APOE and Alzheimer disease: We have selected ApoE isoforms ApoE3 and ApoE4 for comparison, because they differ by only one amino acid substitution at position 112, Cys112 in ApoE3 and Arg112 in ApoE4, yet, ApoE4 is viewed as the genetic risk factor of AD, while ApoE3 is neutral towards AD [10,13].