ALDH2 and urinary bladder carcinoma: This may be explained by our previous finding that those with active ALDH2 alleles showed no increased risk of bladder cancer, even though they drank heavily.8 Moderate to heavy drinkers have more frequently active ALDH2 alleles than never to light drinkers.8 Thus, the frequent active ALDH2 alleles of moderate to heavy drinkers may lead to no significant association between alcohol consumption and bladder cancer.