PTSD, alcohol consumption, and alcohol-related problems have been shown to be heritable in both twin (Heath et al., 1989; Kaprio et al., 1987; Knopik et al., 2004; Stein et al., 2002) and molecular-genetic studies (Clarke et al., 2017; Sanchez-Roige et al., 2019b; Stein et al., 2016). Not surprisingly, the hSNP2 estimates from our study are smaller than those from twin studies, finding estimates of ∼0.38 for PTSD, 0.36–0.40 for consumption, and 0.47 for alcohol misuse, with overall similarities among EA and AA participants. Although the estimated heritability for PTSD [(hSNP2= 0.193, CI 0.052–0.334) v. hSNP2= 0.082, CI 0.053–0.111] and Alcohol Dependence (hSNP2= 0.277, CI −0.044–0.598 v. hSNP2= 0.093, CI 0.052–0.134) appear higher in AA compared to EA respectively they may not be statistically different as there are large standard errors and wide 95% confidence intervals on the AA estimates (see Table 1). This may be due in part to the larger number of participants of EA included in the discovery GWAS datasets. Large genome-wide studies have historically focused on participants of EA, leading to an important gap in knowledge regarding
