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Muscle Involvement in a Large Cohort of Pediatric Patients with Genetic Diagnosis of Mitochondrial Disease

By Cristina Jou, Juan D. Ortigoza-Escobar, Maria M. O’Callaghan, Andres Nascimento, Alejandra Darling, Leticia Pias-Peleteiro, Belén Perez-Dueñas, Mercedes Pineda, Anna Codina, César Arjona, Judith Armstrong, Francesc Palau, Antonia Ribes, Laura Gort, Frederic Tort, Placido Navas, Eduardo Ruiz-Pesini, Sonia Emperador, Ester Lopez-Gallardo, Pilar Bayona-Bafaluy, Raquel Montero, Cecilia Jimenez-Mallebrera, Angels Garcia-Cazorla, Julio Montoya, Delia Yubero and Rafael Artuch


Mitochondrial diseases (MD) are a group of genetic and acquired disorders which present significant diagnostic challenges. Here we report the disease characteristics of a large cohort of pediatric MD patients (n = 95) with a definitive genetic diagnosis, giving special emphasis on clinical muscle involvement, biochemical and histopathological features. Of the whole cohort, 51 patients harbored mutations in nuclear DNA (nDNA) genes and 44 patients had mutations in mitochondrial DNA (mtDNA) genes. The nDNA patients were more likely to have a reduction in muscle fiber succinate dehydrogenase (SDH) stains and in SDH-positive blood vessels, while a higher frequency of mtDNA patients had ragged red (RRF) and blue fibers. The presence of positive histopathological features was associated with ophthalmoplegia, myopathic facies, weakness and exercise intolerance. In 17 patients younger than two years of age, RRF and blue fibers were observed only in one case, six cases presented cytochrome c oxidase (COX) reduction/COX-fibers, SDH reduction was observed in five and all except one presented SDH-positive blood vessels. In conclusion, muscle involvement was a frequent finding in our series of MD patients, especially in those harboring mutations in mtDNA genes

Topics: mitochondrial diseases, myopathy, pediatric patients, biochemical markers, muscle histopathology, next generation sequencing, Medicine, R
Publisher: MDPI AG
Year: 2019
DOI identifier: 10.3390/jcm8010068
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