Genotype–Phenotype Correlation Analysis and Identification of a Novel SRD5A2 Mutation in Four Unrelated Chinese Patients with 5α-Reductase Deficiency

Ting Gui,1,* Fengxia Yao,2,* Xinzhuang Yang,2 Xi Wang,3 Min Nie,3 Xueyan Wu,3 Qinjie Tian1 1Department of Obstetrics and Gynecology, National Clinical Research Center for Obstetric and Gynecologic Diseases, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People’s Republic of China; 2Department of Medical Research Center, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People’s Republic of China; 3Department of Endocrinology, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People’s Republic of China*These authors contributed equally to this workCorrespondence: Qinjie Tian, Department of obstetrics and gynecology, Peking Union Medical College Hospital, No. 1, Shuaifuyuan Road, Dongcheng District, Beijing, 100730, People’s Republic of China, Tel +86 010-69158335, Email tqj_tianqinjie@163.comObjective: The 5α-reductase type 2 deficiency is mainly caused by mutations in the SRD5A2 gene. Our study aims to investigate the SRD5A2 gene mutations and their corresponding manifestations.Methods: Four unrelated Chinese patients with 46, XY ambiguous genitalia were studied. Molecular genetic alterations and clinical presentations were analyzed.Results: Five variants in the SRD5A2 gene were identified, all highly conserved in vertebrate orthologs. The p.P251A was a novel variant, predicted to “Affect protein function” and to be “probably damaging”. Combining patients’ gene mutations with their external genitalia and male sexual characteristics, we found that three variants, p.Q6X, p.N193S, and p.H90Y, were associated with severe undervirilization of external genitalia, and the other two, p.G203S and p.P251A, probably retained part of the enzyme activity.Conclusion: Mutation analysis of SRD5A2 gene is crucial for differential diagnosis in patients with 5α-reductase type 2 deficiency. Patients’ variable manifestations depend on the mutation type and residual enzyme activity. The novel variant p.P251A enlarges the spectrum of SRD5A2 mutations.Keywords: 5α-reductase type 2 deficiency, SRD5A2 gene mutation, androgen receptor insensitivity, disorders of sex development, differential diagnosis