Abstract
BACKGROUND: Physical inactivity contributes to systemic disease burden and premature mortality worldwide. Leisure-time physical activity (LTPA) improves health outcomes; however, its genetic determinants, particularly in Asian populations, remain unclear. This study aimed to identify genetic loci associated with LTPA in the Taiwanese population. METHODS: We conducted genome-wide association studies in 122,258 Taiwan Biobank participants. LTPA was assessed both as a binary trait (regular exerciser vs non-exerciser) and an ordinal trait (categorized by MET-hours per week into low, moderate, and high physical activity levels). Logistic and ordinal logistic regression models were used under an additive genetic model, adjusting for age, age 2 , sex, body mass index, smoking, and the first 10 genetic principal components. Candidate nonsynonymous mutations were further examined in 1494 whole-genome sequenced participants. RESULTS: Binary trait genome-wide association studies identified genome-wide significant (GWS) loci at ATXN2 (12q24.12), FTO (16q12.2), and NOTCH4 (6p21.32), with associations for FTO and NOTCH4 only observed in body mass index (BMI)-adjusted models. Ordinal trait analysis (<10, 10-<20, ≥20 MET·h·wk -1 ) identified a single GWS locus at BRAP (12q24.12). Fine-mapping of 12q24.12 revealed multiple GWS single-nucleotide polymorphisms (SNPs) in strong linkage disequilibrium with lead variants; these signals largely disappeared after conditional analysis, consistent with a single underlying association. Whole-genome sequencing and linkage disequilibrium analysis identified three GWS nonsynonymous mutations, with ALDH2 rs671 emerging as the most likely causal variant. CONCLUSIONS: ATXN2-ALDH2 region on chromosome 12q24.12 was identified as a key locus for LTPA in Taiwanese individuals. These findings enhance our understanding of the genetic basis of physical activity and may inform future precision medicine and public health strategies.