APOE and Alzheimer disease: Our finding that the incidence of Aβ plaques is dependent on specific APOE allelic subtypes, namely, that having even one APOE ε2 allele is associated with an absence of Aβ plaques even in our oldest patient (71y), may in some way be related to a reported decreased risk for AD [27] and a protective effect of inheritance of APOE ε2 against Alzheimer-like neuropathological changes [28].