The above-mentioned observations were supported by the previously published RNA-Seq data obtained for biopsies of several DM1 and non-DM individuals31,32 which suggest that splicing of CELF1 ex4 and ex5, containing alternative AUG codon, is significantly changed in DM1 skeletal muscles (tibialis anterior) and heart (Fig. 1d). The gene discussed is CELF1; the disease is myotonic dystrophy type 1.