CLCN1 and myopathy: Here, to definitively isolate the role of long-term exposure to myotonia in the development of DM1 myopathy, we developed a novel myotonia resistant mouse model through genomic deletion of Clcn1 E7a (ClC-1ΔE7a); the exclusion of E7a in Clcn1 transcripts with ASOs has been demonstrated to eliminate myotonia in DM1 mouse models12.