MBNL1 and myotonic dystrophy type 1: This is the first report of mis-splicing of orthologous exons in brain tissues from human DM1 and Mbnl1 knockout mice, although mis-splicing of exons 3 and 12 (9 in mice) of MAPT has been shown in human DM1 brain [10], [13] and in the CTG transgenic mouse brain [17].