APOE genotype refers to a specific gene variant that produces a protein involved in the regulation of lipid metabolism. This gene variant has been extensively studied in relation to its impact on various health outcomes, particularly in relation to cardiovascular disease and Alzheimer's disease. The APOE gene has three common alleles - ε2, ε3, and ε4 - with the ε4 allele being associated with an increased risk of developing Alzheimer's disease and cardiovascular diseases. Research in this area aims to understand how the APOE genotype influences an individual's risk of developing these diseases, as well as how it may impact treatment and prevention strategies.