Detection of rare mutations in the dystrophin gene

INTRODUCTION: Duchenne/Becker muscular dystrophies (DMD/BMD) are allelic X-linked, recessive proximal muscle disorders, caused by mutations in the dystrophin gene located in Xp21. DMD occurs with the incidence 1:3500, BMD with the incidence of 1:18,500 new-born males. Approximately about 60% of mutations in the dystrophin gene are deletions, 10%--duplications and 30%--point mutations. AIM: The aim of the study was detection of the mutations: rare deletions, duplications and point mutations in the dystrophin gene in patients diagnosed as DMD/BMD in whom the presence of the most common deletions had previously been excluded. MATERIALS AND METHODS: Molecular analysis was performed using DNA samples isolated from 105 DMD and 10 BMD patients. Detection of rare deletions and duplications was carried out by Multiplex Ligation-dependent Probe Amplification (MLPA). Point mutations were identified by analysis of single strand conformation polymorphism (SSCP) and DNA sequencing. RESULTS: 38 Different mutations were detected: 10 rare deletions, 14 duplications and 14 point mutations and microdeletions. Majority of the detected rare deletions (7 out of 10) and point mutations (11 out of 14) are novel mutations. CONCLUSIONS: Application of MLPA technique allows the detection of small, rare deletions and duplications. Identification of the nature and localization of the mutations may, in the future, help to apply appropriate therapeutic approaches in DMD patients.