Number of CGG repeats in the FMR1 gene of Japanese patients with primary ovarian insufficiency

ObjectiveTo define the number of CGG repeats in the FMR1 gene of Japanese patients with primary ovarian insufficiency (POI) and normal controls.DesignRetrospective, controlled cohort study.SettingOutpatient department of an academic tertiary center.Patient(s)One hundred twenty-eight consecutive Japanese patients with sporadic, nonsyndromic POI and 98 controls with normal menstruation.Intervention(s)Deoxyribonucleic acid was obtained from the plasma of each subject.Main Outcome Measure(s)Differences in the distribution of CGG repeat numbers between patients with POI and controls.Result(s)Six alleles in the intermediate range and two in the premutation range were found in five and two patients with POI, respectively, but none were identified in normal controls. The prevalence of FMR1 premutation among Japanese POI patients was 1.56% (2 of 128). The prevalence of having >36 CGG repeats in the FMR1 gene was significantly higher in patients with POI than in controls, and age at the onset of amenorrhea was significantly lower in patients with >38 repeats.Conclusion(s)More than 36 CGG repeats in the FMR1 might intensify the etiology of POI, at least up to the premutation range.