One approach to determining whether shared genetic factors contribute to multiple phenotypes is to estimate the genetic correlation between the phenotypes using linkage disequilibrium (LD) score regression (Bulik-Sullivan et al., 2015a; Bulik-Sullivan et al., 2015b). Using known LD between single nucleotide polymorphisms (SNPs), the intercept computed from LD score regression can be included in GWAS analyses as a powerful correction factor for the inflation of test statistics (Bulik-Sullivan et al., 2015b). In addition, the formula for LD score regression can be permuted to compute the genetic correlation between phenotypes based on GWAS results, termed genetic correlation (Bulik-Sullivan et al., 2015a).
