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.