The CUGexp RNA sequesters MBNL proteins, leading to the disruption of many processes regulated by these proteins and further to disease-associated phenotypes, such as myotonia (caused by CLCN1 missplicing, (18) muscle weakness and insulin resistance (19) or cardiac abnormalities, including fibrosis and conduction anomalies (20,21). Here, MBNL1 is linked to Myotonia.