Elevated Levels of FMR1 mRNA in Granulosa Cells Are Associated with Low Ovarian Reserve in FMR1 Premutation Carriers

AIM: To assess the role of mRNA accumulation in granulosa cells as the cause of low ovarian response among FMR1 premutation carriers undergoing pre-implantation genetic diagnosis (PGD). DESIGN: Case control study in an academic IVF unit. Twenty-one consecutive FMR1 premutation carriers and 15 control women were included. After oocyte retrieval the granulosa cells mRNA levels of FMR1 was measured using RT-PCR. RESULTS: In FMR1 premutation carriers, there was a significant non-linear association between the number of CGG repeats and the number of retrieved oocytes (p<0.0001) and a trend to granulosa cells FMR1 mRNA levels (p = 0.07). The lowest number of retrieved oocytes and the highest level of mRNA were seen in women with mid-size CGG repeats (80–120). A significant negative linear correlation was observed between the granulosa cells FMR1 mRNA levels and the number of retrieved oocytes (R(2) linear = 0.231, P = 0.02). CONCLUSION: We suggest that there is a no-linear association between the number of CGG repeats and ovarian function, resulting from an increased granulosa cells FMR1 mRNA accumulation in FMR1 carriers in the mid-range (80–120 repeats).