Estimation of genetic heritability
We estimated SNP heritability analysis with GCTA6421. SNP heritability indicates the relative proportion of phenotypic variances explained according to SNPs. SNPs were pruned using PLINK with the default option, and the remaining SNPs were used to calculate the genetic relationship matrix (GRM). This GRM was used to estimate SNP heritability with GCTA64. For ascertainment bias, the prevalence of asthma was set to 3.9%22.