Editing Turner syndrome (section)

==Presentation==
Turner syndrome is associated with a number of physical features, including [[short stature]], heart defects, webbed neck, [[Micrognathism|micrognathia]], [[Amenorrhea|amenorrhoea]], and [[infertility]].<ref>{{Cite journal |last1=Gravholt |first1=Claus H. |last2=Viuff |first2=Mette H. |last3=Brun |first3=Sara |last4=Stochholm |first4=Kirstine |last5=Andersen |first5=Niels H. |date=October 2019 |title=Turner syndrome: mechanisms and management |url=https://www.nature.com/articles/s41574-019-0224-4 |journal=Nature Reviews Endocrinology |language=en |volume=15 |issue=10 |pages=601–614 |doi=10.1038/s41574-019-0224-4 |pmid=31213699 |issn=1759-5037}}</ref> The [[phenotype]] of Turner syndrome is affected by [[Mosaic (genetics)|mosaicism]], where cell lines with a single sex chromosome are combined with those with multiple. Individuals with mosaicism of [[45,X/46,XY mosaicism|45,X0/46,XY]] may be phenotypically male, female, or ambiguous, while those with 45,X0/46,XX will be phenotypically female. Patients with 45,X0/46,XY do not receive the diagnosis of Turner syndrome if phenotypically male.<ref name=KNOLL2022/> Around 40%–50% of cases of Turner syndrome are true "monosomy X" with a 45,X0 karyotype, while the remainder are mosaic for another cell line, most commonly 46,XX, or have other structural abnormalities of the X chromosome.<ref name="ajmga1">{{cite journal | vauthors = Lin AE, Prakash SK, Andersen NH, Viuff MH, Levitsky LL, Rivera-Davila M, Crenshaw ML, Hansen L, Colvin MK, Hayes FJ, Lilly E, Snyder EA, Nader-Eftekhari S, Aldrich MB, Bhatt AB, Prager LM, Arenivas A, Skakkebaek A, Steeves MA, Kreher JB, Gravholt CH | title = Recognition and management of adults with Turner syndrome: From the transition of adolescence through the senior years | journal = American Journal of Medical Genetics. Part A | volume = 179 | issue = 10 | pages = 1987–2033 | date = October 2019 | pmid = 31418527 | doi = 10.1002/ajmg.a.61310 | doi-access = free }}</ref> The classic features of Turner syndrome, while distinctive, may be rarer than previously thought; [[Incidental medical findings|incidental diagnosis]], such as in [[biobank]] samples or prenatal testing for older mothers, finds many girls and women with few traditional signs of Turner syndrome.<ref name="pediatrics">{{cite journal | vauthors = Gunther DF, Eugster E, Zagar AJ, Bryant CG, Davenport ML, Quigley CA | title = Ascertainment bias in Turner syndrome: new insights from girls who were diagnosed incidentally in prenatal life | journal = Pediatrics | volume = 114 | issue = 3 | pages = 640–644 | date = September 2004 | pmid = 15342833 | doi = 10.1542/peds.2003-1122-L | s2cid = 22596252 }}</ref><ref name="gim">{{cite journal | vauthors = Tuke MA, Ruth KS, Wood AR, Beaumont RN, Tyrrell J, Jones SE, Yaghootkar H, Turner CL, Donohoe ME, Brooke AM, Collinson MN, Freathy RM, Weedon MN, Frayling TM, Murray A | title = Mosaic Turner syndrome shows reduced penetrance in an adult population study | journal = Genetics in Medicine | volume = 21 | issue = 4 | pages = 877–886 | date = April 2019 | pmid = 30181606 | pmc = 6752315 | doi = 10.1038/s41436-018-0271-6 }}</ref>

===Physiological===
====Stature====
[[File:Relationship between chromosome X dosage in 45, X and 47, XXX females for quantitative traits.png|thumb|upright=1.2|Height comparison for women with full and mosaic Turner's compared to [[trisomy X]] and the general population]]
Turner syndrome is associated with short stature. The mean adult height of women with Turner syndrome without growth hormone therapy is around {{height|cm=20}} shorter than the mean of women in the general population.<ref name="bmri">{{cite journal | vauthors = Bertapelli F, Barros-Filho A, Antonio MÂ, Barbeta CJ, de Lemos-Marini SH, Guerra-Junior G | title = Growth curves for girls with Turner syndrome | journal = BioMed Research International | volume = 2014 | issue = 1 | pages = 687978 | date = 2014 | pmid = 24949463 | pmc = 4052048 | doi = 10.1155/2014/687978 | doi-access = free }}</ref> [[Mosaic (genetics)|Mosaicism]] affects height in Turner syndrome; a large population sample drawn from the [[UK Biobank]] found women with 45,X0 [[karyotype]]s to have an average height of {{height|cm=145}}, while those with 45,X0/46,XX karyotypes averaged {{height|cm=159}}.<ref name="gim" />{{NoteTag|As comparison, the average adult height for women in the [[Anglosphere]] is around {{height|cm=162}}.<ref name="cdc">{{cite journal|url=https://www.cdc.gov/nchs/data/series/sr_03/sr03_039.pdf|title=Anthropometric reference data for children and adults: United States, 2011–2014|journal=National Health Statistics Reports|volume=11|date=August 2016|author=US Dept. of Health and Human Services|display-authors=etal|access-date=23 March 2021|archive-date=2 February 2017|archive-url=https://web.archive.org/web/20170202010330/https://www.cdc.gov/nchs/data/series/sr_03/sr03_039.pdf|url-status=live}}</ref><ref name="australia">{{cite web|title=Australian health survey: first results|url=http://www.abs.gov.au/ausstats/abs@.nsf/Lookup/4338.0main+features212011-13|publisher=Australian Bureau of Statistics|access-date=23 March 2021|date=29 October 2012|archive-date=20 January 2017|archive-url=https://web.archive.org/web/20170120095340/http://www.abs.gov.au/ausstats/abs@.nsf/Lookup/4338.0main+features212011-13|url-status=live}}</ref>}} The strength of the association between Turner syndrome and short stature is such that [[idiopathic]] short stature alone is a major diagnostic indication.<ref name="ajmga1" />

Growth delay in Turner syndrome does not begin at birth; most [[neonate]]s with the condition have a [[birth weight]] in the lower end of the normal range. Height begins to lag in toddlerhood, with a delayed growth velocity becoming apparent as early as 18 months. Marked short stature becomes obvious in mid-childhood. In undiagnosed preadolescents and adolescents, growth delay may be mistaken for a side effect of delayed puberty and improperly treated. 

Short stature in Turner syndrome and its counterpoint, tall stature in sex chromosome [[polysomy]] conditions such as [[Klinefelter syndrome]], [[XYY syndrome]], and [[trisomy X]], is caused by the [[short-stature homeobox gene]] on the X and Y chromosomes. The absence of a copy of the ''SHOX'' gene in Turner's inhibits skeletal growth, resulting both in overall short stature and in a distinctive pattern of skeletal malformations including [[micrognathia]] (small chin), [[cubitus valgus]] (abnormal forearm angles), and shorter fingers.<ref name="eyn">{{cite journal | vauthors = Oliveira CS, Alves C | title = The role of the SHOX gene in the pathophysiology of Turner syndrome | journal = Endocrinologia y Nutricion | volume = 58 | issue = 8 | pages = 433–442 | date = October 2011 | pmid = 21925981 | doi = 10.1016/j.endoen.2011.06.003 }}</ref>

When Turner syndrome is diagnosed in early life, [[growth hormone therapy]] can decrease the degree of short stature.<ref name="ajmga1" /> Treatment with [[human growth hormone]] appears to increase expected adult height by approximately {{height|cm=7}} from an otherwise expected norm of {{height|cm=142}}–{{height|cm=147}}.<ref name="eyn" /><ref name="ec">{{cite journal |vauthors=Li P, Cheng F, Xiu L |date=April 2018 |title=Height outcome of the recombinant human growth hormone treatment in Turner syndrome: a meta-analysis |journal=Endocrine Connections |volume=7 |issue=4 |pages=573–583 |doi=10.1530/EC-18-0115 |pmc=5900457 |pmid=29581156 |doi-access=free}}</ref>{{NoteTag|Expected adult height for untreated women with Turner syndrome ranges from {{height|cm=143}} in the United States and most of Western Europe, to {{height|cm=140}} in Argentina, to {{height|cm=147}} in Scandinavia.<ref name="nelson">{{cite book|title=Nelson Textbook of Pediatrics|edition=19th | vauthors = Kansra AR, Donohoue PA  | veditors = Kliegman R |chapter=Hypofunction of the Ovaries |page=7093 |date=2011 |publisher=Elsevier |location=Amsterdam |isbn=978-1-4377-0755-7}}</ref>}} The effects of growth hormone therapy are at their strongest during the first year of treatment and taper off over time.<ref name="irdr">{{cite journal |vauthors=Cui X, Cui Y, Shi L, Luan J, Zhou X, Han J |date=November 2018 |title=A basic understanding of Turner syndrome: Incidence, complications, diagnosis, and treatment |journal=Intractable & Rare Diseases Research |volume=7 |issue=4 |pages=223–228 |doi=10.5582/irdr.2017.01056 |pmc=6290843 |pmid=30560013 |doi-access=free}}</ref> In some cases [[oxandrolone]], a steroid with a relatively mild masculinizing effect, may be used alongside growth hormone. The addition of oxandrolone to a Turner syndrome treatment regimen adds around {{height|cm=2}} to the final height.<ref name="ec" /><ref name="ijpe">{{cite journal | vauthors = Sheanon NM, Backeljauw PF | title = Effect of oxandrolone therapy on adult height in Turner syndrome patients treated with growth hormone: a meta-analysis | journal = International Journal of Pediatric Endocrinology | volume = 2015 | issue = 1 | pages = 18 | date = 26 August 2015 | pmid = 26322078 | pmc = 4551522 | doi = 10.1186/s13633-015-0013-3 | doi-access = free }}</ref> Oxandrolone is used particularly often in girls diagnosed later in their growth period, due to the reduced impact of growth hormone alone in this population. However, oxandrolone use runs the risk of delayed breast development, voice deepening, increased body hair, or [[clitoromegaly]].<ref name="ajmga1" />

====Physical features====
[[File:Turner Syndrome 1.jpg|thumb|upright=1.2|Girl with Turner syndrome]]
In addition to short stature, Turner syndrome is associated with a number of characteristic physical features. These include a short, webbed neck, low hairline, small chin and lower jaw, [[a arched palate|arched palate]], and broad chest with widely-spaced nipples.<ref name="percy1">{{cite book|title=A Comprehensive Guide to Intellectual and Developmental Disabilities | vauthors = Percy M, Thompson MD, Brown I, Fung WA | veditors = Wehmeyer ML, Brown I, Percy M, Fung WA, Shogren KA |edition=2nd |publisher=Brookes Publishing|location=Baltimore, Maryland|date=2016|chapter=Other Syndromes and Conditions Associated with Intellectual and Developmental Disabilities|page=297|isbn=978-1-59857-602-3}}</ref> [[Lymphedema]] (swelling) of the hands and feet is common at birth and sometimes persistent throughout the lifespan.<ref name="ejhg1">{{cite journal | vauthors = Atton G, Gordon K, Brice G, Keeley V, Riches K, Ostergaard P, Mortimer P, Mansour S | title = The lymphatic phenotype in Turner syndrome: an evaluation of nineteen patients and literature review | journal = European Journal of Human Genetics | volume = 23 | issue = 12 | pages = 1634–1639 | date = December 2015 | pmid = 25804399 | pmc = 4486366 | doi = 10.1038/ejhg.2015.41 | doi-access = free }}</ref>

A number of the external manifestations of Turner syndrome are focused on the limbs, hands, and feet. Lymphedema at birth is one of the classic features of the syndrome; though it often resolves during toddlerhood, recurrence in later life is frequent, often without apparent cause. Cases where the retained X chromosome was inherited from the mother more often experience lymphedema than those where it was from the father. As a consequence of lymphedema's effects on nail anatomy, females with Turner syndrome frequently have small, hypoplastic, upturned nails. Their fingers are shorter and the hands are broad. Their feet are puffy, thicker, and swollen.<ref name="jaad">{{cite journal | vauthors = Lowenstein EJ, Kim KH, Glick SA | title = Turner's syndrome in dermatology | journal = Journal of the American Academy of Dermatology | volume = 50 | issue = 5 | pages = 767–776 | date = May 2004 | pmid = 15097963 | doi = 10.1016/j.jaad.2003.07.031 }}</ref> Shortened [[metacarpal bones]], particularly the fourth metacarpal, are a frequent finding.<ref name="jpem">{{cite journal | vauthors = Miguel-Neto J, Carvalho AB, Marques-de-Faria AP, Guerra-Júnior G, Maciel-Guerra AT | title = New approach to phenotypic variability and karyotype-phenotype correlation in Turner syndrome | journal = Journal of Pediatric Endocrinology & Metabolism | volume = 29 | issue = 4 | pages = 475–479 | date = April 2016 | pmid = 26812779 | doi = 10.1515/jpem-2015-0346 | s2cid = 43332484 | doi-access = free }}</ref> The body shape of individuals with Turner syndrome is frequently quite broad and stocky, as the growth deficiency is more pronounced in the length of bones than in their width. [[Scoliosis]] is common in Turner syndrome, and is seen in 40% of girls without growth hormone treatment.<ref name="Haskin Lowenstein Dermatologic Conditions in Turner Syndrome"/>

Facial features associated with Turner syndrome include 
broad, prominent ears, a low hairline at the nape of the neck, a webbed neck, a small chin with dental [[malocclusion]], and downslanting [[palpebral fissure]]s (the opening between the eyelids). These are thought to be related to lymphedema during the fetal period, specifically to the presence and resorption of excess fluids in the head and neck region.<ref name="ajmga1" /> Neck webbing is a particularly distinctive trait of Turner syndrome, leading to many neonatal diagnoses.<ref name="jcem">{{cite journal | vauthors = Davenport ML | title = Approach to the patient with Turner syndrome | journal =   The Journal of Clinical Endocrinology & Metabolism| volume = 95 | issue = 4 | pages = 1487–1495 | date = April 2010 | pmid = 20375216 | doi = 10.1210/jc.2009-0926 | doi-access = free }}</ref> The underlying [[etiology]] of neck webbing is related to prenatal blood flow issues, and even in populations without Turner's has broad health consequences; the rate of congenital heart disease in webbed neck is 150-fold higher than in the general population, while the feature is also associated with reduced height and minor developmental impairments.<ref name="jaad" /> Some women with Turner syndrome have premature facial wrinkling.<ref name="ajmga1" /> Acne is less common in teenage girls and women with Turner syndrome, though the reasons why are unclear.<ref name="Haskin Lowenstein Dermatologic Conditions in Turner Syndrome"/>

[[File:Baby Turner.JPG|thumb|left|A female infant with Turner syndrome. Notice the broad chest and small chin]]
Other physical features connected to the condition include long eyelashes, sometimes including [[Distichiasis|an additional set of eyelashes]], and unusual [[dermatoglyphics]] (fingerprints). Some women with Turner's report being unable to create [[Identity-based security|fingerprint passwords]] due to hypoplastic dermatoglyphics.<ref name="ajmga1" /> Unusual dermatoglyphics are common to chromosome anomalies like Down Syndrome.<ref name="ajmg2">{{cite journal | vauthors = Reed T | title = Dermatoglyphics in medicine--problems and use in suspected chromosome abnormalities | journal = American Journal of Medical Genetics | volume = 8 | issue = 4 | pages = 411–429 | date = 1981 | pmid = 7018239 | doi = 10.1002/ajmg.1320080407 }}</ref> and in the case of Turner's may be a consequence of fetal lymphedema.<ref name="ajmga1" /> [[Keloid]] scars, or raised hypertrophic scars growing beyond the boundaries of the original wound, are potentially associated with Turner syndrome; however, the association is underresearched. Though traditional medical counselling on the topic urges conservatism about elective procedures such as ear piercing due to the risk of severe scarring, the actual consequences are unclear. Keloids in Turner syndrome are particularly frequent following surgical procedures to reduce neck webbing.<ref name="ajmga1" /><ref name="jaad" /> Turner syndrome has been associated with unusual patterns of hair growth, such as patches of short and long hair. Armpit and pubic hair is often sparse, while arm and leg hair is often thick. Though armpit hair is reduced in amount and thickness, the pattern in which it is implanted in the skin is as in men, rather than as in women.<ref name="Haskin Lowenstein Dermatologic Conditions in Turner Syndrome" />

====Cardiac====
[[File:The basic anatomy of the bicuspid aortic valve.jpg|thumb|upright=1.2|Bicuspid aortic valve]]
Approximately half of individuals with Turner syndrome have [[congenital heart defect]]s. CHDs associated with Turner syndrome include [[bicuspid aortic valve]]s (30%), [[coarctation of the aorta]] (15%), and abnormalities of the arteries in the head and neck.<ref name="ajmga1" /> A rare but potentially fatal complication of heart defects in Turner syndrome is [[aortic dissection]], where the inner layer of the [[aorta]] tears open. Aortic dissection is six times as common in females with Turner syndrome as the general population and accounts for 8% of all deaths in the syndrome. The risk is substantially increased for individuals with bicuspid aortic valves, who make up 95% of patients with aortic dissection compared to 30% of all Turner's patients, and coarctation of the aorta, who make up 90% and 15% respectively.<ref name="adc">{{cite journal | vauthors = Turtle EJ, Sule AA, Webb DJ, Bath LE | title = Aortic dissection in children and adolescents with Turner syndrome: risk factors and management recommendations | journal = Archives of Disease in Childhood | volume = 100 | issue = 7 | pages = 662–666 | date = July 2015 | pmid = 25573747 | doi = 10.1136/archdischild-2014-307080 | s2cid = 206857477 }}</ref>

[[Coronary artery disease]] onsets earlier in life in women with Turner syndrome compared to controls, and mortality from cardiac events is increased. This is thought to be in part a function of the relationship between Turner syndrome and [[obesity]]; women with Turner syndrome have a higher percentage of body fat for their weight than control women, and their short stature makes weight control more difficult. Though coronary artery disease is frequently thought a disease of older adults, young women with Turner syndrome are more likely to develop the disease than their 46,XX peers. Treatment recommendations for women with Turner syndrome and coronary artery disease are as in the general population, but as Turner's increases the risk of type 2 diabetes, women with insulin resistance must weigh up the benefits of [[prophylactic]] or early [[statin]] treatment with the risk of Type II diabetes.<ref name="ajmga1" />

====Internal medicine====
Turner syndrome is associated with a broad variety of health considerations, such as liver and kidney issues, obesity, diabetes, and [[hypertension]].<ref name="ajmga1" /> Liver dysfunction is common in women with Turner syndrome, with 50–80% having elevated [[liver enzymes]].<ref name="nre">{{cite journal | vauthors = Gravholt CH, Viuff MH, Brun S, Stochholm K, Andersen NH | title = Turner syndrome: mechanisms and management | journal = Nature Reviews. Endocrinology | volume = 15 | issue = 10 | pages = 601–614 | date = October 2019 | pmid = 31213699 | doi = 10.1038/s41574-019-0224-4 | s2cid = 190653543 }}</ref> [[Non-alcoholic fatty liver disease]] is increased in prevalence in Turner syndrome, likely related in part to both conditions' associations with obesity. Hepatic vascular diseases are also seen in the syndrome as an aspect of Turner syndrome's broader vascular, aortic and cardiac impacts. [[Primary biliary cholangitis]] is more common in 45,X0 than 46,XX women. An unclear association exists between estrogen replacement therapy and liver dysfunction in Turner syndrome; some studies imply estrogen therapy worsens such conditions, while others imply improvement.<ref name="li">{{cite journal | vauthors = Roulot D | title = Liver involvement in Turner syndrome | journal = Liver International | volume = 33 | issue = 1 | pages = 24–30 | date = January 2013 | pmid = 23121401 | doi = 10.1111/liv.12007 | doi-access = free }}</ref>

[[File:Duplicated ureter.svg|thumb|left|upright=0.75|Duplicated ureter]]
Kidney issues, such as [[horseshoe kidney]], are sometimes observed in Turner syndrome.<ref name="nre" /> Horseshoe kidney, where the kidneys are fused together in a U-shape, occurs in around 10% of Turner's cases compared to less than 0.5% of the general population. A missing kidney is observed in as many as 5% of individuals with Turner syndrome, compared to around 0.1% of the population. A [[duplicated ureter]], where two [[ureter]]s drain a single kidney, occurs in as much as 20–30% of the Turner syndrome population. Kidney malformations ( horseshoe kidney, etc.) in Turner syndrome may be more common in mosaicism than in the full 45,X karyotype.<ref name="pn">{{cite journal | vauthors = Fanos V, Schena S, Dal Moro A, Portuese A, Antoniazzi F | title = Multicystic kidney dysplasia and Turner syndrome: two cases and a literature review | journal = Pediatric Nephrology | volume = 14 | issue = 8–9 | pages = 754–757 | date = August 2000 | pmid = 10955920 | doi = 10.1007/PL00013430 | s2cid = 42881441 }}</ref> Serious complications of the kidney anomalies associated with Turner syndrome are rare, although there is some risk of issues such as [[obstructive uropathy]], where the flow of urine from the kidneys is blocked.<ref name="ajmga1" />

Women with Turner syndrome are more likely than average to have high blood pressure; as many as 60% of women with the condition are hypertensive. [[Isolated diastolic hypertension]] often precedes [[systolic hypertension]] in the condition and may develop at a young age. Treatments for hypertension in Turner syndrome are as in the general population.<ref name="ajmga1" />

Approximately 25–80% of women with Turner syndrome have some level of [[insulin resistance]], and a minority develop [[type 2 diabetes]]. The risk of diabetes in Turner syndrome varies by karyotype and appears to be raised by specific deletions of the [[Locus (genetics)|short arm]] of the X chromosome (Xp). One study found that while a relatively low 9% of women with Xq (long arm) deletions had type 2 diabetes, 18% of those with full 45,X0 karyotypes did, as well as 23% with Xp deletions. 43% of women with [[isochromosome]] Xq, who both lacked the short arm and had an additional copy of the long arm, developed type 2 diabetes.<ref name="nre" /> Though part of the diabetes risk in Turner syndrome is a function of weight control, some is independent; age- and weight-matched women with non-Turner's ovarian failure have a lower diabetes risk than in Turner syndrome. Growth hormone treatment plays an unclear role in diabetes risk, as does estrogen supplementation.<ref name="ajmga1" />

The association between Turner syndrome and other diseases, such as cancer, is unclear. Overall, women with Turner syndrome do not appear more likely to develop cancer than women with 46,XX karyotypes, but the specific pattern of what cancers are highest risk seems to differ. The risk of [[breast cancer]] appears lower in Turner's than in control women, perhaps due to decreased levels of estrogen. [[Neuroblastoma]], a cancer of infancy and early childhood, has been reported in girls with Turner syndrome. Tumours of the nervous system, both the [[central nervous system]] and the [[peripheral nervous system]], are overrepresented amongst cancers in Turner syndrome.<ref name="ajmga1" /> Furthermore, about 5.5% of Turner syndrome individuals have an extra, abnormal [[small supernumerary marker chromosome]] (sSMC) which consists of part of a Y chromosome. This partial Y chromosome-bearing sSMC may include the ''[[SRY]]'' gene located on the p arm of the Y chromosome at band 11.2 (notated as Yp11.2). This gene encodes the [[testis-determining factor]] protein (also known as sex-determining region Y protein). Turner syndrome individuals with this ''SRY'' gene-containing sSMC have a very real increased risk of developing [[gonadal tissue neoplasm]]s such as [[gonadoblastoma]]s and [[in situ]] [[seminoma]]s (also termed [[dysgerminoma]]s to indicate that this tumor has the pathology of the testicular tumor, seminoma, but develops in ovaries<ref name="pmid33961893">{{cite journal | vauthors = Morin JP, Saltzman AF | title = Gonadoblastoma in Turner Syndrome: A Surprise in a Streak | journal = Urology | volume = 154 | issue =  | pages = 278–280 | date = August 2021 | pmid = 33961893 | doi = 10.1016/j.urology.2021.02.050 | s2cid = 233997606 }}</ref>). In one study, 34 Turner syndrome girls without overt evidence of these tumors were found at [[Preventive healthcare|preventative surgery]] to have a gonadoblastoma (7 cases), dysgerminoma (1 case), or non-specific ''in situ'' gonadal neoplasm (1 case).<ref name="pmid31465855">{{cite journal | vauthors = Dabrowski E, Johnson EK, Patel V, Hsu Y, Davis S, Goetsch AL, Habiby R, Brickman WJ, Finlayson C | title = Turner Syndrome with Y Chromosome: Spontaneous Thelarche, Menarche, and Risk of Malignancy | journal = Journal of Pediatric and Adolescent Gynecology | volume = 33 | issue = 1 | pages = 10–14 | date = February 2020 | pmid = 31465855 | pmc = 7413626 | doi = 10.1016/j.jpag.2019.08.011 }}</ref> Turner syndrome girls with this sSMC otherwise have typical features of the Turner syndrome except for a minority who also have [[hirsutism]] and/or [[clitoral enlargement]].<ref name="pmid33870841">{{cite journal | vauthors = Chen J, Guo M, Luo M, Deng S, Tian Q | title = Clinical characteristics and management of Turner patients with a small supernumerary marker chromosome | journal = Gynecological Endocrinology | volume = 37 | issue = 8 | pages = 730–734 | date = August 2021 | pmid = 33870841 | doi = 10.1080/09513590.2021.1911992 | s2cid = 233298107 }}</ref> Surgical removal of the [[gonads]] has been recommended to remove the threat of developing these sSMC-associated neoplasms.<ref name="pmid33870841"/><ref name="pmid21930534">{{cite journal | vauthors = Barros BA, Moraes SG, Coeli FB, Assumpção JG, De Mello MP, Maciel-Guerra AT, Carvalho AB, Viguetti-Campos N, Vieira TA, Amstalden EM, Andrade JG, Esquiaveto-Aun AM, Marques-de-Faria AP, D'Souza-Li LF, Lemos-Marini SH, Guerra G | title = OCT4 immunohistochemistry may be necessary to identify the real risk of gonadal tumors in patients with Turner syndrome and Y chromosome sequences | journal = Human Reproduction | volume = 26 | issue = 12 | pages = 3450–3455 | date = December 2011 | pmid = 21930534 | doi = 10.1093/humrep/der310 | doi-access = free }}</ref><ref name="pmid11768396">{{cite journal | vauthors = Röthlisberger B, Zerova T, Kotzot D, Buzhievskaya TI, Balmer D, Schinzel A | title = Supernumerary marker chromosome (1) of paternal origin and maternal uniparental disomy 1 in a developmentally delayed child | journal = Journal of Medical Genetics | volume = 38 | issue = 12 | pages = 885–888 | date = December 2001 | pmid = 11768396 | pmc = 1734780 | doi = 10.1136/jmg.38.12.885 }}</ref> Turner syndrome individuals with an sSMC that lacks the ''SRY'' gene are not at an increased risk of developing these cancers.<ref name="pmid33870841"/><ref name="pmid31465855"/>

====Sensory====

Hearing loss is common in Turner syndrome. Though at birth hearing is normal with good hearing abilities, chronic middle ear infections are frequent throughout childhood, which can cause permanent [[conductive hearing loss]] or deafness. In adulthood, [[sensorineural hearing loss]] occurs more often than in 46,XX women and at younger ages; though differing thresholds of hearing loss make it difficult to compare between studies, younger adult women with Turner syndrome are routinely found to have disproportionate rates of hearing issues, with sometimes up to half of women in their 20s and 30s having difficulty hearing well.<ref name="ajmgc3">{{cite journal | vauthors = Bonnard Å, Bark R, Hederstierna C | title = Clinical update on sensorineural hearing loss in Turner syndrome and the X-chromosome | journal = American Journal of Medical Genetics. Part C, Seminars in Medical Genetics | volume = 181 | issue = 1 | pages = 18–24 | date = March 2019 | pmid = 30632288 | doi = 10.1002/ajmg.c.31673 | s2cid = 58589784 }}</ref> This hearing loss is progressive; at the age of 40, women with Turner syndrome have equivalent hearing loss to 46,XX women aged 60, on average.<ref name="Bonnard Hultcrantz Ear and Hearing Problems in Turner Syndrome">{{cite book |doi=10.1007/978-3-030-34150-3_10 |chapter=Ear and Hearing Problems in Turner Syndrome |title=Turner Syndrome |date=2020 |last1=Bonnard |first1=Åsa |last2=Hultcrantz |first2=Malou |pages=185–197 |isbn=978-3-030-34148-0 }}</ref> Cohort studies imply hearing loss may be more common in women who also have [[metabolic syndrome]].<ref name="apg">{{cite journal | vauthors = Álvarez-Nava F, Racines-Orbe M, Witt J, Guarderas J, Vicuña Y, Estévez M, Lanes R | title = Metabolic Syndrome as a Risk Factor for Sensorineural Hearing Loss in Adult Patients with Turner Syndrome | journal = The Application of Clinical Genetics | volume = 13 | issue = 13 | pages = 25–35 | date = 13 January 2020 | pmid = 32021381 | pmc = 6971290 | doi = 10.2147/TACG.S229828 | doi-access = free }}</ref> The high prevalence of sensorineural hearing loss in Turner syndrome appears to be related to ''SHOX'' deficiency.<ref name="eyn" />

Ocular and visual disorders are also increased in prevalence in Turner syndrome. More than half of individuals with Turner syndrome have some form of eye disorder. This may be a consequence of shared genes on the X chromosome in both visual and ovarian development.<ref name="Herlihy Rudell Ocular Features in Turner Syndrome">{{cite book |doi=10.1007/978-3-030-34150-3_11 |chapter=Ocular Features in Turner Syndrome |title=Turner Syndrome |date=2020 |last1=Herlihy |first1=Erin P. |last2=Rudell |first2=Jolene C. |pages=199–204 |isbn=978-3-030-34148-0 }}</ref> Nearly half of cases have [[hyperopia]] or [[myopia]], usually mild. [[Strabismus]], or misalignment of the eye, occurs in around one-fifth to one-third of girls with Turner syndrome. As with strabismus outside the Turner's context, it may be treated with glasses, patching, or surgical correction. [[Esotropia]], where the eye turns inwards, is more common than [[exotropia]], where it turns outwards.<ref name="Herlihy Rudell Ocular Features in Turner Syndrome"/><ref name="eye">{{cite journal | vauthors = Denniston AK, Butler L | title = Ophthalmic features of Turner's syndrome | journal = Eye | volume = 18 | issue = 7 | pages = 680–684 | date = July 2004 | pmid = 15002027 | doi = 10.1038/sj.eye.6701323 | s2cid = 7567847 | doi-access = free }}</ref> [[Ptosis (eyelid)|Ptosis]], or a drooping eyelid, is a common facial manifestation of Turner syndrome; it usually has no appreciable impact on vision, but severe cases may limit visual range and require surgical correction.<ref name="Herlihy Rudell Ocular Features in Turner Syndrome"/> The rate of [[red-green colourblindness]] in Turner syndrome is 8%, the same as in XY males. This is due to red-green colourblindness being an [[X-linked recessive]] condition; in people with a single X chromosome, whether normal males or Turner females, only a single mutated X is necessary for symptoms. Red-green colourblindness may be underdiagnosed in the Turner context, as the rarity of the condition in females reduces the likelihood of screening, and practitioners may not connect that the karyotype of Turner syndrome increases the risk from the female baseline.<ref name="eye" />

====Autoimmune====
Women with Turner syndrome are two to three times as likely to develop [[autoimmune disorder]]s as the general population. Specific autoimmune disorders linked to Turner syndrome include [[Hashimoto's disease]], [[vitiligo]], [[psoriasis]] and [[psoriatic arthritis]], [[alopecia]],[[Type I diabetes]], and [[celiac disease]] Type I diabetes, when the immune system attacks the beta cells in the pancreas, is a major autoimmune disorder and is much more common in Turner females than 46,XX and 47,XXX females in most cases.<ref name="Haskin Lowenstein Dermatologic Conditions in Turner Syndrome">{{cite book |doi=10.1007/978-3-030-34150-3_13 |chapter=Dermatologic Conditions in Turner Syndrome |title=Turner Syndrome |date=2020 |last1=Haskin |first1=Alessandra |last2=Lowenstein |first2=Eve |pages=221–236 |isbn=978-3-030-34148-0 }}</ref> [[Inflammatory bowel disease]] is also common,<ref name="Wahbeh Bradshaw White Lee Gastrointestinal and Hepatic Issues in Women with Turner Syndrome">{{cite book |doi=10.1007/978-3-030-34150-3_12 |chapter=Gastrointestinal and Hepatic Issues in Women with Turner Syndrome |title=Turner Syndrome |date=2020 |last1=Wahbeh |first1=Ghassan T. |last2=Bradshaw |first2=Amanda |last3=White |first3=Lauren |last4=Lee |first4=Dale |pages=205–220 |isbn=978-3-030-34148-0 }}</ref> while the prevalence of [[type 1 diabetes]] is unclear, though appears increased.<ref name="Viuff Gravholt Endocrine and Metabolic Consequences of Turner Syndrome">{{cite book |doi=10.1007/978-3-030-34150-3_8 |chapter=Endocrine and Metabolic Consequences of Turner Syndrome |title=Turner Syndrome |date=2020 |last1=Viuff |first1=Mette H. |last2=Gravholt |first2=Claus H. |pages=157–174 |isbn=978-3-030-34148-0 }}</ref>

Thyroid disease is common in Turner syndrome. [[Hypothyroidism]] is prevalent; 30%–50% of women with Turner syndrome have Hashimoto's disease, where the thyroid gland is slowly destroyed by an autoimmune reaction from the immune system. By age 50, half of women with Turner syndrome have subclinical or clinical hypothyroidism.<ref name="Viuff Gravholt Endocrine and Metabolic Consequences of Turner Syndrome"/> [[Hyperthyroidism]] and [[Graves' disease]] are also increased in prevalence, though more modestly. The Turner's presentation of hyperthyroidism is as in the general population, while the presentation of hypothyroidism is often atypical, with a mild early presentation yet a more severe progression.<ref name="ijp">{{cite journal | vauthors = Aversa T, Gallizzi R, Salzano G, Zirilli G, De Luca F, Valenzise M | title = Atypical phenotypic aspects of autoimmune thyroid disorders in young patients with Turner syndrome | journal = Italian Journal of Pediatrics | volume = 44 | issue = 1 | pages = 12 | date = January 2018 | pmid = 29343299 | pmc = 5773039 | doi = 10.1186/s13052-018-0447-3 | doi-access = free }}</ref> Women with isochromosome Xq are more likely to develop autoimmune thyroid disease than women with other forms of Turner syndrome.<ref name="Viuff Gravholt Endocrine and Metabolic Consequences of Turner Syndrome" />

The risk of irritable bowel syndrome is increased around fivefold in Turner syndrome, and that of [[ulcerative colitis]] around fourfold. Celiac disease is also increased in prevalence, with around 4–8% of Turner's patients having comorbid celiac disease compared to 0.5–1% of the general population. Diagnosis of such conditions is difficult due to their nonspecific early symptoms. In the Turner's context, diagnosis may in particular be missed due to growth delay; such conditions cause growth delay and failure to thrive when they onset in childhood, but as girls with Turner syndrome already have such delay, symptoms may be overlooked and ascribed to the original condition.<ref name="Wahbeh Bradshaw White Lee Gastrointestinal and Hepatic Issues in Women with Turner Syndrome"/>

[[Alopecia areata]], or recurrent patchy hair loss, is three times as common in Turner syndrome as the general population. Alopecia in the Turner syndrome context is frequently treatment-resistant, also seen in other chromosome [[aneuploidies]] such as [[Down syndrome]]. Psoriasis is common in Turner syndrome, although the precise prevalence is unclear. Turner's psoriasis may be related to growth hormone treatment, as psoriasis as a side effect of such therapies has been reported in patients without the karyotype. Psoriasis may progress to [[psoriatic arthritis]], and this progression may be more common in Turner syndrome. Vitiligo has been reported in conjunction with Turner syndrome, but the risk is unclear and may be a side effect of increased clinical attention to autoimmune disease in this population.<ref name="Haskin Lowenstein Dermatologic Conditions in Turner Syndrome" />

====Puberty====
[[File:Histological sections of ovarian cortex from patients with TS.png|thumb|upright=1.3|[[Histopathology]] of ovarian tissue in mosaic (A and B) and full (C) Turner syndrome]]
Puberty is delayed or absent in Turner syndrome. A 2019 literature review found that 13% of women with a 45,X0 karyotype could expect to experience spontaneous [[thelarche]] (breast development), while 9% would undergo spontaneous [[menarche]] (beginning of menstruation). These numbers were higher in women with mosaic Turner's; 63% with 45,X0/46,XX karyotypes experienced spontaneous thelarche and 39% spontaneous menarche, while 88% with 45,X0/47,XXX (the presence of a [[trisomy X]] cell line) experienced spontaneous thelarche and 66% spontaneous menarche. Unexpectedly, women with Y-chromosome cells also had increased rates of thelarche and menarche compared to the 45,X baseline, at 41% and 19%. However, few women with trisomy X or Y-chromosome cell lines were covered in the review, impeding extrapolation from these results.<ref name="hrp">{{cite journal | vauthors = Dabrowski E, Jensen R, Johnson EK, Habiby RL, Brickman WJ, Finlayson C | title = Turner Syndrome Systematic Review: Spontaneous Thelarche and Menarche Stratified by Karyotype | journal = Hormone Research in Paediatrics | volume = 92 | issue = 3 | pages = 143–149 | date = 2019 | pmid = 31918426 | doi = 10.1159/000502902 | s2cid = 210131881 | doi-access = free }}</ref> 6% of women with Turner syndrome have regular menstrual cycles; the rest experience primary or secondary [[amenorrhea]] or other menstrual dysfunction.<ref name="Klein et al Estrogen Replacement in Turner Syndrome">{{cite book |doi=10.1007/978-3-030-34150-3_5 |chapter=Estrogen Replacement in Turner Syndrome |title=Turner Syndrome |date=2020 |last1=Klein |first1=Karen O. |last2=Rosenfield |first2=Robert L. |last3=Santen |first3=Richard J. |last4=Gawlik |first4=Aneta M. |last5=Backeljauw |first5=Philippe |last6=Gravholt |first6=Claus H. |last7=Sas |first7=Theo C. J. |last8=Mauras |first8=Nelly |pages=93–122 |isbn=978-3-030-34148-0 }}</ref>{{rp|84}}

In girls with Turner syndrome who do not experience spontaneous puberty, [[exogenous]] estrogen is used to induce and maintain feminization. Estrogen replacement is recommended to begin at around age 11–12, although some parents prefer to delay the induction of puberty in girls with lower social and emotional preparedness. The dose of estrogen in induced puberty begins at 10% of adult estrogen levels and is steadily increased at six-month intervals, with a full adult dose attained two to three years after the beginning of treatment. Estrogen replacement may interfere with growth hormone therapy, due to the closing effects of estrogen on growth plates; individuals must weigh up their preferences for taller height versus greater feminization.<ref name="Klein et al Estrogen Replacement in Turner Syndrome" />{{rp|97–103}}

====Fertility====
Women with Turner syndrome are at extremely high risk for primary ovarian insufficiency (POI) and infertility. Although about 70–80% have no spontaneous pubertal development and 90% experience primary amenorrhea, the remainder may possess a small residual of ovarian follicles at birth or early childhood.<ref>{{cite journal | vauthors = ((Journal of Pediatric and Adolescent Gynecology)) | title = Fertility Preservation in Women with Turner Syndrome: A Comprehensive Review and Practical Guidelines | journal = Journal of Pediatric and Adolescent Gynecology | volume = 29 | issue = 5 | pages = 409–416 | date = October 2016 | doi = 10.1016/j.jpag.2015.10.011 | pmid = 26485320 | pmc = 5015771 }}</ref>

Early in gestation, fetuses with Turner syndrome have a normal number of [[gamete]]s in their developing ovaries, but this starts decreasing rapidly as early as 18 weeks of pregnancy; by birth, girls with the condition have markedly reduced follicular counts.<ref name="Finlayson Lia Reema Fertility Preservation for Turner Syndrome">{{cite book |doi=10.1007/978-3-030-34150-3_4 |chapter=Fertility Preservation for Turner Syndrome |title=Turner Syndrome |date=2020 |last1=Finlayson |first1=Courtney |last2=Bernardi |first2=Lia |last3=Habiby |first3=Reema |pages=79–91 |isbn=978-3-030-34148-0 }}</ref> Women with Turner syndrome who wish to raise families but are incapable of conception with their own [[oocyte]]s have the options of adoption or of pregnancy with [[Egg donation|donor eggs]]; the latter has a comparable success rate to donor pregnancy in women with 46,XX karyotypes.<ref name="ajmga1" />

Pregnancy in Turner syndrome is inherently [[High-risk pregnancy|high-risk]]; the [[maternal death]] rate is 2%.<ref>{{cite journal | vauthors = ((Practice Committee of the American Society for Reproductive Medicine)) | title = Increased maternal cardiovascular mortality associated with pregnancy in women with Turner syndrome | journal = Fertility and Sterility | volume = 97 | issue = 2 | pages = 282–284 | date = February 2012 | pmid = 22192347 | doi = 10.1016/j.fertnstert.2011.11.049 | doi-broken-date = 1 November 2024 }}</ref>

Usually, estrogen replacement therapy is used to spur the growth of secondary sexual characteristics at the time when puberty should onset. While very few women with Turner syndrome menstruate spontaneously, estrogen therapy requires a regular shedding of the uterine lining ("withdrawal bleeding") to prevent its overgrowth. Withdrawal bleeding can be induced monthly, like menstruation, or less often, usually every three months, if the patient desires. Estrogen therapy does not make a woman with nonfunctional ovaries fertile, but it plays an important role in assisted reproduction; the health of the uterus must be maintained with estrogen if an eligible woman with Turner Syndrome wishes to use IVF (using donated [[oocyte]]s).{{citation needed|date=September 2021}}

Especially in mosaic cases of Turner syndrome that contains Y-chromosome (e.g., 45,X/46,XY) due to the risk of development of ovarian malignancy (most common is [[gonadoblastoma]]) gonadectomy is recommended.<ref name=Elsheikh>{{cite journal | vauthors = Elsheikh M, Dunger DB, Conway GS, Wass JA | title = Turner's syndrome in adulthood | journal = Endocrine Reviews | volume = 23 | issue = 1 | pages = 120–140 | date = February 2002 | pmid = 11844747 | doi = 10.1210/edrv.23.1.0457 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Gravholt CH, Fedder J, Naeraa RW, Müller J | title = Occurrence of gonadoblastoma in females with Turner syndrome and Y chromosome material: a population study | journal = The Journal of Clinical Endocrinology and Metabolism | volume = 85 | issue = 9 | pages = 3199–3202 | date = September 2000 | pmid = 10999808 | doi = 10.1210/jcem.85.9.6800 | doi-access = free }}</ref> Turner syndrome is characterized by primary [[amenorrhoea]], premature ovarian failure (hypergonadotropic hypogonadism), [[Gonadal dysgenesis|streak gonads]] and infertility (however, technology (especially oocyte donation) provides the opportunity of pregnancy in these patients). Failure to develop secondary sex characteristics (sexual infantilism) is typical.{{fact|date=July 2024}}

===Cognition===

====Neurodevelopmental====
Individuals with Turner syndrome have normal intelligence. [[Verbal IQ]] is usually higher than [[performance IQ]]; one review of thirteen studies found an average verbal IQ of 101 compared to an average performance IQ of 89.<ref name="rovet1">{{cite book |doi=10.1201/9780429305870-3 |chapter=The Cognitive and Neuropsychological Characteristics of Females with Turner Syndrome |title=Sex Chromosome Abnormalities and Human Behavior |date=2019 |last1=Rovet |first1=Joanne F. |pages=38–77 |isbn=978-0-429-30587-0 }}</ref>

People with Turner syndrome demonstrate relative strengths in verbal skills, but may exhibit weaker nonverbal skills – particularly in arithmetic, select visuospatial skills, and processing speed. They have difficulties with directional sense, visualization of three-dimensional shapes, properties of shapes, and symmetry and may have dyscalculia. <ref>{{cite journal | vauthors = Mazzocco MM | title = The cognitive phenotype of Turner syndrome: Specific learning disabilities | journal = International Congress Series | volume = 1298 | pages = 83–92 | date = October 2006 | pmid = 19750135 | pmc = 2742423 | doi = 10.1016/j.ics.2006.06.016 }}</ref> Turner syndrome does not typically cause [[intellectual disability]] or impair cognition. However, learning difficulties are common among women with Turner syndrome, particularly a specific difficulty in perceiving spatial relationships, such as [[nonverbal learning disorder]]. This may also manifest itself as a difficulty with motor control or with [[mathematics]].<ref>{{Cite web|url=https://www.mayoclinic.org/diseases-conditions/turner-syndrome/symptoms-causes/syc-20360782|title=Turner Syndrome|date=November 18, 2017|website=Mayo Clinic|access-date=October 20, 2018}}</ref> While it is not correctable, in most cases it does not cause difficulty in daily living. Most Turner syndrome patients are employed as adults and lead productive lives.

Also, a rare variety of Turner syndrome, known as "Ring-X Turner syndrome", has about a 60% association with intellectual disability{{clarify|reason=use of association is non-standard|date=April 2016}}. This variety accounts for around 2–4% of all Turner syndrome cases.<ref>{{cite journal | vauthors = Berkovitz G, Stamberg J, Plotnick LP, Lanes R | title = Turner syndrome patients with a ring X chromosome | journal = Clinical Genetics | volume = 23 | issue = 6 | pages = 447–453 | date = June 1983 | pmid = 6883789 | doi = 10.1111/j.1399-0004.1983.tb01980.x | s2cid = 13544594 }}</ref>

==== Psychological ====
Social difficulties appear to be an area of vulnerability for TS girls.<ref>{{cite journal | vauthors = McCauley E, Feuillan P, Kushner H, Ross JL | title = Psychosocial development in adolescents with Turner syndrome | journal = Journal of Developmental and Behavioral Pediatrics | volume = 22 | issue = 6 | pages = 360–365 | date = December 2001 | pmid = 11773800 | doi = 10.1097/00004703-200112000-00003 | s2cid = 39749059 }}</ref> Counseling affected individuals and their families about the need to carefully develop social skills and relationships may prove useful in advancing social adaptation. Women with Turner syndrome may experience adverse psychosocial outcomes which can be improved through early intervention and the provision of appropriate psychological and psychiatric care. Although Turner syndrome constitutes a chronic medical condition, with possible physical, social, and psychological complications in a woman's life, hormonal and estrogen replacement therapy, and assisted reproduction, are treatments that can be helpful for Turner syndrome patients and improve their quality of life.<ref>{{cite journal | vauthors = Christopoulos P, Deligeoroglou E, Laggari V, Christogiorgos S, Creatsas G | title = Psychological and behavioural aspects of patients with Turner syndrome from childhood to adulthood: a review of the clinical literature | journal = Journal of Psychosomatic Obstetrics and Gynaecology | volume = 29 | issue = 1 | pages = 45–51 | date = March 2008 | pmid = 17852655 | doi = 10.1080/01674820701577078 | s2cid = 8149629 }}</ref> Research shows a possible association between age at diagnosis and increased substance use and depressive symptoms.<ref name="pmid29753544">{{cite journal | vauthors = Reimann GE, Bernad Perman MM, Ho PS, Parks RA, Comis LE | title = Psychosocial Characteristics of Women with a Delayed Diagnosis of Turner Syndrome | journal = The Journal of Pediatrics | volume = 199 | pages = 206–211 | date = August 2018 | pmid = 29753544 | pmc = 6063780 | doi = 10.1016/j.jpeds.2018.03.058 }}</ref> <!-- This article has a delayed release (embargo) and will be available in PMC on August 1, 2019-->

=== Prenatal ===
Despite the excellent postnatal prognosis, 99% of Turner syndrome conceptions are thought to end in miscarriage or stillbirth,<ref name=AboutPregnancyLoss>{{cite web| vauthors = Danielsson K |title=Turner Syndrome (Monosomy X) and Pregnancy Loss |url= http://miscarriage.about.com/od/congenitaldisorders/p/turnersyndrome.htm|access-date=17 March 2012 |date=March 12, 2009|url-status=live|archive-url=https://web.archive.org/web/20120315042034/http://miscarriage.about.com/od/congenitaldisorders/p/turnersyndrome.htm|archive-date=15 March 2012}}</ref> and as many as 15% of all spontaneous abortions have the 45,X karyotype.<ref>{{cite book| vauthors = Curtis M, Antoniewicz L, Linares ST |title=Glass' Office Gynecology|date=2014|publisher=Lippincott Williams & Wilkins |isbn=978-1-60831-820-9 |page=226|url=https://books.google.com/books?id=w2AGBAAAQBAJ&pg=PA226 }}</ref><ref>{{cite book| vauthors = Weston G, Vollenhoven B, McNeilage J |title=Practice OSCEs in Obstetrics & Gynaecology: A Guide for the Medical Student and MRANZCOG exams |date=2009 |publisher=Elsevier Health Sciences|isbn=978-0-7295-7867-7 |page=85 |url= https://books.google.com/books?id=_oso9VMFwD0C&pg=PA85}}</ref><!-- About 50% due to chromosomal abnormalities and of chromosomal abnormalities up to 25% are X0 --> Among cases that are detected by routine amniocentesis or chorionic villus sampling, one study found that the prevalence of Turner syndrome among tested pregnancies was 5.58 and 13.3 times higher, respectively, than among live neonates in a similar population.<ref name=Gravholt>{{cite journal | vauthors = Gravholt CH, Juul S, Naeraa RW, Hansen J | title = Prenatal and postnatal prevalence of Turner's syndrome: a registry study | journal = BMJ | volume = 312 | issue = 7022 | pages = 16–21 | date = January 1996 | pmid = 8555850 | pmc = 2349728 | doi = 10.1136/bmj.312.7022.16 }}</ref>