Zespół edwardsa (trisomia 18) – Etiologia i przyczyny

Zespół edwardsa (trisomia 18)
Etiologia i przyczyny

Zespół Edwardsa (trisomia 18) to genetyczne zaburzenie spowodowane obecnością dodatkowego chromosomu 18, najczęściej w wyniku nierozdzielenia chromosomów podczas mejozy II u matki (około 90% przypadków). Wyróżnia się trzy typy trisomii 18: pełną (94%), mozaikową (5%) oraz częściową (2%), z których pełna forma wiąże się z najcięższym fenotypem i wysoką śmiertelnością. Krytyczny region dla fenotypu trisomii 18 to długie ramię chromosomu 18 od q11.2. Ryzyko wystąpienia zespołu wzrasta wraz z wiekiem matki, szczególnie powyżej 35. roku życia, a także nieznacznie z wiekiem ojca. Częstość występowania trisomii 18 wśród żywych urodzeń wynosi około 1:3000-8000, z wyraźną przewagą u dziewczynek (3:1), co wynika z wyższej śmiertelności wewnątrzmacicznej płodów męskich. W około 2% przypadków etiologia jest związana z translokacją chromosomową, co wymaga badania kariotypu rodziców w celu oceny ryzyka dziedziczenia.

Etiologia Zespołu Edwardsa (trisomii 18)

Zespół Edwardsa (trisomia 18) to rzadkie zaburzenie genetyczne, charakteryzujące się obecnością dodatkowego materiału genetycznego z chromosomu 18. Jest to druga co do częstości występowania trisomia autosomalna występująca u żywo urodzonych dzieci, zaraz po zespole Downa (trisomia 21).¹² Choroba została po raz pierwszy opisana w 1960 roku przez Johna Hiltona Edwardsa, brytyjskiego genetyka medycznego.³⁴

Mechanizm powstawania trisomii 18

Podstawową przyczyną zespołu Edwardsa jest obecność dodatkowego (trzeciego) chromosomu 18 w komórkach organizmu zamiast typowych dwóch kopii.⁵ Ten dodatkowy materiał genetyczny zakłóca prawidłowy przebieg rozwoju, powodując charakterystyczne cechy i wady związane z trisomią 18.⁶ Większość przypadków trisomii 18 jest wynikiem błędu w podziale komórkowym nazywanym nierozdzieleniem (nondisjunction), który występuje podczas tworzenia się komórek rozrodczych (gamet) – jaj lub plemników.⁷⁸

Nierozdzielenie chromosomów powoduje, że komórka rozrodcza zawiera dwie kopie chromosomu 18 zamiast jednej. Po zapłodnieniu normalną gametą partnera (zawierającą jedną kopię chromosomu 18), powstaje zygota z trzema kopiami chromosomu 18, co prowadzi do rozwoju zespołu Edwardsa.⁹¹⁰ Proces ten może zachodzić w różnych etapach podziału komórkowego:

Podczas mejozy I lub II w procesie tworzenia się komórek jajowych lub plemników
Podczas mitozy po zapłodnieniu, we wczesnym rozwoju zarodka

⁸¹¹

W około 90% przypadków trisomii 18, dodatkowy chromosom 18 pochodzi od matki, a około 50% błędów nierozdzielenia w oogenezii zachodzi podczas mejozy II, co jest rzadsze w porównaniu z innymi trisomiami ludzkimi, gdzie nieprawidłowa segregacja chromosomów częściej występuje w mejozie I.⁸¹²

Rodzaje trisomii 18

Istnieją trzy główne typy zespołu Edwardsa, różniące się zarówno pod względem mechanizmu powstania, jak i obrazu klinicznego:²

Pełna trisomia 18 (około 94% przypadków) – każda komórka organizmu zawiera trzy pełne kopie chromosomu 18. Jest to najcięższa postać zespołu, związana z wysoką śmiertelnością i najpoważniejszymi wadami rozwojowymi.¹³¹⁴
Mozaikowa trisomia 18 (około 5% przypadków) – część komórek organizmu zawiera trzy kopie chromosomu 18, a pozostałe komórki mają prawidłową liczbę chromosomów. Fenotyp może być bardzo zróżnicowany – od pełnego obrazu zespołu Edwardsa z wczesną śmiertelnością do fenotypu niemal prawidłowego, w zależności od proporcji komórek z trisomią.²¹⁵
Częściowa trisomia 18 (około 2% przypadków) – obecny jest tylko fragment chromosomu 18q w trzech kopiach, często w wyniku zrównoważonej translokacji lub inwersji występującej u jednego z rodziców. Fenotyp jest zmienny w zależności od lokalizacji i wielkości powielonego fragmentu.¹⁶¹⁷

Za krytyczny region dla fenotypu trisomii 18 uważa się obszar długiego ramienia chromosomu 18 począwszy od regionu q11.2, chociaż istnieją pewne kontrowersyjne dane na ten temat.¹⁸¹⁶

Czynniki ryzyka trisomii 18

Większość przypadków trisomii 18 występuje sporadycznie i nie jest dziedziczona.¹⁹ Najważniejszymi czynnikami ryzyka związanymi z wystąpieniem zespołu Edwardsa są:

Zaawansowany wiek matki – ryzyko wystąpienia trisomii 18 wzrasta wraz z wiekiem matki, podobnie jak w przypadku innych trisomii autosomalnych. Jest to związane ze zwiększoną częstością występowania błędów nierozdzielenia chromosomów podczas oogenezy u starszych kobiet.²⁰⁸
Zaawansowany wiek ojca – zaobserwowano również niewielki pozytywny związek między wiekiem ojca a ryzykiem wystąpienia trisomii 18, podobny do obserwowanego w zespole Downa.¹⁸
Wcześniejsze urodzenie dziecka z trisomią – rodzice, którzy mieli dziecko z trisomią 18, mają nieznacznie zwiększone ryzyko posiadania kolejnego dziecka z tym zaburzeniem (około 1% powyżej ryzyka związanego z wiekiem matki).⁴
Nosicielstwo zrównoważonej translokacji – w rzadkich przypadkach, gdy jeden z rodziców jest nosicielem zrównoważonej translokacji obejmującej chromosom 18, ryzyko urodzenia dziecka z częściową trisomią 18 jest znacznie wyższe.¹¹¹³

Badania genetyczne przyczyn zespołu Edwardsa

Badania nad dokładnymi mechanizmami molekularnymi prowadzącymi do nierozdzielenia chromosomów w trisomii 18 wciąż trwają. Dotychczasowe badania sugerują pewne potencjalne czynniki genetyczne, które mogą przyczyniać się do tego zaburzenia:

Opisano wyższą częstość występowania polimorfizmów genu reduktazy metylenotetrahydrofolianowej (MTHFR) u matek płodów z trisomią 18 w porównaniu z innymi grupami, chociaż wynik ten nie został jeszcze potwierdzony w innych badaniach.¹⁴
Badania przeprowadzone przez RIKEN i Uniwersytet Zdrowia Fujita sugerują, że nierozdzielenie chromosomów może być związane ze zmniejszeniem czynników pomagających utrzymać prawidłowy status chromosomów wraz z wiekiem.²¹

Warto podkreślić, że zespół Edwardsa nie jest wynikiem czegokolwiek, co rodzice zrobili lub czego nie zrobili przed lub w trakcie ciąży. Jest to przypadkowy błąd w podziale komórkowym, który jest nieprzewidywalny.²²²³ Nie ma obecnie znanego sposobu zapobiegania wystąpieniu trisomii 18, ponieważ jest to zaburzenie genetyczne.²³²⁴

Genetyczne podłoże Zespołu Edwardsa

Zespół Edwardsa (trisomia 18) to złożone zaburzenie genetyczne wynikające z obecności dodatkowego materiału chromosomowego. Dokładne zrozumienie genetycznego podłoża tej choroby jest kluczowe dla właściwej diagnostyki i poradnictwa genetycznego.⁹⁶

Molekularne mechanizmy nierozdzielenia chromosomów

Głównym mechanizmem prowadzącym do powstania trisomii 18 jest nierozdzielenie (nondisjunction) chromosomów podczas podziału komórkowego.²⁵ Proces ten może wystąpić na różnych etapach:

Nierozdzielenie podczas mejozy – występuje w procesie tworzenia gamet (komórek rozrodczych). W prawidłowym podziale mejotycznym każda gameta otrzymuje pojedynczą kopię chromosomu 18. W przypadku nierozdzielenia, jedna z gamet otrzymuje dwie kopie chromosomu 18, a druga nie otrzymuje żadnej.²⁶
Nierozdzielenie podczas mitozy – zachodzi po zapłodnieniu, we wczesnych etapach rozwoju zarodka, prowadząc zazwyczaj do trisomii mozaikowej.¹²

W około 90% przypadków trisomii 18, błąd nierozdzielenia pochodzi od matki i często występuje podczas mejozy II.⁷ Jest to interesująca różnica w porównaniu z innymi trisomiami, gdzie błędy częściej zachodzą podczas mejozy I.⁸

Translokacje chromosomowe w trisomii 18

W około 2% przypadków zespołu Edwardsa, zaburzenie jest wynikiem translokacji chromosomowej.¹⁶ Translokacja występuje, gdy fragment chromosomu 18 przyłącza się do innego chromosomu. Może to nastąpić na dwa sposoby:

De novo translokacja – powstaje spontanicznie podczas formowania się gamet lub wczesnego rozwoju zarodka
Dziedziczna translokacja – jeden z rodziców jest nosicielem zrównoważonej translokacji, co oznacza, że całkowita ilość materiału genetycznego jest prawidłowa, ale część chromosomu 18 jest przyłączona do innego chromosomu⁶²⁷

W przypadku translokacji dziedzicznej, rodzic będący nosicielem zazwyczaj nie ma objawów choroby, ponieważ posiada normalną ilość materiału genetycznego, tylko inaczej zorganizowaną. Jednak istnieje 50% ryzyko, że każde potomstwo odziedziczy niezrównoważoną translokację, prowadzącą do częściowej trisomii 18.²⁷

Trisomia mozaikowa

Mozaikowa trisomia 18 występuje, gdy nierozdzielenie chromosomów zachodzi po zapłodnieniu, podczas wczesnych podziałów zarodka.²⁸ W rezultacie tylko część komórek organizmu zawiera dodatkowy chromosom 18, podczas gdy pozostałe komórki mają prawidłowy kariotyp.

Stopień nasilenia objawów klinicznych w mozaikowej trisomii 18 jest bardzo zróżnicowany i zależy od proporcji komórek z trisomią oraz ich rozmieszczenia w różnych tkankach organizmu.² Fenotyp może wahać się od klasycznego obrazu zespołu Edwardsa do prawie normalnego wyglądu i funkcjonowania.²⁹

Krytyczne regiony chromosomu 18

Badania nad częściową trisomią 18 pozwoliły zidentyfikować potencjalne krytyczne regiony chromosomu 18, których potrojenie jest odpowiedzialne za charakterystyczny fenotyp zespołu Edwardsa. Region długiego ramienia chromosomu 18 (18q) począwszy od obszaru q11.2 został zaproponowany jako krytyczny dla fenotypu trisomii 18, choć istnieją pewne kontrowersyjne dane na ten temat.¹⁷¹⁶

Zależność między genotypem a fenotypem w trisomii 18 jest złożona, a dodatkowy materiał genetyczny z chromosomu 18 zaburza ekspresję i interakcję różnych genów, co prowadzi do nieprawidłowego rozwoju i funkcjonowania organizmu.²⁶

Dziedziczenie trisomii 18

Większość przypadków trisomii 18 (pełnej i mozaikowej) nie jest dziedziczna i występuje sporadycznie.⁶ Ryzyko ponownego wystąpienia trisomii 18 w kolejnej ciąży jest tylko nieznacznie zwiększone (około 1%) w porównaniu z ogólnym ryzykiem populacyjnym skorygowanym o wiek matki.⁴

Jedyną formą trisomii 18, która może być dziedziczona, jest częściowa trisomia 18 wynikająca z translokacji. W takich przypadkach zaleca się badania chromosomalne u obojga rodziców w celu wykrycia potencjalnego nosicielstwa zrównoważonej translokacji.¹³

Warto podkreślić, że zespół Edwardsa nie jest spowodowany przez żadne działania lub zaniechania rodziców przed lub w trakcie ciąży.³⁰ Jest to wynik przypadkowego błędu w podziale komórkowym, który może wystąpić u każdej pary planującej dziecko.³¹

Epidemiologia Zespołu Edwardsa

Zespół Edwardsa (trisomia 18) jest drugim najczęściej występującym zespołem trisomii autosomalnej u żywo urodzonych dzieci, zaraz po zespole Downa (trisomia 21).¹ Dokładne dane epidemiologiczne są kluczowe dla zrozumienia skali problemu i planowania odpowiedniej opieki medycznej.³²

Częstotliwość występowania

Częstość występowania trisomii 18 wśród żywych urodzeń szacuje się na około:

1 na 3000-8000 żywych urodzeń według różnych źródeł⁴³³
1 na 5000 żywych urodzeń według innych badań³⁴³
1 na 6000-8000 żywych urodzeń według kolejnych źródeł³⁵

Warto zauważyć, że częstość występowania trisomii 18 wśród wszystkich poczęć jest znacznie wyższa, ponieważ około 95% płodów z trisomią 18 ulega samoistnym poronieniom lub obumiera wewnątrzmacicznie.¹³⁶

Rozkład płci

Zauważalna jest wyraźna dysproporcja w częstości występowania zespołu Edwardsa między płciami:

Trisomia 18 występuje około trzy razy częściej u dziewczynek niż u chłopców³⁷

Ta dysproporcja może wynikać z wyższej śmiertelności wewnątrzmacicznej płodów męskich z trisomią 18, co prowadzi do częstszego rozpoznawania zespołu u płodów żeńskich i żywo urodzonych dziewczynek.³⁷

Związek z wiekiem matki

Istnieje wyraźny związek między wiekiem matki a ryzykiem wystąpienia trisomii 18:

Ryzyko wystąpienia trisomii 18 wzrasta wraz z wiekiem matki²⁰³⁸
Szczególnie znaczący wzrost ryzyka obserwuje się u kobiet powyżej 35. roku życia³⁹⁴⁰

Ten związek z wiekiem matki wynika z wyższej częstości występowania błędów nierozdzielenia chromosomów podczas oogenezy u starszych kobiet.⁸ Zaobserwowany wzrost ogólnej częstości występowania trisomii 18 w ostatnich latach jest prawdopodobnie związany ze zmianami w strukturze wiekowej matek w tym okresie.¹⁷

Różnice geograficzne i etniczne

Dotychczasowe badania nie wykazały znaczących różnic w częstości występowania trisomii 18 między różnymi grupami etnicznymi czy geograficznymi. Zespół Edwardsa występuje z podobną częstością we wszystkich populacjach na świecie.³¹

Tendencje i zmiany w epidemiologii

W ostatnich dekadach zaobserwowano pewne zmiany w epidemiologii zespołu Edwardsa:

Wzrost średniego wieku matek w wielu krajach przyczynił się do zwiększenia częstości występowania trisomii 18³⁸
Upowszechnienie prenatalnych badań przesiewowych i diagnostycznych umożliwiło wcześniejsze wykrywanie trisomii 18, co wpłynęło na dane epidemiologiczne¹⁵

Zmiany w podejściu do leczenia noworodków z trisomią 18, szczególnie w krajach takich jak USA i Japonia, gdzie zapewnia się szybką intensywną opiekę, mogą wpływać na wskaźniki przeżywalności i tym samym na dane epidemiologiczne.⁴¹

Przyczyny śmiertelności w Zespole Edwardsa

Zespół Edwardsa (trisomia 18) charakteryzuje się wysoką śmiertelnością, zarówno w okresie prenatalnym, jak i po urodzeniu. Zrozumienie głównych przyczyn zgonów jest istotne dla optymalizacji opieki medycznej nad pacjentami z tym zespołem.⁴²¹

Śmiertelność wewnątrzmaciczna

Znaczna część płodów z trisomią 18 nie przeżywa do urodzenia:

Około 95% zarodków i płodów z trisomią 18 ulega samoistnym poronieniom lub wewnątrzmacicznemu obumarciu¹
Trisomia chromosomu 18 jest częstą przyczyną poronień samoistnych w pierwszym trymestrze ciąży⁴³

Główne przyczyny śmiertelności wewnątrzmacicznej obejmują poważne wady rozwojowe, w tym wady serca i innych narządów wewnętrznych, które uniemożliwiają prawidłowy rozwój płodu.⁴⁴

Przyczyny zgonów w okresie noworodkowym

Wśród dzieci z trisomią 18, które urodziły się żywe, główne przyczyny zgonów w okresie noworodkowym to:

Nagła śmierć z powodu centralnego bezdechu – zaburzenia neurologiczne prowadzące do zatrzymania oddychania¹³²⁹
Niewydolność serca – wynikająca z wrodzonych wad serca, które występują u większości pacjentów z trisomią 18⁴²¹³
Niewydolność oddechowa – spowodowana hipowentylacją, aspiracją, niedrożnością górnych dróg oddechowych lub kombinacją tych czynników¹³

Wskaźniki przeżywalności

Przeżywalność dzieci z zespołem Edwardsa jest niska, ale wykazuje pewne zróżnicowanie w zależności od typu trisomii i dostępnej opieki medycznej:

Około 50% noworodków z trisomią 18 nie przeżywa pierwszego tygodnia życia³⁷
5-10% dzieci przeżywa ponad rok⁴⁵¹
Wskaźniki przeżywalności dla dzieci z trisomią 18 wynoszą około 60-75% po pierwszym tygodniu, spadają do około 20-40% po miesiącu i utrzymują się na poziomie około 10% po roku²⁹

Dzieci z mozaikową lub częściową trisomią 18 mają lepsze rokowanie niż dzieci z pełną trisomią 18.⁴¹ Wskaźniki przeżywalności mogą się poprawiać dzięki zmianom w podejściu do leczenia noworodków z trisomią 18, szczególnie w krajach, gdzie zapewnia się szybką intensywną opiekę.⁴¹

Czynniki wpływające na przeżywalność

Na przeżywalność dzieci z zespołem Edwardsa wpływają różne czynniki:

Typ trisomii – dzieci z mozaikową lub częściową trisomią 18 mają lepsze rokowanie⁴¹
Rodzaj i nasilenie wad wrodzonych – szczególnie istotne są wady serca i układu oddechowego¹
Dostępność i jakość opieki medycznej – w tym szybkość interwencji i dostęp do intensywnej terapii⁴¹

Należy zaznaczyć, że nie ma obecnie znanego leczenia przyczynowego, które mogłoby poprawić rokowanie dla dziecka z trisomią 18.³⁴ Dostępne metody leczenia mają charakter objawowy i paliatywny, koncentrując się na zapewnieniu jak najlepszej jakości życia.²²⁴⁶

Wysoka śmiertelność w trisomii 18 jest bezpośrednio związana z poważnymi zaburzeniami rozwojowymi wywołanymi przez obecność dodatkowego materiału genetycznego z chromosomu 18, który zakłóca prawidłowy rozwój i funkcjonowanie wielu układów i narządów.²⁶

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Materiały źródłowe

#1 Trisomy 18: Practice Essentials, Pathophysiology, Epidemiology
https://emedicine.medscape.com/article/943463-overview
Trisomy 18 is characterized by severe psychomotor and growth retardation, microcephaly, microphthalmia, malformed ears, micrognathia or retrognathia, microstomia, distinctively clenched fingers, and other congenital malformations. Among liveborn children, it is the second most common autosomal trisomy after trisomy 21. […] Trisomy 18 was independently described by Edwards et al and Smith et al, in 1960. […] The high mortality rate in trisomy 18 is usually due to the presence of cardiac and renal malformations, feeding difficulties, sepsis, and apnea caused by CNS defects. Severe psychomotor and growth retardation are invariably present in those who survive beyond infancy. […] Approximately 95% of conceptuses with trisomy 18 die as embryos or fetuses; 5-10% of affected children survive beyond the first year of life.
#2 Edwards Syndrome – StatPearls – NCBI Bookshelf
https://www.ncbi.nlm.nih.gov/books/NBK570597/
Edwards syndrome typically results from an extra copy of chromosome 18q. There are 3 types of Edwards syndrome: complete trisomy 18, partial trisomy 18, and mosaic trisomy 18. […] Complete trisomy 18 is the most common form (94%). In this type, every cell contains 3 complete copies of chromosome 18. The extra chromosome is due to nondisjunction, mostly during meiosis II. The extra chromosome is most often of maternal origin. The frequency of nondisjunction errors increases with advancing maternal age. […] Mosaic trisomy 18 is the second most common type (5%). In this type, both a complete trisomy 18 and a normal cell line exist. Thus, the phenotype can range from a complete trisomy 18 phenotype with early mortality to a normal phenotype. […] Partial trisomy 18 accounts for 2% of Edwards syndrome. In this type, only a partial segment of chromosome 18q is present in triplicate. The partial triplicate often results from a balanced translocation or inversion carried by 1 of the parents. The phenotype of partial trisomy 18 is variable based on the location and extent of the triplicated segment.
#3 Trisomy 18 (Edwards Syndrome) | Embryo Project Encyclopedia
https://embryo.asu.edu/pages/trisomy-18-edwards-syndrome
John Hilton Edwards first described the symptoms of the genetic disorder known as Trisomy 18one of the most common forms of human trisomy, which occurs when cells have an extra copy of a chromosome, in 1960. […] The presence of an extra copy of chromosome 18 is a genetic anomaly that arises during the production of sperm and egg cells in either meiosis I, or more commonly meiosis II. Trisomy 18 results from defects in the mothers eggs in 90 percent of its cases; further, the incidence rate increases with maternal age. […] Most instances of Trisomy 18 are full trisomies, meaning that every cell in the childs body has the extra chromosome 18. […] Although most medical literature that refers to Trisomy 18 discusses it as a disease linked to a full trisomy of chromosome 18, partial and mosaic trisomies of the chromosome also exist. […] Additionally, a form of Trisomy 18, known as translocation trisomydefined by an extra chromosomes attachment to another, independent chromosomeoccurs in 2 percent of cases. […] Though the severity of the symptoms of Trisomy 18 ranges from fatal to manageable, the disorder is currently incurable.
#4 Edwards syndrome | Radiology Reference Article | Radiopaedia.org
https://radiopaedia.org/articles/edwards-syndrome-1?lang=us
Edwards syndrome, also known as trisomy 18, along with Down syndrome (trisomy 21) and Patau syndrome (trisomy 13), make up the only three autosomal trisomies to be compatible with extrauterine life in non-mosaic forms, albeit in the case of Edward syndrome only for a week or so. […] After Down syndrome, it is the second most common autosomal trisomy and the overall incidence is estimated to be at ~1:3000-8000. There is an increase in incidence with increasing maternal age. […] The syndrome carries an extremely poor prognosis with a mean infant survival of 48 days. The risk of recurrence for a future pregnancy is ~1% greater than that adjusted for maternal age. […] The syndrome was first described by John Hilton Edwards, a British medical geneticist. Historically it was also called E-trisomy or trisomy E.
#5 Edwards Syndrome (Trisomy 18): Genetic Condition, Symptoms & Outlook
https://my.clevelandclinic.org/health/diseases/22172-edwards-syndrome
Edwards syndrome (trisomy 18) is a genetic condition that causes physical growth delays during fetal development. […] The condition occurs when a person has an extra copy of chromosome 18, which is random and unpredictable. […] Having three copies of chromosome 18 instead of the typical two causes Edwards syndrome (trisomy 18). […] The incorrect number of chromosomes is unpredictable and random and isn’t the result of something the parents did before or during pregnancy. […] When a third copy of a cell joins a pair, a trisomy occurs. Trisomy means three bodies. If someone receives an Edwards syndrome diagnosis, they have a third copy of chromosome 18 in their cells.
#6 Trisomy 18: MedlinePlus GeneticsLock
https://medlineplus.gov/genetics/condition/trisomy-18/
Trisomy 18, also called Edwards syndrome, is a chromosomal condition associated with abnormalities in many parts of the body. […] Most cases of trisomy 18 result from having three copies of chromosome 18 in each cell in the body instead of the usual two copies. The extra genetic material disrupts the normal course of development, causing the characteristic features of trisomy 18. […] Approximately 5 percent of people with trisomy 18 have an extra copy of chromosome 18 in only some of the body’s cells. In these people, the condition is called mosaic trisomy 18. […] Very rarely, part of the long (q) arm of chromosome 18 becomes attached (translocated) to another chromosome during the formation of reproductive cells (eggs and sperm) or very early in embryonic development. […] Most cases of trisomy 18 are not inherited, but occur as random events during the formation of eggs and sperm. An error in cell division called nondisjunction results in a reproductive cell with an abnormal number of chromosomes. […] Mosaic trisomy 18 is also not inherited. It occurs as a random event during cell division early in embryonic development. […] Partial trisomy 18 can be inherited. An unaffected person can carry a rearrangement of genetic material between chromosome 18 and another chromosome.
#7 Trisomy 18 | Radiology Key
https://radiologykey.com/trisomy-18/
Trisomy 18 (Edwards syndrome) is the second most common autosomal trisomy in newborns. More than 90% of cases are the result of maternal nondisjunction of chromosome 18. […] The incidence of trisomy 18 is increased in women with advanced maternal age. Most cases of trisomy 18 are the result of maternal meiotic nondisjunction (more than 90%). Paternal meiotic nondisjunction may also occur (5%). Occasionally, trisomy 18 is the result of chromosomal translocation.
#8 The trisomy 18 syndrome | Orphanet Journal of Rare Diseases | Full Text
https://ojrd.biomedcentral.com/articles/10.1186/1750-1172-7-81
The trisomy 18 syndrome, also known as Edwards syndrome, is a common chromosomal disorder due to the presence of an extra chromosome 18, either full, mosaic trisomy, or partial trisomy 18q. […] Most authorities have suggested that the extra chromosome is present because of nondisjunction. In parent-of-origin analyses the extra chromosome is most often of maternal origin, the result of an error during the segregation of chromosomes in meiosis or postzygotic mitosis. […] About 50% of the nondisjunctional errors in oogenesis occur in meiosis II, unlike other human trisomies where the malsegregation is more frequent in meiosis I. […] The cause of nondisjunction is unknown. […] As in the other common autosomal trisomies, the frequency of nondisjunctional errors increases with advancing maternal age.
#9 Edwards syndrome: Definition, causes, and symptoms
https://www.medicalnewstoday.com/articles/what-chromosomes-are-affected-by-edwards-syndrome
Edwards syndrome, also known as trisomy 18, describes a rare genetic condition where a person has three copies of chromosome 18. Having an extra copy of this chromosome causes a variety of symptoms that can result in severe complications. […] Trisomy 18, also known as Edwards syndrome, refers to a genetic condition that occurs due to having an extra chromosome 18 in some or all of the body’s cells. […] Unlike many other genetic conditions, a person does not typically inherit the genes for Edwards syndrome. Instead, an error in cell division known as nondisjunction occurs, which results in an egg or sperm gaining an extra copy of chromosome 18. […] In other cases, a person may have partial trisomy 18, which is the only form of trisomy 18 that a person may inherit from a parent. This type occurs due to a genetic change known as a translocation.
#10 Edwards Syndrome (Trisomy 18) | Concise Medical Knowledge
https://www.lecturio.com/concepts/edwards-syndrome-trisomy-18/
Edwards syndrome, or trisomy 18, is a genetic syndrome caused by the presence of an extra chromosome 18. […] In 90% of trisomy 18 cases, the presence of 3 copies of the 18th chromosome is due to nondisjunction. […] Types: Trisomy 18 due to nondisjunction, translocation involving chromosome 18, trisomy 18 mosaicism. […] Nondisjunction is the failure of homologous chromosomes or chromatids to segregate during mitosis or meiosis with the result that one daughter cell has both of a pair of parental chromosomes or chromatids and the other has none. […] Trisomy 18 is present 3 times (or has 3 copies). […] The egg with a chromosome 18 pair is fertilized by a normal haploid cell (2 from the egg and 1 from the sperm = 3). […] The sperm with a chromosome 18 pair fertilizes a normal haploid cell (2 from the sperm and 1 from the egg = 3). […] Translocation occurs when a part of the chromosome either attaches to or interchanges with a segment of another chromosome. […] Translocation trisomy 18 or partial trisomy 18 occurs in 2% of cases. […] Mosaicism occurs in 5% of cases; extra chromosome 18 is not carried by all cells.
#11 Trisomy 18 and 13 | Boston Children’s Hospital
https://www.childrenshospital.org/conditions/trisomy-18-and-13
Trisomy 18 and 13 are usually caused by spontaneous genetic mutations that occur at the time of fertilization. Normally, each egg and sperm cell contains 23 chromosomes. The union of these cells creates 23 pairs, or 46 total chromosomes, half from the mother and half from the father. Sometimes, an error occurs when an egg or sperm cell is forming, causing it to have an extra chromosome #18 or #13. […] When this cell contributes the extra chromosome 18 to the embryo, trisomy 18 results. […] When this cell contributes the extra chromosome 13 to the embryo, trisomy 13 results. […] The extra chromosome 18 or 13 can come from either the mother’s egg cell or the father’s sperm cell. […] In some instances, the extra chromosome 18 or 13 is attached to another chromosome in the egg or sperm. This is called translocation and is the only form of trisomy 18 or 13 that can be inherited. Sometimes, a parent can carry a „balanced” rearrangement in which chromosome 18 or 13 is attached to another chromosome. However, since the parent does not have any extra or missing chromosome material, they are said to have a „balanced translocation” and they are usually normal and healthy.
#12 Trisomy 18 Clinical Presentation: History, Physical, Causes
https://emedicine.medscape.com/article/943463-clinical
Full trisomy 18 is responsible for 95% of Edwards syndrome cases. Mosaicism and translocations cause few cases. An extra chromosome 18 is responsible for the phenotype. […] The incidence rate increases with advanced maternal age. In approximately 90% of cases, the extra chromosome is maternal in origin, with meiosis II errors occurring twice as frequently as meiosis I errors. This is in contrast to other human trisomies, which exhibit a higher frequency of nondisjunction in maternal meiosis I. Among cases resulting from paternal nondisjunction, most are the result of postzygotic mitotic errors. […] Although full trisomy results from meiotic nondisjunction, mosaic trisomy is due to postzygotic mitotic nondisjunction. Mosaic trisomy 18 occurs when both a trisomy 18 cell line and a normal cell line are present in the same individual. Mosaic trisomy 18 accounts for approximately 5% of trisomy 18 cases.
#13 Edwards’ Syndrome: Causes, Symptoms, and Treatment | Doctor
https://patient.info/doctor/edwards-syndrome-trisomy-18-pro
Edwards’ syndrome (trisomy 18) is a common autosomal chromosomal disorder due to the presence of an extra chromosome 18. […] The Edwards’ syndrome phenotype results from full, mosaic or partial trisomy 18q. Full trisomy 18 is the most common form occurring in about 94% of cases. […] A personal or close family history of giving birth to an affected child increases the risk. 2% of pregnancies with Edwards’ syndrome result from a balanced translocation or inversion carried by one parent. […] Risk rises with rising maternal age. […] The major causes of death are sudden death due to central apnoea, cardiac failure due to cardiac malformations and respiratory insufficiency due to hypoventilation, aspiration, upper airway obstruction or a combination of these factors. […] If Edwards’ syndrome is due to an unbalanced translocation, both parents should undergo chromosomal analysis.
#14 The trisomy 18 syndrome
https://pmc.ncbi.nlm.nih.gov/articles/PMC3520824/
The trisomy 18 syndrome, also known as Edwards syndrome, is a common chromosomal disorder due to the presence of an extra chromosome 18, either full, mosaic trisomy, or partial trisomy 18q. […] Most authorities have suggested that the extra chromosome is present because of nondisjunction. In parent-of-origin analyses the extra chromosome is most often of maternal origin, the result of an error during the segregation of chromosomes in meiosis or postzygotic mitosis. […] The cause of nondisjunction is unknown. Recently a higher prevalence of methylene tetrahydrofolate reductase gene (MTHFR) polymorphisms in mothers of trisomy 18 fetuses compared with other groups was reported but this result has not been replicated. […] As in the other common autosomal trisomies, the frequency of nondisjunctional errors increases with advancing maternal age.
#15 Presentation: Clinical suspicion of Edwards syndrome (trisomy 18) — In the Clinic
https://www.genomicseducation.hee.nhs.uk/genotes/in-the-clinic/presentation-clinical-suspicion-of-edwards-syndrome-trisomy-18/
Edwards syndrome (trisomy 18) is a severe, multi-system genetic condition resulting from the presence of three (rather than the usual two) copies of chromosome 18. […] Most cases are identified at this stage. Many parents opt to have routine screening for Edwards syndrome (alongside Down syndrome and Patau syndrome), and signs are typically evident on prenatal ultrasounds. […] A minority of individuals with Edwards syndrome have some cells with trisomy 18 and some cells with the usual two copies of chromosome 18. This is termed mosaicism.
#16 Trisomy 18 Clinical Presentation: History, Physical, Causes
https://emedicine.medscape.com/article/943463-clinical
Translocation trisomy gives rise to partial trisomy 18 syndrome. Partial trisomy 18 occurs when a segment of chromosome 18 is present in triplicate, often resulting from a balanced translocation carried by one parent. It accounts for approximately 2% of trisomy 18 cases. […] The smallest extra region necessary for expression of serious anomalies of trisomy 18 appears to be 18q11-12.
#17 The trisomy 18 syndrome
https://pmc.ncbi.nlm.nih.gov/articles/PMC3520824/
The observed increased overall prevalence of trisomy 18 in the last years is likely due to changes in the maternal age distribution during this time period. […] The trisomy 18 (or Edwards syndrome) phenotype results from full, mosaic, or partial trisomy 18q. […] In the partial trisomy form only a segment of the chromosome 18 long arm is present in triplicate, often resulting from a balanced translocation or inversion carried by one parent. This type of trisomy accounts for approximately 2% of cases presenting with the Edwards phenotype. […] The region of long arm of chromosome 18 extending from q11.2 has been proposed as the critical region for trisomy 18 phenotype, but some controversial data have been reported.
#18 The trisomy 18 syndrome | Orphanet Journal of Rare Diseases | Full Text
https://ojrd.biomedcentral.com/articles/10.1186/1750-1172-7-81
A small positive association of paternal age with trisomy 18, similar to that observed in Down syndrome, has also been observed. […] In individuals carrying mosaic trisomy 18 (less than 5% of cases), both a complete trisomy 18 and a normal cell line exist. […] The phenotype is extremely variable, ranging from complete trisomy 18 phenotype with early mortality to apparently phenotypically normal adults, in which the mosaicism is detected after the diagnosis of complete trisomy 18 in a child. […] In the partial trisomy form only a segment of the chromosome 18 long arm is present in triplicate, often resulting from a balanced translocation or inversion carried by one parent. […] The location and the extent of the triplicated segment and the possible associated deletion of genomic material due to unbalanced translocation can explain the variable phenotype associated with partial trisomy. […] The region of long arm of chromosome 18 extending from q11.2 has been proposed as the critical region for trisomy 18 phenotype, but some controversial data have been reported.
#19 Trisomy 18: MedlinePlus Medical EncyclopediaLock
https://medlineplus.gov/ency/article/001661.htm
Trisomy 18 is a genetic disorder in which a person has a third copy of material from chromosome 18, instead of the usual 2 copies. Rarely, the extra material may be attached to another chromosome (translocation). Most cases are not passed down through families. Instead, the problems that lead to this condition occur in either the sperm or the egg that forms the fetus. […] Most cases of Trisomy 18 are not passed down through families (inherited). Instead, the events that lead to trisomy 18 occur in either the sperm or the egg that forms the fetus.
#20 Trisomy 18 (Edwards Syndrome): Symptoms, Causes, Diagnosis
https://www.webmd.com/baby/what-is-trisomy-18
Trisomy 18 is a condition caused by a problem in your chromosomes. It’s also called Edwards syndrome, after the doctor who first described it. […] Sometimes the mother’s egg or the father’s sperm contains the wrong number of chromosomes. As the egg and sperm combine, this mistake is passed on to the baby. […] The risk of having a child with trisomy 18 increases with the age of the mother, though women of any age can have a child with trisomy 18. There isn’t anything you can do to lessen your chances of having a child with the condition as it’s due to a chromosome disorder. […] Like trisomy 18, no one knows why some babies get this condition. It’s known that the chance increases with the mother’s age, though women of any age can have a child with trisomy 13.
#21 What is Chromosome 18 Trisomy (Edwards Syndrome)? Symptoms, treatment and prognosis [Doctor Supervised] What is Prenatal DiagnosisTypesDisadvantagesAbortion Rate | (EN)
https://www.hiro-clinic.or.jp/nipt/edwards-syndrome/?lang=en
The last type, called mosaicism, is thought to account for about 10% of all cases. […] Chromosome disjunctions are thought to be related to maternal age, and a 2015 RIKEN study and a Fujita Health University study found that this may be due to a decrease in factors that help maintain normal chromosome status as we age.
#22 Trisomy 18 | Causes, Types, Diagnosis & Treatment
https://www.cincinnatichildrens.org/health/t/trisomy-18
Trisomy 18 happens when there is an extra copy of chromosome 18 in either the egg or the sperm before conception. This means that the baby will have three copies of chromosome 18 instead of two. The extra chromosome can cause differences in the way a baby develops. Most often, trisomy 18 happens by chance. It is not caused by anything you did or did not do during your pregnancy. […] Most babies with trisomy 18 will have abnormal ultrasound findings during pregnancy. […] There are no treatments or cures for the extra chromosome that causes trisomy 18. Treatment for babies and children with trisomy 18 is focused on the symptoms they have.
#23 Edwards syndrome – symptoms, treatments and causes | healthdirect
https://www.healthdirect.gov.au/edwards-syndrome-trisomy-18
Edwards syndrome is a rare genetic condition. […] It’s caused when your baby has an extra copy of chromosome 18. […] Edwards syndrome is a genetic condition that causes serious health problems and disabilities. It’s caused by an extra copy of chromosome 18. […] Children with Edwards syndrome have 3 copies of part or all of chromosome 18. This is why it’s also called trisomy 18. People who don’t have this condition have 2 copies of chromosome 18. […] It is usually caused by a change in the egg or sperm before the baby is conceived. […] Edwards syndrome is a genetic disease, so can’t be prevented. […] The condition does not usually run in families. It’s not caused by anything you have done.
#24 What is Trisomy 18? – Edwards Syndrome Association
https://edwardssyndrome.org/what-is-trisomy-18/
Trisomy 18, also called Edwards Syndrome, is a genetic condition caused by having an extra copy of chromosome 18. […] The exact cause of Trisomy 18 is unknown, but it is generally related to a problem in cell division. Most cases are not inherited but occur as random events during the formation of eggs and sperm. Advanced maternal age has been identified as a risk factor for Trisomy 18, with the condition being more likely in children born to older mothers.
#25 Trisomy 18 – Wikipedia
https://en.wikipedia.org/wiki/Trisomy_18
Trisomy 18, also known as Edwards syndrome, is a genetic disorder caused by the presence of a third copy of all or part of chromosome 18. […] Most cases of trisomy 18 occur due to problems during the formation of the reproductive cells or during early development. […] The chance of this condition occurring increases with the mother’s age. […] Rarely, cases may be inherited. […] Trisomy 18 (47,XX,+18) is caused by a meiotic nondisjunction event. […] A small percentage of cases occur when only some of the body’s cells have an extra copy of chromosome 18, resulting in a mixed population of cells with a differing number of chromosomes. […] Such cases are sometimes called mosaic trisomy 18. […] Very rarely, a piece of chromosome 18 becomes attached to another chromosome (translocated) before or after conception.
#26 Trisomy 18 (Edwards Syndrome): Life Expectancy Symptoms & Causes
https://www.emedicinehealth.com/trisomy_18_edwards_syndrome/article_em.htm
Trisomy 18 (Edwards syndrome) results from the presence of an extra copy of chromosome 18. […] Trisomy 18 is not an inherited condition. It occurs as the result of random events during egg and sperm formation. The type of error that occurs is known as nondisjunction, and this leads to an egg or sperm cell with an abnormal number of chromosomes. […] It is not known precisely why the extra genetic material causes the abnormalities specific to trisomy 18. As with Down syndrome (trisomy 21), experts believe that the presence of the extra chromosomal material interferes with the expression and interaction of various genes, resulting in impaired development and function.
#27 Edwards syndrome | EBSCO Research Starters
https://www.ebsco.com/research-starters/health-and-medicine/edwards-syndrome
Edwards syndrome, also known as Trisomy 18, is a severe congenital genetic condition caused by the presence of an extra chromosome 18. […] An error in (sperm or oocyte) division resulting in meiotic nondisjunction (failure of a replicating chromosome to divide) is the typical of Edwards syndrome. In 95 percent of cases, the somatic cells contain three copies of chromosome 18 rather than the normal two. […] This extra genetic material is responsible for the multiple anomalies and developmental and cognitive deficits present with this syndrome. […] The remaining 5 percent of cases exhibit mosaicism (trisomy in some but not all cells) or translocation (extra chromosome 18 genetic material is attached to a normal chromosome). […] Complete (affecting all cells) and are not inherited but result from a de novo (new) mutation. Translocation trisomic individuals have a 50 percent chance of each offspring inheriting complete trisomy 18.
#28 Trisomy 18 (Edwards syndrome)
https://www.aboutkidshealth.ca/trisomy-18-edwards-syndrome?contentid=875&language=English&hub=genetics
Trisomy 18 is a rare condition caused by an extra copy of chromosome 18. […] What causes trisomy 18? […] Sometimes, an error occurs when the egg or sperm cell is forming, causing it to have an extra chromosome. When this cell contributes the extra chromosome 18 to the embryo, trisomy 18 results. The extra chromosome 18 can come from either the mothers egg cell or the fathers sperm cell. The abnormalities seen in babies with trisomy 18 result from having this extra chromosome 18 in each of the bodys cells. […] Rarely, mosaic trisomy 18 may occur when the error in cell division occurs after fertilization. These babies have some cells with an extra chromosome 18 and others with the normal number. These babies usually have milder forms of trisomy 18.
#29 Edwards Syndrome (Trisomy 18) – MD Searchlight
https://mdsearchlight.com/genetic-disorders/edwards-syndrome-trisomy-18/
The second most common type, found in less than 5% of cases, is mosaic Edwards syndrome. This means that some cells have an extra copy of chromosome 18 while others are normal. […] The rarest type is partial Edwards syndrome, which only accounts for about 2% of all cases. With this type, only part of chromosome 18 is extra. […] The chance of having a baby with Edwards syndrome increases as the mother gets older. […] The primary cause of death in children with Edwards syndrome is cardio-respiratory failure. […] The survival rate for these babies is roughly 60% to 75% after the first week, which decreases to about 20% to 40% after a month, and then remains at around 10% after a year. […] The key causes of sudden death due to Edwards syndrome are complications related to the nervous system, and respiratory or heart failure.
#30 Edwards’ syndrome | NHS inform
https://www.nhsinform.scot/illnesses-and-conditions/chromosomal-conditions/edwards-syndrome/
Edwards syndrome (also known as trisomy 18) is a genetic condition that begins to affect babies when theyre in the womb, and continues to impact their health throughout their life. Its a rare but serious condition. […] If a baby has Edwards syndrome, they have inherited an extra copy of chromosome 18. This extra copy can be present in some or all of the babys cells and can lead to health problems for the baby. […] Most cases result from a random change in the egg or sperm in healthy parents. This change is not caused by anything the parents did before or during pregnancy.
#31
https://www.gov.uk/government/publications/trisomy-18-description-in-brief/edwards-syndrome-information-for-parents
Babies with Edwards syndrome have an extra copy of chromosome 18 in all or some cells. […] We do not know exactly what causes Edwards syndrome. It is not caused by something you have or have not done. Babies with Edwards syndrome are born to mothers of all ages but the chance of having a baby with this condition increases as the age of the mother increases. […] Edwards syndrome happens in about one baby out of every 1,500 (0.06%).
#32 Home | Trisomy 18 Foundation
https://trisomy18.org/
Trisomy 18 is a life-threatening disorder that impacts about 1 out of every 2000 pregnancies in the U.S. […] Advancing Research Research is critical to creating a brighter future for children with Trisomy 18 syndrome and related disorders. […] The Trisomy 18 Foundation is committed to funding research that seeks to reduce or eliminate life-threatening and quality of life challenges facing patients with Trisomy 18.
#33 Edwards syndrome (trisomy 18) — Knowledge Hub
https://www.genomicseducation.hee.nhs.uk/genotes/knowledge-hub/edwards-syndrome-trisomy-18/
Edwards syndrome occurs when there is an extra copy of chromosome 18 in all or some cells. […] Edwards syndrome usually arises when each cell has three copies of chromosome 18 (94% trisomy 18). […] Some individuals with Edwards syndrome (around 1-in-20) have three copies of chromosome 18 in some of their cells and two in the other cells. This is known as mosaic Edwards syndrome. […] A small number of individuals with Edwards syndrome (around 1-in-100) have partial trisomy 18. […] Edwards syndrome usually arises spontaneously owing to an error in cell division. […] The chance increases with maternal age. […] A minority of families may have a reciprocal translocation a structural rearrangement of the chromosomes in which one copy of chromosome 18 is attached to another chromosome.
#34 Trisomy 18 (Edwards Syndrome) Types & Diagnosis | Cardinal Glennon
https://www.ssmhealth.com/cardinal-glennon/fetal-care-institute/fetal-conditions-we-treat/genetic-syndromes/trisomy-18-(edwards-syndrome)
Around 1 in every 5,000 babies is diagnosed with Trisomy 18, also known as Edwards syndrome. […] Trisomy 18 is caused when a person has three copies of chromosome #18 instead of the usual two, for a total of 47 chromosomes. […] When a couple has a baby with Trisomy 18, it is usually unexpected. Nevertheless, some risk factors exist. For example, the chance of having a baby with Trisomy 18 is higher in older mothers. In other cases, Trisomy 18 can be inherited due to a familial chromosome rearrangement called a translocation. Trisomy 18 is never the result of anything a mother or father did, or didn’t do. […] We don’t know why many of these babies pass away before birth or within their first year of life. […] There is no known prenatal treatment that will improve the outcome for a baby with Trisomy 18, but our team can provide a family with support, education, and a safe environment in which to receive their care.
#35 Trisomy 18 (Edwards syndrome)
https://www.aboutkidshealth.ca/trisomy-18-edwards-syndrome
Trisomy 18 is a rare condition caused by an extra copy of chromosome 18. […] Trisomy 18 is a rare chromosome abnormality that affects approximately one in every 6,000 to 8,000 live births. […] Trisomy 18 results from having this extra chromosome 18 in each of the body’s cells. […] The extra chromosome 18 can come from either the mother’s egg cell or the father’s sperm cell. […] Rarely, mosaic trisomy 18 may occur when the error in cell division occurs after fertilization.
#36 Trisomy 18 – Wikiwand
https://www.wikiwand.com/en/articles/Trisomy_18
Trisomy 18, also known as Edwards syndrome, is a genetic disorder caused by the presence of a third copy of all or part of chromosome 18. […] Most cases of trisomy 18 occur due to problems during the formation of the reproductive cells or during early development. The chance of this condition occurring increases with the mother’s age. […] Trisomy 18 (47,XX,+18) is caused by a meiotic nondisjunction event. In nondisjunction, a pair of chromosomes fails to separate during cell division; thus, a gamete (i.e., a sperm or egg cell) is produced with an extra copy of a chromosome (for a total of 24 chromosomes). […] A small percentage of cases occur when only some of the body’s cells have an extra copy of chromosome 18, resulting in a mixed population of cells with a differing number of chromosomes. Such cases are sometimes called mosaic trisomy 18. […] Trisomy 18 occurs in about 1 in 5,000 live births, but more pregnancies are affected by the syndrome as the majority of those diagnosed with the condition prenatally will not survive to birth.
#37 SSA – POMS: DI 23022.390 – Edwards Syndrome (Trisomy 18) – 12/27/2023
https://secure.ssa.gov/apps10/poms.nsf/lnx/0423022390
Edwards syndrome is a genetic disorder in which a person has an extra third copy (trisomy) of genetic material from chromosome 18, instead of the usual two copies. This chromosomal condition causes severe intellectual disability and congenital abnormalities. […] This disorder is a relatively common syndrome affecting approximately 1 out of 3,000 live births. It is three times more common in girls than boys. […] Fifty percent of infants with this condition do not survive beyond the first week of life. Some children have survived to teenage years, but with serious medical and developmental problems.
#38 EDWARDS SYNDROME (TRISOMY 18)
https://medicover-genetics.com/product/edwards-syndrome/
Edwards Syndrome, also known as Trisomy 18, is a rare autosomal chromosome aneuploidy in which there are three copies of chromosome 18. In 80% of cases, a complete trisomy 18 is found, in 10% a mosaic trisomy, and in another 10% there is an unbalanced translocation. […] Most cases of Trisomy 18 are caused by an extra copy of chromosome 18 in all cells of the body. 5% of the cases have an extra copy of chromosome 18 in some cells of the body, which is known as mosaic trisomy 18. There are also some cases in which a part of the long arm of chromosome 18 is duplicated, which arises mostly from a parental translocation. […] Maternal age plays a role in trisomy 18, and with the mean maternal age having increased during the last 20 years, prevalence rates of trisomy 18 have risen.
#39 Causes and Treatment For Edwardsâ Syndrome (Trisomy 18) in Children
https://www.mfine.co/guides/edwards-syndrome-india
Edwards syndrome is a genetic abnormality in which the baby has an extra copy of chromosome 18. […] This abnormal number of chromosomes is mostly the result of nondisjunction, an error during cell division which causes the baby’s organs to develop abnormally. […] There is no known, definite cause of Edwards syndrome. However, many studies over the years have emphasised on certain risk factors that may increase your chances. […] The likelihood of having a Edwards syndrome baby is higher in older mothers. […] The risk of having a baby with Trisomy 18 increases with advancing maternal age. […] Edwards syndrome isn’t always inherited. In fact, most of the cases occur randomly during cell division, right in the early stages of fetal development. […] The most critical risk factor is an older mother. The risk increases with advancing maternal age, especially after 32 years.
#40 Chromosomal Disorders: Understanding Trisomy 18 (Edwardâs Syndrome) – Youth STEMM Award
https://ysawards.co.uk/2024/07/11/chromosomal-disorders-understanding-trisomy-18-edwards-syndrome/
Trisomy 18, or Edwardâs Syndrome, is a severe chromosomal disorder affecting one in every 5000 live births. […] This occurs randomly during conception with an unknown cause and its prevention is not yet possible. […] Unfortunately, there is no cure for babies with Edwardâs syndrome currently, and it cannot be prevented as it is a genetic disease. […] The chances of having a baby with Trisomy 18 is increased in women of an older age (over 35) as errors in meiosis can be more likely to happen as a result of the aging process.
#41 Edwards’ syndrome
https://www.babycentre.co.uk/a1024183/edwards-syndrome
Edwards’ syndrome is a rare condition caused by an abnormal number of chromosomes in the cells of the body. A baby with Edwards’ syndrome has three copies of chromosome 18, rather than the usual pair. The condition is also known as trisomy 18. The causes are not known, but the risk of having a baby with Edwards’ syndrome increases slightly as you become older. It is usually caused by a genetic abnormality in either the egg or sperm that created your baby. […] The condition causes problems with feeding and breathing, and severe learning disabilities. […] Babies with mosaic trisomy 18 and partial trisomy 18 are more likely to survive than babies with full Edwards’ syndrome. […] The chances for these babies may be improving because of a change in how they are treated soon after birth. Studies from countries such as the US and Japan suggest that babies’ chances of survival are improved if they receive swift intensive care.
#42 Trisomy 18 (Edwards Syndrome): Symptoms, Life Expectancy & Treatment
https://www.medicinenet.com/trisomy_18_edwards_syndrome/article.htm
Trisomy 18 or Edwards syndrome is a genetic disorder that causes a raft of life-threatening birth defects. It occurs in 1 in 5,000 live births and it is caused by the presence of an extra chromosome 18 and similar to Down syndrome. […] Trisomy 18 is caused by the presence of an extra chromosome 18, and most frequently is of maternal origin and includes the entire chromosome in most cases (90%) rather than a part of the chromosome (also known as partial trisomy or incomplete trisomy). […] The major cause of death in many of these infants is sudden death due to neurological instability, cardiac failure, and respiratory failure.
#43 Edwards syndrome – WikiLectures
https://www.wikilectures.eu/w/Edwards_syndrome
Edwards syndrome is a complex genetic syndrome conditioned by the karyotype 47,XX,+18 or 47,XY,+18 (trisomy of chromosome 18). […] Most individuals with Edwards syndrome have 3 copies of chromosome 18 in each cell, due to an error in nondisjunction (in the division of homologous chromosomes in meiotic division I). This leads to an increased number of chromosomes in sex cells. Excess genetic material disrupts the course of normal development and causes the characteristic features of trisomy 18. […] Trisomy of chromosome 18 is also a common cause of spontaneous abortion in the first trimester.
#44 Trisomy 18 – Embryology
https://embryology.med.unsw.edu.au/embryology/index.php?title=Trisomy_18
Trisomy 18 is a chromosomal abnormality associated with the presence of an extra chromosome 18 and characterized by growth delay, dolichocephaly, a characteristic facies, limb anomalies and visceral malformations. […] An aneuploidy, first recognized as a specific clinical entity by the discovery of an extra chromosome 18 in babies with a particular pattern of malformation by independent groups and named after one of the key authors, John Hilton Edwards. […] In many cases associated abnormalities include: fetal growth restriction, polyhydramnios and congenital heart defects. […] Both trisomy 13 and trisomy 18 are generally considered fatal anomalies, with a majority of infants dying in the first year after birth. […] The trisomy 18 syndrome, also known as Edwards syndrome, is a common chromosomal disorder due to the presence of an extra chromosome 18, either full, mosaic trisomy, or partial trisomy 18q.
#45
https://www.birthinjuryhelpcenter.org/birth-injuries/congenital-birth-defects/trisomy-18/
Trisomy 18 is a genetic chromosomal disorder characterized by an extra chromosome that causes abnormalities in various parts of the body. Also known as Edwards syndrome, it is the second most common trisomy behind Trisomy 21 (Down Syndrome). […] Trisomy 18 occurs when chromosome cells fail to properly divide during gestation. […] In cases of trisomy 18, a person develops a third chromosome in the 18th pair. The extra chromosome, which will be present in every cell in the body, causes severe and often fatal birth defects. […] Most cases of trisomy 18 are not hereditary. […] Parents who have a child with trisomy 18 do, however, have a greater risk of having another child with this chromosomal abnormality. […] Partial trisomy 18: A very rare form of trisomy 18 that occurs when an extra chromosome is only partially present in the cells. It occurs when a piece of chromosome 18 attaches itself to another chromosome, which can happen before or after conception. In this instance, the syndrome could be caused by hereditary factors. […] Unfortunately, studies show that there is a very high mortality rate associated with the condition. […] The average lifespan for infants that are born with this condition is between 3 days 2 weeks. […] Studies have shown a 5-10% chance of surviving the first year.
#46 Edward’s Syndrome: Causes, Symptoms and Treatment
https://www.netmeds.com/health-library/post/edwards-syndrome-causes-symptoms-and-treatment?srsltid=AfmBOopmiCHrFnQdt0tO4vo5igFcw1uFdRrZC2a548MYe4gNK8AGXRih
Edwards Syndrome, termed medically as Trisomy 18 is a type of birth defect caused due to the presence of added genetic material i.e. a third copy of the chromosome 18 instead of the natural 2 copies. […] When either of the parents carries a wrong number of chromosomal materials, the defect is passed on to the foetus, which now has a wrong number of chromosomes. […] In case of Trisomy 18 or Edwards syndrome, the baby has 3 copies of the chromosome 18 which may ultimately lead to several abnormalities. […] The abnormalities associated with Trisomy 18 or Edwards syndrome are so severe that most women often suffer a miscarriage or if the babies are born, they often die within the first year after birth. […] Till date, there is no cure for this condition, treatment options usually consist of offering the child palliative and supportive care throughout life to bestow the best quality of life possible.