Early onset familial forms of AD are associated with autosomal dominant mutations in three genes [amyloid precursor protein (APP), presenilin (PS) 1 and 2] (Selkoe et al., 2012), the elevated production of Aβ peptides, and the presence of neuronal injuries (dystrophic neurites) in the vicinity of amyloid plaques. The gene discussed is APP; the disease is Alzheimer disease.