Carriage of an APOE-ε4 or ε2 allele has been associated with earlier or later clinical onset, respectively, in both sporadic AD and PSEN1 AD subjects28,29; our logistic regression analysis confirmed this effect of the APOE-ε4 allele but we had insufficient numbers of APOE-ε2 subjects to confirm the earlier reports. This evidence concerns the gene APOE and Alzheimer disease.