MBNL1 and myotonic dystrophy type 1: Noteworthy is the major difference between the DMSXL and LC15 models in that the LC15 mice contain a smaller (250–400) CTG insert and lack other key DM1 phenotypes such as decreased motor performance and primary DM1 mechanisms such as MBNL1 sequestration (Seznec et al., 2000; Algalarrondo et al., 2015; Tylock et al., 2020).