These mutant RNA with CUG repeats in the nucleus accumulates as a ribonuclear foci, sequestering and deregulating muscleblind-like protein1 (MBNL1) and CUG-BP-ELAV-Like family member1 (CUGBP1 or CELF1), which are important regulators of alternative splicing of other genes and core proteins in DM1 disease complexity [11,45,46]. This evidence concerns the gene CELF1 and myotonic dystrophy type 1.