Background: Alcohol-induced asthma, a phenomenon characteristic of Asians, is due to differences in alcohol metabolism, particularly acetaldehyde metabolism. We investigated the effect of polymorphism in acetylaldehyde dehydrogenase 2 (ALDH2) gene on the response to alcohol challenge testing in a group of Japanese asthmatic subjects and normal subjects.
Methods: Subjects were 32 asthmatic subjects and 30 healthy individuals. We measured the change in FEV1 after ingestion of 30 gm of ethanol. Blood ethanol, acetylaldehyde, and histamine concentrations were determined. ALDH2 gene type was established by polymerase chain reaction.
Results: Ethanol provocation test results were positive in 15 (47% responders) asthmatic subjects. The blood ethanol concentration was similar in responders and nonresponders. The fall in FEV1 was associated with a rise in blood acetaldehyde and histamine concentrations. The response to oral ethanol challenge was positive in three (19%) of 16 patients with normal homozygote ALDH2 genotype, 10 (71%) of 14 patients with type mutant heterozygote, and two (100%) of two patients with type mutant homozygote ALDH2 genotype.
Conclusions: Alcohol-induced asthma is probably caused by increased blood acetaldehyde concentration resulting from abnormalities of ALDH2 enzyme activity based on ALDH2 genotype differences.