The accumulation of acetaldehyde in the body has many consequences in addition to the aversion to consuming ethanol. Li et al. (2006) showed that the Glu504Lys polymorphism was associated with efficacy of sublingual nitroglycerin and recently Chen et al. (2008) showed that ALDH2 activity is critical for protection from ischemia. These findings emphasize the importance of the studies on genetic variation at ALDH2. The 504Lys variant is believed to increase the risk of many disorders, including many cancers. Cancer incidences increase among alcoholics in organs including esophagus, stomach, liver, upper aerodigestive tract in which acetaldehyde is produced by the alcohol dehydrogenases (Yokoyama et al., 2001). Esophageal cancer is of particular interest because studies have shown an increased risk of developing esophageal cancer in ALDH2*504Lys heterozygotes in different East Asian populations (Yokoyama & Omori, 2005; Yokoyama et al., 2006; Yang et al., 2007; Li et al., 2008; Druesne-Pecollo et al., 2009). The geographic distribution of esophageal cancer, with its much higher frequencies in individuals of East Asian ancestry (Parkin et al., 1997), suggests a potential association of this cancer to ALDH2*504Lys.
