Mitochondrial myopathy and encephalopathy

Abstract

We describe three patients with mitochondrial myopathy, dementia, loss of vision and hearing, seizure disorder with myoclonus, intermittent headaches of a vascular type, visual hallucinations, cerebellar dysfunction, and lactic acidosis. Muscle biopsies in all patients and liver biopsy in one revealed abnormal mitochondria. The disorder may be due to a deficiency of mitochondrial NADH-CoQ dehydrogenase.

A mitochondrial encephalomyopathy: the first case with an established defect at the level of coenzyme Q

“…Therefore, the clinical resemblance of cases of mitochondrial encephalomyopathy with previously reported cases does not justify a localisation of their biochemical defect in the NADH-coenzyme Q region, as suggested by Holliday et al [6], without any biochemical investigation. The present patient is the first case described in whom the defect is restricted to the micro-environment of coenzyme Q.…”

Oxidative Phosphorylation Diseases

“…Hearing loss and ataxia are common findings (Wallace et al, 1988b;Rosing et al, 1985;Fitzsimons et al, 1981;Berkovic et al, 1987a-c;Morgan-Hughes et al, 1982;Holliday et al, 1983). However, in some cases hearing is normal (Fukuhara et al, 1980;Feit et al, 1983;Byrne et al, 1985).…”

“…MERRF is characterized by progressive myoclonic epilepsy, a mitochondrial myopathy with ragged-red fibers, and a slowly progressive dementia (Wallace et al, 1988b;Rosing et al, 1985;Fitzsimons et al, 1981;Berkovic et al, 1987a-c;Byrne et al, 1985;Fukuhara et al, 1980;Morgan-Hughes et al, 1982;Ogasahara and Engel, 1988;Holliday et al, 1983;Feit et al, 1983;Lombes et al, 1989). Hearing loss and ataxia are common findings (Wallace et al, 1988b;Rosing et al, 1985;Fitzsimons et al, 1981;Berkovic et al, 1987a-c;Morgan-Hughes et al, 1982;Holliday et al, 1983).…”

“…However, in some cases hearing is normal (Fukuhara et al, 1980;Feit et al, 1983;Byrne et al, 1985). Onset ranges from late childhood and adolescence (Rosing et al, 1985;Wallace et al, 1988b;Fukuhara et al, 1980;Holliday et al, 1983;Feit et al, 1983; to adulthood (Holliday et al, 1983;Morgan-Hughes et al, 1982;Byrne et al, 1985;Fitzsimons et al, 1981). The absence of strokelike episodes appears to differentiate MERRF from MELAS (mitochondrial encephalomyopathy, lactic acidosis, and strokelike episodes) (Pavlakis et al, 1984).…”

Heteroplasmy in Chronic External Ophthalmoplegia: Clinical and Molecular Observations

“…Conversely, dysfunction of a given site along the electro n transport chain has been associated with man y seemingly disparate clinical phenotypes (40,41): some cases of norm oglycemic congenital lactic acidosis (42)(43)(44)(45); individual cases with Leigh's polioencephalopathy (46)(47)(48); MELAS syndrome (49-51); MERRF syndrome (26,(52)(53)(54)(55); and proximal myopath y with easy fatiguability (2). Despite their biochemical and histologic similarities, they have been described as distinct clinical syndromes.…”