Is muscle biopsy still necessary for the diagnosis of mitochondrial disease?

Paulo Victor S. Souza; Wladimir B. V. R. Pinto; Acary S. B. Oliveira
J. Bras. Patol. Med. Lab. 2018;54(5):272


Mitochondria are essential organelles for human life and play a central role in diverse cellular processes such as energy production, reactive oxygen species, biosynthetic intermediates, autophagy, amino acid and fatty acid synthesis and degradation, heme synthesis, intracellular calcium homeostasis and apoptosis in physiological and pathological conditions(1).

Mitochondrial diseases are an inherited genetic group of disorders characterized by abnormal oxidative phosphorylation that results from mitochondrial deoxyribonucleic acid (mtDNA) or nuclear (n)DNA genes giving rise to a constellation of multisystemic manifestations and a wide spectrum of neurological manifestations (metabolic myopathy, seizures, ataxia, encephalopathy, movement disorders, peripheral neuropathy and psychiatric disturbances) from birth to senescence(2, 3).

Skeletal muscle is an ancestral source of accessing and studying mitochondrial dysfunction in primary mitochondrial diseases and in other conditions, such as neurodegenerative or inflammatory disorders and in physiological processes like aging. Classical morphological findings such as ragged-red fibers (RRF), blue fibers (BF) and cytochrome c oxidase negative (COX-) fibers are in the imaginary and biological references of various health professionals and remained as diagnostic markers until the identification of the first genetic alterations in mitochondrial DNA in 1988(4, 5).Read more…