ELISA quantitation of dystrophin for the diagnosis of duchenne and becker muscular dystrophies

Duchenne muscular dystrophy patients express little or no dystrophin, while patients with the milder Becker variant produce dystrophin of altered size or quantity. Dystrophin is currently evaluated on Western blots, but quantitation is difficult and the procedure is not available in most clinical laboratories. We describe an enzyme–linked immunosorbent assay (ELISA) for dystrophin that utilizes a carboxyl–terminal capture antibody, and detection antibodies spanning 65% of the molecule. This configuration is selective for dystrophin and reduces the potential for false diagnosis due to loss of antigenic determinants by deletion or the presence of truncated products resulting from frame–shift muations. The dystrophin ELISA distinguished Duchenne muscular dystrophy patients from those with unrelated disorders and may have prognostic value for patients with Becker dystrophy. This assay should prove to be an accessible and rapid tool for the diagnosis of Duchenne/Becker muscular dystrophies and for evaluating therapies that attempt to introduce dystrophin or augment its expression.