MBNL1 and myotonic dystrophy type 1: A major patho-mechanism underpinning DM1 is the generation of toxic RNAs containing expanded CUG triplets that accumulate as distinctive nuclear foci and dysregulate the activity of RNA processing factors, including MBNL1 and CELF1 as well as Staufen1 and DDX5 [6,7,8,9,10,11,12].