RESUMO-A distrofia muscular congênita (DMC) compõe um grupo de miopatias caracterizadas por hipo-tonia e fraqueza muscular notadas já no primeiro ano de vida. A forma de Ullrich é caracterizada por re t r a ç õ e s musculares proximais e hiperextensibilidade distal. Cerca de 40% destes pacientes apresentam mutações em um dos genes que codificam as três sub-unidades do colágeno VI (COL6), acarretando deficiência total ou parcial na marcação da proteína. Analisamos, através de imunofluorescência, a marcação do COL6 em f r a g-mentos musculares de 50 pacientes com DMC, 20 deles com ausência da marcação para merosina. Iden-tificamos 4 casos com deficiência total da marcação do COL6 (8% do total), representando 13% dos casos com marcação normal para merosina. As alterações histológicas musculares dos pacientes com COL6 defi-ciente eram indistinguíveis das outras formas de DMC, porém mais brandas que as observadas na DMC com deficiência de merosina. Em três dos pacientes com COL6 deficiente observou-se hipotonia e fraqueza m u s c u l a r, notadas já no período neonatal, atraso do desenvolvimento motor, retrações musculares em joelhos e cotovelos, hiperextensibilidade distal e luxação congênita do quadril (dois pacientes). Um paciente per-deu a capacidade para a marcha, e outro faleceu por problemas respiratórios. A análise da marcação do COL6, assim como da merosina, no tecido muscular de pacientes com DMC pode auxiliar na identificação e caracterização fenotípica dos diversos subtipos de DMC. PALAVRAS-CHAVE: colágeno tipo VI, distrofia muscular congênita, imunofluorescência. Analysis of the expression of collagen VI in congenital muscular dystrophy ABSTRACT-Congenital muscular dystrophy (CMD) composes a group of disorders characterized by hypotonia and muscular weakness noticed in the first year of life. The Ullrich`s form is characterized by proximal joint contractures and distal hiperextensibility. About 40% of these patients present mutations in one of the genes that codify the sub-units of the collagen VI protein (COL6), producing total or partial deficiency of the protein expression. We analyzed, through immunohistochemistry, the expression of COL6 in muscle fragments of 50 patients with CMD; 20 of them presented merosin expression deficiency. We identified 4 cases with total COL6 deficiency (8% of the total), representing 13% of the cases with normal merosin expression. The histological findings of patients with deficiency of COL6 were indistinguishable from other forms of CMD, but milder than that abnormalities observed in merosin deficient patients. In three COL6 deficient patients were observed hypotonia and weakness in the neonatal period, delayed of motor milestones , muscular retractions of knees and elbows, distal joint hiperextensibility and congenital hip dislocation (two patients). One patient lost the ability to walk; and one died due to respiratory problems. The analysis of COL6 expression, as well as merosin expression, in the muscle tissue from CMD patients, can be import a n t for identification...
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