Definition of Turner syndrome

Turner syndrome: A chromosome disorder in females that is characterized by the absence of all or part of a second sex chromosome in some or all cells. The condition occurs in 1 in 2,500 to 3,000 girls born.

The physical features often include webbing of the neck (due to congenital lymphedema), short stature, delayed growth of the skeleton, shortened fourth and fifth fingers, broad chest, cardivascular abnormalities, and gonadal dysgeneesis. Women with Turner syndrome are usually infertile due to ovarian failure.

The clinical diagnosis is confirmed by a chromosome study including a href="/script/main/art.asp?articlekey=4085">karyotypes of cells from a sample of blood. About half of cases are due to monosomy X (45,X) while up to a tenth have an isochromosome of the long (q) arm of one X (46,X,i(Xq)). Most of the remaining cases have mosaicism with two or more cell lines usually including a line with 45,X.

Treatment may include human growth hormone and estrogen replacement therapy.