The pivotal role of StAR in the regulation of steroidogenesis was strengthened after the identification of mutations causing premature stop codons in the StAR gene of patients affected by the most common form of congenital lipoid adrenal hyperplasia (CAH) (28, 29), a rare disorder of steroid biosynthesis. The gene discussed is STAR; the disease is congenital lipoid adrenal hyperplasia due to STAR deficency.