APOE and Alzheimer disease: Along with the identification of altered RXRα expression, this study highlights closely correlated expression of RXRα with the downstream target genes that have been previously implicated in AD pathogenesis including ApoE and ABCA1. One parsimonious interpretation of these findings is that changes in the expression of RXR become evident before the advent of the neuropathological hallmarks of AD and raise the possibility that the upregulation of RXR may be responsible for the changes in subsequent progressive cholesterol dyshomeostasis and AD neuropathology.