DUPLICATION DETECTION IN JAPANESE DUCHENNE MUSCULAR-DYSTROPHY PATIENTS AND IDENTIFICATION OF CARRIERS WITH PARTIAL GENE DELETIONS USING PULSED-FIELD GEL-ELECTROPHORESIS

DNA samples from 21 unrelated Japanese patients with Duchenne muscular dystrophy (DMD) with nondeletion-type abnormality in the dystrophin g ene and three samples from possible deletion carriers were analyzed us ing pulsed-field gel electrophoresis (PFGE). Among the 21 patients, 7 were found to carry partial duplications of the dystrophin gene spanni ng 50-400 kb. Of these 7 patients, 4 carried duplications correspondin g to the major hot-spot regions for deletions (7.5-8.5 kb from the 5' end of cDNA), whereas two cases contained duplications in a region abo ut 10 kb from the 5' end of cDNA, where causative mutations are report ed to be rare. Only 1 case was found to contain a duplication of a reg ion about 1 kb from the 5' end of cDNA, which is the reported duplicat ion prone region. A combination of Southern blot analyses of conventio nal agarose gel electrophoresis and PFGE was confirmed to be useful, n ot only for detecting duplications and deletions, per se, but also for identifying carriers in the affected family.