[Clinical significance of dystrophin test for patients with various neuromuscular diseases--immunofluorescence and immunoblot analyses of dystrophin abnormalities].

The dystrophin test was performed on skeletal muscle specimens from 81 cases with various neuromuscular diseases by using two new monoclonal antibodies. The results were compared with those obtained by using four polyclonal antibodies. These monoclonal and polyclonal antibodies were raised against various portions of the dystrophin molecule. On immunohistochemical analysis, the two new monoclonal antibodies showed the same staining pattern as the four polyclonal antibodies. Non-specific immunostaining of the cytoplasm, often seen with polyclonal antibodies, was not observed with monoclonal antibodies. With the application of monoclonal antibodies, the connective tissue sometimes showed non-specific immunostaining which originated from the second fluorescent antibody. On immunoblot analysis, one of the two monoclonal antibodies, antibody 4-4 C 5, showed weak immunoreactivity, and the 400 kDa dystrophin band was not detected. Three cases out of 15 with Duchenne muscular dystrophy (DMD), and one case out of 3 with limb-girdle type muscular dystrophy which had previously been diagnosed on the basis of clinical data, were found to have non-dystrophin-related muscular dystrophy, and Becker muscular dystrophy (BMD), respectively. Three and two of five cases were diagnosed as DMD and BMD, respectively, though clinical diagnosis had not been possible because they were too young. Clinical diagnosis of congenital muscular dystrophy was confirmed in 9 patients by the dystrophin test. Only one of three certain DMD carriers had a so-called mosaic staining pattern. We conclude that all six antibodies are useful tools for the diagnosis of neuromuscular diseases, because of their high specificity for dystrophin.