Male pseudohermaphroditism due to 5 alpha-reductase deficiency in a Swedish family.

Three sibs with an inherited form of male pseudohermaphroditism are described. They were all born with ambiguous external genitalia but no diagnosis of a possible enzyme defect was made during childhood. First seen at the ages of 16, 14 and 10 years respectively, they were investigated in order to establish the pathogenetic nature of the disorder. Serum concentrations of testosterone and dihydrotestosterone before and after stimulation with human chorionic gonadotropin suggested 5 alpha-reductase deficiency. Measurement of steroid metabolites in urine confirmed this diagnosis. It is essential to recognize this condition in order to decide the sex of rearing of the children.