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

Objective: To investigate the influence of the 5,10-methylenetetrahydrofolate reductase 677C -> T mutation on the E-2 synthesis in human granulosa cells (GCs). Design: In vitro cell culture study. Setting: Research laboratory of a university hospital. Patient(s): Follicular fluids (n = 139) and GCs (n = 66) were obtained from patients undergoing controlled ovarian hyperstimulation for TVF 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 E-2 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 E-2-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 E, 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 E-2 in follicular fluid and decreased E-2 synthesis of GC from homozygous T/T individuals suggest that reduced follicular E-2 is a result of impaired E-2 production of human GC. (Fertil Steril (R) 2009; 91:56-61. (c) 2009 by American Society for Reproductive Medicine.)