Abstract
BACKGROUND: Despite the well-established regulatory role of vitamin D in maintaining bone health, little is known about the shared genetics and causality of the association between serum 25-hydroxyvitamin D (25OHD) and bone mineral density (BMD).</p>
METHODS: Leveraging individual-level data from the UK Biobank (UKB) cohort and summary-level data from the genome-wide association studies (GWASs) conducted on European individuals for serum 25OHD (N = 417,580) and estimated heel BMD (eBMD, N = 426,824), we systematically elucidated the shared genetic architecture underlying serum 25OHD and eBMD through a comprehensive genome-wide cross-trait design.</p>
RESULTS: Despite a lack of global genetic correlation (rg = -0.001, P = 0.95), a significant local signal was discovered at 5p11-5q11.9. Two-sample Mendelian randomization (MR) indicated no causal association in the overall population (β = 0.003, 95% CI = -0.04∼0.03, P = 0.93), while positive causal effects were observed in males (β = 0.005, 95% CI = 0.00∼0.01, P = 0.03) and the elderly (β = 0.009, 95% CI = 0.00∼0.02, P = 0.01) according to one-sample MR. A total of 49 pleiotropic SNPs, with 4 novel SNPs (rs1077151, rs79873740, rs12150353, and rs4760401), were identified, and a total of 95 gene-tissue pairs exhibited overlap, predominantly enriched in the nervous, digestive, exo-/endocrine and cardiovascular systems. Protein-protein interaction analysis identified RPS9 and RPL7A as hub genes.</p>
CONCLUSIONS: This study illuminates the potential health benefits of enhancing serum 25OHD levels to mitigate the risk of osteoporosis among males and the elderly. It also unveils a shared genetic basis between serum 25OHD and eBMD, offering valuable insights into the intricate biological pathways.</p>