Turner syndrome
Turner syndrome (TS), also known as 45,X, or 45,X0, is a genetic disorder in which a person's cells have only one X chromosome or are partially missing an X chromosome (sex chromosome monosomy).[2][6] Most people have two sex chromosomes (XX or XY). The chromosomal abnormality is often present in just some cells, in which case it is known as Turner syndrome with mosaicism.[7] 45,X0 with mosaicism can occur in males or females,[8] but Turner syndrome without mosaicism only occurs in females.[2][6] Signs and symptoms vary among those affected.[1] 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.[1] Typically, those affected do not develop menstrual periods or breasts without hormone treatment and are unable to have children without reproductive technology.[1] Heart defects, diabetes, and hypothyroidism occur in the disorder more frequently than average.[1] Most people with Turner syndrome have normal intelligence; however, many have problems with spatial visualization that may be needed in order to learn mathematics.[1] Vision and hearing problems also occur more often than average.[7]
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.[9][10] No environmental risks are known, and the mother's age does not play a role.[9][11] While most people have 46 chromosomes, people with Turner syndrome usually have 45 in some or all cells.[6] In cases of mosaicism, the symptoms are usually fewer, and possibly none occur at all.[12] Diagnosis is based on physical signs and genetic testing.[3]
No cure for Turner syndrome is known.[13] Treatment may help with symptoms.[13] Human growth hormone injections during childhood may increase adult height.[13] Estrogen replacement therapy can promote development of the breasts and hips.[13] Medical care is often required to manage other health problems with which Turner syndrome is associated.[13]
Turner syndrome occurs in between one in 2,000[4] and one in 5,000 females at birth.[5] All regions of the world and cultures are affected about equally.[9] Generally people with Turner syndrome have a shorter life expectancy, mostly due to heart problems and diabetes.[7] American endocrinologist Henry Turner first described the condition in 1938.[14] In 1964, it was determined to be due to a chromosomal abnormality.[14]
As a chromosomal condition, there is no cure for Turner syndrome. However, much can be done to minimize the symptoms.[85] While most of the physical findings are harmless, significant medical problems can be associated with the syndrome. Most of these significant conditions are treatable with surgery and other therapies including hormonal therapy.[86]
Epidemiology[edit]
Turner syndrome occurs in between one in 2000[4] and one in 5000 females at birth.[5]
Approximately 99 percent of fetuses with Turner syndrome spontaneously terminate during the first trimester.[91] Turner syndrome accounts for about 10 percent of the total number of spontaneous abortions in the United States.[61]
History[edit]
The syndrome is named after Henry Turner, an American endocrinologist, who described it in 1938.[92] In Europe, it is often called Ullrich–Turner syndrome and was sometimes called Bonnevie–Ullrich syndrome although the latter term is rarely used today.[93] Both syndrome names acknowledge(d) that earlier cases had also been described by European doctors Kristine Bonnevie and Otto Ullrich. In Russian and Soviet literature, it is called Shereshevsky–Turner syndrome to acknowledge that the condition was first described as hereditary in 1925 by the Soviet endocrinologist Nikolai Shereshevsky, who believed that it was due to the underdevelopment of the gonads and the anterior pituitary gland and was combined with congenital malformations of internal development.[94]
The first published report of a female with a 45,X karyotype was in 1959 by Charles Ford and colleagues in Harwell near Oxford, and Guy's Hospital in London.[95] It was found in a 14-year-old girl with signs of Turner syndrome.[96]