Cholesterol Side-Chain Cleavage Enzyme (SCC) Deficiency.

Cholesterol side-chain cleavage enzyme (SCC) catalyzes the conversion of cholesterol to pregnenolone, the first step in the biosynthesis of all steroid hormones. It was once postulated that SCC deficiency would be lethal, but recent studies have established that SCC deficiency is an autosomal recessive disorder caused by inactivating mutations in the CYP11A1 gene. Clinical manifestations include adrenal insufficiency and 46,XY sex reversal due to disrupted steroidogenesis, which are similar to StAR deficiency. Further accumulation of patients with SCC deficiency should clarify the similarities and differences between SCC deficiency and StAR deficiency.