In women with PCOS, ovarian theca cells are recognized as one of the primary sources of excessive androgen biosynthesis, which is associated with augmented expression of several steroidogenic enzymes, such as cytochrome P450c17 which has both 17α-hydroxylase and C17, 20 lyase activities [5, 6]. The gene discussed is CYP17A1; the disease is polycystic ovary syndrome.