1720-lyase deficiency

17,20-ly·ase de·fi·cien·cy (liґās) a disorder of steroidogenesis caused by mutation in the CYP17A1 gene (locus: 10q24.3), which encodes steroid 17α-monooxygenase, resulting in deficiency of 17α-hydroxyprogesterone aldolase, an enzyme activity of steroid 17α-monooxygenase that normally catalyzes the conversion of C₂₁ to C₉ steroid hormones (androgens and estrogens). The result is a type of congenital adrenal hyperplasia (type V). Males are pseudohermaphroditic and both sexes remain sexually infantile. See also 17α-hydroxylase deficiency and see table at hyperplasia.