Both positive and negative selection pressures contribute to the polymorphism pattern of the duplicated human CYP21A2 gene.
The human steroid 21-hydroxylase gene (CYP21A2) participates in cortisol and aldosterone biosynthesis, and resides together with its paralogous (duplicated) pseudogene in a multiallelic copy number variation (CNV), called RCCX CNV.Concerted evolution caused by non-allelic gene conversion has been described in great ape CYP21 genes, and the same con