DMPK and myotonic dystrophy type 1: Consistent with a key role for expanded CUG repeat RNA in DM1 cardiac pathophysiology, inducible expression of high levels ∼960 interrupted CTG repeats located in the DMPK 3′UTR results in arrhythmias and cardiomyopathy that often lead to death of the transgenic animals within a few weeks after induction of the transgene [24].