Phenotypic Duchenne muscular dystrophy with C-terminal domain

We report a patient with X-linked muscular dystrophy who had rapidly progressive muscle weakness and became wheelchair-bound at age 10 years. Clinically, he was diagnosed as having Duchenne muscular dystrophy; however, he was diagnosed as having Becker muscular dystrophy by dystrophin tests using a C-terminal monoclonal antibody. No immunolabelling was observed with a monoclonal antibody against the N-terminal domain. Multiplex polymerase chain reaction analysis revealed the deletion of exons 3–19. The data suggest that the deletion of the N-terminal domain of dystrophin can cause a severe phenotype even when the C-terminus of the protein is well preserved.