Novel Heterozygous Mutations of NR5A1 and Their Functional Characteristics in Patients with 46,XY Disorders of Sex Development without Adrenal Insufficiency.

Background/aims: Heterozygous mutations of NR5A1, which encodes steroidogenic factor 1 (SF1), were identified in patients with 46,XY disorders of sex development (DSD) with normal adrenal function. This study was aimed to identify and functionally characterize mutations of NR5A1 in patients with 46,XY DSD.

Methods: This study included 51 patients from 49 unrelated families with 46,XY DSD. Genomic DNA was extracted from peripheral blood leukocytes, and direct sequencing of all coding exons and their flanking introns of NR5A1 was performed. Transient transfections and dual-luciferase® reporter assays were performed to evaluate the effect of NR5A1 variants on transcriptional activity.

Results: Four of 49 patients (8.2%) harbored a novel heterozygous sequence variant of NR5A1: c.80G>C (p.G26A), c.847T>C (p.C283R), c.1151del (p.L384Rfs*7), and c.1333G>T (p.E445*). They presented with female external genitalia with clitoromegaly in infancy or childhood, or primary amenorrhea in adolescence. In vitro functional studies of SF1 activity determined that each variant, except p.E445*, led to a reduced expression of downstream target genes and disturbed the regulation of gonadal development.

Conclusions: Loss-of-function mutations of NR5A1 are a relatively common cause of 46,XY DSD. Therefore, genetic defects of NR5A1 should be considered as an etiology in subjects with 46,XY DSD without adrenal insufficiency.