In summary, this evaluation of effect size across studies of the association between 5HTTLPR and alcohol dependence diagnosis found that those with this diagnosis had a 15% greater likelihood of possessing at least 1 s allele relative to control participants. This effect should be interpreted with caution given the indication that a small number of negative findings could result in the reduction of this finding to non-significance. These results are similar to those found in a previous analysis (Feinn et al., 2005), in which alcohol dependent groups were 18% more likely to possess at least 1 s allele. Given the continued finding of a modest relationship between 5HTTLPR and alcohol dependence, future research on potential modulators of this association, such as affective variables, is of particular importance.
