Practical issues in genome‐wide association studies for physical activity

Genome-wide association studies (GWAS) have successfully identified many genetic variants that are associated with many complex traits. For example, GWAS can be useful for understanding the genetic basis of physical activity (PA). To date, however, there have been only a few GWAS regarding PA. In this article, we overview some practical issues for more efficient GWAS for PA: phenotype definition of PA, the analysis method, population stratification, replication, and sample size. We discuss these issues within a large-scale GWA data set from the Korea Association REsource (KARE) project, including 8,842 samples and 352,228 single nucleotide polymorphism (SNP) markers. Information on PA was obtained from questionnaires, and GWA analysis was performed to find genetic associations between PA and SNP markers in the Korean population.