Genetic Determinants of Leisure-Time Physical Activity in the Taiwanese Population: A Genome-Wide Association Study

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 (GWASs) 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/week into low, moderate, and high PA levels). Logistic and ordinal logistic regression models were used under an additive genetic model, adjusting for age, age2, sex, BMI, smoking, and the first 10 genetic principal components. Candidate nonsynonymous mutations were further examined in 1,494 whole-genome sequenced participants. Results Binary trait GWAS 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 BMI-adjusted models. Ordinal trait analysis (MET-hours/week <10, 10-<20, ≥20) 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 (LD) with lead variants; these signals largely disappeared after conditional analysis, consistent with a single underlying association. Whole-genome sequencing and LD 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.