Key result
C-terminal domain, Dp116, and Dp71 mutations were associated with decreased wheelchair use, while Dp140 mutations significantly predicted cardiomyopathy in patients with DMD and BMD.
Why the study?
The reading frame rule does not always hold true, making an understanding of genotype-phenotype relationships important for informing diagnosis, disease management, and genetic therapy development.
Observational (n=402)
Yes
Specific genetic mutations in Duchenne and Becker muscular dystrophy, such as Dp140, significantly predict clinical phenotypes like cardiomyopathy, which can inform disease management and targeted therapies.
May support genotype-specific cardiomyopathy surveillance in DMD/BMD; extends associations but leaves open prospective validation.
gene. In contrast, in-frame mutations usually give rise to the milder Becker muscular dystrophy (BMD). However, this reading frame rule does not always hold true. Therefore, an understanding of the relationships between genotype and phenotype is important for informing diagnosis and disease management, as well as the development of genetic therapies. Here, we evaluated genotype-phenotype correlations in DMD and BMD patients enrolled in the Canadian Neuromuscular Disease Registry from 2012 to 2019. Data from 342 DMD and 60 BMD patients with genetic test results were analyzed. The majority of patients had deletions (71%), followed by small mutations (17%) and duplications (10%); 2% had negative results. Two deletion hotspots were identified, exons 3-20 and exons 45-55, harboring 86% of deletions. Exceptions to the reading frame rule were found in 13% of patients with deletions. Surprisingly, C-terminal domain mutations were associated with decreased wheelchair use and increased forced vital capacity. Dp116 and Dp71 mutations were also linked with decreased wheelchair use, while Dp140 mutations significantly predicted cardiomyopathy. Finally, we found that 12.3% and 7% of DMD patients in the registry could be treated with FDA-approved exon 51- and 53-skipping therapies, respectively.
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Lim et al. (2020) conducted an observational in Duchenne and Becker Muscular Dystrophy (n=402). C-terminal domain, Dp116, and Dp71 mutations were associated with decreased wheelchair use, while Dp140 mutations significantly predicted cardiomyopathy in patients with DMD and BMD.
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