ALDH2 and lung adenocarcinoma: However, almost half of East Asians carry the loss-of-function ALDH2 rs671 variant (ALDH2*2 allele), which reduces acetaldehyde metabolism, causing dangerous accumulation of acetaldehyde in tissues (40).Excessive acetaldehyde production leads to DNA damage and significantly increases the risk of various malignant tumors, including liver cancer, esophageal cancer, and lung adenocarcinoma (41–43).