Notably, in many instances, these genetic mutations lead to the misfolding and aggregation of specific proteins such as amyloid precursor protein (APP) in AD, α-synuclein (SNCA) in PD and Chromosome 9 open reading frame 72 (C9orf72) in FTD/ALS (Schellenberg and Montine, 2012; Stefanis, 2012; Balendra and Isaacs, 2018). The gene discussed is APP; the disease is Alzheimer disease.