GTS5:Turner syndrome: Difference between revisions

Turner Syndrome (TS) is a rare chromosomal disorder resulting from complete or partial loss of the second sex chromosome. The most common clinical manifestations include short stature, ovarian failure, primary or secondary amenorrhea associated with hypergonadotropic hypogonadism, congenital lymphedema of the hands and feet, Madelung deformity of the forearm and wrist, webbed neck, cardiac anomalies such as coarctation of the aorta, bicuspid aortic valves, mitral valve prolapse, hypertension, ischemic heart disease and arteriosclerosis, impaired glucose tolerance, thyroid disease and hearing loss.<ref name=":0">{{Cite journal|last=Gravholt|first=Claus H.|date=2005-11|title=Clinical practice in Turner syndrome|url=https://pubmed.ncbi.nlm.nih.gov/16929365|journal=Nature Clinical Practice. Endocrinology & Metabolism|volume=1|issue=1|pages=41–52|doi=10.1038/ncpendmet0024|issn=1745-8366|pmid=16929365}}</ref><ref>{{Cite journal|last=Bondy|first=Carolyn A.|last2=Bakalov|first2=Vladimir K.|date=2006-07|title=Investigation of cardiac status and bone mineral density in Turner syndrome|url=https://pubmed.ncbi.nlm.nih.gov/16624607|journal=Growth hormone & IGF research: official journal of the Growth Hormone Research Society and the International IGF Research Society|volume=16 Suppl A|pages=S103–108|doi=10.1016/j.ghir.2006.03.008|issn=1096-6374|pmid=16624607}}</ref><ref>{{Cite journal|last=Dhooge|first=Ingeborg J. M.|last2=De Vel|first2=E.|last3=Verhoye|first3=C.|last4=Lemmerling|first4=M.|last5=Vinck|first5=B.|date=2005-03|title=Otologic disease in turner syndrome|url=https://pubmed.ncbi.nlm.nih.gov/15793396|journal=Otology & Neurotology: Official Publication of the American Otological Society, American Neurotology Society [and] European Academy of Otology and Neurotology|volume=26|issue=2|pages=145–150|doi=10.1097/00129492-200503000-00003|issn=1531-7129|pmid=15793396}}</ref><ref>{{Cite journal|last=Güngör|first=N.|last2=Böke|first2=B.|last3=Belgin|first3=E.|last4=Tunçbilek|first4=E.|date=2000-10|title=High frequency hearing loss in Ullrich-Turner syndrome|url=https://pubmed.ncbi.nlm.nih.gov/11039128|journal=European Journal of Pediatrics|volume=159|issue=10|pages=740–744|doi=10.1007/pl00008338|issn=0340-6199|pmid=11039128}}</ref><ref>{{Cite journal|last=Zinn|first=A. R.|last2=Tonk|first2=V. S.|last3=Chen|first3=Z.|last4=Flejter|first4=W. L.|last5=Gardner|first5=H. A.|last6=Guerra|first6=R.|last7=Kushner|first7=H.|last8=Schwartz|first8=S.|last9=Sybert|first9=V. P.|date=1998-12|title=Evidence for a Turner syndrome locus or loci at Xp11.2-p22.1|url=https://pubmed.ncbi.nlm.nih.gov/9837829|journal=American Journal of Human Genetics|volume=63|issue=6|pages=1757–1766|doi=10.1086/302152|issn=0002-9297|pmc=1377648|pmid=9837829}}</ref><ref>{{Cite journal|last=Sävendahl|first=L.|last2=Davenport|first2=M. L.|date=2000-10|title=Delayed diagnoses of Turner's syndrome: proposed guidelines for change|url=https://pubmed.ncbi.nlm.nih.gov/11035820|journal=The Journal of Pediatrics|volume=137|issue=4|pages=455–459|doi=10.1067/mpd.2000.107390|issn=0022-3476|pmid=11035820}}</ref> Despite considerable phenotypic variability, short stature and gonadal dysgenesis are the most consistent findings. While individuals with TS may experience impairments in nonverbal developmental skills, they generally have normal intellectual ability.<ref>{{Cite journal|last=Kesler|first=Shelli R.|date=2007-07|title=Turner syndrome|url=https://pubmed.ncbi.nlm.nih.gov/17562588|journal=Child and Adolescent Psychiatric Clinics of North America|volume=16|issue=3|pages=709–722|doi=10.1016/j.chc.2007.02.004|issn=1056-4993|pmc=2023872|pmid=17562588}}</ref>Turner syndrome should be suspected prenatally when a prenatal ultrasound reveals fetal hydrops, cystic hygroma, or cardiac defects. Approximately 50% of TS patients have monosomy X (45,X), while the remaining 50% exhibit various structural abnormalities of the X chromosome or mosaicism with a normal female or normal male cell line.

In individuals with mosaic TS and Y chromosomal material, external genitalia may vary from normal male to ambiguous to female with TS characteristics. The Y chromosome, if present, may also be structurally abnormal. A patient with TS showing evidence of virilization is more likely to be mosaic for a Y-containing cell line, which increases the risk for gonadoblastoma.<ref name=":0" /><ref name=":1">{{Cite journal|last=Gravholt|first=Claus H.|last2=Andersen|first2=Niels H.|last3=Christin-Maitre|first3=Sophie|last4=Davis|first4=Shanlee M.|last5=Duijnhouwer|first5=Anthonie|last6=Gawlik|first6=Aneta|last7=Maciel-Guerra|first7=Andrea T.|last8=Gutmark-Little|first8=Iris|last9=Fleischer|first9=Kathrin|date=2024-06-05|title=Clinical practice guidelines for the care of girls and women with Turner syndrome|url=https://pubmed.ncbi.nlm.nih.gov/38748847|journal=European Journal of Endocrinology|volume=190|issue=6|pages=G53–G151|doi=10.1093/ejendo/lvae050|issn=1479-683X|pmid=38748847}}</ref> Molecular screening for Y chromosomal material is recommended in such cases.

TS and its variants occur in approximately 1 in 2000 to 1 in 2500 live-born females.<ref>{{Cite journal|last=Cui|first=Xiaoxiao|last2=Cui|first2=Yazhou|last3=Shi|first3=Liang|last4=Luan|first4=Jing|last5=Zhou|first5=Xiaoyan|last6=Han|first6=Jinxiang|date=2018-11|title=A basic understanding of Turner syndrome: Incidence, complications, diagnosis, and treatment|url=https://pubmed.ncbi.nlm.nih.gov/30560013|journal=Intractable & Rare Diseases Research|volume=7|issue=4|pages=223–228|doi=10.5582/irdr.2017.01056|issn=2186-3644|pmc=6290843|pmid=30560013}}</ref><ref>{{Cite journal|last=Nielsen|first=J.|last2=Wohlert|first2=M.|date=1991-05|title=Chromosome abnormalities found among 34,910 newborn children: results from a 13-year incidence study in Arhus, Denmark|url=https://pubmed.ncbi.nlm.nih.gov/2037286|journal=Human Genetics|volume=87|issue=1|pages=81–83|doi=10.1007/BF01213097|issn=0340-6717|pmid=2037286}}</ref> However, TS is among the most common chromosomal disorders, affecting 1–2% of conceptions, with approximately 99% of affected pregnancies resulting in pregnancy loss.<ref>{{Cite journal|last=Urbach|first=Achia|last2=Benvenisty|first2=Nissim|date=2009|title=Studying early lethality of 45,XO (Turner's syndrome) embryos using human embryonic stem cells|url=https://pubmed.ncbi.nlm.nih.gov/19137066|journal=PloS One|volume=4|issue=1|pages=e4175|doi=10.1371/journal.pone.0004175|issn=1932-6203|pmc=2613558|pmid=19137066}}</ref> The true prevalence of TS is difficult to ascertain, as many individuals remain undiagnosed or are only diagnosed later in adulthood.<ref>{{Cite journal|last=Gunther|first=Daniel F.|last2=Eugster|first2=Erica|last3=Zagar|first3=Anthony J.|last4=Bryant|first4=Constance G.|last5=Davenport|first5=Marsha L.|last6=Quigley|first6=Charmian A.|date=2004-09|title=Ascertainment bias in Turner syndrome: new insights from girls who were diagnosed incidentally in prenatal life|url=https://pubmed.ncbi.nlm.nih.gov/15342833|journal=Pediatrics|volume=114|issue=3|pages=640–644|doi=10.1542/peds.2003-1122-L|issn=1098-4275|pmid=15342833}}</ref>

|''SHOX''

|The ''short stature homeobox'' (''SHOX'') gene belongs to the paired homeobox family and is located in the pseudoautosomal region 1 (PAR1) on the short arms of the X (Xp22.3) and Y (Yp11.3) chromosomes.<ref>{{Cite journal|last=Rao|first=E.|last2=Weiss|first2=B.|last3=Fukami|first3=M.|last4=Rump|first4=A.|last5=Niesler|first5=B.|last6=Mertz|first6=A.|last7=Muroya|first7=K.|last8=Binder|first8=G.|last9=Kirsch|first9=S.|date=1997-05|title=Pseudoautosomal deletions encompassing a novel homeobox gene cause growth failure in idiopathic short stature and Turner syndrome|url=https://pubmed.ncbi.nlm.nih.gov/9140395|journal=Nature Genetics|volume=16|issue=1|pages=54–63|doi=10.1038/ng0597-54|issn=1061-4036|pmid=9140395}}</ref> It plays a crucial role in skeletal development, particularly in the growth plates of bones, where it regulates the proliferation and differentiation of chondrocytes, the cells responsible for cartilage formation. ''SHOX'' is vital for normal bone growth and stature, and pathogenic variants or deletions in this gene are associated with TS and other syndromes, including Leri-Weill dyschondrosteosis, and idiopathic short stature.<ref name=":2">{{Cite journal|last=Binder|first=Gerhard|date=2011-02|title=Short stature due to SHOX deficiency: genotype, phenotype, and therapy|url=https://pubmed.ncbi.nlm.nih.gov/21325865|journal=Hormone Research in Paediatrics|volume=75|issue=2|pages=81–89|doi=10.1159/000324105|issn=1663-2826|pmid=21325865}}</ref> Both males and females typically have two copies of the ''SHOX'' gene, as it escapes X chromosome inactivation.<ref name=":2" /><ref>{{Cite journal|last=Berletch|first=Joel B.|last2=Yang|first2=Fan|last3=Xu|first3=Jun|last4=Carrel|first4=Laura|last5=Disteche|first5=Christine M.|date=2011-08|title=Genes that escape from X inactivation|url=https://pubmed.ncbi.nlm.nih.gov/21614513|journal=Human Genetics|volume=130|issue=2|pages=237–245|doi=10.1007/s00439-011-1011-z|issn=1432-1203|pmc=3136209|pmid=21614513}}</ref>

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