FOCAL CYTOCHROME-C-OXIDASE DEFICIENCY IN THE BRAIN AND DORSAL-ROOT GANGLIA IN A CASE WITH MITOCHONDRIAL ENCEPHALOMYOPATHY (TRNA(IIE)-4269 MUTATION) - HISTOCHEMICAL, IMMUNOHISTOCHEMICAL, AND ULTRASTRUCTURAL-STUDY

This is the first report with histochemical and immunohistochemical te chniques of an autopsy case with mitochondrial encephalomyopathy cause d by the mitochondrial tRNA(Ile) (nt4269) A to G mutation showing foca l cytochrome c oxidase (COX) deficiency of neuronal cells. The 18-year -old male patient had cardiomyopathy, hearing disability, mental retar dation, and seizures. Muscle biopsy exhibited many ragged-red fibers a nd focal COX deficiency. A postmortem histochemical study on frozen se ctions of the cerebral cortex, cerebellum, brain stem, and dorsal root ganglia revealed a loss of COX activity in some neuronal cells. On im munohistochemical staining, COX was also defective in a mosaic pattern . Focal COX deficiency may cause variable neurological manifestations in mitochondrial encephalomyopathies.