turner syndrome turner syndrome turner syndrome (ts), also known as 45,x, or 45,x0, is a genetic disorder in which a female is partially or completely missing an x chromosome. signs and symptoms vary among those affected. often, a short and webbed neck, low-set ears, low hairline at the back of the neck, short stature, and swollen hands and feet are seen at birth. typically, those affected do not develop menstrual periods, or breasts without hormone treatment and are unable to have children without reproductive technology. heart defects, diabetes, and low thyroid hormone occur in the disorder more frequently than average. most people with turner syndrome have normal intelligence; however, many have problems with spatial visualization that may be needed in order to learn mathematics. vision and hearing problems also occur more often than average. turner syndromeother namesullrich–turner syndrome, bonnevie–ullrich–turner syndrome, gonadal dysgenesis; 45x, 45x0five girls and women with turner syndromespecialtypediatrics, medical geneticssymptomswebbed neck, short stature, swollen hands and feetcomplicationsheart defects, diabetes, low thyroid hormoneonsetat birthdurationlong termcausesmissing an x chromosomediagnostic methodphysical signs, genetic testingmedicationhuman growth hormone, estrogen replacement therapyprognosisreduced life expectancyfrequency1 in 2,000 to 5,000 turner syndrome is not usually inherited; rather, it occurs during formation of the reproductive cells in a parent or in early cell division during development. no environmental risks are known, and the mother's age does not play a role. while most people have 46 chromosomes, people with turner syndrome usually have 45 in some or all cells. the chromosomal abnormality is often present in just some cells, in which case it is known as turner syndrome with mosaicism. in these cases the symptoms are usually fewer, and possibly none occur at all. diagnosis is based on physical signs and genetic testing. no cure for turner syndrome is known. treatment may help with symptoms. human growth hormone injections during childhood may increase adult height. estrogen replacement therapy can promote development of the breasts and hips. medical care is often required to manage other health problems with which turner syndrome is associated. turner syndrome occurs in between one in 2,000 and one in 5,000 females at birth. all regions of the world and cultures are affected about equally. generally people with turner syndrome have a shorter life expectancy, mostly due to heart problems and diabetes. american endocrinologist henry turner first described the condition in 1938. in 1964, it was determined to be due to a chromosomal abnormality. presentation turner syndrome has a number of physical and psychological impacts, including short stature, heart defects, neck webbing, delayed or absent puberty, and infertility. the phenotype of turner syndrome is affected by mosaicism, where cell lines with a single sex chromosome are combined with those with multiple. 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. the classic features of turner syndrome, while distinctive, may be rarer than previously thought; 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. height 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 20 cm (8 in) shorter than the mean of women in the general population. mosaicism affects height in turner syndrome; a large population sample drawn from the uk biobank found women with 45,x0 karyotypes to have an average height of 145 cm (4 ft 9 in), while those with 45,x0/46,xx karyotypes averaged 159 cm (5 ft 2+1⁄2 in). the strength of the association between turner syndrome and short stature is such that idiopathic short stature alone is a major diagnostic indication. growth delay in turner syndrome does not begin at birth; most neonates 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. when girls with turner syndrome begin school, their height is usually still not remarkably unusual; 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 short fingers. when turner syndrome is diagnosed in early life, growth hormone therapy can decrease the degree of short stature. the use of growth hormone therapy in turner's originated from a series of studies in the 1980s finding it to substantially increase the height of treated girls, compared to prior adult height predictions and turner's growth charts; treatment with human growth hormone appears to increase expected adult height by approximately 7 cm (3 in) from an otherwise expected norm of 142 cm (4 ft 8 in)–147 cm (4 ft 10 in). 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's treatment regimen adds around 2 cm (1 in) to the final height. 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. the effects of growth hormone therapy are at their strongest during the first year of treatment and taper off over time. physical features webbed neck in a teenage girl with turner syndrome in addition to short stature, turner syndrome is associated with a number of characteristic physical features. these include a webbed neck, a low hairline, a small chin and jaw, a high-arched palate, and a broad chest with wide-spaced nipples. lymphedema (swelling) of the hands and feet is common at birth and sometimes persistent throughout the lifespan. some turner's stigmata, such as cubitus valgus and shortened fingers, are related to shox gene dosage effects. 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 nails. shortened metacarpal bones, particularly the fourth metacarpal, are a frequent finding. 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. facial features associated with turner syndrome include prominent ears, a low hairline, a webbed neck, a small chin with dental malocclusion, and downslanting palpebral fissures (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. neck webbing is a particularly distinctive trait of turner syndrome, leading to many neonatal diagnoses. 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. some women with turner syndrome have premature facial wrinkling. acne is less common in teenage girls and women with turner syndrome, though the reasons why are unclear. an infant with turner syndrome other physical features connected to the condition include long eyelashes, sometimes including an additional set of eyelashes, and unusual dermatoglyphics (fingerprints). some women with turner's report being unable to create fingerprint passwords due to hypoplastic dermatoglyphics. unusual dermatoglyphics are common to chromosome anomalies and in the case of turner's may be a consequence of fetal lymphedema. 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. 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. cardiac bicuspid aortic valve approximately half of individuals with turner syndrome have congenital heart defects. chds associated with turner syndrome include bicuspid aortic valves (30%), coarctation of the aorta (15%), and abnormalities of the arteries in the head and neck. 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. 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 diabetes. internal medicine turner syndrome is associated with a broad variety of health considerations, such as liver and kidney issues, obesity, diabetes, and hypertension. liver dysfunction is common in women with turner syndrome, with 50%–80% having elevated liver enzymes. 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 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. duplicated ureter kidney issues, such as horseshoe kidney, are sometimes observed in turner syndrome. 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 ureters drain a single kidney, occurs in as much as 20%–30% of the turner syndrome population. kidney malformations in turner syndrome may be more common in mosaicism than in the