ALDH1A1 is a cytosolic enzyme that has a low affinity for acetaldehyde (Table 3). It is expressed at lower levels than ALDH2 in most tissues except stomach (Figure 4). As with ALDH1B1, it probably plays only a small role in acetaldehyde elimination, predominantly when ALDH2 is not active and thus acetaldehyde levels are high. Low activity of this enzyme (measured in erythrocytes) correlated with a mild flushing reaction in Europeans that did not affect alcohol consumption (Ward et al., 1994, Yoshida et al., 1989).
