The mixed-design Group (HC, AD) × Derivation (Fz, Cz, Pz) analysis of variance yielded a significant main effect for the Group factor (F1,38 = 13.42; p = 0.0007), with a lower KC density in AD (X = 0.36; SE = 0.04) than in HC (X = 0.59; SE = 0.05). The gene discussed is CALCA; the disease is Alzheimer disease.