Population genetic differentiation of human complex traits

MR Robinson

Queensland Brain Institute, The University of Queensland, Brisbane 4072, Australia

Across-nation differences in the mean of complex traits are common, but the reasons for these are unknown. Here, we find that many independent loci create population genetic differences in height and body mass index (BMI) in 9,416 individuals across 14 European countries. Using discovery data on over 250,000 individuals and unbiased effect size estimates from 17,500 sib pairs, we estimate that 24% (95% CI: 9%, 41%) and 8% (95% CI: 4%, 16%) of the captured additive genetic variance for height and BMI reflect population genetic differences. Population genetic divergence differed significantly from a null model (height: P<3.94e-08, BMI: P<5.95e-04), and we find an among-population genetic correlation for tall, slender nations (r=-0.80, 95% CI: -0.95, -0.60), consistent with correlated selection on both phenotypes. Observed height differences reflected the predicted genetic means (r = 0.51, P<0.001), but environmental differences across Europe mask the genetic differentiation for BMI (P<0.58). This framework is then further developed and extended to other human phenotypes across world-wide populations.