At the cellular level, our findings support a potential link between SORBS1 exon 25 mis‐splicing and the ultrastructural defects observed at the NMJ in DM1 mouse models, pointing to a broader impact of toxic CUG repeat expansion and MBNL protein sequestration on neuromuscular synapse homeostasis. This evidence concerns the gene SORBS1 and myotonic dystrophy type 1.