Novel bone morphogenetic protein 15 (BMP15) gene variants implicated in premature ovarian insufficiency

Abstract

Background: Bone morphogenetic protein 15 (BMP15) is expressed in oocytes and plays a crucial role in the reproduction of mono-ovulating species. In humans, BMP15 gene mutations lead to imperfect protein function and premature ovarian insufficiency. Here we investigated the BMP15 gene variants in a population of Iranian women with premature ovarian insufficiency. We conducted predictive bioinformatics analysis to further study the outcomes of BMP15 gene alterations. Methods: Twenty-four well-diagnosed premature ovarian insufficiency cases with normal karyotype participated in this study. The entire coding sequence and exon-intron junctions of the BMP15 gene were analyzed by direct sequencing. In-silico analysis was applied using various pipelines integrated into the Ensembl Variant Effect Predictor online tool. The clinical interpretation was performed based on the approved guidelines. Results: By gene screening of BMP15, we discovered p.N103K, p.A180T, and p.M184T heterozygous variants in 3 unrelated patients. The p.N103K and p.M184T were not annotated on gnomAD, 1000 Genome and/or dbSNP. These mutations were not identified in 800 Iranians whole-exome sequencing that is recorded on Iranom database. We identified the p.N103K variant in a patient with secondary amenorrhea at the age of 17, elevated FSH and atrophic ovaries. The p.M184T was detected in a sporadic case with atrophic ovaries and very high FSH who developed secondary amenorrhea at the age of 31. Conclusions: Here we newly identified p.N103K and p.M184T mutation in the BMP15 gene associated with idiopathic premature ovarian insufficiency. Both mutations have occurred in the prodomain region of protein. Despite prodomain cleavage through dimerization, it is actively involved in the mature protein function. Further studies elucidating the roles of prodomain would lead to a better understanding of the disease pathogenesis.