Turner syndrome

Turner syndrome is a chromosomal condition that affects development. Females typically have two X chromosomes, but in individuals with Turner syndrome, one copy of the X chromosome is missing or altered.

The most common feature of Turner syndrome is short stature, which becomes evident by about age 5. Reduced functioning of the ovaries, the female reproductive organs that produce egg cells (oocytes) and female sex hormones, is also very common. The ovaries develop normally at first, but egg cells usually die prematurely and most ovarian tissue breaks down before birth. 

Many females with Turner syndrome do not undergo puberty unless they receive hormone therapy, and most are unable to become pregnant naturally. A small percentage of people with Turner syndrome retain normal ovarian function through young adulthood.

About 30 percent of individuals with Turner syndrome have extra folds of skin on the neck (webbed 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 that leaves the heart (coarctation of the aorta) or abnormalities of the valve that connects the aorta to the heart (the aortic valve). Complications associated with these heart defects can be life-threatening.

Most people with Turner syndrome have normal intelligence. Developmental delays, nonverbal learning disabilities, and behavioral problems are possible, although these characteristics vary among affected individuals.