Many complex traits and diseases have a shared genetic etiology, either via shared genetic variant(s) with nonzero effect sizes (pleiotropy) or via a correlation between causal effect sizes (genetic correlation). Indeed, many instances of genetic variants with pleiotropic effects on multiple traits have been identified91–96. A recent study applied a Bayesian framework to summary association statistics from pairs of traits to estimate, at each locus in the genome, the probability that an associated variant has pleiotropic effects on both traits97. Pleiotropic SNPs can also be utilized as instrumental variables in Mendelian randomization analyses from summary statistics98–100, with one such analysis showing that increased body mass index causally increases triglyceride levels97.
