The phenotype and genotype characteristics of 41 patients with steroid 5α-reductase type 2 deficiency

Objective To investigate the clinical phenotype and the genotype of forty-one patients with steroid 5α-reductase type 2 deficiency. Methods The clinical data were collected including physical examination, medical history, laboratory test, as well as ultrasonic examination. Genomic DNA was extracted from peripheral blood leukocytes. Sanger sequencing and targeted gene captured next-generation sequencing were applied to detect the SRD5A2 gene mutation. Results All the patients are Han nationality and their ages ranged from 4 months to 11 years old. The karyotypes of 41 patients were 46, XY and all SRY genes were detected as positive. There were 26 (63%) patients manifested isolated micropenis, and the rest of fifteen patients were hypospadias associated with microphallus accounting for 37%. There were 39 patients who carried biallelic mutation. Two cases just identified one allele mutation. Sixteen gene mutation types were confirmed. Among them c. 725A>G(p.Tyr242Cys), c. 694C>G(p.His232Asp), and c. 548-9T>G are the novel gene types. The allele frequency of c. 680G>A(p.Arg227Gln) is 60% (48/80). Conclusion The primary manifestations of patients with steroid 5α-reductase type 2 deficiency were micropenis or hypospadias accompanied with micropenis. c. 680G>A(p.Arg227Gln) is the predominantly mutation type of Chinese patient with steroid 5α-reductase type 2 deficiency. Key words: 5α-reductase; SRD5A2; Targeted gene captured next-generation sequencing; Micropenis; Hypospadias