APOC2 and early-onset autosomal dominant Alzheimer disease: The APOC4 gene is located on the chromosome 19q12-13.2, constructs the APOE/C1/C4/C2 gene cluster with apolipoprotein CI (APOC1), apolipoprotein CII (APOC2) and apolipoprotein E (APOE) [13], which is closely associated with plasma lipid levels, atherosclerotic plaque formation, and thus with the development of coronary artery disease and alzheimer’s disease [14, 15].