CCDC8 and post-traumatic stress disorder: Leading variants in significant loci mapped to an intron of PRUNE on chromosome 1, the intron of noncoding RNA AC068490.2 on chromosome 2, the intron of SGCD on chromosome 5, an intron of FOXP2 on chromosome 7 (also identified in the PGC-PTSD GWAS), an intergenic region in chromosome 14 near MDGA, and upstream of CCDC8 on chromosome 19.