A patient with mitochondrial myopathy associated with isolated succinate dehydrogenase deficiency

We report on a boy with normal mental development who had muscle hypotonia anti congenital dislocation of the hip and knee joints. Histochemical and b iochemical examinations of his muscle specimen revealed no succinate dehydr ogenase (SDH) activity. Since the NADH cytochrome c reductase and cytochrom e c oxidase activities were normal, we concluded that he had an isolated SD H deficiency. Our patient provides further evidence for the clinical variab ility of this disorder. (C) 2000 Elsevier Science B.V. All rights reserved.