Identification of a mutation in GDF9 as a novel cause of diminished ovarian reserve in young women

Abstract

Do any mutations in growth differentiation factor 9 (GDF9) have a role in diminished ovarian reserve (DOR) in young women? The GDF9 p.R146C mutation may be a source of DOR in some young women. DOR affects 10% of women under 37 years of age and is associated with accelerated expenditure of follicles. GDF9 is an oocyte-secreted factor that plays a critical role in follicular development and female fertility. Several GDF9 variants have been linked to ovarian dysfunction. This case-control study included 139 women with DOR and 152 controls aged under 37 years. All women were recruited in a Chinese tertiary center and underwent DNA sequencing of GDF9 gene. We then determined the molecular and biological properties of mutant GDF9 proteins using protein expression, structural prediction and functional analyses. We identified two mutations in the proregion of GDF9 gene: c.169T > G (p.D57Y) and c.436T > C (p.R146C). The p.R146C mutation was found in three women with DOR but was absent in the control population. This mutation was also associated with significant reductions in GDF9 mature protein secretion in cultured cells. Functional studies with human granulosa cells (GCs) showed that the p.R146C mutation reduced the abilities of GDF9 to stimulate GC proliferation and to activate the Smad2 pathway. Protein structure modeling predicted that p.R146C disrupted an α-helix in GDF9 protein. In contrast with p.R146C, the p.D57Y mutation, found in both the DOR and control groups (6 versus 2), had no obvious deleterious effects. Larger studies in varying populations may validate the role of GDF9 mutation in young women with DOR. These results may provide new insights into the pathophysiological mechanisms of early-onset DOR.