CSNK1D and myotonic dystrophy type 1: Likewise, significantly decreased inclusion of CSNK1D exon 9 and MPRIP exon 9 were found in DM1 hiNeurons relative to ctrl hiNeurons (p = 0.0212 and p = 0.0017, respectively) (Fig 5c and 5d), resembling previous observations in post-mortem DM1 brain tissue [11, 22, 48].