accounted for 1.3%, 1.1%, and 0.6% of the variability in PTSD, alcohol dependence and cocaine dependence, respectively. While effect sizes are quite modest, these results extend previous research that have shown significant genetic correlations between PTSD and alcohol dependence [6, 8], further suggesting that there is shared genetic risk for these disorders. These results further support the importance of exploring the co-occurrence of substance use problems, specifically alcohol dependence and PTSD, when investigating genetic influence on either of these disorders.
