As expected, the analysis of the alternative splicing of the TNNT2 gene showed that the fetal isoform (exon 5 including) was significantly more expressed in DM1 BB (Mann–Whitney: p = 0.001), DM2 BB (Mann–Whitney: p = 0.004), and DM1 TA (Mann–Whitney: p = 0.001) compared to the corresponding CTR muscles. The gene discussed is TNNT2; the disease is myotonic dystrophy type 1.