Turner syndrome

What is Turner syndrome?
Turner syndrome results when one normal X chromosome is present in a female’s cells and the other sex chromosome is missing or structurally altered. The missing genetic material affects development before and after birth. About half of individuals with Turner syndrome have monosomy X, which means each cell in the individual’s body has only one copy of the X chromosome instead of the usual two sex chromosomes. Turner syndrome can also occur if one of the sex chromosomes is partially missing or rearranged rather than completely absent.

Signs and symptoms
The most common feature of Turner syndrome is short stature, which becomes evident by about age 5. An early loss of ovarian function is also very common. The ovaries develop normally at first, but egg cells usually die prematurely and most ovarian tissue degenerates before birth. Many affected girls do not undergo puberty unless they receive hormone therapy, and most are unable to conceive (infertile). A small percentage of females with Turner syndrome retain normal ovarian function through young adulthood. Other symptoms include extra folds of skin on the neck, a low hairline at the back of the neck, puffiness or swelling (lymphedema) of the hands and feet, skeletal abnormalities, or kidney problems. One third to one half of individuals with Turner syndrome are born with a heart defect, such as a narrowing of the large artery leaving the heart or abnormalities the aortic valve.

Children with Turner syndrome
Turner syndrome affects about 1 in every 2,500 girls. Girls who have this condition usually are shorter than average and infertile due to early loss of ovarian function.

Diagnosis of Turner syndrome
Turner syndrome may be diagnosed before birth (prenatally), during infancy or in early childhood. Occasionally, in females with mild signs and symptoms of Turner syndrome, the diagnosis is delayed until the teen or young adult years.

Sources and useful links:
Medline Plus 
Mayo Clinic 
KidsHealth