MAPT and Alzheimer disease: Many NDD genes are characterized by the formation of insoluble and non-degraded specific protein aggregates (e.g., beta-amyloid Aβ40–42 in AD, α-synuclein in PD, phosphorylated tau neurofibrilles in fronto-temporal dementia and other tauopathies), which often are the main marker for diagnosis and disease classification [14,15].