Clinical, hormonal, and molecular-genetic characteristics of three cases of 46XY disorder of sex development caused by type II 5-alpha reductase deficiency

Deficiency of type II 5-alpha reductase (5-ARII) is known to be responsible for abnormal sexual differentiation in boys. Of primary importance is differential diagnosis between this condition and incomplete form of androgen resistance. In the latter case, adaptation to male gender is highly undesirable because of inefficiency of androgen therapy. In contrast, such adaptation is socially justified in patients with type II 5-alpha reductase deficiency; sometimes, it permits to preserve fertility. The cases reported in this paper demonstrate low diagnostic value of the T/DHT ratio (at least as determined by the immunoenzyme assay) and emphasize the necessity of analysis of the SRD5A2 gene in all patients with suspected deficiency of type II 5-alpha reductase.