Context: Nonclassical congenital adrenal hyperplasia owing to 21-hydroxylase deficiency (NC21OHD) is the most frequent of all autosomal recessive genetic diseases occurring in 1 in 100 in persons the heterogeneous New York City population. NC21OHD occurs with increased frequency in certain ethnic groups, such as Ashkenazi Jews, in who 1 in 27 express the disease. NC21OHD is underdiagnosed in both male and female patients with hyperandrogenic symptoms because hormonal abnormalities in NC21OHD are only mild to moderate, not severe as in the classical disease. Unlike classical congenital adrenal hyperplasia, NC21OHD is not associated with ambiguous genitalia in the female.

Main outcome measures: The hyperandrogenic symptoms include advanced bone age, early pubic hair, precocious puberty, tall stature and early arrest of growth in children; infertility, severe cystic acne, and short stature in both adult males and females; hirsutism, frontal balding, polycystic ovaries and irregular menstrual periods in females; and testicular adrenal rest tissue in males.

Conclusions: The signs and symptoms of hyperandrogenism are reversed with dexamethasone treatment.