DMPK and myotonic dystrophy type 1: Expression of DMPK mRNAs containing CTG repeats interferes with the splicing of SERCA, RyR1 and Cav1.1 in DM1 skeletal muscle [17,19,29], ensuing expression of fetal splice products, whose properties are not optimal for the function of adult muscle fibers and calcium balance.Therefore, we asked whether the splicing pattern of RyR1, SERCA 1 and Cav1.1 were altered in T10 and T15 DM1 myotubes.