To investigate shared molecular mechanisms, we tested the genetic overlap (i.e., shared risk alleles) of PTSD REX symptoms with respect to a wide range of phenotypic characteristics, including pathological and physiological traits. Genetic correlations were calculated using the LDSC method (available at https://github.com/bulik/ldsc)41. LDSC results regarding 232 traits were extracted from the data available at LDHub v2.0 (http://ldsc.broadinstitute.org/ldhub/)42,43,44. Genetic correlations for an additional 1,547 traits were calculated using the GWAS summary association results available at https://sites.google.com/broadinstitute.org/ukbbgwasresults. These GWAS used data regarding ~337,000 unrelated individuals of British descent from the UK Biobank (UKB)45. False Discovery Rate (FDR) was applied to correct the genetic-correlation results for multiple testing and q values < 0.05 were considered to be significant. Individuals with admixed ancestral background such as AAs are a mosaic of haplotypes from different ancestral origins. As LDSC requires a LD reference panel, we did not perform these analyses for AA samples because LD reference is not considered reliable with respect to admixed populations, as also highlighted by the LDSC developers42.
