Exome Sequencing to Identify Novel Variants Associated with Secondary Amenorrhea and Premature Ovarian Insufficiency (POI) in Saudi Women

Abstract

Background and objectives: Post-pubertal disappearance of menstrual cycles (secondary amenorrhea) associated with premature follicular depletion is a heterogeneous condition. Patients with this disease have low levels of gonadal hormones and high levels of gonadotropins. It is one of the causes of female infertility and a strong genetic component is attributed as an underlying cause of this condition. Although variants in several genes have been associated with the condition, the cause of the disease remains undetermined in the vast majority of cases. Methodology and Materials: Ten Saudi married women experiencing secondary amenorrhea were referred to a center for genetics and inherited diseases for molecular investigation. A family-based study design was used. Intensive clinical examinations, including pelvic ultra-sonography (U/S) and biochemical evaluations, were carried out. Karyotypes were normal in all cases and polycystic ovarian syndrome (PCOS) was excluded by using Rotterdam consensus criteria. Patients’ DNA samples were whole-exome sequenced (WES). Bidirectional Sanger sequencing was then utilized to validate the identified candidate variants. The pathogenicity of detected variants was predicted using several types of bioinformatics software. Results: Most of the patients have a normal uterus with poor ovarian reserves. Exome sequence data analysis identified candidate variants in genes associated with POI in 60% of cases. Novel variants were identified in HS6ST1, MEIOB, GDF9, and BNC1 in POI-associated genes. Moreover, a homozygous variant was also identified in the MMRN1 gene. Interestingly, mutations in MMRN1 have never been associated with any human disease. The variants identified in this study were not present in 125 healthy Saudi individuals. Conclusions: WES is a powerful tool to identify the underlying variants in genetically heterogeneous diseases like secondary amenorrhea and POI. In this study, we identified six novel variants and expanded the genotype continuum of POI. Unravelling the genetic landscape of POI will help in genetic counselling, management, and early intervention.