Alzheimer’s disease is characterized by a complex underlying pathology in the CNS, including accumulation of Aß plaques, abnormal phosphorylation of tau, development of tau tangles, inflammation, and progressive loss of neurons, all of which combine to precipitate a progressive decline in cognitive function. Apoplipoprotein (APOE), a lipid transport protein, is the major transporter of cholesterol in the brain and is involved in synaptic integrity and plasticity, glucose metabolism, and cerebrovascular function.
Presence of APOE4 is the most common genetic risk factor for Alzheimer’s disease. The prevalent APOE alleles are APOE4, APOE3 and APOE2, with the E4 allele increasing risk and reducing the age of onset and the E2 allele decreasing risk and markedly delaying the age of onset. APOE4 homozygous patients, individuals who have two copies of the E4 allele, are at the highest risk and are approximately fifteen times more likely to develop Alzheimer’s disease than the general population.
