New NOBOX Mutations Identified in a Large Cohort of Women With Primary Ovarian Insufficiency Decrease KIT-L Expression

CONTEXT: Primary ovarian insufficiency (POI) is a major cause of anovulation and infertility in women. This disease affects 1% of women before 40 years, and several genetic causes have been reported. OBJECTIVE: The aim of the study was to evaluate the prevalence of NOBOX mutations in a new large cohort of women with POI and to characterize these variants and identify a NOBOX novel target gene. PATIENTS AND METHODS: A total of 213 unrelated patients with POI were screened for NOBOX mutations, and luciferase reporter assays were performed for the mutations identified. RESULTS: We reported 3 novel and 2 recurrent heterozygous missense NOBOX rare variants found in 12 patients but not in 724 alleles from ethnic-matched individual women with occurrence of menopause at a normal age. Their functional impact had been tested on the classic growth differentiation factor-9 (GDF9) promoter and on KIT-L, a new NOBOX target gene. The p.Gly91Thr, p.Gly111Arg, p.Arg117Trp, p.Lys371Thr, and p.Pro619Leu mutations were deleterious for protein function. CONCLUSIONS: In our series, 5.6% of the patients with POI displayed heterozygous NOBOX mutations. We demonstrate that KIT-L could be now a direct NOBOX target. These findings replicate the high prevalence of the association between the NOBOX rare variants and POI.