FMR6 may play a role in the pathogenesis of fragile X-associated premature ovarian insufficiency

Abstract

The aim of this study was to evaluate whether long noncoding RNA accumulation play a role in the pathophysiology of fragile X-associated premature ovarian insufficiency (FXPOI). The study population consisted of 22 consecutive fragile X mental retardation 1 (FMR1) premutation carriers (CGGn 55–199 repeats) undergoing in vitro fertilization and pre-implantation genetic diagnosis (IVF–PGD) treatment. The control group consists of 11 patients, with <55 CGG repeats, undergoing IVF–ICSI for male factor infertility, matched by age, treated in the same period. After oocyte retrieval, granulosa cells from follicular fluid were washed and stored at −80 °C. RNA was transcribed to generate cDNA and the RNA levels were measured using RT–PCR. Transcripts levels in granulosa cells of long noncoding RNA’s FMR4 and FMR6 were measured. In FMR1 premutation carriers there was a significant nonlinear association between the number of CGG repeats and the levels of FMR6 (p = 0.03), but not FMR4. The highest level of FMR6 was seen in women with mid-size CGG repeats (80–120). In addition, a significant negative linear correlation was observed between the number of oocytes retrieved and the RNA levels in granulosa cells of FMR6 (r = −0.53, p = 0.01) but not FMR4. Our study supports previous findings suggesting RNA toxic gain-of-function as one of the possible pathophysiologic mechanisms underlying FXPOI.