Inherited Missense Mutation Occurring in Arginine76 of the SRY Gene Does Not Account for Familial 46, XY Sex Reversal

Background: SRY (sex determining region of Y) is one of the important genes involved in the process of human sex determination. The disturbed sex determination caused by an SRY mutation accounts for 10% to 15% of cases with 46, XY sex reversal. Recently, 3 distal enhancers were identified upstream of the SOX9 gene.

Objectives: The purpose of this study was to investigate the molecular etiology of 46, XY sex reversal in 3 familial patients and a sporadic patient.

Design: Next-generation sequencing was used to reveal the genotype and inherited pattern. Copy number variations and single nucleotide polymorphism haplotyping were analyzed to observe the alteration of enhancers of SOX9. Transcriptional activity of SRY mutation were assessed by a dual luciferase reporting system, and nuclear translocation was observed by confocal microscopy.

Results: Two novel SRY gene mutations, p.Arg76Leu and p.Glu89flx15, were identified. In the pedigree with multiple patients, p.Arg76Leu mutation in SRY and p.Gly212Ser mutation in NR5A1 were identified in the proband. The heterozygous deletion far upstream of the SOX9 gene in chromosome 17 was identified in the 3 patients in this family, containing the distal enhancer eSR-A of SOX9 but not eSR-B and eALDI. The frameshift mutation p.Glu89flx15 was revealed to inhibit the transcriptional activity of the target gene, whereas the missense mutation p.Arg76Leu barely showed an effect.

Conclusion: In contrast to sporadic cases, inherited single nucleotide variations of SRY are not the main cause of the severe phenotype of 46, XY sex reversal, and the enhancers of SOX9 should be investigated carefully in such patients.