APP and familial Alzheimer disease: In familial AD (fAD), mutations in amyloid precursor protein (APP) and presenilin 1 and 2 (PSEN 1 and 2) promote disrupted neurogenesis and reduced learning and memory in animal models, such as double transgenic mice expressing a chimeric mouse/human amyloid precursor protein (Mo/HuAPP695swe) and a mutant human presenilin 1 (PS1-dE9) (APP/PS1), both directed to CNS neurons [6].