ATP2A1 and myotonic dystrophy type 1: We then investigated the effect of JM642 on the mis‐splicing of pre‐mRNAs in the DM1 mouse model (HSALR), which expresses r(CUG)220 and exhibits the mis‐splicing of Clcn1 and Atp2a1 pre‐mRNAs.[38]JM642 (10 mg kg−1 or 20 mg kg−1 per day) was administrated to the HSALR mice (n=3 in each group) by daily intraperitoneal (i.p.)injection for five days.