[The importance of DNA analysis in the diagnosis of steroid 5-alpha-reductase deficiency].

The deficiency of steroid 5 alpha-reductase leads to the disturbances in sex differentiation that cause symptoms of male pseudohermaphroditism. The methods of DNA analysis used to diagnose mutations of steroid 5 alpha-reductase gene (SRD5A2) were presented and discussed. Within the group of 21 patients with the deficiency of steroid 5 alpha-reductase 2 described so far in literature, the analysis of SRD5A2 gene revealed two "major" deletions, one "minor" deletion, 16 point mutations (incl. 5 transitions and 11 transversions), in one case a mutation causing premature termination of translation and in one case mutation leading to defective splicing of the mRNA. The mutations localized in exons 2 and 5 cause a decrease in affinity of 5 alpha-reductase 2 to the substrate (testosterone), while the mutations in exons 1 and 4, a decrease in affinity to the coenzyme (NADPH).