Neurodegenerative disorders may be distinguished upon presence and absence of disease specific protein aggregates e.g. α-synuclein in Parkinson, and amyloid precursor protein in Alzheimer's disease or the microtubule associated protein tau (MAPT or tau) as observed in for example AD, FTD, PiD, PSP [4], [5]. The gene discussed is MAPT; the disease is early-onset autosomal dominant Alzheimer disease.