rs4646996

This candidate gene study identified four SNPs in the DRD3 (dopamine D3 receptor) gene associated with reduced risk for posttraumatic stress disorder (PTSD) in a discovery sample of 491 white non-Hispanic trauma-exposed veterans and partners (rs2134655, rs201252087, rs4646996, and rs9868039; odds ratios 0.59-0.69; corrected p-values 0.005-0.049). In a replication sample of 601 trauma-exposed African Americans, rs2251177, located 149 bp from the top discovery SNP, showed nominal association with PTSD in men (OR=0.32, uncorrected p=0.01). The protective alleles suggest DRD3 dysfunction may mediate PTSD through effects on executive functioning and emotional reactivity.

This pharmacogenetic study examined determinants of non-ergoline dopamine agonist discontinuation in 90 Parkinson's disease patients. Non-genetic factors associated with discontinuation included apomorphine use (HR 6.26) and levodopa dosages 500-1000 mg (HR 2.31). In the genetic subgroup (n=38), the absence of a 15× DRD2 CA repeat allele was significantly associated with decreased discontinuation (HR 0.23; 95% CI 0.07-0.81), while DRD3 Msp I polymorphism showed a suggestive allele dose effect.