APOE and early-onset autosomal dominant Alzheimer disease: APOE-ε4 burden (i.e. number of ε4 alleles), in addition to APOE-ε4 status, showed the same pattern, although at a reduced magnitude: P ≤ 7.74e-03 for contrasts involving CN subjects and P = 0.306 for the association between MCI and Alzheimer’s disease, confirming that APOE-ε4 burden was predictive of diagnosis beyond APOE-ε4 status.