9. Turner Syndrome

Turner Syndrome is the term given to individuals with a 45,XO karyotype. Turner patients can exhibit webbing of the neck, a broad chest, horseshoe kidneys, cardiovascular abnormalities, and short stature. Turner patients do not possess ovaries, but instead possess gonadal streaks. Turner patients have normal female external genitalia, but because they lack functioning ovaries (and thus the estrogens produced by ovaries) neither breast development, nor menstruation occurs spontaneously at puberty. The following chart illustrates the steps of sexual differentiation associated with Turner Syndrome compared to those of unaffected males and females.

10. 45,XO/46,XY Mosaicism

Individuals born with 45,XO/46,XY Mosaicism can appear male, female, or ambiguous at birth. Males experience normal male sex differentiation and females are essentially identical to girls born with Turner Syndrome. For the purpose of this booklet, only patients with 45,XO/46,XY Mosaicism, who experience ambiguous sex differentiation, will be described on the following chart.

Mosaicism means that two or more sets of chromosomes influence the development of an individual. 45,XO/46,XY Mosaicism represents the most common mosaic condition involving the Y chromosome. Because the Y chromosome is affected, abnormal sex differentiation can result from this condition. The following chart illustrates the steps of sex differentiation associated with 45,XO/46,XY Mosaicism compared to those of unaffected males and females.