Next, we conducted a large (N = 694,894) meta-analysis of summary statistics from mixed-sex analyses (Supplementary Figure 5). We identified 10 lead SNPs and estimated a SNP heritability due to the X chromosome of ~0.3% (Supplementary Table 4). This heritability is lower than that expected for an autosome of similar length (Supplementary Figure 6, Supplementary Table 5). We cannot distinguish whether the lower heritability is due to smaller per-allele effect sizes for SNPs on the X chromosome or to the combination of haploidy in males and (partial) X-inactivation in females.
