Puberty in a case with novel 17-hydroxylase mutation and the putative role of estrogen in development of pubic hair

17-Hydroxylase/17,20-lyase deficiency (17OHD) results from mutations in the CYP17A1 gene, leading to failure to synthesize cortisol, adrenal androgens, and gonadal steroids. Adrenarche is a consequence of the increased production of adrenal androgens. Here, we report a case carrying novel R239Q mutation causing complete functional loss of CYP17A1, and thus absence of adrenal and gonadal sex hormone production. The patient has had unexpected pubic hair development and insufficient breast development with estrogen replacement therapy. Possible mechanisms leading to pubic hair development and breast underdevelopment are discussed.