A Novel Nonsense Mutation p.L9X in the SRY Gene Causes Complete Gonadal Dysgenesis in a 46,XY Female Patient

Abstract

Mammalian sex is determined by a gene localized on the Y chromosome known as SRY (sex-determining region of the Y chromosome). SRY is a transcription factor that plays a key role in the initiation of the cascade of male sexual differentiation. In 46,XY humans, SRY mutations cause complete gonadal dysgenesis (CGD) with male to female sex reversal, which results in female genitalia without testis differentiation. The aim of this study was to look for mutations of SRY gene in a 46,XY CGD Tunisian female patient by direct sequencing. This method allowed us to identify a novel nonsense mutation L9X, occurring within the NH2 terminal domain of SRY. This novel mutation led to the appearance of a premature stop codon, resulting in a truncated protein, missing the entire HMG box functional domain and the COOH terminal domain. Because of an increased risk of developing gonadoblastoma, early molecular diagnosis allows the orientation of the clinical supervision by removing the dysgenetic gonads to prevent gonadal malignancy. Furthermore, it provides valuable information for the understanding of molecular mechanisms behind the gonadal dysgenesis.