Molecular investigation of mutations in androgen receptor and 5‐alpha‐reductase‐2 genes in 46,XY Disorders of Sex Development with normal testicular development

An Extremely Rare SRD5A2 Gene c.485A>C Mutation in a Compound Heterozygous Newborn with Disorders of Sex Development First Identified in Vietnam

SRD5A2 (steroid 5-alpha-reductase 2) mutation, which impairs 5α-reductase-2 enzyme activity, is among the causes of 46,XY disorders of sex development (DSD). Here, we report a rare pathogenic mutation NM_000348.4:c.485A>C (NP_000339.2:p.His162Pro) of SRD5A2 gene in a compound heterozygous state first identified in a Vietnamese newborn with 5α-reductase-2 enzyme deficiency. We also first submitted this rare mutation to ClinVar database (VCV000973099.1). The patient presented with hyperpigmented labia-majora-like bifid scrotum, clitoris-like phallus, perineoscrotal hypospadias, and blind-ending vagina. The other mutation NM_000348.4:c.680G>A (NP_000339.2:p.Arg227Gln) was reported previously. This compound heterozygous mutation was first detected by next-generation sequencing. By Sanger sequencing, we confirmed that the c.485A>C mutation was maternal inherited, whereas the c.680G>A mutation was paternal inherited. Up to date, this is the first report of this rare compound heterozygous state of SRD5A2 c.485A>C and c.680G>A mutations in patients with 46,XY DSD generally as well as in Vietnamese population particularly and is also the second report in the world carrying the pathogenic mutation NM_000348.4:c.485A>C (NP_000339.2:p.His162Pro). Our finding has enriched the understanding of the spectrum of SRD5A2 variants and phenotypic correlation in Asian patients with 46,XY DSD.

A novel SRD5A2 mutation in an Iranian family with sex development disorder

Disorders of sex development (DSD) are different types of conditions that their accurate diagnosis by using conventional phenotypic and biochemical approaches is a challenging issue. Precise determination of DSD is critical due to the detection of possible life-threatening associated disorders. It may also assist parents in choosing the most suitable management for their affected child. In this study, two affected kids born from consanguineous families who were clinically diagnosed for sex development disorder were investigated for the main cause of the disease. Biochemical analysis failed to make an accurate diagnosis. Karyotype analysis showed an abnormal sex chromosome pattern. Whole exome sequencing was sequentially applied to precisely ascertain the genetic cause of the disease. A novel deletion, g.40936_53878del12943insTG (NG_008365.1), and one known mutation, c.586G>A (p.Gly196Ser), were detected in SRD5A2 gene in case I and case II respectively. Further analysis was performed using polymerase chain reaction, primer walking and Sanger sequencing to detect the nucleotides changes accurately. Segregation analysis in the families confirmed 13kb novel homozygous deletion of SRD5A2 in case I and c.586G>A in case II. The present study confirms the diagnostic value of whole exome sequencing in the detection of DSD aetiology, especially when several differential diagnoses are possible.