the first mlpa analysis of ddystrophin gene duplications in iranian dmd/bmd patients

duchenne muscular dystrophy (dmd) and becker muscular dystrophy (bmd) can be caused by deletions, duplications or point mutations in the dmd gene that encodes dystrophin. partial gene duplications account for up to 5-10 % of dmd and up to 5- 19% of bmd cases. cases with gene duplication in dmd/bmd are determined by quantitative methods such as maph, sothern blotting and q-pcr that are laborious and technically demanding. we have applied multiplex ligation-dependent probe amplification (mlpa) assay to simultaneously screen all 79 dmd gene exons for deletions and duplications in dmd/bmd patients. mlpa was performed using the salsa mlpa kit p034-a2 and p035-a2 (mrc-holland, amsterdam, the netherlands) based on the instructions of themanufacturer. mlpa samples consisted of approximately 200 ng of genomic dna. all amplified fragments were separated using capillary electrophoresis on abi prism 3130 genetic analyzer (applied bio- systems). the area under peak for each individual amplified fragment was measured using the gene marker software (v.1.6). analysis of mutations was performed in 20 unrelated dmd patients previously found to be negative for large deletions by standard multiplex pcr assays. gene duplication was found in five patients (25%) with various lengths from 4 to 22 exons across dystrophin gene. this is the first report of the relative frequency of duplicational mutations in iranian dmd/bmd patients. this project is still ongoing. the dmd mlpa test provides a simple and cheap dna- based test for deletion/duplication screening of total dystrophin gene. this technique can be followed by real-time pcr assay to confirm the genetic defects in dmd gene and to improve the precision of genetic counseling.