Aging is recognized as the main risk factor for the late-onset sporadic form of AD (SAD), while early-onset familial AD (FAD) has been linked to autosomal dominant mutations in the gene for the amyloid-β precursor protein (AβPP) and the genes for the presenilin 1 (PS1) and presenilin 2 (PS2) proteins [1], [2]. The gene discussed is PSEN2; the disease is Alzheimer disease.