Apolipoprotein E, or ApoE, is a protein that plays a crucial role in lipid metabolism and the transport of fats in the bloodstream. It is primarily produced in the liver and brain and is essential for the normal catabolism of triglyceride-rich lipoprotein constituents. ApoE helps to clear cholesterol and other fats from the bloodstream, which is vital for maintaining cardiovascular health. There are three major alleles of the ApoE gene: ε2, ε3, and ε4. These variants influence an individual's risk for developing conditions such as Alzheimer's disease and cardiovascular diseases. The ε4 variant is associated with a higher risk of Alzheimer's, while the ε2 variant may offer some protective effects. Understanding ApoE is important for research into these health issues.