Clinical, Hormonal, and Genetic Characteristics of 5α-Reductase Type 2 Deficiency in 103 Chinese Patients

OBJECTIVE: 5α-Reductase type 2 (5α-RD2) deficiency causes variable degrees of undervirilization in patients. The correlation between its genotype and phenotype is unclear. METHODS: We retrospectively evaluated 103 patients with 46,XY disorders of sex development who were diagnosed with 5α-RD2 deficiency. RESULTS: The prevalence of female sex assignment (P = .008) and the incidences of cryptorchidism (P = .0003) and bifid scrotum (P = .0002) in the non-p.R227Q variant group were higher, but there were no significant differences in the incidences of hypospadias and isolated microphallus. The external masculinization score in the non-p.R227Q variant group was lower than that in the homozygous p.R227Q variant (P = .019) and compound heterozygous p.R227Q variant groups (P = .013). The level of anti-Mullerian hormone in the non-p.R227Q variant group was lower than that in the homozygous p.R227Q variant (P < .001) and compound heterozygous p.R227Q variant groups (P = .006). The testosterone-to-dihydrotestosterone ratio of the homozygous p.R227Q variant group was higher than that of the non-p.R227Q variant (P = .018) and compound heterozygous p.R227Q variant groups (P = .029). Twenty-three reportedly pathogenic variants and 11 novel steroid 5α-reductase 2 (SRD5A2) variants were identified. CONCLUSION: Compared with patients without p.R227Q, patients with p.R227Q exhibited higher external masculinization scores and anti-Mullerian hormone expression, a lower prevalence of female sex assignment, and lower incidences of cryptorchidism and bifid scrotum. We identified 23 reportedly pathogenic SRD5A2 variants and 11 novel SRD5A2 variants that led to 5α-RD2 deficiency. We established a genotype-phenotype correlation, and patients with p.R227Q showed a relatively mild phenotype.