As seen previously by Chiang et al.,57APOE-ɛ4 significantly interacted with baseline CSF Aβ42 (β = 0.11, P = 0.0004, Fig. 1) on hippocampal volume such that APOE-ɛ4 carriers with higher brain amyloid burden display lower hippocampal volumes and more rapid hippocampal atrophy. The gene discussed is APOE; the disease is hippocampal atrophy.