PEMT and neoplasm: The enzyme PEMT catalyzes the reaction for de novo synthesis of choline, which is then oxidized to betaine, and betaine further serves as a substrate for methionine production, eventually becoming S-adenosylmethionine, the universal methyl donor for most methylation reactions, including DNA methylation [17], choline and betaine are key components in the OCM pathway, and they may be involved in DNA synthesis and repair owing to their close interrelationships and complex interactions with the folate cycle, thus potentially affecting tumor carcinogenesis.