Our data, which reveals that YOAD patients had greater amyloid burden and APOE ɛ4 alleles than controls, provides strong evidence that APOE ɛ4 is a driving force for amyloid deposition in YOAD, and is consistent with the observations that APOE ɛ4 lowers the age of onset of AD especially if there is a family history [38]. Here, APOE is linked to Alzheimer disease.