ABSTRACT
The molecular features of 5α-reductase deficiency were elucidated in fibroblasts cultured from the genital skin of affected individuals (Moore et al., 1975; Wilson, 1975; Moore and Wilson, 1976). In contrast to normal fibroblasts, cells isolated from these patients failed to show 5α-reductase activity with an acidic pH optimum. A second activity was detected at an alkaline pH optimum in both genital and non genital fibroblasts from affected individuals. Further insight into the meaning of these findings and the existence of multiple isoenzymes was hampered by the extreme insolubility of the protein. The characterization of cDNA clones obtained by using expression cloning strategy provided the molecular explanation for these two activities, which are in fact encoded by two different genes (Andersson and Russell, 1990; Andersson et al., 1991; Jenkins et al., 1992). The first enzyme cloned was designated steroid 5α-reductase type 1 and exhibits an alkaline pH optimum, whereas the acidic pH enzyme was termed steroid 5α-reductase type 2.
