Recent evidence suggests that the tau protein encoded by the MAPT (Microtubule Associated Protein Tau; OMIM *157140) gene located on chromosome 17 may play a central role, independent of alpha-synuclein, in the degeneration of the substantia nigra of the brain and in the development of parkinsonism and Parkinson’s disease [2,3]. The gene discussed is MAPT; the disease is Parkinson disease.