Introduction: A proximal myopathy develops in some patients with muscle channelopathies, but the causative molecular mechanisms are unknown.
Methods: We reviewed retrospectively all clinical and muscle biopsy findings of 3 patients with channelopathy and additional myositis. Direct DNA sequencing was performed.
Results: Pathogenic mutations were identified in each case. Biopsies demonstrated inflammatory infiltrates.
Conclusions: Clinicians should consider muscle biopsy in channelopathy patients with severe myalgia and/or subacute weakness and accompanying elevated creatine kinase. Chance association of myositis and channelopathy is statistically unlikely. An alternative hypothesis suggests that inflammatory insults could contribute to myopathy in some patients.
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