Screening for acetaldehyde dehydrogenase 2 genotype in alcohol-induced asthma by using the ethanol patch test.

We have previously reported that alcohol-induced asthma in Japanese patients is caused by increased blood acetaldehyde concentration resulting from abnormalities of acetaldehyde dehydrogenase 2 (ALDH2) enzyme activity on the basis of ALDH2 genotype differences. The purpose of the present study was to determine whether the ethanol patch test could predict the ALDH2 genotype in Japanese asthmatic subjects. An ethanol patch test on the upper arm and a questionnaire survey addressing the past history of alcohol-induced asthma were administered to 148 adult Japanese asthmatic subjects. The ALDH2 genotypes in these 148 subjects were also determined by means of PCR. The genotype distribution of ALDH2 determined by PCR in 68 subjects with positive ethanol patch test results was 4 (5.9%), 56 (82.4%), and 8 (11.8%) for genotypes NN (normal homozygote), NM (mutant heterozygote), and MM (mutant homozygote). The ALDH2 genotype in 80 subjects with a negative test result was only NN. The distribution of ALDH2 genotype in 78 (52.7%) subjects who had experienced alcohol-induced asthma symptoms on the basis of the questionnaire was 27 (34.6%), 44 (56.4%), and 7 (9.0%) for genotypes NN, NM, and MM, respectively. On the other hand, 70 subjects had never experienced alcohol-induced asthma symptoms. In these subjects the ALDH2 genotype was NN in 51 (72.9%), NM in 18 (25.7%), and MM in 1 (1.4%). Our results indicate that the results of ethanol patch testing correlate well with ALDH2 genotype, as determined by means of PCR, suggesting that the ethanol patch test is useful for the screening of alcohol-induced asthma.