DRD2 and post-traumatic stress disorder: It was noted that RMG clusterB or gene clusterB exhibited elevated levels of expression for SLC6A3, COMT, ADCYAP1R1, DRD2, SLC6A2, CRHR1, and SRD5A2 associated with nervous and endocrine systems compared to RMG clusterA or gene clusterA (Figure 9D,E), suggesting that cluster B exhibiting higher expression levels in multiple key genes highly relevant to the neurobiology of PTSD.