations, leaving approximately 20% who meet clinical diagnostic criteria but do not have definitive mutations. […] Additional loci associated with HHT have been identified on chromosomes 5q31 (HHT3) and 7q14 (HHT4), but have not been completely characterized. […] All three identified causative genes are involved in cell signaling via the TGF-/BMP signaling pathway, which has roles in cell growth, apoptosis, smooth muscle cell differentiation, and vascular remodeling and maintenance.

• #43

  https://www.jci.org/articles/view/176379

  These disparities put forth the second-hit hypothesis in HHT, which is becoming more and more accepted by the HHT scientific community. […] This hypothesis implies that the germline mutation (first hit) predisposes the endothelium to vascular defects that strictly develop in the presence of additional, local factors (second hit) that could be either environmental or genetic. […] Several preclinical studies have demonstrated the role of proangiogenic and proinflammatory triggers in driving HHT pathogenesis. […] In addition to the well-documented HHT symptoms, i.e., epistaxis, telangiectases, and AVMs, HHT patients exhibit a heightened infectious risk in soft tissues, bones, and joints involving Staphylococcus aureus as well as cerebral infections involving bacteria from the orodigestive flora. […] HHT is also associated with immunological abnormalities, mainly characterized by a T-helper lymphopenia, although these abnormalities lack clear correlation with the aforementioned infectious risks.

• #44

  https://haematologica.org/article/view/8582

  In patients with HHT, mutations in endoglin, ALK1, or one of several other proteins in this pathway alter the normal endothelial response. […] The haploinsufficiency of these proteins along with a second hit, such as tissue injury, infection or hypoxia, likely cause the focal vascular lesions of HHT1 and HHT2 as reduced levels of endoglin or ALK1 cannot maintain the balance needed for normal blood vessel formation. […] Vascular endothelial growth factor, an endothelial-specific factor for angiogenesis, is of major interest in diseases of vascular malformation and is elevated in HHT patients. […] Therefore, any mutation along the ALK1 pathway (BMP9, ACVRL1, ENG, MADH4) results in elevation of VEGF through reduced ALK1 pathway signaling. […] While this is a simplified discussion of complex vascular biology, it illustrates why mutations in ENG, ACVRL1/ALK1, MADH4/SMAD4, and BMP9/GDF2 result in the HHT phenotype.

• #45 Hereditary Hemorrhagic Telangiectasia: Genetics, Pathophysiology, Diagnosis, and Management

  https://www.mdpi.com/2077-0383/11/17/5245

  […] […] Two other less recognized theories about the development of HHT are the dominant negativity theory and the double knockout hypothesis. The first searches to explain the development of the disease in patients with nonsense mutations in the ENG and ACVRL1 genes. These truncated proteins could inhibit endoglin protein expression on the vascular endothelium. On the other hand, somatic mutations in telangiectases of the skin have driven to propose a double hit hypotheses. In this scenario, more localized lesions (such as cutaneous telangiectasias) would be explained by somatic mutations that are caused by environmental stress (sun exposure). […] […] […] The relationship between the endothelium and affected genes in HHT is based on the positive regulation of angiogenesis by ENG and ACVRL1, a process in which the pathways of endothelial cell migration and proliferation are central. All affected genes encode proteins that participate in the transforming growth factor β (TGF-β) signaling pathway. The TGF-β family is a large and continuously expanding group of regulatory polypeptides. They are subdivided into two functional groups, the first includes the activins, inhibins, and the nodal growth differentiation factor; and the second includes the bone morphogenetic proteins (BMPs), most of the growth differentiation factors (GDFs), and antimullerian hormone (AMH), among others.

• #46

  https://haematologica.org/article/view/8582

  In patients with HHT, mutations in endoglin, ALK1, or one of several other proteins in this pathway alter the normal endothelial response. […] The haploinsufficiency of these proteins along with a second hit, such as tissue injury, infection or hypoxia, likely cause the focal vascular lesions of HHT1 and HHT2 as reduced levels of endoglin or ALK1 cannot maintain the balance needed for normal blood vessel formation. […] Vascular endothelial growth factor, an endothelial-specific factor for angiogenesis, is of major interest in diseases of vascular malformation and is elevated in HHT patients. […] Therefore, any mutation along the ALK1 pathway (BMP9, ACVRL1, ENG, MADH4) results in elevation of VEGF through reduced ALK1 pathway signaling. […] While this is a simplified discussion of complex vascular biology, it illustrates why mutations in ENG, ACVRL1/ALK1, MADH4/SMAD4, and BMP9/GDF2 result in the HHT phenotype.

• #47 Osler-Weber-Rendu Disease (Hereditary Hemorrhagic Telangiectasia) Treatment & Management: Approach Considerations, Treatment of Epistaxis, Treatment of Gastrointestinal Bleeding

  https://emedicine.medscape.com/article/2048472-treatment

  Children who have a parent with HHT carry a 50% chance of harboring the same genetic mutation. Accordingly, pulmonary AVM screening and long-term follow-up are advocated for these children, beginning in childhood. […] Studies recommend that women with HHT who conceive should be considered to have high-risk pregnancies because of rare major complications and improved survival outcome following prior recognition. […] Prospective trials aimed at determining ideal management of HHT have been limited by the small and varied population and by the multiorgan nature of the disease. A coordinated team approach is recommended. […] Preclinical work targeting endoglin (also known as CD105) has shown promising results in cancer-related research. […] In September 2020, the Second International Hereditary Hemorrhagic Telangiectasia (HHT) Guidelines, aimed at developing evidence-based consensus guidelines for the management and prevention of HHT-related symptoms and complications, were published.

• #48 Hereditary Hemorrhagic Telangiectasia: Genetics, Pathophysiology, Diagnosis, and Management

  https://www.mdpi.com/2077-0383/11/17/5245

  […] […] Endoglin could help as an adhesion molecule for leukocyte infiltration. It has been proposed that during inflammation, endoglin is excised and its soluble fraction (sol-eng) could promote adhesion and chemotaxis for mononuclear cells (MNC). In HHT, leukocyte infiltration mediated by the expression of adhesion molecules and chemokines synthesized by the endothelium could be impaired, affecting vascular repair and remodeling.

• #49 Hereditary Hemorrhagic Telangiectasia (HHT) > Fact Sheets > Yale Medicine

  https://www.yalemedicine.org/conditions/hht

  A condition that causes abnormally formed blood vessels, which increases risk for clots. […] Hereditary Hemorrhagic Telangiectasia (HHT) is a genetic disorder that affects the blood vessels. […] People with this genetic condition have multiple malformed blood vessel connections that bypass capillaries, which normally connect arteries to veins. […] In the absence of capillaries, direct links between arteries and veins (called telangiectasia when small and arteriovenous malformations [AVM], when larger) occur. […] HHT is a genetic disorder of the blood vessels that affects people of all ages and backgrounds. […] There are three main types of HHT: Type 1 is caused by mutations in the endoglin gene, Type 2 is caused by mutations in the ACVRL1 (ALK1) gene, HHT-juvenile polyposis syndrome is caused by mutations in the SMAD4 gene.

• #50 Hereditary hemorrhagic telangiectasia | Radiology Reference Article | Radiopaedia.org

  https://radiopaedia.org/articles/hereditary-haemorrhagic-telangiectasia?lang=us

  Hereditary hemorrhagic telangiectasia (HHT), also known as Osler-Weber-Rendu syndrome, is a rare inherited disorder characterized by abnormal blood vessel formation in the skin, mucous membranes, and organs including the lungs, liver, and central nervous system. […] It is an autosomal dominant multi-organ vascular dysplasia, characterized by multiple arteriovenous malformations (AVMs) that lack an intervening capillary network. […] Mutations have been found in one of several genes (three known so far). […] De novo mutations are rare, almost all have a first-degree relative affected.

• #51 Hereditary Hemorrhagic Telangiectasia (HHT) | UAMS Health

  https://uamshealth.com/condition/hereditary-hemorrhagic-telangiectasia/

  Hereditary hemorrhagic telangiectasia (HHT) is a genetic disorder that causes abnormalities of a small percentage of the blood vessels in the body. […] If these problematic blood vessels rupture, severe bleeding occurs. […] Abnormalities of small vessels are usually diagnosed as telangiectasias while larger blood vessels are diagnosed as arteriovenous malformations (AVM).

• #52 Hereditary hemorrhagic telangiectasia – Wikipedia

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

  Telangiectasias and arteriovenous malformations in HHT are thought to arise because of changes in angiogenesis, the development of blood vessels out of existing ones. The exact mechanism by which the HHT mutations influence this process is not yet clear, and it is likely that they disrupt a balance between pro- and antiangiogenic signals in blood vessels.

• #53 Hereditary Hemorrhagic Telangiectasia: Diagnosis and Management | AAFP

  https://www.aafp.org/pubs/afp/issues/2010/1001/p785.html

  Hereditary hemorrhagic telangiectasia is an uncommon autosomal dominant disease that occurs in approximately one in 5,000 to 8,000 persons. […] Hereditary hemorrhagic telangiectasia (HHT), also known as Osler-Weber-Rendu disease, is an autosomal dominant disorder of abnormal blood vessel formation. […] Most have a mutation in one of two genes that are required for normal angiogenesis. […] In addition, vascular endothelial growth factor levels are increased and may play a role in abnormal angiogenesis.

• #54

  https://haematologica.org/article/view/8582

  In patients with HHT, mutations in endoglin, ALK1, or one of several other proteins in this pathway alter the normal endothelial response. […] The haploinsufficiency of these proteins along with a second hit, such as tissue injury, infection or hypoxia, likely cause the focal vascular lesions of HHT1 and HHT2 as reduced levels of endoglin or ALK1 cannot maintain the balance needed for normal blood vessel formation. […] Vascular endothelial growth factor, an endothelial-specific factor for angiogenesis, is of major interest in diseases of vascular malformation and is elevated in HHT patients. […] Therefore, any mutation along the ALK1 pathway (BMP9, ACVRL1, ENG, MADH4) results in elevation of VEGF through reduced ALK1 pathway signaling. […] While this is a simplified discussion of complex vascular biology, it illustrates why mutations in ENG, ACVRL1/ALK1, MADH4/SMAD4, and BMP9/GDF2 result in the HHT phenotype.

• #55 Hereditary Hemorrhagic Telangiectasia: Genetics, Pathophysiology, Diagnosis, and Management

  https://www.mdpi.com/2077-0383/11/17/5245

  […] […] Two other less recognized theories about the development of HHT are the dominant negativity theory and the double knockout hypothesis. The first searches to explain the development of the disease in patients with nonsense mutations in the ENG and ACVRL1 genes. These truncated proteins could inhibit endoglin protein expression on the vascular endothelium. On the other hand, somatic mutations in telangiectases of the skin have driven to propose a double hit hypotheses. In this scenario, more localized lesions (such as cutaneous telangiectasias) would be explained by somatic mutations that are caused by environmental stress (sun exposure). […] […] […] The relationship between the endothelium and affected genes in HHT is based on the positive regulation of angiogenesis by ENG and ACVRL1, a process in which the pathways of endothelial cell migration and proliferation are central. All affected genes encode proteins that participate in the transforming growth factor β (TGF-β) signaling pathway. The TGF-β family is a large and continuously expanding group of regulatory polypeptides. They are subdivided into two functional groups, the first includes the activins, inhibins, and the nodal growth differentiation factor; and the second includes the bone morphogenetic proteins (BMPs), most of the growth differentiation factors (GDFs), and antimullerian hormone (AMH), among others.

• #56 Hereditary Hemorrhagic Telangiectasia (HHT) > Fact Sheets > Yale Medicine

  https://www.yalemedicine.org/conditions/hht

  A condition that causes abnormally formed blood vessels, which increases risk for clots. […] Hereditary Hemorrhagic Telangiectasia (HHT) is a genetic disorder that affects the blood vessels. […] People with this genetic condition have multiple malformed blood vessel connections that bypass capillaries, which normally connect arteries to veins. […] In the absence of capillaries, direct links between arteries and veins (called telangiectasia when small and arteriovenous malformations [AVM], when larger) occur. […] HHT is a genetic disorder of the blood vessels that affects people of all ages and backgrounds. […] There are three main types of HHT: Type 1 is caused by mutations in the endoglin gene, Type 2 is caused by mutations in the ACVRL1 (ALK1) gene, HHT-juvenile polyposis syndrome is caused by mutations in the SMAD4 gene.

• #57 Hereditary haemorrhagic telangiectasia

  https://dermnetnz.org/topics/hereditary-haemorrhagic-telangiectasia

  Hereditary haemorrhagic telangiectasia (HHT) is also known as Osler-Rendu-Weber syndrome. It is a rare inherited disorder that affects blood vessels throughout the body and is characterised by a tendency for bleeding (haemorrhage, American spelling hemorrhage), in particular recurrent epistaxis (nosebleeds); and skin telangiectasia (skin lesions resulting from dilation of blood vessels). […] The two major types of HHT are HHT1 and HHT2. They are caused by mutations in the endoglin (ENG) and activin receptor-like kinase type 1 (ACVLR1) genes found on chromosome 9 and 12 respectively. Two other genes have also been identified. A defect in just one of these genes causes an abnormality in the formation of blood vessels, which may easily rupture and bleed. The abnormal blood vessels are known as telangiectases, or arteriovenous malformations (AVM) if larger blood vessels are involved.

• #58 Hereditary Hemorrhagic Telangiectasia (HHT) > Fact Sheets > Yale Medicine

  https://www.yalemedicine.org/conditions/hht

  A condition that causes abnormally formed blood vessels, which increases risk for clots. […] Hereditary Hemorrhagic Telangiectasia (HHT) is a genetic disorder that affects the blood vessels. […] People with this genetic condition have multiple malformed blood vessel connections that bypass capillaries, which normally connect arteries to veins. […] In the absence of capillaries, direct links between arteries and veins (called telangiectasia when small and arteriovenous malformations [AVM], when larger) occur. […] HHT is a genetic disorder of the blood vessels that affects people of all ages and backgrounds. […] There are three main types of HHT: Type 1 is caused by mutations in the endoglin gene, Type 2 is caused by mutations in the ACVRL1 (ALK1) gene, HHT-juvenile polyposis syndrome is caused by mutations in the SMAD4 gene.

• #59 HEREDITARY HEMORRHAGIC TELANGIECTASIA (OSLER–WEBER–RENDU DISEASE) (Chapter 17) – Uncommon Causes of Stroke

  https://www.cambridge.org/core/books/uncommon-causes-of-stroke/hereditary-hemorrhagic-telangiectasia-oslerweberrendu-disease/4FF7DC3712989382740E917EED95D223

  Hereditary hemorrhagic telangiectasia (HHT) also known as Osler-Weber-Rendu syndrome is one of the most common autosomal dominant disorders. […] Three different phenotypes of vascular malformations have been differentiated in the central nervous system (CNS), including large fistulae characterized by a direct arteriovenous shunt without nidus but with an ectatic draining vein, small arteriovenous malformations (AVMs) with a nidal size between 1 and 3 cm, and micro-AVMs with a nidus smaller than 1 cm. […] Apart from paradoxical embolism, two other mechanisms could favor cerebral ischemic manifestations in HHT patients, including blood hyperviscosity related to polycythemia and air embolism from the lung to the brain. […] Prevalence of cerebrovascular malformations in HHT is estimated at 5% using only computed tomography (CT), but it increases up to approximately 20% when magnetic resonance imaging (MRI) is performed.

• #60 HHT – Pulmonary Hypertension Association

  https://phassociation.org/patients/aboutph/diseases-and-conditions-associated-with-ph/hht/

  Hereditary Hemorrhagic Telangiectasia (HHT) is a genetic disorder that causes abnormalities of blood vessels, usually resulting in excessive bleeding (known as hemorrhaging). […] A person with HHT has a tendency to form blood vessels that lack capillaries between the arteries and veins, meaning that arterial blood under high pressure flows directly into a vein without first going through the very small capillaries. […] This type of abnormal blood vessel is called a telangiectasia if it involves small blood vessels. It is called an arteriovenous malformation (AVM) if it involves large blood vessels. […] About 15 to 20 percent of people with HHT have at least mildly elevated pulmonary artery pressures, which means they either have or are developing PH. […] In HHT-associated pulmonary arterial hypertension, abnormal blood flow through the blood vessels in the lungs causes elevated blood pressure.

• #61 HEREDITARY HEMORRHAGIC TELANGIECTASIA (OSLER–WEBER–RENDU DISEASE) (Chapter 17) – Uncommon Causes of Stroke

  https://www.cambridge.org/core/books/uncommon-causes-of-stroke/hereditary-hemorrhagic-telangiectasia-oslerweberrendu-disease/4FF7DC3712989382740E917EED95D223

  Hereditary hemorrhagic telangiectasia (HHT) also known as Osler-Weber-Rendu syndrome is one of the most common autosomal dominant disorders. […] Three different phenotypes of vascular malformations have been differentiated in the central nervous system (CNS), including large fistulae characterized by a direct arteriovenous shunt without nidus but with an ectatic draining vein, small arteriovenous malformations (AVMs) with a nidal size between 1 and 3 cm, and micro-AVMs with a nidus smaller than 1 cm. […] Apart from paradoxical embolism, two other mechanisms could favor cerebral ischemic manifestations in HHT patients, including blood hyperviscosity related to polycythemia and air embolism from the lung to the brain. […] Prevalence of cerebrovascular malformations in HHT is estimated at 5% using only computed tomography (CT), but it increases up to approximately 20% when magnetic resonance imaging (MRI) is performed.

• #62 Hereditary hemorrhagic telangiectasia – Symptoms and causes – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/hht/symptoms-causes/syc-20351135

  Hereditary hemorrhagic telangiectasia (tuh-lan-jee-uk-TAY-zhuh) is a condition that’s passed through families, called inherited. […] HHT is a condition of gene changes, called genetic, that you get from your parents. It is an autosomal dominant disorder. That means if one of your parents has HHT, you have a 50% chance of getting it. If you have HHT, each of your children has a 50% chance of getting it from you. […] The major risk factor for hereditary hemorrhagic telangiectasia is having a parent with the condition.

• #63 Hereditary hemorrhagic telangiectasia | Beacon Health System

  https://www.beaconhealthsystem.org/library/diseases-and-conditions/hereditary-hemorrhagic-telangiectasia?content_id=CON-20155449

  This inherited blood vessel condition can cause bad nosebleeds, strokes, bleeding in the digestive tract and anemia. […] Hereditary hemorrhagic telangiectasia (tuh-lan-jee-uk-TAY-zhuh) is a condition that’s passed through families, called inherited. […] Also called Osler-Weber-Rendu disease and HHT, hereditary hemorrhagic telangiectasia passes from parents to children. […] HHT is a condition of gene changes, called genetic, that you get from your parents. It is an autosomal dominant disorder. That means if one of your parents has HHT, you have a 50% chance of getting it. If you have HHT, each of your children has a 50% chance of getting it from you. […] The major risk factor for hereditary hemorrhagic telangiectasia is having a parent with the condition.

• #64 Frequently Asked Questions about Hereditary Hemorrhagic Telangiectasia (HHT)

  https://www.upmc.com/services/hht/frequently-asked-questions

  HHT is a genetic disease. It happens when a person inherits a mutated gene from his or her parents. […] In HHT, an error in your genetic blueprints causes you to produce a single defective protein. That defective protein leads to the development of abnormal blood vessels. […] If you inherit the gene, then you will get HHT. […] If you do not inherit the gene, you will not get HHT. […] HHT is an autosomal dominant disease. […] If you have one abnormal copy of an HHT-associated gene (endoglin, ACVRL-1, or SMAD-4), you have HHT. […] If you have HHT, each child has a 50-percent chance of inheriting the HHT gene and getting HHT.

• #65 Hereditary Hemorrhagic Telangiectasia (HHT) – Patient Worthy

  https://patientworthy.com/hereditary-hemorrhagic-telangiectasia/

  Hereditary hemorrhagic telangiectasia (HHT) is a disorder of the blood vessels, passed by heredity, that causes excessive bleeding. HHT is caused by mutation in one of several genes that control blood vessel development and is passed in an autosomal dominant pattern. […] HHT is inherited through an autosomal dominant pattern. This means that though HHT is uncommon in the general population, it has a 50% chance of being passed from an affected parent to that parent’s child. In rare cases, HHT may be caused by a spontaneous genetic mutation.

• #66

  https://haematologica.org/article/view/8582

  Hereditary hemorrhagic telangiectasia (HHT), also known as Osler-Weber-Rendu syndrome, is an autosomal dominant disorder that causes abnormal blood vessel formation. […] Genetic mutations that have been identified include ENG, ACVRL1/ALK1, and MADH4/SMAD4, among others. […] There is considerable inter- and intra-family variation in disease onset and clinical severity, even in cases resulting from an identical mutation. […] Over 80% of HHT patients have identifiable mutations, leaving approximately 20% who meet clinical diagnostic criteria but do not have definitive mutations. […] Additional loci associated with HHT have been identified on chromosomes 5q31 (HHT3) and 7q14 (HHT4), but have not been completely characterized. […] All three identified causative genes are involved in cell signaling via the TGF-/BMP signaling pathway, which has roles in cell growth, apoptosis, smooth muscle cell differentiation, and vascular remodeling and maintenance.

• #67 Osler-Weber-Rendu Disease: Causes, Symptoms & Diagnosis

  https://www.healthline.com/health/osler-weber-rendu-syndrome

  Osler-Weber-Rendu syndrome (OWR) is also known as hereditary hemorrhagic telangiectasia (HHT). Its a genetic blood vessel disorder that often leads to excessive bleeding. […] Instead, this condition is caused by problems with the blood vessels themselves. […] People with OWR inherit an abnormal gene that causes their blood vessels to form incorrectly. OWR is an autosomal dominant disorder. This means that only one parent needs to have the abnormal gene to pass it on to their children. OWR doesnt skip a generation. However, the signs and symptoms may vary greatly between family members. If you have OWR, its possible that your child could have a milder or more severe course than you. […] In very rare cases, a child can be born with OWR even when neither parent has the syndrome. This happens when one of the genes that cause OWR mutates in an egg or sperm cell.

• #68 What is hereditary hemorrhagic telangiectasia (HHT)?

  https://www.medicalnewstoday.com/articles/hereditary-hemorrhagic-telangiectasia

  Hereditary hemorrhagic telangiectasia (HHT) is an inherited disorder that affects the blood vessels. […] HHT is a genetic condition that affects the blood vessels. Specifically, it results in multiple telangiectasias throughout the body. […] HHT is a genetic disorder. Alterations in five different genes can cause HHT. […] Every person who has HHT has one gene variation that causes them to have the disorder. […] If someone with HHT has a child, they have a 50% chance of inheriting the gene alteration. […] In some rare cases, a person may develop HHT due to the result of a spontaneous genetic change. This is a new variation that they have not inherited from a parent.

• #69 HHT | Symptoms, Diagnosis & Treatment

  https://www.cincinnatichildrens.org/health/h/hht

  Hereditary hemorrhagic telangiectasia (HHT), also known as Osler-Rendu-Weber syndrome, is a genetic condition which affects the blood vessels. […] HHT is caused by genetic changes in one of three genes (ACVRL1, ENG and SMAD4). Almost everyone with a clinical diagnosis of HHT will have a change in one of these genes. […] Three other genes have also recently been reported to be found with HHT-like features (GDF2, RASA1, and EPH4). Overall, about 10-15% of people with HHT will not be found to have a genetic change in any gene. Therefore, some people do have HHT, but its not possible to identify the genetic change causing them to have it. […] HHT is a dominant condition. If you have HHT, you have a 50 percent chance of passing it on to each of your children. […] Very rarely, HHT is not inherited from a parent. It may be new or de novo or it may be „mosaic”. In these cases, other people in the family do not have HHT; but the person diagnosed with HHT still has a 50 percent chance of passing it on to each child.

• #70 Hereditary haemorrhagic telangiectasia

  https://dermnetnz.org/topics/hereditary-haemorrhagic-telangiectasia

  HHT is a rare autosomal dominant condition, which means that only one abnormal gene needs to be inherited from one affected parent to express the disease. HHT is often passed from generation to generation as each child of a person with HHT has a 50% chance of getting the disease. However, the signs and symptoms of HHT within a single family can vary considerably. […] In addition to visible telangiectases, abnormal blood vessel formation may occur in many other organs. Telangiectases can be found anywhere in the gastrointestinal (GI) system, including the oesophagus, stomach, and small and large intestines. GI bleeding occurs in about 25% of patients with HHT and the risk is increased in patients older than 50 years. […] HHT cannot be prevented but most cases can be treated symptomatically. One third of the cases of HHT are mild, one third are moderate, and one third are severe. Mild cases usually require no treatment. HHT should be treated if it is causing significant problems, such as severe and/or frequent nosebleeds, or if there is a high risk of causing other problems, such as a stroke from a lung AVM.

• #71 Clinical manifestations and diagnosis of hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu syndrome) – UpToDate

  https://www.uptodate.com/contents/clinical-manifestations-and-diagnosis-of-hereditary-hemorrhagic-telangiectasia-osler-weber-rendu-syndrome

  Hereditary hemorrhagic telangiectasia (HHT; also called Osler-Weber-Rendu syndrome) is a vascular disorder inherited as an autosomal dominant trait, with a variety of clinical manifestations that vary between relatives who have the same HHT pathogenic gene variant. […] In addition, arteriovenous malformations (AVMs) frequently affect the pulmonary, hepatic, and/or cerebral circulations, demanding knowledge of the risks and benefits of screening and treatment of patients with these complications. […] The pathophysiology, epidemiology, and diagnosis of HHT will be reviewed here.

• #72 Updates on diagnostic criteria for hereditary haemorrhagic telangiectasia in the light of whole genome sequencing of ‘gene-negative’ individuals recruited to the 100 000 Genomes Project | Journal of Medical Genetics

  https://jmg.bmj.com/content/61/2/182

  Different causal genes are now shown to distinguish individuals with HHT from HHT-like vasculopathies that overlap phenotypically with HHT. […] Restricting to the major HHT causal genes of ENG and ACVRL1, recent studies emphasise that even in adults, genetically confirmed HHT may result in few Curaao Criteria, while HHT bleeding severity may be modified by HHT-independent DNA variants. […] The important conclusion for the scientific field is that there is now no evidence for an independent HHT3 locus. […] The data support use of a likely HHT designation even if three criteria are present for a relative of a patient with known HHT.

• #73 Hereditary haemorrhagic telangiectasia

  https://dermnetnz.org/topics/hereditary-haemorrhagic-telangiectasia

  HHT is a rare autosomal dominant condition, which means that only one abnormal gene needs to be inherited from one affected parent to express the disease. HHT is often passed from generation to generation as each child of a person with HHT has a 50% chance of getting the disease. However, the signs and symptoms of HHT within a single family can vary considerably. […] In addition to visible telangiectases, abnormal blood vessel formation may occur in many other organs. Telangiectases can be found anywhere in the gastrointestinal (GI) system, including the oesophagus, stomach, and small and large intestines. GI bleeding occurs in about 25% of patients with HHT and the risk is increased in patients older than 50 years. […] HHT cannot be prevented but most cases can be treated symptomatically. One third of the cases of HHT are mild, one third are moderate, and one third are severe. Mild cases usually require no treatment. HHT should be treated if it is causing significant problems, such as severe and/or frequent nosebleeds, or if there is a high risk of causing other problems, such as a stroke from a lung AVM.

• #74 Pediatric hereditary hemorrhagic telangiectasia (HHT) or Osler-Weber-Rendu syndrome – Children’s Health

  https://www.childrens.com/specialties-services/conditions/hht

  Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant genetic disorder. If a parent has HHT, his or her children have a 50 percent chance of being diagnosed with it. […] HHT affects blood vessels and can lead to bleeding when abnormally structured blood vessels rupture. […] HHT can affect many organs. However, the first sign is often unpredictable, severe nosebleeds. […] Arteriovenous malformations (AVMs) are large vascular malformations that can occur elsewhere in the body, including the lungs, liver, brain and spine. […] The types are differentiated primarily by the genetic cause, signs and symptoms. […] Symptoms develop earlier in Type 1, which has a higher risk of blood vessel malformation in lungs and brain. […] Symptoms develop later than type 1 in Type 2, which has a higher risk of blood vessel malformation in the liver.

• #75 Predictors of mortality in patients with hereditary hemorrhagic telangiectasia | Orphanet Journal of Rare Diseases | Full Text

  https://ojrd.biomedcentral.com/articles/10.1186/s13023-020-01579-2

  Retrospective questionnaire and healthcare administrative data suggest reduced life expectancy in untreated hereditary hemorrhagic telangiectasia (HHT). […] HHT is characterized by the presence of vascular malformations (VMs), including arteriovenous malformations (AVMs) of the lung, liver, brain, spinal cord and smaller mucosal lesions (telangiectasia) of the nose, mouth and gastro-intestinal (GI) tract. […] These lesions lead to acute life-threatening bleeding, stroke, heart failure and death, as well as chronic bleeding from the nose and GI tract. […] Mortality and its predictors remain poorly understood in HHT to date. […] One group reported no difference in life-expectancy by HHT gene mutated, the other reporting worse life-expectancy in patients with ENG mutation, with the largest difference in women.

• #76 Hereditary hemorrhagic telangiectasia – Wikipedia

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

  Hereditary hemorrhagic telangiectasia (HHT), also known as Osler-Weber-Rendu disease and Osler-Weber-Rendu syndrome, is a rare autosomal dominant genetic disorder that leads to abnormal blood vessel formation in the skin, mucous membranes, and often in organs such as the lungs, liver, and brain. […] HHT is transmitted in an autosomal dominant fashion, and occurs in one in 5,000-8,000 people in North America. […] Five genetic types of HHT are recognized. Of these, three have been linked to particular genes, while the two remaining have currently only been associated with a particular locus. More than 80% of all cases of HHT are due to mutations in either ENG or ACVRL1. […] Both ENG and ACVRL1 mutations lead predominantly to underproduction of the related proteins, rather than misfunctioning of the proteins.

• #77 Hereditary haemorrhagic telangiectasia – myDr.com.au

  https://mydr.com.au/heart-stroke/hereditary-haemorrhagic-telangiectasia/

  Hereditary haemorrhagic telangiectasia (HHT) is a condition where malformations of small blood vessels occur in multiple areas throughout the body. […] Hereditary haemorrhagic telangiectasia is rare, occurring in approximately one in 5000-10,000 people. As the name suggests, this condition is inherited. A person who has HHT has a 50 per cent chance of passing it on to their child. […] Larger AVMs may occur in organs such as the lungs, liver and brain these AVMs can cause problems if they bleed. […] The diagnosis of hereditary haemorrhagic telangiectasia is based on the symptoms as well as genetic testing, which is available through specialised centres. […] A definite diagnosis requires 3 out of 4 criteria; 2 out of 4 means the disorder is suspected; while having only one criteria makes the diagnosis of HHT unlikely. […] If scans reveal AVMs in the brain or the lungs, the decision to have them treated depends on a number of factors, such as the site of the lesion, the risks of treatment and the age of the person.

• #78 Cure HHT – The Cornerstone of the HHT Community

  https://curehht.org/

  Hereditary Hemorrhagic Telangiectasia (HHT), also known as Osler-Weber-Rendu Syndrome, is an inherited disease that leads to malformed blood vessels in multiple organs of the body and typically begins with nosebleeds during childhood. HHT can result in serious health problems if not promptly diagnosed and treated. […] 1 in 5,000 Hereditary Hemorrhagic Telangiectasia (HHT) is a genetic disorder of the blood vessels that affects approximately 1 in 5,000 people worldwide. 90% of people with HHT are undiagnosed.

• #79 Hereditary Hemorrhagic Telangiectasia (Osler-Weber-Rendu Syndrome) | Cedars-Sinai

  https://www.cedars-sinai.org/health-library/diseases-and-conditions/h/hereditary-hemorrhagic-telangiectasia-osler-weber-rendu-syndrome.html

  Hereditary hemorrhagic telangiectasia is a type of arteriovenous malformation (AVM) caused by a change in the genes known as ACVRL1, ENG and SMAD4. The condition is inherited, and the patient needs to have only one copy of the abnormal gene from one parent in order to develop it. […] The condition is underdiagnosed, because some individuals have mild or no symptoms. Hereditary hemorrhagic telangiectasia is diagnosed in 1 out of every 5,000 people. The condition affects men and women equally and can be diagnosed at any age.

• #80 Hereditary Hemorrhagic Telangiectasia (HHT) > Fact Sheets > Yale Medicine

  https://www.yalemedicine.org/conditions/hht

  A condition that causes abnormally formed blood vessels, which increases risk for clots. […] Hereditary Hemorrhagic Telangiectasia (HHT) is a genetic disorder that affects the blood vessels. […] People with this genetic condition have multiple malformed blood vessel connections that bypass capillaries, which normally connect arteries to veins. […] In the absence of capillaries, direct links between arteries and veins (called telangiectasia when small and arteriovenous malformations [AVM], when larger) occur. […] HHT is a genetic disorder of the blood vessels that affects people of all ages and backgrounds. […] There are three main types of HHT: Type 1 is caused by mutations in the endoglin gene, Type 2 is caused by mutations in the ACVRL1 (ALK1) gene, HHT-juvenile polyposis syndrome is caused by mutations in the SMAD4 gene.

• #81 Cure HHT – The Cornerstone of the HHT Community

  https://curehht.org/

  Hereditary Hemorrhagic Telangiectasia (HHT), also known as Osler-Weber-Rendu Syndrome, is an inherited disease that leads to malformed blood vessels in multiple organs of the body and typically begins with nosebleeds during childhood. HHT can result in serious health problems if not promptly diagnosed and treated. […] 1 in 5,000 Hereditary Hemorrhagic Telangiectasia (HHT) is a genetic disorder of the blood vessels that affects approximately 1 in 5,000 people worldwide. 90% of people with HHT are undiagnosed.

• #82 Hereditary Hemorrhagic Telangiectasia (HHT) | UC San Diego Health

  https://health.ucsd.edu/care/blood-disorders/hht/

  HHT is an inherited condition that causes malformed blood vessels and pulmonary arteriovenous malformations (PAVM). […] An estimated 90 percent of those with HHT go undiagnosed, so it’s important that you recognize common signs and symptoms of the disorder: […] If you have signs and symptoms of HHT, we strongly recommend that you undergo a thorough screening and consultation to make sure your condition is correctly diagnosed and treated. […] We offer comprehensive treatment options to address all the different parts of the body that the disorder may affect, including:

• #83 Hereditary Hemorrhagic Telangiectasia (HHT) | University of Michigan Health

  https://www.uofmhealth.org/conditions-treatments/ear-nose-throat/hereditary-hemorrhagic-telangiectasia-hht

  Hereditary Hemorrhagic Telangiectasia (HHT) is a genetic disorder that affects about 1 in 5,000 to 1 in 10,000 people and commonly causes nosebleeds, with more frequent nosebleeds typically starting after about age 12. […] Patients with HHT have a tendency to form blood vessels that are abnormal, fragile, and bleed more easily. […] Over time, however, this genetic disorder can effect blood vessels in many areas of the body, including the nose, lungs, brain, gastrointestinal tract, skin, liver, and other organs. […] Complications from HHT can occasionally occur in patients with few or no symptoms at all. […] If you have a blood relative with the disease, and you are concerned you might have HHT, or would like to be certain, visit our Medical Genetics page to learn more about making an appointment to see our genetic counselors.

• #84 Pediatric hereditary hemorrhagic telangiectasia (HHT) or Osler-Weber-Rendu syndrome – Children’s Health

  https://www.childrens.com/specialties-services/conditions/hht

  HHT types 1, 2 and 3 don’t increase the likelihood of polyps. […] HHT is sometimes referred to as the „great masquerader” because children may not exhibit any symptoms. […] If children screen positive for vascular abnormalities, further testing will be ordered. […] Three out of four of the following criteria must be met before doctors will make a clinical diagnosis of HHT: Family history of a parent, sibling or child with HHT, recurrent nosebleeds, visible telangiectases on the mouth, lips, fingers and nose, AVMs in the lungs, spine, brain, digestive tract or liver.

• #85 Hereditary Hemorrhagic Telangiectasia – GeneReviews® – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK1351/

  Hereditary hemorrhagic telangiectasia (HHT) is characterized by the presence of multiple arteriovenous malformations (AVMs) that lack intervening capillaries and result in direct connections between arteries and veins. […] Identification of a heterozygous pathogenic variant in ACVRL1, ENG, or SMAD4 establishes the diagnosis if clinical features are inconclusive. […] HHT is inherited in an autosomal dominant manner with considerable intrafamilial variability. […] The clinical diagnosis of HHT can be established in a proband using criteria referred to as the Curaao criteria, which require three or more of the above suggestive findings. […] Molecular genetic testing approaches can include a combination of concurrent gene or serial single-gene testing, use of a multigene panel, and more comprehensive genomic testing. […] Currently, all known genetic defects that cause HHT are in genes that encode proteins within the transforming growth factor beta (TGF-) signaling pathway. […] Loss of function.

• #86 Hereditary Hemorrhagic Telangiectasia – HHT | Choose the Right Test

  https://arupconsult.com/content/hereditary-hemorrhagic-telangiectasia

  Hereditary hemorrhagic telangiectasia (HHT) is a rare autosomal dominant disorder characterized by multiple telangiectases in the skin and mucous membranes. […] Pathogenic variants of the ACVRL1 (also known as ALK1) and ENG genes are the most common causes of HHT. […] The diagnosis of hereditary hemorrhagic telangiectasia (HHT) is based on specific established clinical criteria. […] HHT is considered confirmed in individuals who meet three or more criteria, suspected in those who meet two criteria, and unlikely in those who meet a single criterion. […] For this reason, establishing a diagnosis by genetic testing is recommended in children born to a parent with confirmed HHT and a known causative variant. […] Identification of a heterozygous pathogenic variant in ACVRL1, ENG, or SMAD4 establishes the diagnosis of HHT.

• #87 Hereditary haemorrhagic telangiectasia – myDr.com.au

  https://mydr.com.au/heart-stroke/hereditary-haemorrhagic-telangiectasia/

  Hereditary haemorrhagic telangiectasia (HHT) is a condition where malformations of small blood vessels occur in multiple areas throughout the body. […] Hereditary haemorrhagic telangiectasia is rare, occurring in approximately one in 5000-10,000 people. As the name suggests, this condition is inherited. A person who has HHT has a 50 per cent chance of passing it on to their child. […] Larger AVMs may occur in organs such as the lungs, liver and brain these AVMs can cause problems if they bleed. […] The diagnosis of hereditary haemorrhagic telangiectasia is based on the symptoms as well as genetic testing, which is available through specialised centres. […] A definite diagnosis requires 3 out of 4 criteria; 2 out of 4 means the disorder is suspected; while having only one criteria makes the diagnosis of HHT unlikely. […] If scans reveal AVMs in the brain or the lungs, the decision to have them treated depends on a number of factors, such as the site of the lesion, the risks of treatment and the age of the person.

• #88 Hereditary Hemorrhagic Telangiectasia – HHT | Choose the Right Test

  https://arupconsult.com/content/hereditary-hemorrhagic-telangiectasia

  Hereditary hemorrhagic telangiectasia (HHT) is a rare autosomal dominant disorder characterized by multiple telangiectases in the skin and mucous membranes. […] Pathogenic variants of the ACVRL1 (also known as ALK1) and ENG genes are the most common causes of HHT. […] The diagnosis of hereditary hemorrhagic telangiectasia (HHT) is based on specific established clinical criteria. […] HHT is considered confirmed in individuals who meet three or more criteria, suspected in those who meet two criteria, and unlikely in those who meet a single criterion. […] For this reason, establishing a diagnosis by genetic testing is recommended in children born to a parent with confirmed HHT and a known causative variant. […] Identification of a heterozygous pathogenic variant in ACVRL1, ENG, or SMAD4 establishes the diagnosis of HHT.

• #89 Pediatric hereditary hemorrhagic telangiectasia (HHT) or Osler-Weber-Rendu syndrome – Children’s Health

  https://www.childrens.com/specialties-services/conditions/hht

  HHT types 1, 2 and 3 don’t increase the likelihood of polyps. […] HHT is sometimes referred to as the „great masquerader” because children may not exhibit any symptoms. […] If children screen positive for vascular abnormalities, further testing will be ordered. […] Three out of four of the following criteria must be met before doctors will make a clinical diagnosis of HHT: Family history of a parent, sibling or child with HHT, recurrent nosebleeds, visible telangiectases on the mouth, lips, fingers and nose, AVMs in the lungs, spine, brain, digestive tract or liver.

• #90 Hereditary Hemorrhagic Telangiectasia – GeneReviews® – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK1351/

  Hereditary hemorrhagic telangiectasia (HHT) is characterized by the presence of multiple arteriovenous malformations (AVMs) that lack intervening capillaries and result in direct connections between arteries and veins. […] Identification of a heterozygous pathogenic variant in ACVRL1, ENG, or SMAD4 establishes the diagnosis if clinical features are inconclusive. […] HHT is inherited in an autosomal dominant manner with considerable intrafamilial variability. […] The clinical diagnosis of HHT can be established in a proband using criteria referred to as the Curaao criteria, which require three or more of the above suggestive findings. […] Molecular genetic testing approaches can include a combination of concurrent gene or serial single-gene testing, use of a multigene panel, and more comprehensive genomic testing. […] Currently, all known genetic defects that cause HHT are in genes that encode proteins within the transforming growth factor beta (TGF-) signaling pathway. […] Loss of function.

• #91 Hereditary Hemorrhagic Telangiectasia – HHT | Choose the Right Test

  https://arupconsult.com/content/hereditary-hemorrhagic-telangiectasia

  Hereditary hemorrhagic telangiectasia (HHT) is a rare autosomal dominant disorder characterized by multiple telangiectases in the skin and mucous membranes. […] Pathogenic variants of the ACVRL1 (also known as ALK1) and ENG genes are the most common causes of HHT. […] The diagnosis of hereditary hemorrhagic telangiectasia (HHT) is based on specific established clinical criteria. […] HHT is considered confirmed in individuals who meet three or more criteria, suspected in those who meet two criteria, and unlikely in those who meet a single criterion. […] For this reason, establishing a diagnosis by genetic testing is recommended in children born to a parent with confirmed HHT and a known causative variant. […] Identification of a heterozygous pathogenic variant in ACVRL1, ENG, or SMAD4 establishes the diagnosis of HHT.

• #92 Hereditary Hemorrhagic Telangiectasia – GeneReviews® – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK1351/

  Hereditary hemorrhagic telangiectasia (HHT) is characterized by the presence of multiple arteriovenous malformations (AVMs) that lack intervening capillaries and result in direct connections between arteries and veins. […] Identification of a heterozygous pathogenic variant in ACVRL1, ENG, or SMAD4 establishes the diagnosis if clinical features are inconclusive. […] HHT is inherited in an autosomal dominant manner with considerable intrafamilial variability. […] The clinical diagnosis of HHT can be established in a proband using criteria referred to as the Curaao criteria, which require three or more of the above suggestive findings. […] Molecular genetic testing approaches can include a combination of concurrent gene or serial single-gene testing, use of a multigene panel, and more comprehensive genomic testing. […] Currently, all known genetic defects that cause HHT are in genes that encode proteins within the transforming growth factor beta (TGF-) signaling pathway. […] Loss of function.

• #93 Hereditary Hemorrhagic Telangiectasia – HHT | Choose the Right Test

  https://arupconsult.com/content/hereditary-hemorrhagic-telangiectasia

  Identification of a heterozygous pathogenic variant in GDF2 (also known as BMP9) establishes the diagnosis of an HHT-like telangiectasia syndrome. […] Identification of pathogenic variants in RASA1 and EPHB4 can be used to rule out the diagnosis of HHT and establish the diagnosis of capillary malformation-arteriovenous malformation syndrome (CM-AVM). […] A multigene panel that includes analysis of genes that cause either HHT (ACVRL1 and ENG) or a disorder with clinical overlap (SMAD4, GDF2, and genes that cause CM-AVM) can be used if clinical findings are inconclusive. […] Genetic testing should be offered to children of parents with HHT, even in the absence of symptoms.

• #94 For Patients | UNC HHT Center of Excellence

  https://www.med.unc.edu/hhtcenter/about-hht/

  Hereditary Hemorrhagic Telangiectasia (HHT) or Osler-Weber-Rendu Syndrome is an inherited disorder that causes abnormal development of some of the blood vessels in the body. […] HHT has an autosomal dominant inheritance which means that each child of someone with HHT has a 50% chance of inheriting HHT. […] Both children and adults with HHT are at an increased risk of cerebral hemorrhage, embolic stroke, seizures and brain abscess if brain and lung AVMs are not detected and treated. […] Other potential complications of HHT can include iron deficiency anemia, low oxygen levels, and pulmonary hypertension.

• #95 Hereditary hemorrhagic telangiectasia (HHT): Evaluation and therapy for specific vascular lesions – UpToDate

  https://www.uptodate.com/contents/hereditary-hemorrhagic-telangiectasia-hht-evaluation-and-therapy-for-specific-vascular-lesions

  Hereditary hemorrhagic telangiectasia (HHT; also called Osler-Weber-Rendu syndrome) is an autosomal dominant vascular disorder associated with a variety of clinical manifestations including mucocutaneous telangiectasia, epistaxis, gastrointestinal bleeding, and iron deficiency anemia. Arteriovenous malformations (AVMs) commonly occur in the pulmonary, hepatic, and cerebral circulations. […] This topic review discusses the management of vascular lesions in individuals with HHT, including epistaxis; gastrointestinal lesions; and pulmonary, hepatic, and cerebral AVMs. […] Other aspects of HHT care are discussed separately: Pathophysiology, epidemiology, and diagnosis – (See „Clinical manifestations and diagnosis of hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu syndrome).”) […] Screening for asymptomatic AVMs and testing and counseling of family members – (See „Hereditary hemorrhagic telangiectasia (HHT): Routine care including screening for asymptomatic AVMs.”)

• #96 Hereditary Hemorrhagic Telangiectasia – HHT | Choose the Right Test

  https://arupconsult.com/content/hereditary-hemorrhagic-telangiectasia

  Identification of a heterozygous pathogenic variant in GDF2 (also known as BMP9) establishes the diagnosis of an HHT-like telangiectasia syndrome. […] Identification of pathogenic variants in RASA1 and EPHB4 can be used to rule out the diagnosis of HHT and establish the diagnosis of capillary malformation-arteriovenous malformation syndrome (CM-AVM). […] A multigene panel that includes analysis of genes that cause either HHT (ACVRL1 and ENG) or a disorder with clinical overlap (SMAD4, GDF2, and genes that cause CM-AVM) can be used if clinical findings are inconclusive. […] Genetic testing should be offered to children of parents with HHT, even in the absence of symptoms.

• #97 Osler-Weber-Rendu Disease (Hereditary Hemorrhagic Telangiectasia) Treatment & Management: Approach Considerations, Treatment of Epistaxis, Treatment of Gastrointestinal Bleeding

  https://emedicine.medscape.com/article/2048472-treatment

  Children who have a parent with HHT carry a 50% chance of harboring the same genetic mutation. Accordingly, pulmonary AVM screening and long-term follow-up are advocated for these children, beginning in childhood. […] Studies recommend that women with HHT who conceive should be considered to have high-risk pregnancies because of rare major complications and improved survival outcome following prior recognition. […] Prospective trials aimed at determining ideal management of HHT have been limited by the small and varied population and by the multiorgan nature of the disease. A coordinated team approach is recommended. […] Preclinical work targeting endoglin (also known as CD105) has shown promising results in cancer-related research. […] In September 2020, the Second International Hereditary Hemorrhagic Telangiectasia (HHT) Guidelines, aimed at developing evidence-based consensus guidelines for the management and prevention of HHT-related symptoms and complications, were published.

• #98 Hereditary hemorrhagic telangiectasia – Wikipedia

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

  Hereditary hemorrhagic telangiectasia (HHT), also known as Osler-Weber-Rendu disease and Osler-Weber-Rendu syndrome, is a rare autosomal dominant genetic disorder that leads to abnormal blood vessel formation in the skin, mucous membranes, and often in organs such as the lungs, liver, and brain. […] HHT is transmitted in an autosomal dominant fashion, and occurs in one in 5,000-8,000 people in North America. […] Five genetic types of HHT are recognized. Of these, three have been linked to particular genes, while the two remaining have currently only been associated with a particular locus. More than 80% of all cases of HHT are due to mutations in either ENG or ACVRL1. […] Both ENG and ACVRL1 mutations lead predominantly to underproduction of the related proteins, rather than misfunctioning of the proteins.

• #99

  https://umiamihealth.org/en/treatments-and-services/interventional-radiology/vascular-disease/hereditary-hemorrhagic-telangiectasia-(hht)

  Hereditary Hemorrhagic Telangiectasia (HHT, also known as Osler-Weber-Rendu Syndrome) is a complex disease involving malformed blood vessels that can impact multiple organ systems. […] HHT is caused by an autosomal dominant genetic mutation. There are different mutations in each of the three genes known to cause HHT. This condition does not skip a generation, and each child born to an HHT parent has a 50% chance of inheriting the genetic mutation.

• #100 Hereditary Hemorrhagic Telangiectasia: Genetics, Pathophysiology, Diagnosis, and Management

  https://www.mdpi.com/2077-0383/11/17/5245

  Hereditary hemorrhagic telangiectasia (HHT), also known as Rendu–Osler–Weber Syndrome, is a rare disease characterized by multisystemic vascular dysplasia. This disease is caused, in approximately 90% of cases, by a heterozygous mutation of the endoglin gene (ENG) or the activin-like receptor kinase 1, called ALK1 (also known as ACVRL1), characterized by an autosomal dominant inheritance pattern. Disruption of the ENG gene, located on chromosome 9 (9q3.3-q3.4), causes HHT type 1 (HHT1), while mutation of the ACVRL1 gene, located on chromosome 12 (12q13), causes HHT type 2 (HHT2). The haploinsufficiency model in HHT is the most accepted theory for the pathogenesis of disease development. It is explained by the fact that mutations in ENG and ACVRL1 genes generate altered proteins that fail to be expressed in the cell membranes of endothelial cells. There have been more than 900 mutations described on the ENG and ACVRL1 genes including deletions, insertions, nonsense, missense, and splice site mutations. This lack of protein expression results in impairment on routes via ENG or ACVRL1 that normally enhances endothelial migration and proliferation. Importantly, animal models show that involvement of the endoglin and ALK1 pathways will also lead to a decrease in ALK5 pathway activity as a possible adaptation response to compensate the reduced expression of endoglin and ALK1.

• #101 Hereditary haemorrhagic telangiectasia | Nature Reviews Disease Primers

  https://www.nature.com/articles/s41572-024-00585-z

  Hereditary haemorrhagic telangiectasia (HHT) is a vascular dysplasia inherited as an autosomal dominant trait and caused by loss-of-function pathogenic variants in genes encoding proteins of the BMP signalling pathway. Up to 90% of disease-causal variants are observed in ENG and ACVRL1, with SMAD4 and GDF2 less frequently responsible for HHT. […] Management goals encompass control of epistaxis and intestinal bleeding from telangiectases, screening for and treatment of iron deficiency (with or without anaemia) and AVMs, genetic counselling and evaluation of at-risk family members. […] Although HHT is associated with increased morbidity, the appropriate screening and treatment of visceral AVMs, and the effective management of bleeding and anaemia, improves quality of life and overall survival.

• #102 Hereditary Hemorrhagic Telangiectasia (HHT) – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK578186/

  Hereditary hemorrhagic telangiectasias (HHT) is an autosomal dominant bleeding disorder caused by malformed vessels. […] HHT is an autosomal dominant disorder affecting blood vessels within multiple organ systems. The condition is suspected of haploinsufficiency, where 1 functional gene copy cannot produce the required protein to preserve function. […] In 97% of patients with a definite clinical HHT diagnosis, a causative mutation is identified in 1 of 3 genes described below. […] These mutations disrupt signaling by transforming growth factor-beta (TGF-B), essential for maintaining vascular integrity. […] HHT1 stems from mutations in the gene ENG, which codes for endoglin on chromosome 9. […] HHT2 results from Activin A receptor-like type I (ACVRL1) mutations, which codes for the protein activin receptor-like kinase 1 (ALK1) on chromosome 12.

• #103

  https://www.jci.org/articles/view/176379

  Together, mutations in ENG, ACVRL1, and SMAD4 are responsible for more than 90% of HHT cases, leaving a minority of clinically diagnosed individuals with an unknown genetic basis. […] In some cases, this can be attributed to limitations of current sequencing technologies in detecting certain variants in the previously identified loci or to the exclusion of testing noncoding regions; however, additional chromosomal loci could also be implicated in HHT development. […] The LOF nature of HHT causal mutations and the autosomal dominant inheritance of the disease led to the longstanding belief that HHT is caused by haploinsufficiency of the mutated gene product. […] However, the haploinsufficiency model does not explain why HHT vascular lesions develop focally in characteristic vascular beds despite the presence of the germline HHT causal mutation in all endothelial cells of the body.

• #104

  https://www.jci.org/articles/view/176379

  These disparities put forth the second-hit hypothesis in HHT, which is becoming more and more accepted by the HHT scientific community. […] This hypothesis implies that the germline mutation (first hit) predisposes the endothelium to vascular defects that strictly develop in the presence of additional, local factors (second hit) that could be either environmental or genetic. […] Several preclinical studies have demonstrated the role of proangiogenic and proinflammatory triggers in driving HHT pathogenesis. […] In addition to the well-documented HHT symptoms, i.e., epistaxis, telangiectases, and AVMs, HHT patients exhibit a heightened infectious risk in soft tissues, bones, and joints involving Staphylococcus aureus as well as cerebral infections involving bacteria from the orodigestive flora. […] HHT is also associated with immunological abnormalities, mainly characterized by a T-helper lymphopenia, although these abnormalities lack clear correlation with the aforementioned infectious risks.

• #105

  https://haematologica.org/article/view/8582

  In patients with HHT, mutations in endoglin, ALK1, or one of several other proteins in this pathway alter the normal endothelial response. […] The haploinsufficiency of these proteins along with a second hit, such as tissue injury, infection or hypoxia, likely cause the focal vascular lesions of HHT1 and HHT2 as reduced levels of endoglin or ALK1 cannot maintain the balance needed for normal blood vessel formation. […] Vascular endothelial growth factor, an endothelial-specific factor for angiogenesis, is of major interest in diseases of vascular malformation and is elevated in HHT patients. […] Therefore, any mutation along the ALK1 pathway (BMP9, ACVRL1, ENG, MADH4) results in elevation of VEGF through reduced ALK1 pathway signaling. […] While this is a simplified discussion of complex vascular biology, it illustrates why mutations in ENG, ACVRL1/ALK1, MADH4/SMAD4, and BMP9/GDF2 result in the HHT phenotype.

• #106

  https://haematologica.org/article/view/8582

  In patients with HHT, mutations in endoglin, ALK1, or one of several other proteins in this pathway alter the normal endothelial response. […] The haploinsufficiency of these proteins along with a second hit, such as tissue injury, infection or hypoxia, likely cause the focal vascular lesions of HHT1 and HHT2 as reduced levels of endoglin or ALK1 cannot maintain the balance needed for normal blood vessel formation. […] Vascular endothelial growth factor, an endothelial-specific factor for angiogenesis, is of major interest in diseases of vascular malformation and is elevated in HHT patients. […] Therefore, any mutation along the ALK1 pathway (BMP9, ACVRL1, ENG, MADH4) results in elevation of VEGF through reduced ALK1 pathway signaling. […] While this is a simplified discussion of complex vascular biology, it illustrates why mutations in ENG, ACVRL1/ALK1, MADH4/SMAD4, and BMP9/GDF2 result in the HHT phenotype.

• #107 Osler-Weber-Rendu Disease (Hereditary Hemorrhagic Telangiectasia) Treatment & Management: Approach Considerations, Treatment of Epistaxis, Treatment of Gastrointestinal Bleeding

  https://emedicine.medscape.com/article/2048472-treatment

  Children who have a parent with HHT carry a 50% chance of harboring the same genetic mutation. Accordingly, pulmonary AVM screening and long-term follow-up are advocated for these children, beginning in childhood. […] Studies recommend that women with HHT who conceive should be considered to have high-risk pregnancies because of rare major complications and improved survival outcome following prior recognition. […] Prospective trials aimed at determining ideal management of HHT have been limited by the small and varied population and by the multiorgan nature of the disease. A coordinated team approach is recommended. […] Preclinical work targeting endoglin (also known as CD105) has shown promising results in cancer-related research. […] In September 2020, the Second International Hereditary Hemorrhagic Telangiectasia (HHT) Guidelines, aimed at developing evidence-based consensus guidelines for the management and prevention of HHT-related symptoms and complications, were published.

• #108 Hereditary hemorrhagic telangiectasia, embolization, and Young’s procedure: oral surgical management | Journal of Oral Medicine and Oral Surgery

  https://www.jomos.org/articles/mbcb/full_html/2018/02/mbcb170009/mbcb170009.html

  Hereditary hemorrhagic telangiectasia (HHT) is a genetic vascular dysplasia. […] HHT, also called OWRD, is a constitutional vascular dysplasia. It is a rare genetic disease, affecting approximately 1 in 5000 individuals. […] It is linked to an angiogenesis disorder that causes arteriovenous malformations and frequent nosebleeds. […] The management of patients affected by HHT needs rigorous hemostatic methods and outpatient postoperative monitoring. […] HHT has serious orofacial implications. […] The hemorrhagic risk: This is linked to capillary fragility. […] Youngs operation is a technique used for severe epistaxis. […] A previous study has reported on treating HHT with thalidomide and antiangiogenic agents (bevacizumab).

• #109 Hereditary haemorrhagic telangiectasia | Nature Reviews Disease Primers

  https://www.nature.com/articles/s41572-024-00585-z

  Hereditary haemorrhagic telangiectasia (HHT) is a vascular dysplasia inherited as an autosomal dominant trait and caused by loss-of-function pathogenic variants in genes encoding proteins of the BMP signalling pathway. Up to 90% of disease-causal variants are observed in ENG and ACVRL1, with SMAD4 and GDF2 less frequently responsible for HHT. […] Management goals encompass control of epistaxis and intestinal bleeding from telangiectases, screening for and treatment of iron deficiency (with or without anaemia) and AVMs, genetic counselling and evaluation of at-risk family members. […] Although HHT is associated with increased morbidity, the appropriate screening and treatment of visceral AVMs, and the effective management of bleeding and anaemia, improves quality of life and overall survival.

• #110 Hereditary Hemorrhagic Telangiectasia (HHT)

  https://www.uabmedicine.org/specialties/hereditary-hemorrhagic-telangiectasia/

  Hereditary hemorrhagic telangiectasia, or HHT, is a rare genetic (runs in families) disorder that affects the blood vessels. […] HHT may cause blood vessels to form without capillaries, the tiny vessels between arteries and veins, so blood passes directly from arteries to veins. […] HHT also can lead to a condition called telangiectasia (spider veins), in which enlarged or broken blood vessels in the skin appear as delicate red or purplish spots on the legs, hands, fingertips, face, lips, lining of the mouth, or nose. […] The symptoms may not be obvious, so genetic testing is needed to accurately diagnose HHT. […] Nosebleeds are the most common symptom, and bleeding in the stomach or intestines is another possible sign of HHT. […] There is no cure, but effective treatments are available. […] Therapy for HHT usually involves treating the symptoms, including controlling bleeding and anemia (low levels of red blood cells in the blood) and preventing complications from abnormal artery-vein connections in the brain, spine, lungs, and other areas of the body.

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