APOE and early-onset autosomal dominant Alzheimer disease: The protein encoded by this gene is a major apoprotein of the chylomicron and is essential for the normal catabolism of triglyceride-rich lipoprotein constituents. This protein Mediates the binding, internalization, and catabolism of lipoprotein particles and can serve as a ligand for the LDL (Apo B/E) receptor. Mutations in this gene result in an impaired clearance of chylomicron and VLDL remnants. Further, several evidences in literature associate specific APOE isoforms with an increased risk of Alzheimer disease.