Several neuroimaging studies on AD and aMCI have shown smaller hippocampus volume and a faster rate of hippocampus atrophy in APOE ε4 carriers than non-carriers (Hashimoto et al., 2001; Schuff et al., 2009; Spampinato et al., 2011; Manning et al., 2014). The gene discussed is APOE; the disease is Alzheimer disease.