PARKINSONISM is not generally considered to be hereditary. Many textbooks of neurology mention only that cases have been reported in which heredity appeared to play a part. However, the impression that parkinsonism has a hereditary tendency has been documented by a number of authors. Doshay feels that idiopathic parkinsonism has a well-defined hereditary liability, that it is related to myoclonic epilepsy, and that both these conditions represent a form of "cumulative metabolic neuronal lipoidosis." Medea and Clerice in 1898 reported the illness to be present in 4 of 10 siblings. In 1899 Collins and Muskins commented on the high incidence of this affliction in the Irish, and 4 of their reported 24 patients had "a straight forward history of direct inheritance." In these 4, one of the parents was afflicted, and in 3 of the 4 cases an aunt or an uncle also had the disease. Hart in 1904 reported