As discussed in the ‘Lipoid CAH’ section above, lipoid CAH was initially thought to be a defect in P450scc, but no defects were found in P450scc, ferredoxin (FDX), ferredoxin reductase (FDXR) or in some factors thought to facilitate cholesterol’s entry into the mitochondria. Here, FDXR is linked to congenital adrenal hyperplasia.