MAPT and Parkinson disease: Aggregation-prone proteins, e.g. α-synuclein (α-syn), amyloid-β (aβ), Tau and polyglutamine-containing proteins (poly Q) are closely related to age-related neurodegeneration as seen in Parkinson’s disease (PD), Alzheimer’s disease (AD), Huntington’s disease (HD)1, 2, 3.