Dopamine D-2 receptor (DRD2) gene and susceptibility to posttraumatic stress disorder: A study and replication

Subjects on an addiction treatment unit who had been exposed to severe combat conditions in Vietnam were screened for posttraumatic stress disorder (PTSD). Of 24 with PTSD, 58.3% carried the D2Al allele. Of the remaining eight who did not meet PTSD criteria, 12.5% carried the D2Al allele (p = 0.04). In a replication study of 13 with PTSD, 61.5% carried the D2Al allele. Of the remaining II who did not meet criteria for PTSD, 0% carried the D2Al allele (P = 0.002). For the combined group 59.5% of those with PTSD carried the D2Al allele versus 5.3% of those who did not have PTSD (p = 0.0001). These results suggest that a DRD2 variant in linkage disequilibrium with the D2Al allele confers an increased risk to PTSD, and the absence of the variant confers a relative resistance to PTSD.