The effect of CGG repeat number on ovarian response among fragile X premutation carriers undergoing preimplantation genetic diagnosis

ObjectiveTo assess ovarian response among carriers of FMR1 premutation who undergo preimplantation genetic diagnosis (PGD).DesignRetrospective study.SettingAcademic IVF unit.Patient(s)Of 18 carriers of FMR1 premutation referred to PGD, eight had <100 CGG repeats and ten had ≥100 CGG repeats.Intervention(s)Controlled ovarian stimulation (COH) and PGD.Main Outcome Measure(s)Correlation between the number of CGG repeats and the level of E2 at day of hCG administration, number of retrieved oocytes, number of two-pronuclear (2PN) zygotes, and dose of recombinant FSH.Result(s)There was a positive correlation between CGG repeats and the level of E2 at day of hCG administration, number of retrieved oocytes, and number of 2PN zygotes. There was a negative correlation between number of CGG repeats and the total dose of gonadotropins. The E2 level and the number of retrieved oocytes and 2PN zygotes were significantly higher and the dose of gonadotropins significantly lower for premutation patients with ≥100 CGG repeats compared with <100 CGG repeats.Conclusion(s)There is a positive correlation between E2 level, retrieved oocytes, 2PN zygotes, and number of CGG repeats. Premutation carriers with <100 CGG repeats suffer from impaired ovarian response and decreased fertilization rate.