Classic 3β-hydroxysteroid dehydrogenase type 2 (3β-HSD II) deficiency causes congenital adrenal hyperplasia with glucocorticoid, mineralocorticoid, and sex steroid deficiency. We present a female patient with congenital adrenal hyperplasia detected in newborn screening due to elevated 17OH-progesterone. Female external genitalia and non-measurable androgen levels elicited the suspicion of a defect early in the steroid cascade. Two loss-of-function HSD3B2 mutations (1 novel) were detected and confirmed in silico. We argue that in a girl with glucocorticoid and mineralocorticoid deficiency without virilization, 3β-HSD II deficiency is an important differential diagnosis. 17OH-progesterone may initially be elevated due to placental and peripheral activity of 3β-HSD I, whereas dehydroepiandrosterone may not be increased.
