Hereditary myoclonus and chorea: the spectrum of hereditary nonprogressive hyperkinetic movement disorders

We report three members of a single family who developed a newly described combination of myoclonus and chorea in association with mild ataxia. The occurrence of this and related syndromes suggests that inherited, slowly progressive myoclonus, chorea, and dystonia, alone or in combination, should be viewed as a spectrum of hyperkinetic involuntary movements, and that each motor component may represent variable expression of the same genetic defect.