A clinical case study has reported the virilization of a female fetus due to a maternal androgen-producing adrenal tumour, and while 21-hydroxylase deficiency and cytochrome P450 oxidoreductase (POR) deficiency (PORD; presumably related to aromatase activity) were excluded as possible causes, levels of C11-oxy androgens were markedly elevated in the mother. The gene discussed is POR; the disease is congenital adrenal hyperplasia due to cytochrome P450 oxidoreductase deficiency.