Functional Characterization of c.870+3_6delGAGT Splice Site Mutation in NR5A1

Novel NR5A1 mutations found in Chinese patients with 46, XY disorders of sex development

OBJECTIVE

To analyze nuclear receptor subfamily 5 group A member 1 (NR5A1) gene mutations in a cohort of Chinese patients with 46, XY Disorders of Sex Development (DSD).

METHODS

Sixty 46, XY DSD patients were recruited at Peking Union Medical College Hospital. Targeted next-generation and Sanger sequencing were performed to investigate pathogenic gene variants and validate NR5A1 gene variants, respectively. In silico tools and in vitro function studies were used to analyze the pathogenicity of rare variants. The clinical and endocrinological characteristics of patients with NR5A1 variants were retrospectively analyzed.

RESULTS

A total of four novel and three recurrent NR5A1 variants were identified in seven 46, XY DSD patients. These variants widely spread almost all the functional domains. Functional studies showed that novel mutations including p.S32N, p.N44del and p.G91D reduced transactivation of CYP11A1, while the other missense variant p.A168E did not impact protein function. All patients with NR5A1 rare variants had normal adrenal function and showed genital defects. Results of the genitalia examination showed female external genitalia (three patients), ambiguous external genitalia (two patients), female external genitalia with clitoromegaly (one patient), and hypospadias (one patient). All seven patients had bilateral testis and five of seven patients lacked Müllerian structures.

CONCLUSIONS

Four novel mutations in the NR5A1 gene were identified in our cohort with 46, XY DSD, expanding the spectrum of NR5A1 gene mutations. All patients with NR5A1 rare variants had normal adrenal function and showed genital defects.

Two Unrelated Undervirilized 46,XY Males with Inherited NR5A1 Variants Identified by Whole-Exome Sequencing

BACKGROUND

Undervirilized 46,XY males with bifid scrotum often pose a diagnostic challenge, and the majority of cases typically do not receive a genetic diagnosis. NR5A1 mutations can be seen in 10-20% of the cases and are a relatively common cause of undervirilization.

METHODS

Whole-exome sequencing was utilized to study 10 undervirilized 46,XY subjects with bifid scrotum.

RESULTS

Exome sequencing identified novel NR5A1 variants, both affecting exon 7, in 2 of the 10 subjects with bifid scrotum. Subject 1 had a heterozygous frameshift variant, c.1150delC, p.Leu384fsTer1, within the ligand-binding domain inherited from his unaffected father. Subject 2 had a novel splice-site variant c.1139-2T>C, affecting the canonical splice acceptor site for exon 7 and also disrupting the ligand-binding domain. Both subjects had serum testosterone levels within the normal range as infants.

CONCLUSIONS

We describe two novel NR5A1 variants, demonstrating mutations in this gene as a common cause of milder cases of 46,XY undervirilization. Whole-exome sequencing results yielded the diagnosis in 2 out of 10 cases without a previous diagnosis, supporting the value of this approach. Significant genotype-phenotype variability was also noted with Subject 1's paternal inheritance from his unaffected father.