Genetic correlation
In multivariate behavioral & quantitative genetics, a genetic correlation (denoted or ) is the proportion of variance that two traits share due to genetic causes, the correlation between the genetic influences on a trait and the genetic influences on a different trait estimating the degree of pleiotropy or causal overlap. A genetic correlation of 0 implies that the genetic effects on one trait are independent of the other, while a correlation of 1 implies that all of the genetic influences on the two traits are identical. The bivariate genetic correlation can be generalized to inferring genetic latent variable factors across >2 traits using factor analysis. Genetic correlation models were introduced into behavioral genetics in the 1970s-1980s.
Genetic correlations have applications in validation of GWAS results, breeding, prediction of traits, and discovering the etiology of traits & diseases.
They can be estimated using twin studies and molecular genetics. Genetic correlations have been found to be common in non-human genetics and to be broadly similar to their respective phenotypic correlations, but also in human traits. This finding of widespread pleiotropy has implications for artificial selection in agriculture, interpretation of phenotypic correlations, social inequality, attempts to use Mendelian randomization in causal inference, the understanding of the biological origins of complex traits, and the design of GWASes.
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