DMPK and myotonic dystrophy type 1: Since the DMPK protein is encoded by the DMPK gene, which is abnormally expanded in the 3′UTR region in DM1, these mutant transcripts with abnormal CUG expansions are not efficiently transported to the cytoplasm and accumulate in cell nuclei; therefore, they are not translated into protein [6,10,23,30,31].