Clinical application of multiplex ligation-dependent probe amplification for the detection exonic copy number alterations in the Dystrophin gene

Abstract

To clarify advantages and disadvantages of using multiplex ligation-dependent probe amplification (MLPA) for detecting exonic deletions and duplications of the Dystrophin gene, and to explore the appropriate management for single-exon abnormality detected by MLPA. MLPA were performed to detect exonic copy number changes in 70 Duchenne/Becker muscular dystrophy (DMD/BMD) patients diagnosed by clinical and histological findings. PCR, DNA sequencing and real-time PCR were applied to the samples in which MLPA indicated single-exon deletion or duplication. Of all 70 patients, MLPA detected exonic deletions in 42 (60%), including 12 with single-exon deletion and one with ambiguous single-exon deletion. Exon duplications were found in 7 patients (10%), among which two were single-exon duplication. 21 patients showed normal results (30%). For the 12 patients with single-exon deletion, MLPA results were confirmed by PCR in 11. In one patient, a deletion of two nucleotides (c.4470-4471delAA) was found by sequencing. A novel two-nucleotide deletion (c.4746-4747delCT) was identified in the patient with the ambiguous single-exon deletion. For the two patients showed single-exon duplication, MLPA results were confirmed by real-time PCR. MLPA should be the first choice in detecting Dystrophin gene exon deletions and duplications. Single-exon deletion/duplication resulted from MLPA should be further evaluated by other methods.