Bivariate Genome-Wide Association Study Implicates ATP6V1G1 as a Novel Pleiotropic Locus Underlying Osteoporosis and Age at Menarche.

Objective: Age at menarche (AAM) is determined by the overall duration of endocrine-tissue sex hormone exposure levels. Osteoporosis, the most common metabolic bone disease, is characterized primarily by reduced bone mineral density (BMD) and an increased risk of low trauma fractures. Bone was an endocrine organ regulating the synthesis and secretion of sex steroid hormones. The mutual dependence between bone and gonads underscore the importance of genetic approaches to identify novel pleiotropic genetic factors coregulating BMD and AAM. In this study, we performed a bivariate genome-wide association study (GWAS) to explore novel ethnic common loci and/or genes that may influence both AAM and BMD.

Methods: We analyzed genotyping data available for 826 unrelated Chinese subjects using genome-wide human genotyping arrays. After quality control, a total of 702 413 single-nucleotide polymorphisms (SNPs) were tested for association using a bivariate linear regression model. The interesting SNPs were replicated in three independent cohorts including 1728 unrelated Caucasians, 709 African-Americans, and 408 Hispanic-Americans.

Results: We found four SNPs (rs10817638, rs7851259, rs10982287, and rs4979427), located upstream of the ATP6V1G1 gene, were bivariately associated with hip BMD-AAM (P = 4.90 × 10(-7), P = 1.07 × 10(-6), P = 1.28 × 10(-5), and P = 5.42 × 10(-5), respectively). These four SNPs were replicated in African-Americans, with corresponding values of P = 1.95 × 10(-2), P = 3.18 × 10(-2), P = 2.57 × 10(-2), and P = 3.64 × 10(-2), respectively. rs10817638 and rs10982287 were further replicated in Caucasians (P = 1.76 × 10(-2) and P = 9.42 × 10(-3), respectively) and Hispanic-Americans (P = 8.37 × 10(-3) and P = 1.52 × 10(-3), respectively). Meta-analyses yielded stronger association signals for rs10817638 and rs10982287 with combined values of P = 3.02 × 10(-9) and P = 3.49 × 10(-9), respectively.

Conclusions: Our study implicated ATP6V1G1 as a novel pleiotropic gene underlying variation of both BMD and AAM. The findings enhance our knowledge of genetic associations between BMD and AAM and provide a rationale for subsequent functional studies of these implicated genes in the pathophysiology of diseases/traits, such as osteoporosis and AAM.