FAMILIAL EPISODIC ATAXIA - CLINICAL HETEROGENEITY IN 4 FAMILIES LINKED TO CHROMOSOME 19P

We describe the clinical and oculographic findings in 4 families with episodic ataxia and interictal nystagmus (EA-2) linked to chromosome 1 9p. Episodes varied from pure ataxia to combinations of symptoms sugge sting involvement of the cerebellum, brainstem, and cortex. Some affec ted individuals exhibited a progressive ataxia syndrome phenotypically indistinguishable from the dominantly inherited spinocerebellar ataxi a (SCA) syndromes. About one-half of the affected individuals had migr aine headaches and several had episodes typical of basilar migraine. O culographic findings were localizing to the vestibulocerebellum and po sterior vermis. Additional genetic and environmental factors must acco unt for the marked clinical heterogeneity in these families with an ab normal gene on chromosome 19p.