However, disease-associated reduction of functional pool of MBNL1 results in exon 7a inclusion and NMD-based turnover of CLCN1 transcript which manifests in reduced chloride ion conduction and myotonia affecting skeletal muscles in myotonic dystrophy type 1 (DM1) [8]. This evidence concerns the gene CLCN1 and myotonic dystrophy type 1.