Genetic variation in alcohol dehydrogenase (ADH1A, ADH1B, ADH1C,
ADH7) and aldehyde dehydrogenase (ALDH2), alcohol consumption and gastric cancer risk in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort.
ADH7 variation modulates extraversion and conscientiousness in substance-dependent subjects.
More recent evidence suggests that genetic variants in the ADHIA, ADHIB, ADHI C ADHS, ADH6, and
ADH7 genes are associated with illicit drug dependence and that this association is not purely attributable to co-morbid alcohol dependence (Luo et al.
Finally, variations in the
ADH7 gene may play a protective role against alcoholism through epistatic effects.
The subunits are encoded by six different genetic loci (ADH1A, ADH1B*1, ADH1C*1, and ADH4-ADH7--formerly ADH1 through
ADH7, respectively).
An association study by Osier and colleagues (2004) found a potential epistatic interaction between the ADHIB and
ADH7 genes among a Han Chinese population.
For example, several studies found other variations in and near the ADH1B gene, as well as in or near the ADH4, ADH1C, ADH5, ADH6, and
ADH7 genes that affect risk for alcoholism or the level of alcohol consumption (see the article by Hurley and Edenberg, pp.
Humans have seven different genes, called ADH1A, ADH1B, ADH1C, ADH4, ADH5, ADH6, and
ADH7, that encode medium-chain ADHs (see Table 1).
* The
ADH7 gene has a limited expression pattern and mainly is found in endothelial cells, such as those lining the esophageal and stomach tissues, as well as during embryonic development when it may contribute to the metabolism of retinol, a form of vitamin A (Hurley et al.