The prevalence of the 118G (Asp40) allele shows considerable variation between different ethnic populations (reviewed by Arias et al., 2006; van der Zwaluw et al., 2007). Lowest frequencies have been observed in individuals with African origins (<5%) and the highest frequencies in Asians (25–45%). In Caucasian populations the frequency has been reported to be 10–15% (reviewed by Arias et al., 2006; van der Zwaluw et al., 2007). Compared with these previous results obtained from the Caucasian populations, the frequency in the Finnish study populations analyzed in the current study was high, ∼19%. The results were similar in all three cohorts analyzed, i.e. 20.8, 18.6 and 19.0%. The populations were genotyped with different reliable methods (Taqman, Sequenom and lllumina chip technologies) and so erroneous frequencies obtained due to genotyping errors are highly unlikely. In a previous study testing Finnish subjects the frequency of the 118G allele was considerably lower, i.e. 11.1% in unaffected controls and 13.6% among alcohol-dependent individuals (Bergen et al., 1997). There are no explicit explanations for such big discrepancies between the studies. However, in the study of Bergen
