We first determined the optimal concentration of AONs to evaluate the efficacy of exon inclusion. AONs were transfected at various concentrations to type 1 SMA patient fibroblasts (Fig. 2b). The RT-PCR analysis using SMN2 specific primers revealed that 5 nM or higher concentration of AONs #1–5 efficiently induced SMN2 exon 7 inclusion in treated cells (Fig. 2b).