ALDH2*2 but not ADH1B*2 is a causative variant gene allele for Asian alcohol flushing after a low-dose challenge: correlation of the pharmacokinetic and pharmacodynamic findings.

OBJECTIVE

It has been well documented that variant alleles of both ADH1B2 of alcohol dehydrogenase (ADH) and ALDH22 of aldehyde dehydrogenase (ALDH) protect against the development of alcoholism in East Asians. However, it remains unclear whether ADH1B*2 contributes significantly toward the accumulation of systemic blood acetaldehyde and whether it plays a critical role in the alcohol flushing reaction.

PARTICIPANTS AND METHODS

Sixty-one adult Han Chinese men were recruited and divided into six combinatorial genotypic groups: ALDH2*1/1-ADH1B1/1 (12), ALDH21/1-ADH1B1/2 (11), ALDH21/1-ADH1B2/2 (11); ALDH21/2-ADH1B1/1 (9), ALDH21/2-ADH1B1/2 (9), and ALDH21/2-ADH1B2/*2 (9). After ingesting 0.3 g/kg of alcohol, blood ethanol, acetaldehyde, and acetate concentrations, as well as the facial skin blood flow (FSBF) and pulse rate were measured for 130 min.

RESULTS

The ALDH2*1/2 heterozygotes carrying three ADH1B allelotypes showed significantly higher peak levels and areas under the concentration curve (AUCs) of the blood acetaldehyde as well as significantly greater increases in the peak pulse rate and peak FSBF compared with the ALDH21/1 homozygotes. However, no significant differences in peak levels and AUCs of blood ethanol, acetaldehyde or acetate, or the peak cardiovascular responses, were found between the ADH1B allelotypes carrying ALDH21/1 or between those with ALDH21/*2. Partial correlation analyses showed that peak blood acetaldehyde, rather than the blood ethanol or acetate, was correlated significantly with the peak responses of pulse rate and FSBF.

CONCLUSION

Findings indicate that ALDH22, rather than ADH1B22, is a causal variant allele for the accumulation of blood acetaldehyde and the resultant facial flushing during low alcohol consumption.