Genotype and age at diagnosis in Thai boys with Duchenne muscular dystrophy (DMD)

Gene-based therapy is a treatment for Duchenne muscular dystrophy (DMD) has become lately available; limited use for specific of mutation and percentages of the patients. Diagnosis in Thailand is made by muscle biopsy or multiplex ligation-dependent probe amplification (MLPA). Appropriate treatment in developing countries is difficult because gene sequencing is expensive and has limited availability. We aimed to identify the clinical and genetic characteristics of Thai DMD. Patients aged 0-22 years were recruited from the pediatric neuromuscular clinic of Siriraj Hospital during 2017-2019. Ninety-four charts were reviewed for clinical and laboratory data. Patients with negative MLPA who underwent next generation sequencing were consented. The mean age at onset and diagnosis was 4 and 7 years, respectively. Approximately 70% of patients had loss of ambulation by the mean age of 9.6 ± 1.8 years. Eighty percent were treated with glucocorticoids. Genetic testing was performed in 70 patients. Molecular analysis revealed mutations in 90% of cases, including exon deletions in 48.57%, nonsense mutations in 20%, frameshift mutations in 12.86%, splice site in 7.14%, exon duplications in 5.71%, and in-frame deletion in 2.86%. Gene sequencing should be performed because baseline genetic mutation data is essential for gene-based therapies that will become available in the future.