Leigh's disease with decreased activities of pyruvate carboxylase and pyruvate decarboxylase

Mitochondrial abnormalities in choroid plexus of Leigh disease

Morphological study of the choroid plexuses in three patients with Leigh disease revealed a marked increase in the number of mitochondria in almost all of the choroidal epithelial cells. This finding is considered the morphological expression of a biochemical defect in the mitochondrial metabolism underlying Leigh disease, and the probable explanation for increased CSF levels of lactate and pyruvate in this disease.

Cytochrome c oxidase deficiency in Leigh syndrome

We studied 6 mitochondrial enzymes in crude extracts and isolated mitochondria from 5 children with pathologically proven subacute necrotizing encephalomyelopathy (Leigh syndrome). Samples were taken from brain (5 patients), skeletal muscle (4 patients), liver (4 patients), kidney (4 patients), heart (1 patient), and cultured fibroblasts (3 patients). An isolated defect of cytochrome c oxidase (COX) activity was found in brain (decrease of activity to 15 to 39% of the normal mean), muscle (9 to 20%), kidney (1 to 67%), and in the 1 available heart (4%) from a patient with cardiopathy. COX activity was also decreased in liver of 3 patients (2 to 13% of normal) and in cultured fibroblasts of 2 patients (18 and 27%), but it was normal in both liver and fibroblasts from 1 patient. Immunotitration using polyclonal antibodies against human heart COX showed essentially normal amounts of cross-reacting enzyme protein in various tissues from different patients. Electrophoresis of COX immunoprecipitated from brain mitochondrial extracts showed normal patterns of COX subunits in 2 patients. This study confirms the theory that COX deficiency is an important cause of Leigh syndrome.

Familial Leigh's syndrome: association with a defect in oxidative metabolism probably restricted to brain

Four siblings with Leigh's syndrome are described. The diagnosis was confirmed by pathological examination in one case. Chemical and biochemical investigations of serum and urine revealed no abnormalities of pyruvate metabolism, but all patients had marked elevations of CSF pyruvate and lactate concentrations. In three of the siblings, [1-14C]pyruvate oxidation rates were normal in fibroblasts and leucocytes. In one patients, extensive biochemical and histochemical studies of liver and muscle tissue revealed no mitochondrial dysfunction. A defect of oxidative metabolism restricted to brain seems probable.

Leigh syndrome, a mitochondrial encephalo(myo)pathy. A review of the literature

Results of a literature survey of 173 patients with Leigh syndrome are presented, with emphasis on signs and symptoms in relation to age at onset, contributions of technical investigations to the diagnosis, pathophysiology, genetic considerations and therapeutic aspects. Based on this study we are of the opinion that it is possible to come to a diagnosis of "most probable Leigh syndrome" durante vitamin on the combination of clinical signs and symptoms, autosomal recessive mode of inheritance, association with a defect of energy metabolism, and CT or MRI abnormalities.

Subacute necrotizing encephalomyelopathy (Leigh syndrome) associated with disturbed oxidation of pyruvate, malate and 2-oxoglutarate in muscle and liver

We studied a 17-year-old girl with subacute necrotizing encephalomyelopathy (Leigh syndrome). Lactate and pyruvate levels were increased in serum and cerebrospinal fluid. The oxidation rates of all substrates tested, i.e. pyruvate in liver, and pyruvate, malate and 2-oxoglutarate in muscle, were decreased, as was the production of adenosine triphosphate plus creatine phosphate. Cytochrome content was normal. The data imply a defect in oxidative phosphorylation, outside the cytochrome region.

Studies on pyruvate carboxylase, pyruvate decarboxylase and lipoamide dehydrogenase in subacute necrotizing encephalomyelopathy

In two autopsy-proven cases of subacute necrotizing encephalomyelopathy (SNE, Leigh's Disease) the activities of pyruvate carboxylase, pyruvate decarboxylase and lipoamide dehydrogenase were investigated in cultured fibroblasts. Normal activities of pyruvate carboxylase and lipoamide dehydrogenase were found in both cases. The activity of pyruvate decarboxylase was low in one of the cases (p less than 0.05), while the activity in the other was within normal limits. The concentrations of alanine, lactate and pyruvate were normal or only slightly increased. The relationship between SNE and a defect in pyruvate metabolism is under discussion, and it is concluded that the general assumption that pyruvate carboxylase deficiency is the cause of SNE is not in agreement with our results or the present literature. However, pyruvate decarboxylase deficiency may in some cases contribute to the development of SNE.