Protein subunit of chylomicrons that transport cholesterol and fatty acids through the bloodstream. Alterations of this protein affect the binding and release of fatty acids and cholesterol, especially at the site of lipoprotein lipase at the blood brain barrier. One gene variant, ApoE4, is considered a genetic risk factor for AD. Approximately 50% of diagnosed AD patients are ApoE4+ and have an alteration of their chylomicrons that causes fatty acids and cholesterol to be more tightly bound and less available for the brain.
a gene that has been linked to an increased risk of Alzheimer's disease. People with a variant form of the gene, called apoE epsilon 4, have about ten times the risk of developing Alzheimer's disease.
a protein that carries cholesterol in blood and that appears to play some role in brain function. The gene that produces ApoE comes in several forms, or alleles - e2, e3, and e4. The APOE e2 allele is relatively rare and may provide some protection against AD. APOE e3 is the most common allele and it appears to play a neutral role in AD. APOE e4 occurs in about 40 percent of all AD patients who develop the disease in later life; it increases the risk of developing AD.