APOE and Alzheimer disease: When we performed multiple regressions of iron in the group stratified upon APOE ε4 (including age, sex and diagnosis as covariates), we found that the elevation in iron in AD cases compared to controls was greater for people carrying the ε4 allele (No-AD: 48.9 μg/g; AD: 60.0 μg/g; +22.7%; β[S.E.] = 0.701 [0.165]; P = 4 × 10−5) than for those without it (No-AD: 50.6 μg/g; AD: 54.3 μg/g; +7.7%; β[S.E.] = 0.273 [0.100]; P = 0.007; Fig. 1A).