First, we identified Fhos exon 16′ missplicing in DM1 flies and demonstrated that this splicing event and Serca exon 13 inclusion, previously identified as altered in the Drosophila DM1 model, both are regulated by Muscleblind C (Fig. S2a,b)45. Here, FHOD1 is linked to myotonic dystrophy type 1.