MBNL1 and Myotonia: For example, the striking recapitulation of mis-splicing of the chloride channel 1 (Clcn1) gene specific to skeletal muscles and myotonia in homozygous Mbnl1 exon 3 knock-out mice (Mbnl1ΔE3/ΔE3 mice) confirms that the loss of function of this RBP is a major cause of the muscular symptoms manifested by DM1 patients [167].