Support for this RNA-dominant disease process comes from observations that Mbnl1 knockout (Mbnl1−/−) mice30 display multi-systemic features that resemble DM1 and that defects of alternative splicing induced by expression of CUGexp RNAs or by ablation of the Mbnl1 gene are very similar.31 Here, MBNL1 is linked to myotonic dystrophy type 1.