MSH2 and colonic neoplasm: Given that significantly higher plasma levels of acetaldehyde were present in both ethanol-treated (compared with water-treated) induced conditional and constitutive Aldh1b1 Msh2-LS mice, these experiments provide strong evidence for a gene/environment interaction between dMMR and acetaldehyde in accelerating colonic neoplasm formation, and for a relationship between higher numbers of colonic neoplasms and increasing acetaldehyde levels, indicating a dose-dependent acetaldehyde-tumour association.