Mitochondrial Encephalomyopathy Associated with Pyruvate Dehydrogenase Complex Deficiency: Eight Clinical Cases

Background . Defects in pyruvate dehydrogenase complex (PDC), involved in the glycolysis products integration into the cells' energy metabolism, are one of the reasons of mitochondrial pathology development. The diagnosis of this condition can be pretty complicated also due to the lack of description of such patients with encephalomyopathy associated with PDC deficiency in Russian population. Clinical Cases Description . We have performed the analysis of clinical manifestations polymorphism of progressive mitochondrial encephalomyopathy caused by pathogenic variants in nuclear X linked gene, PDHA1 (encodes alpha subunit of pyruvate dehydrogenase), in 8 boys aged from 1 to 8 years. The adverse perinatal period was mentioned in all cases. The major features of symptom complex by the time of hospital examination were psychomotor retardation, ataxy, myopathic manifestations. Dystonic attacks were observed in 2 sibs. All patients had changes on brain magnetic resonance imaging: in basal ganglia in 6 children and ventriculomegaly in 2 children. All children had lactic acidosis. Clinical examination has shown that 4 patients had severe damage of nervous system, other 4 patients had moderate damage. Missense mutations in the PDHA1 gene were revealed in 6 children, insertions and duplications including 6 and 16 base pairs — in 2 children. The moderate positive dynamics was noticed as a result of complex treatment of children: stabilization of the overall condition, no metabolic crises, decrease in frequency of dystonic attacks. Conclusion . The clinical polymorphism of mitochondrial encephalomyopathy associated with PDC deficiency is described. The differences in manifestations of severe and moderate forms of disease are shown. The presented description may be useful for medico-genetic counseling and providing medico-genetic care for families.