Aldehyde dehydrogenase polymorphism: molecular basis and phenotypic relationship to alcohol sensitivity

Individual differences in response to alcohol have been observed in various ethnic and racial groups. A positive correlation between alcohol sensitivity and elevated blood acetaldehyde level in conjunction with deficiency of an isozyme of aldehyde dehydrogenase (ALDH I) was noted in Japanese subjects given an acute dose of alcohol. Invariably, significantly higher blood acetaldehyde levels were measured in ALDH I-deficient subjects after ethanol loading. The initial flushing in Orientals after alcohol ingestion might be due to their inability to metabolize acetaldehyde quickly and effectively in the absence of the low Km ALDH I isozyme. While Oriental populations of Mongoloid origin showed varying degree of isozyme deficiency, none of the Caucasian or Negroid populations have this isozyme abnormality.