Fig. 1: Study overview.

a The study population comprised 55,551 Japanese individuals who purchased the MYCODE genetic kit. Genotypes were obtained using microarrays, and genetic data were processed through imputation, phasing, quality control, and linkage disequilibrium pruning. Figure 1a includes a person icon by Valerie Lamm and a Japan map icon by Rahe, both from The Noun Project (CC BY 3.0) b After applying eligibility criteria, genotype allele matrices from 49,440 participants were analyzed using PCA-UMAP and DBSCAN to uncover fine-scale genetic structure within the homogenous population. This analysis resulted in 43,726 participants being retained for further analysis, including FST analysis, GWAS, and post-GWAS analyses for genomic interpretation. c Statistical analyses were conducted on lifestyle and dietary data for the same 43,726 participants. Geographical analyses focused on follow-up questionnaire responses from 2268 participants. d This approach integrates genomic interpretation with epidemiological methods to explore interactions among population structure, lifestyle, and dietary habits. Icons in Figure 1c and d are created by Freepik from Flaticon.com.