To test the potential effects of MBNL3 deficiency in the development of DM1 pathophysiology we developed Mbnl3ΔE2 mice on a 129sv background, in which exon 2 of the X-linked Mbnl3 gene was replaced by a Neomycin expression cassette34. This evidence concerns the gene MBNL3 and myotonic dystrophy type 1.