Clinical Usefulness of Molecular Diagnosis in Dystrophin Gene Mutations Using the Multiplex Ligation-dependent Probe Amplification (MLPA) Method

ABSTRACT

BACKGROUND: Duchenne/Becker muscular dystrophy (DMD/BMD), which is the most common X-linked muscular dystrophy, is caused by mutations in the dystrophin gene. These mutations comprise deletions in approximately 55~65% of patients, duplications in 5~10%, and point mutations or small insertion/deletions in the remainder. Unfortunately, current diagnostic assays for dystrophin do not accurately detect duplication mutations or female carriers. In this study we employed multiplex ligation-dependent probe amplification (MLPA) analysis to detect deletions or duplications of the dystrophin gene in patients with DMD/BMD, and in potential female carriers. METHODS: A total of 41 subjects was recruited for this study, comprising 35 male DMD/BMD patients, 1 female patient with Turner syndrome, and 5 females with a family history of DMD/BMD. The MLPA method was employed to determine the copy number of each of the 79 exons of the dystrophin gene in the 41 subjects. RESULTS: MLPA analysis for dystrophin was informative in 71.4% (25/35) of patients with DMD/BMD patients, identifying deletions in 60.0% (21/35) and duplications in 11.4% (4/35). MLPA analysis showed the presence of a deletion of the DMD gene in one female patient with Turner syndrome. Of the five female patients with a family history of DMD/BMD, this assay revealed exon deletion in one and duplications in one. CONCLUSIONS: The reported findings reveal that the MLPA method is a powerful tool for detecting duplications and female carriers, as well as DMD gene deletions. MLPA should be considered the method of choice for an initial genetic analysis of DMD/BMD patients.