Overview on AON design.

Antisense-mediated exon skipping is an attractive tool to study gene function as well as a promising therapeutic application for a number of diseases. In order for antisense oligonucleotides (AONs) to induce effective exon skipping during pre-mRNA splicing, they have to fulfill certain criteria. These include resistance against endo- and exonucleases and RNase H-induced cleavage and suitable thermodynamic properties. Furthermore, the AON-target sequence needs to be accessible and should contain sequence motives that are essential for proper inclusion of the exon into the mRNA. For most genes, only a few AONs have been designed, with the exception of the DMD gene, for which over 400 AONs targeting the majority of DMD exons have been reported. This allows retrospective analysis of effective and ineffective AONs to obtain guidelines to optimize future AON design.