In the case of CaV1.1 (CACNA1S) alternative splicing of exon 29 generates a calcium conducting CaV1.1e that enhances calcium influx and generates spontaneous calcium sparklets in muscle fiber during EC coupling, resulting in reduced force and enhanced endurance as observed in myotonic dystrophies DM1 and DM2 [138, 139]. This evidence concerns the gene CACNA1S and myotonic dystrophy type 1.