Résumé :
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The metabolic myopathies are characterized for alterations in the biochemical anabolic or catabolic reactions and they can be found in the different groups of illnesses of the metabolism, are presented for any of the 11 enzymes specific involved in the corporal production of energy. Generally they are detected in the childhood or adult life, not are fatal and the biopsy confirms the diagnosis. The mitochondrial myopathies frequently are congenital and affect other systems besides the muscle, present abnormalities in the mitochondrial metabolism and are characteristics the crystalloid inclusions detected by microscopy. In base to this we present the finds of the structural aspects and biochemical observed in 5 cases of myopathy in four children, 3 males and 1 female with ages from 20 months to 9 years and one male adult of 29 years. The muscle biopsy taking from the quadriceps was processed for stain techniques of routine, enzymatic and not enzymatic histochemistry for studies by light and electronic microscopy, and biochemical test for detect mutations in mtDNA. The muscular tissue presented mainly morphologic changes due to an accentuated atrophy and/or hypertrophy of both fibers type with a lower mean or over the normal diameter average for the age, with irregularities in the oxidative reactions by hyperactivity or hypo activity in the sarcolemma and in the sarcoplasm, besides with deficit in the phosphorylase and excess of glycogen and lipids. Joined to the variable quantity of mitochondria (much diminished or very numerous) besides the structural changes in the form, in size, and aspect or density of cristae and mitochondrial matrix, but in none of the cases crystalloid inclusions were seen. Molecular studies of the mtDNA showed 80% of the tRNA Leu with mutation in A3248G, in 3 of 5 analyzed cases. The results indicated mitochondrial myopathy in some cases.
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