Normalizing genetic covariance by the SNP-heritabilities yields genetic correlation: rg:=ρg/h12h22, where hi2 denotes the SNP-heritability [11] from study i. Genetic correlation ranges between −1 and 1. Results similar to Equation 1 hold if one or both studies is a case/control study, in which case genetic covariance is on the observed scale. Details are provided in the Supplementary Note. There is no distinction between observed and liability scale genetic correlation for case/control traits, so we can define and estimate genetic correlation between a case/control trait and a quantitative trait and genetic correlation between pairs of case/control traits without the need to specify a scale (Supplementary Note).
