APOE and early-onset autosomal dominant Alzheimer disease: Three APOE isoforms, created by the ε2, ε3, and ε4 alleles with two single-base changes (APOE rs7412 and APOE rs429358) in the coding region of APOE, are the most well-defined common variants that determine plasma lipid levels, coronary risk, and Alzheimer disease [9,10,11,12].