Anti-sense oligonucleotides (ASO) targeting a strong intronic splicing silencer (ISS) at the beginning of intron 7 (named ISS-N1), which contains a bipartite motif bound by hnRNP A1, have been shown to enhance SMN2 exon 7 inclusion in cell culture (Hua et al., 2007) and in SMA mouse models (Hua et al., 2011, 2015). Here, SMN2 is linked to proximal spinal muscular atrophy.