Abstract:
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Communication n° 394 Mutations in dysferlin gene (DYSF) cause different muscular dystrophy phenotypes including Limb Girdle Muscular Dystrophy 2B (LGMD2B), Miyoshi Myopathy (MM) and Distal Anterior Compartment myopathy (DAT). These disorders are characterized by autosomal recessive inheritance, adult onset and elevated levels of serum creatine kinase. DYSF gene, that maps to chromosome 2p13, has 55 exons and codifies a protein of about 237 kD that is located in the sarcolemma. The function is unknown but recent studies have demonstrated the involvement of dysferlin in membrane reparation events. We report the study of 32 patients from 20 families clinically diagnosed as MM, LGMD2B and DAT. Dysferlin expression was studied by immonohistochemistry in muscle biopsies and by Western blot analysis in peripheral blood monocytes CD14+. The absence of dysferlin in monocytes always correlated with absence of the sarcolemmal staining in the muscle biopsy. We did not find reduction of expression either in the monocytes or the muscle biopsy in any of the patients with confirmed dysferlinopathy. The screening of mutations in DYSF gene was performed using the analysis of genomic DNA extracted from total peripheral blood and cDNA was obtained from monocytes. Obtained cDNAs were amplified using primers that covers the 55 exons in 14 fragments and directly sequenced. Study of genomic DNA was done to check mutations found in monocytes RNA. We identified 14 different polymorphisms and 17 different mutations: 7 missense, 4 nonsense and 6 frameshift. Five of them were never described elsewhere and in some cases the three different phenotypes are caused by the same mutation. This work was supported by grants from the Fondo de Investigaciones Sanitarias (PI03/1387, PI02/0388), Red INERGEN (C03/05) and Association Française contre les Myopathies (AFM).
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