Figure 1 details the study selection process. Our search methods yielded a total of 145 potential studies. Of these, 22 met our inclusion criteria (15 were included in the Feinn et al., 2005 paper). Two studies included in the Feinn and colleagues meta-analysis (Edenberg et al., 1998; Lichtermann et al., 2000) were not included in the analysis because they used the transmission disequilibrium test (TDT) methodology, which may compromise the ease of comparison to the majority of studies using case-control methods. In addition, two studies published since the Feinn et al. analysis were excluded because they also did not use the case-control method (i.e. Samochowiec et al., 2006, used the TDT, and Dick et al., 2007, used the Pedigree Disequilibrium Test). Notably, these studies reported mixed results, with Edenberg et al. (1998), Dick et al. (2007), and Samochowiec et al. (2006) reporting no association and Lichtermann et al. (2000) reporting a strong association between the presence of any s allele and alcohol dependence. One study (Schuckit et al., 1999) that was also included in the Feinn et al. paper, and
