CELF1 and myotonic dystrophy type 1: In patients with myotonic dystrophy type 1 (DM1), an adult-onset form of muscular dystrophy caused by the expression of mutant transcripts from the DMPK gene containing expanded CUG repeats [11]–[13], CELF1 is aberrantly up-regulated in the heart and skeletal muscles [10], [14].