Consistent with these reports, increased inclusion of CLCN1 exon7a or exclusion of CACNA1S exon29 was associated moderately with longer vHOTthumb times in all DM1 participants; no such associations of myotonia with causative RNA mis‐splicing events have been previously reported in human DM1 studies. The gene discussed is CLCN1; the disease is myotonic dystrophy type 1.