7. Congenital Adrenal Hyperplasia (CAH) in 46,XX Individals

In CAH excess adrenal androgens are produced as an indirect result of a cortisol biosynthetic defect (by far the most frequent defect is a cytochrome P450,CYP21 deficiency). In 46,XX individuals, excess adrenal androgens can lead to ambiguous development of the external genitalia, so that these babies have an enlarged clitoris and a fused labia which resembles a scrotum. The chart on the following page illustrates the steps of sexual differentiation associated with 46,XX CAH (21-hydroxylase deficiency) individuals compared to those of unaffected males and females.

8. Klinefelter Syndrome

Klinefelter Syndrome is the term given to individuals with a 47,XXY karyotype. At puberty Klinefelter men can experience female breast growth, low androgen production, small testes, and decreased sperm production. Additionally, although Klinefelter men undergo normal male differentiation of the external genitalia, they often possess a penis that is smaller than that of normal men. The following chart illustrates the steps of sexual differentiation associated with individuals who have Klinefelter Syndrome, compared to those of unaffected males and females.