Duchenne/Becker muscular dystrophy (DMD/BMD; OMIM#310200; 300376), the most common X-linked muscular dystrophy, is caused by mutations in the enormously large DMD gene (2.4 Mb; 79 coding exons). About 60% of the cases are due to deletions of one or more exons, ~20% to duplications of one or more exons [1], and in 10% to point mutations of different type and location [1]. So far, the deletions have been mainly screened on the hot-spot regions by standard multiplex polymerase chain reaction (mPCR) [2,3]. Precise deletion borders have rarely been clarified by analysis of single exons, and then only for research rather than a diagnostic purpose [4,5].

Recently, MLPA (multiplex ligation-dependent probe amplification) analysis [6] was successfully applied in the study of the DMD gene and resolved many complications of routine diagnostic approaches that are offered to DMD/ BMD families. Although not yet approved for diagnostic purposes, MLPA has been broadly applied for analyzing different genes [6]. However, it has been accepted as a standard in analysis of DMD/BMD patients and in preparing them for future gene therapy, and is required for inclusion in the Treat-NMD Network [7]. Here we present our results and experience in use of MLPA/direct sequencing for molecular analysis of the DMD gene in Bulgaria.