The candidate genes included DOCK2, SLC6A3, DICER1, DRD2, ADCYAP1, ADCYAP1R1, SKA2, OXTR, STMN1, SLC6A4, DBH, ZNF626, TRAIP, TSNAIRE1, and IMMP2L. Our team has previously found DOCK2, an amyloid-plaque associated gene in Alzheimer’s, to be associated with PTSD in an epigenome-wide study in Australian veterans (Mehta et al., 2017) and here have validated this gene in the MZ PTSD twins. Here, OXTR is linked to post-traumatic stress disorder.