Findings from this study suggest an interaction of ALDH2 and ADH1B on alcohol sensitivity. This gene-gene interaction emerged as significant only in the two continuous dependent measures, retrospective reports of total number of alcohol-related symptoms from one or two drinks and initial level of response to alcohol, with a significant effect of ADH1B found only in individuals who were heterozygous for ALDH2. These findings suggest the effects of ADH1B*2 may be felt more strongly in Asians who already have some heightened sensitivity to alcohol from possessing one ALDH2*2 allele, but who are not too sensitized to alcohol from possessing two ALDH2*2 alleles. This pattern of results is consistent with previous studies of retrospective self-reported facial flushing in Asians that find the strongest effect of ADH1B*2 alleles in ALDH2 heterozygotes (Takashita et al., 1996; 2001; Yokoyama et al., 1999). Similarly, an alcohol challenge study found Asians with two ADH1B*2 alleles had greater objective (e.g., vomiting) and subjective (e.g., feeling less “great”) responses to a moderate dose of alcohol than individuals with one ADH1B*2 allele, but that this occurred only in ALDH2
