This binding can mark a specific mRNA for degradation or, in the case of its use in SMA therapy, binding to specific cis-acting splicing regulatory motifs can promote exon 7 inclusion in SMN2. Antisense oligonucleotides need to highly promote exon retention, be resistant to cellular degradation and have high target specificity, low toxicity and high penetrance to target cells including neurons within the central nervous system (CNS). This evidence concerns the gene SMN2 and proximal spinal muscular atrophy.