APOE and Alzheimer disease: For the AD population, in a few SNPs from APOE and (its physically close linkage partner) TOMM40 genes (Yu et al., 2007; Guerreiro and Hardy, 2012), the observed distribution of reference allele (Ref) and MFA in the case and control populations was far (orders of magnitude) from what can be accounted for by chance (Figures 1A,C).