Turner syndrome

Turner syndrome
Other names	Ullrich–Turner syndrome, Bonnevie–Ullrich–Turner syndrome, 45X, 45X0
Five girls and women with Turner syndrome
Specialty	Pediatrics, medical genetics
Symptoms	Webbed neck, short stature, heart defects[1]
Onset	At birth[1]
Duration	Long term
Causes	Single sex chromosome[2]
Diagnostic method	Karyotype[3]
Frequency	1 in 2,000 to 5,000[4][5]
Named after	Henry Turner

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]