Given the limitations of the ASPCR technique with respect to detecting isoforms of the same size, we performed a standard RT-qPCR using specific primers against neonatal (exon 6a) and adult (exon 6b) isoforms of SCN5A. The results revealed a down-regulation of the adult exon 6b isoform in both DM1-300 and DM1-1300 iPSC-CMs compared to CTRL iPSC-CMs (Fig. 2D) at 30 days and 60 days (data not shown) post-differentiation. The gene discussed is SCN5A; the disease is myotonic dystrophy type 1.