A novel desmin (DES) indel mutation causes severe atypical cardiomyopathy in combination with atrioventricular block and skeletal myopathy

BACKGROUND: DES mutations cause different cardiac and skeletal myopathies. Most of them are missense mutations. METHODS: Using a next‐generation sequencing cardiac 174 gene panel, we identified a novel heterozygous in‐frame indel mutation (DES‐c.493_520del28insGCGT, p.Q165_A174delinsAS) in a Caucasian patient with cardiomyopathy in combination with atrioventricular block and skeletal myopathy. This indel mutation is located in the coding region of the first exon. Family anamnesis revealed a history of sudden cardiac death. We performed cell transfection experiments and in vitro assembly experiments to prove the pathogenicity of this novel DES indel mutation. RESULTS: These experiments revealed a severe filament formation defect of mutant desmin supporting the pathogenicity. In addition, we labeled a skeletal muscle biopsy from the mutation carrier revealing cytoplasmic desmin positive protein aggregates. In summary, we identified and functionally characterized a pathogenic DES indel mutation causing cardiac and skeletal myopathy. CONCLUSION: Our study has relevance for the clinical and genetic interpretation of further DES indel mutations causing cardiac or skeletal myopathies and might be helpful for risk stratification.