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 females cells have only one X chromosome or are partially missing an X chromosome (sex chromosome monosomy) leading to the complete or partial deletion of the pseudoautosomal regions (PAR1, PAR2) in the affected X chromosome.[2][6][7] 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][8] 45,X0 with mosaicism can occur in males or females,[9] 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.[10][11] No environmental risks are known, and the mother's age does not play a role.[10][12] 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.[13] Diagnosis is based on physical signs and genetic testing.[3]
No cure for Turner syndrome is known.[14] Treatment may help with symptoms.[14] Human growth hormone injections during childhood may increase adult height.[14] Estrogen replacement therapy can promote development of the breasts and hips.[14] Medical care is often required to manage other health problems with which Turner syndrome is associated.[14]
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.[10] 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.[15] In 1964, it was determined to be due to a chromosomal abnormality.[15]