Mutation spectrum analysis of gene in Indonesian Duchenne and Becker muscular dystrophy patients.

Background: Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) are allelic disorders caused by mutations in the gene. The full mutation spectrum of the gene in Indonesian patients is currently unknown. Mutation-specific therapies are currently being developed, such as exon skipping or stop codon read-through therapy. This study was conducted with the aim of identifying the mutation spectrum of the gene in Indonesia to guide future development and application of feasible therapeutic strategies.

Methods: This study is a cross sectional study that enrolled 43 male patients with a clinical suspicion of or BMD. Multiplex ligation-dependent probe amplification (MLPA) reaction was performed to screen for the common mutations in the gene.

Results: Out of 43 subjects, deletions accounted for 69.77% (n=30) cases, while duplications were found in 11.63% (n=5) cases. One novel duplication spanning exons 2 to 62 was identified. Deletion mutations clustered around the distal (66.67%) and proximal (26.67%) hot spot regions of the gene while duplication mutations were observed solely at the proximal region. Two false positive cases of single exon deletion detected through MLPA were attributed to sequence mutations affecting primer ligation sites, confirming the need to validate all single exon deletions when using this screening method. Analysis of available maternal DNA samples showed that the rate of de novo mutations (48.15%) appears higher than expected in this population. Out of 31 patients who were classified as DMD based on clinical and genotype characterizations, 60.47% (n=26) of cases were suitable for exon skipping therapy.

Conclusion: This is the first comprehensive study showing the feasibility of implementing the MLPA method for routine screening of patients in Indonesia. This is also the first study showing the potential applicability of exon skipping therapy in the majority of cases in the country.