Turner syndrome

Turner syndrome
Other names	Ullrich–Turner syndrome, X0 syndrome, 45,X, 45, X0
Five Latino girls and women with Turner syndrome with wide neck and low-set ears
Specialty	Pediatrics, medical genetics
Symptoms	Neck webbing, short stature, heart defects, ptosis, cupped ears [1]
Onset	At birth[1]
Duration	Lasts for a lifetime
Causes	1 X chromosome and no Y chromosome [2]
Risk factors	Nondisjunction in sperm
Diagnostic method	Karyotype[3]
Frequency	1 in 2,000 to 5,000 female births [4][5]
Named after	Henry Turner

Turner syndrome (TS), commonly known as 45,X, or 45,X0^{[note 1]}, is a chromosomal disorder in which 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, additional skin folds on the neck , arched palate, low-set ears, low hairline at the nape of the neck, shorter height, and lymphedema of the hands and feet.^[1] Typically, those affected do not develop menstrual periods or mammary glands without hormone treatment and are unable to have kids and grandkids without assistive reproductive technology. Small chin(micrognathia),loose folds of skin on the neck, slanted eyes, and prominent ears are found in Turner syndrome, though not all will show it. ^[1] Heart defects, Type II 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] Ptosis (droopy eyelids) and conductive hearing loss also occur more often than average.^[7]

Turner syndrome is caused by one X chromosome (45,X), a ring X chromosome, 45,X/46,XX mosaicism, or a small piece of the Y chromosome in what should be a X chromosome. They may have a total of 45 chromosomes or will not develop menstrual periods due to loss of ovarian function genes. Their karyotype often lacks Barr bodies due to lack of a second X or may have Xp deletions. 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]

Cite error: There are <ref group=note> tags on this page, but the references will not show without a {{reflist|group=note}} template (see the help page).