Importantly, Mbnl1 and Mbnl2 knockout mice develop RNA splicing abnormalities that are characteristic of DM1 (Kanadia et al. 2003; Charizanis et al. 2012; Suenaga et al. 2012), demonstrating that the loss of MBNL splicing factors is a central contributor of DM1 pathogenesis. Here, MBNL1 is linked to myotonic dystrophy type 1.