Based on these potent effects via variation in the ALDH2 gene, there is also considerable interest in the ALDH1A1 gene. In contrast to the ALDH2 gene, which is responsible for mitochrondrial ALDH activity, ALDH1A1 is responsible for cytosolic ALDH activity (Edenberg, 2007). Variants of the ALDH1A1 gene occur at relatively low frequencies and findings to date have been mixed. For example, Ehlers et al. (2004) found that Southwest California Indians possessing the less functional variant (i.e., resulting in greater acetaldehyde buildup) experienced a protective effect against alcoholism, but Hansell et al. (2005) did not find a protective effect in an Australian community sample. At this point, although variation in ALDH1A1 is promising candidate for exerting similar effects on aversive subjective effects of alcohol and in turn affecting AUD risk, the data are far from definitive.
