Both Alzheimer’s (AD) and Parkinson’s disease (PD) are neurodegenerative disorders deeply linked to age wherein protein aggregates, extracellular amyloid beta plaques, and intracellular neurofibrillary tau tangles in AD, alpha-synuclein in intraneuronal Lewy bodies in PD, accumulate in distinctive areas, the hippocampus and neocortex in AD, the substantia nigra (pars compacta) and striatum in PD. The gene discussed is SNCA; the disease is Alzheimer disease.