Shared genetics between nonobstructive azoospermia and primary ovarian insufficiency

A novel homozygote nonsense variant of MSH4 leads to primary ovarian insufficiency and non-obstructive azoospermia

BACKGROUND

Both non-obstructive azoospermia (NOA) and primary ovarian insufficiency (POI) are pathological conditions characterized by premature and frequently complete gametogenesis failure. Considering that the conserved meiosis I steps are the same between oogenesis and spermatogenesis, inherited defects in meiosis I may result in common causes for both POI and NOA. The present research is a retrospective investigation on an Iranian family with four siblings of both genders who were affected by primary gonadal failure.

METHODS

Proband, an individual with NOA, was subjected to clinical examination, hormonal assessment, and genetic consultation. After reviewing the medical history of other infertile members of the family, patients with NOA went through genetic investigations including karyotyping and assessment of Y chromosome microdeletions, followed by Whole exome sequencing (WES) on the proband. After analyzing WES data, the candidate variant was validated using Sanger sequencing and traced in the family.

RESULTS

WES analysis of the proband uncovered a novel homozygote nonsense variant, namely c.118C>T in MSH4. This variant resulted in the occurrence of a premature stop codon in residue 40 of MSH4. Notably, the variant was absent in all public exome databases and in the exome data of 400 fertile Iranian individuals. Additionally, the variant was found to co-segregate with infertility in the family. It was also observed that all affected members had homozygous mutations, while their parents were heterozygous and the fertile sister had no mutant allele, corresponding to autosomal recessive inheritance. In addition, we conducted a review of variants reported so far in MSH4, as well as available clinical features related to these variants. The results show that the testicular sperm retrieval and ovarian stimulation cycles have not been successful yet.

CONCLUSION

Overall, the results of this study indicate that the identification of pathogenic variants in this gene will be beneficial in selecting proper therapeutic strategies. Also, the findings of this study demonstrate that clinicians should obtain the history of other family members of the opposite sex when diagnosing for POI and/or NOA.

Novel MEIOB variants cause primary ovarian insufficiency and non-obstructive azoospermia

Background: Infertility is a global health concern. MEIOB has been found to be associated with premature ovarian insufficiency (POI) and non-obstructive azoospermia (NOA), but its variants have not been reported in Chinese patients. The aim of this study was to identify the genetic aetiology of POI or NOA in three Han Chinese families.

Methods: Whole-exome sequencing (WES) was used to identify candidate pathogenic variants in three consanguineous Chinese infertile families with POI or NOA. Sanger sequencing was performed to validate these variants in the proband of family I and her affected family members. In vitro functional analyses were performed to confirm the effects of these variants.

Results: Two novel homozygous frameshift variants (c.258_259del and c.1072_1073del) and one novel homozygous nonsense variant (c.814C > T) in the MEIOB gene were identified in three consanguineous Han Chinese families. In vitro functional analyses revealed that these variants produced truncated proteins and affected their function.

Conclusion: We identified three novel MEIOB loss-of-function variants in local Chinese patients for the first time and confirmed their pathogenicity using in vitro functional analyses. These results extend the mutation spectrum of the MEIOB gene and have important significance for genetic counselling in these families.