Familial cerebellar ataxia with muscle coenzyme Q10 deficiency

Objective: To describe a clinical syndrome of cerebellar ataxia associated with muscle coenzyme Q10 (CoQ10) deficiency. Background: Muscle CoQ10 defic iency has been reported only in a few patients with a mitochondrial encepha lomyopathy characterized by 1) recurrent myoglobinuria; 2) brain involvemen t (seizures, ataxia, mental retardation), and 3) ragged-red fibers and Lipi d storage in the muscle biopsy. Methods: Having found decreased CoQ10 level s in muscle from a patient with unclassified familial cerebellar ataxia, th e authors measured CoQ10 in muscle biopsies from other patients in whom cer ebellar ataxia could not be attributed to known genetic causes. Results: Th e authors found muscle CoQ10 deficiency (26 to 35% of normal) in six patien ts with cerebellar ataxia, pyramidal signs, and seizures, All six patients responded to CoQ10 supplementation; strength increased, ataxia improved, an d seizures became less frequent. Conclusions: Primary CoQ10 deficiency is a potentially important cause of familial ataxia and should be considered in the differential diagnosis of this condition because CoQ10 administration seems to improve the clinical picture.