NONISOTOPIC SINGLE-STRAND CONFORMATION ANALYSIS OF THE 5-ALPHA-REDUCTASE TYPE-2 GENE FOR THE DIAGNOSIS OF 5-ALPHA-REDUCTASE DEFICIENCY

5 alpha-Reductase deficiency is a rare autosomal recessive disorder of defective virilization in karyotypic males due to reduced conversion of testosterone to dihydrotestosterone. The gene encoding the affected 5 alpha-reductase type 2 enzyme has recently been cloned, and mutatio ns within the coding region have been discovered as the cause of this disease. We address the possibility of a rapid nonradioactive molecula r genetic screening technique for initial diagnosis and report differe nt point mutations in this gene in eight unrelated patients with clini cal features of 5 alpha-reductase deficiency. For molecular genetic an alysis, DNA from peripheral blood leukocytes was studied. The coding r egion of the 5 alpha-reductase type 2 gene was characterized by exon-s pecific PCR amplification, nonradioactive single strand conformation a nalysis, and direct sequencing. In seven patients, homozygous point mu tations were identified (Leu(55)-Gln, Delta Met(157), Gly(196)-Ser, Ar g(227)-Gln, Ala(228)-Thr, and His(231)-Arg). One individual was a comp ound heterozygote carrier of two mutations (Ile(112)-Asn and Gln(126)- Arg). We conclude that molecular genetic characterization of point mut ations in the 5 alpha-reductase type 2 gene may be used as an addition al valuable procedure for the diagnosis of this disorder.