In order to rigorously assess genetic correlation of the MDD GWAS with other neuropsychiatric disease, we utilized available GWAS from PGC, including Bipolar Disorder and three Schizophrenia GWAS (different versions of the Schizophrenia PGC datasets), as well as neurodegenerative disease GWAS to test pairwise genetic correlation with the 23andMe MDD GWAS dataset using LD score regression. Due to the use of overlapping controls in the PGC datasets we did not use the results of the meta-analysis between 23andMe and PGC. The highest correlation with the primary 23andMe GWAS was observed for the PGC2 Schizophrenia GWAS (r = 0.282, SE = 0.03, p-val= 2.18×10−21) followed by Bipolar Disorder and the additional Schizophrenia GWAS (Table 4); however, we observed little to no correlation for the Parkinson’s disease and Alzheimer’s disease datasets. Additionally, we checked for correlation between 23andMe MDD and a trait with no known epidemiological correlation to depression (LDL Cholesterol) and observed no genetic correlation between the two traits.
