Textbook examples are amyloid plaques in AD that comprise fragments of aberrantly cleaved amyloid precursor protein (APP) [5-8], Lewy bodies in PD that comprise forms of alpha-synuclein (ASYN) [9], tangles in AD, FTD, PD and MND that comprise forms of tau [10-14], and more recently TAR DNA binding protein 43 (TDP-43) containing aggregates in MND, FTD, AD and PD [15, 16]. This evidence concerns the gene APP and Parkinson disease.