Five missense mutations (A284P, R454H, V489E, C566Y, and V605F) and a splicing mutation in the POR genes have been found in patients who had hormonal evidence for combined deficiencies of two steroidogenic cytochrome P450 enzymes - P450c17 CYP17A1, which catalyzes steroid 17α-hydroxylation and 17,20 lyase reaction, and P450c21 21-Hydroxylase, which catalyzes steroid 21-hydroxylation.
cytochrome b | cytochrome ''b'' | Cytochrome c oxidase | cytochrome c oxidase | cytochrome ''c'' oxidase | 5-alpha reductase | HMG-CoA reductase | Rubredoxin—NAD(P)+ reductase | Ribonucleoside-triphosphate reductase | GMP reductase | Flavanone 4-reductase | D-xylose reductase | Cytochrome P450, family 1, member A1 | Cytochrome P450 | cytochrome P450 | Cytochrome c oxidase subunit I |