Revisiting GDF9 variants in primary ovarian insufficiency: A shift from dominant to recessive pathogenicity?

BACKGROUND: Primary ovarian insufficiency (POI) affects around 2-4% of women before the age of 40. Genetic factors play an important role in POI. The GDF9 gene has been identified as a significant genetic contributor of POI. However, the pathogenicity and penetrance of GDF9 variants remain uncertain. METHODS: A next-generation sequencing approach was employed to investigate the entire coding region of the GDF9 gene in a cohort of 1281 patients with POI or diminished ovarian reserve (DOR). The frequency of each identified GDF9 variant was then compared with that of the general population, taking into account the ethnicity of each individual. RESULTS: By screening the entire coding region of the GDF9 gene, we identified 19 different variants, including 1 pathogenic frameshift variant. In total, 36 patients with POI/DOR (2.8%) carried at least one GDF9 variant. With regard to missense variants, no significant overrepresentation of the most common variants was observed in our POI/DOR cohort in comparison to the general or specific ethnic subgroups. Only one homozygous subject had a frameshift loss of function variant. CONCLUSION: This epidemiological study suggests that the vast majority of heterozygous missense variants could be considered as variants of uncertain significance and the homozygous loss-of-function variant could be considered as a pathogenic variant. The identification of a novel case of a homozygous POI patient with a heterozygous mother carrying the same variant with normal ovarian function strongly suggests that GDF9 syndrome is an autosomal recessive disorder.

Shifting the landscape: Dominant C-terminal rare missense FOXL2 variants in non-syndromic primary ovarian failure etiology.

Pathogenic germline variants in the FOXL2 gene are associated with Blepharophimosis, Ptosis, and Epicanthus Inversus syndrome (BPES) in humans, an autosomal dominant condition. Two forms of BPES have emerged: (i) type I (BPES-I), characterized by ocular signs and primary ovarian failure (POI), and (ii) type II (BPES-II) with no systemic associations. This study aimed to compare the distribution of FOXL2 variants in idiopathic POI/DOR (diminished ovarian reserve) and both types of BPES, and to determine the involvement of FOXL2 in non-syndromic forms of POI/DOR. We studied the whole coding region of the FOXL2 gene using next-generation sequencing in 1282 patients with non-syndromic POI/DOR. Each identified FOXL2 variant was compared to its frequency in the general population, considering ethnicity. Screening of the entire coding region of the FOXL2 gene allowed us to identify 10 different variants, including nine missense variants. Of the patients with POI/DOR, 14 (1%) carried a FOXL2 variant. Significantly, six out of nine missense variants (67%) were overrepresented in our POI/DOR cohort compared to the general or specific ethnic subgroups. Our findings strongly suggest that five rare missense variants, mainly located in the C-terminal region of FOXL2 are high-risk factors for non-syndromic POI/DOR, though FOXL2 gene implication accounts for approximately 0.54% of non-syndromic POI/DOR cases. These results support the implementation of routine genetic screening for patients with POI/DOR in clinical settings.

NOBOX gene variants in premature ovarian insufficiency: ethnicity-dependent insights.

PURPOSE: Premature ovarian insufficiency (POI) affects approximately 1% of women before the age of 40. Genetic contribution is a significant component of POI. The NOBOX gene was considered one of the major genetic causes of POI. However, the pathogenicity and the penetrance of NOBOX variants remain unclear. METHODS: We studied the whole coding region of the NOBOX gene by next generation sequencing in a cohort of 810 patients with POI, and we compared the frequency of each identified NOBOX variant to the general population taking into account the ethnicity of each individual. RESULTS: Screening of the whole coding region of the NOBOX gene allowed us to identify 35 different variants, including 5 loss-of-function variants. In total, 171 patients with POI (25%) carried out at least one NOBOX variant. Regarding missense variants, we observed a significant overrepresentation of the most frequent ones in our 810 POI patients as compared to the general, except for p.(Arg117Trp). However, taking into account the ethnic origin of the individuals, we observed no significant OR difference for p.(Arg44Leu) and p.(Arg117Trp) in African subgroup and for p.(Asp452Asn) in European subgroup. CONCLUSION: This population study suggests that the p.(Arg44Leu) variant could be considered benign variant and that the p.(Asp452Asn) and p.(Arg117Trp) variants could be considered moderate risk pathogenic variants with probably partial and very low penetrance and/or expressivity. In contrast, p.(Gly91Trp) and p.(Gly152Arg) variants could be considered pathogenic variants with a moderate functional impact.