DMPK and myotonic dystrophy type 1: In myotonic dystrophy type 1 and 2 (DM1 and DM2), for example, mutations in the DMPK and ZNF9/CNBP genes, respectively, disrupt the alternative splicing of the CLCN1 gene, creating a secondary reduction in sarcolemmal ClC-1 protein expression and current density (181–184).