Nuclearmagnetic resonance (NMR) studies revealed these inhibitors bind tothe 1 × 1 UU internal loops formed when r­(CUG)exp folds.Five of these molecules rescued two cellular hallmarks of DM1 in patient-derivedmyotubes, alternative pre-mRNA splicing defects and formation of nuclearr­(CUG)/MBNL1-positive foci. The gene discussed is MBNL1; the disease is myotonic dystrophy type 1.