APOE and Alzheimer disease: Several genes, including previously identified AD risk genes, have been reported to contribute to the episodic memory disturbances, including APOE, CLU, BIN1, brain-derived neurotrophic factor (BDNF), and WW and C2 domain containing 1 (WWC1/KIBRA) (Egan et al., 2003; Burgess et al., 2011).