Myoclonic Epilepsy with Ragged-red Fibers (MERRF): An Immunohistochemical Study of the Brain

Myoclonic epilepsy with ragged-red fibers (MERRF) is a maternally inherited disorder of oxidative phos-phorylation due to specific point mutations within the mitochondrial tRNA^Lvs gene. Mitochondrial dysfunction in the central nervous system (CNS) of patients with MERRF accounts for the neurological manifestations of the disease. Antibodies against subunits of complex I, III, IV and V of the respiratory chain were used to study the expression of these proteins in the frontal cortex, cerebellum and medulla from an autoptic case of MERRF. We found a selective decreased expression of subunit II of cytochrome c oxidase (COX-II) in these regions. Immunohistochemical abnormalities were more widespread than the lesions described by traditional histopathological techniques and made possible an attempt of explanation for the neurological symptoms of the patient.