A DNA adduct is a segment of DNA that binds to a chemical carcinogen. Some adducts that cause lesions to DNA included oxidatively modified bases, propano-, etheno-, and MDA-induced adducts.  5‐Hydroxymethyluracil is an example of an oxidatively modified base where oxidation of the methyl group of thymine occurs. This adduct interferes with the binding of transcription factors to DNA which can trigger apoptosis or result in deletion mutations. Propano adducts are derived by species generated by lipid peroxidation. For example, HNE is a major toxic product of the process. It regulates the expression of genes that are involved in cell cycle regulation and apoptosis. Some of the aldehydes from lipid peroxidation can be converted to epoxy aldehydes by oxidation reactions. These epoxy aldehydes can damage DNA by producing etheno adducts. An increase in this type of DNA lesion exhibits conditions resulting in oxidative stress which is known to be associated with an increased risk of cancer. Malondialdehyde (MDA) is another highly toxic product from lipid peroxidation and also in the synthesis of prostaglandin. MDA reacts with DNA to form the M1dG adduct which causes DNA lesions.