Benign hereditary non-progressive chorea of early onset. Clinical genetics of the syndrome and report of a new family.

The syndrome of benign non-progressive chorea (of early onset) is described in three brothers and some of their relatives. Clinical genetic study of the family showed an autosomal dominant mode of inheritance and suggested presence of the gene in both sides of the family. Thus, the propositi might be homozygous for the dominant gene (suggested by increased clinical manifestations as compared with other affected members on both sides of the family) which shows relatively high penetrance and variable expressivity. The phenotypic spectrum of the syndrome is differentiated from similar observations in the literature, and genetic implications are discussed. The condition is differentiated from hereditary essential tremor and from paramyoclonus multiplex.