The identification of point mutations in Duchenne muscular dystrophy patients by using reverse-transcription PCR and the protein truncation test.

The protein truncation test (PTT) is a mutation-detection method that monitors the integrity of the open reading frame (ORF). More than 60% of cases of Duchenne muscular dystrophy (DMD) result from gross frame-shifting deletions in the dystrophin gene that are detectable by a multiplex PCR system. It has become apparent that virtually all of the remaining DMD mutations also disrupt the translational reading frame, making the PTT a logical next step toward a comprehensive strategy for the identification of all DMD mutations. We report here a pilot study involving 22 patients and describe the mutations characterized. These constitute 12 point mutations or small insertions/deletions and 4 gross rearrangements. We also have a remaining five patients in whom there does not appear to be a mutation in the ORF. We believe that reverse-transcription--PCR/PTT is an efficient method by which to screen for small mutations in DMD patients with no deletion.