There are several limitations to the present study. First, only published studies were included in the review and thus studies that have not been published due to null findings are not included. Given the low fail-safe N found in this study, the presence of a “file drawer” effect could substantially change the results of this analysis. In addition, differences in methodology precluded the combination of case-control and family-based studies and thus several studies examining the association between 5HTTLPR and alcohol dependence were excluded from the present study due to use of family-based designs (Dick et al., 2007; Edenberg et al., 1998; Lichtermann et al., 2000; Samochowiec et al., 2006).
