inflation attributed to polygenic signal, from confounding biases such as population stratification or polygenicity (LD Score regression intercept > 1; Bulik-Sullivan et al. 2015b; Bulik-Sullivan et al. 2015a). As expected under polygenicity, we observed inflation of the median test statistic (Mean χ2 = 1.05), and adjusted for a genomic control inflation factor λ (the ratio of the observed median χ2 to that expected by chance) = 1.02. LD score intercept of 1.01 (SE = 0.01) suggested that deviation from the null was due to a polygenic structure rather than inflation due to population structure biases.
