ALDH2 and esophageal squamous cell carcinoma: We found that the frequency of Signature E4 mutations in ESCC from drinkers with the risk ALDH2 genotype (rs671-AG/-AA) was significantly higher than that in ESCC from drinkers with the non-risk genotype (rs671-GG; P=0.003, unpaired Wilcoxon rank-sum test).