Common 677C→T mutation of the 5,10-methylenetetrahydrofolate reductase gene affects follicular estradiol synthesis

ObjectiveTo investigate the influence of the 5,10-methylenetetrahydrofolate reductase 677C→T mutation on the E2 synthesis in human granulosa cells (GCs).DesignIn vitro cell culture study.SettingResearch laboratory of a university hospital.Patient(s)Follicular fluids (n = 139) and GCs (n = 66) were obtained from patients undergoing controlled ovarian hyperstimulation for IVF with or without ICSI.Intervention(s)Granulosa cells were cultured for a total of 5 days. On day 3, the cells either were stimulated with recombinant (r-) FSH or r-LH (80 IU/L for 48 h) or were sham stimulated.Main Outcome Measure(s)Estradiol and protein content were measured in the pooled follicular fluids of each individual. At the end of each GC-culturing period, the concentrations of E2 were measured in the supernatants of triplicate cultures by immunoassays. The 5,10-methylenetetrahydrofolate reductase 677C→T genotype was determined by RFLP analysis.Result(s)The E2-protein ratio of homozygous T/T carriers was significantly lower compared with that of homozygous C/C individuals. Furthermore, basal and r-FSH– as well as r-LH–stimulated E2 synthesis of GC obtained from homozygous T/T patients was significantly reduced, compared with GC from heterozygous C/T and homozygous C/C subjects.Conclusion(s)Decreased E2 in follicular fluid and decreased E2 synthesis of GC from homozygous T/T individuals suggest that reduced follicular E2 is a result of impaired E2 production of human GC.