CYP19A1 Gene

Aromatase deficiency is a condition characterized by reduced levels of the female sex hormone estrogen and increased levels of the male sex hormone testosterone.

Females with aromatase deficiency have a typical female chromosome pattern (46,XX) but are born with external genitalia that do not appear clearly female or male (ambiguous genitalia). These individuals typically have normal internal reproductive organs, but develop ovarian cysts early in childhood, which impair the release of egg cells from the ovaries (ovulation). In adolescence, most affected females do not develop secondary sexual characteristics, such as breast growth and menstrual periods. They tend to develop acne and excessive body hair growth (hirsutism).

Men with this condition have a typical male chromosome pattern (46,XY) and are born with male external genitalia. Some men with this condition have decreased sex drive, abnormal sperm production, or testes that are small or undescended (cryptorchidism).

There are other features associated with aromatase deficiency that can affect both males and females. Affected individuals are abnormally tall because of excessive growth of long bones in the arms and legs. The abnormal bone growth results in slowed mineralization of bones (delayed bone age) and thinning of the bones (%%PX0000U8osteoporosis%%), which can lead to bone fractures with little trauma. Males and females with aromatase deficiency can have abnormally high blood sugar (hyperglycemia) because the body does not respond correctly to the hormone insulin. In addition, they can have excessive weight gain and a fatty liver.

Women who are pregnant with fetuses that have aromatase deficiency often experience mild symptoms of the disorder even though they themselves do not have the disorder. These women may develop hirsutism, acne, an enlarged clitoris (clitoromegaly), and a deep voice. These features can appear as early as 12 weeks of pregnancy and go away soon after delivery.

Aromatase excess syndrome is a condition characterized by elevated levels of the female sex hormone estrogen in both males and females. Males with aromatase excess syndrome experience breast enlargement (gynecomastia) in late childhood or adolescence. The bones of affected males grow and develop more quickly and stop growing sooner than usual (advanced bone age). As a result males have an early growth spurt, typically during late childhood, with short stature as an adult. Affected females rarely show signs and symptoms of the condition, but they may have increased breast growth (macromastia), irregular menstrual periods, and short stature. The ability to have children (fertility) is usually normal in both males and females with aromatase excess syndrome.