As an endophenotype, maximum drinks is expected to show both a phenotypic and a genetic correlation – the proportion of additive genetic effect shared between the phenotypes – with AD. In this sample, the genetic correlation between AD and maximum drinks (ρg) is 0.36 (std. error = 0.29), with age included as a covariate as calculated in SOLAR. This correlation is similar to that seen between maximum drinks and flushing (ρG = -0.39, std. error = 0.29, with age included as a covariate). The genetic correlation between AD and flushing is significantly larger than the correlation between maximum drinks and either of these phenotypes (ρG = -0.68, std. error = 0.33, with age included as a covariate). When rs671 genotype is included as a covariate, ρG values become non-significantly different from zero for each pair of phenotypes, indicating that the majority of the genetic correlation detected within the power constraints of this sample is due to the effect of ALDH2.
