AON-based degradation of c.151C>T mutant transcripts associated with dominantly inherited hearing impairment DFNA9.

The c.151C>T founder mutation in is a frequent cause of late-onset, dominantly inherited hearing impairment and vestibular dysfunction (DFNA9) in the Dutch/Belgian population. The initial clinical symptoms only manifest between the 3rd and 5th decade of life, which leaves ample time for therapeutic intervention. The dominant inheritance pattern and established non-haploinsufficiency disease mechanism indicate that suppressing translation of mutant transcripts has high therapeutic potential. Single-molecule real-time (SMRT) sequencing resulted in the identification of 11 variants with a low population frequency (<10%) that are specific to the c.151C>T mutant allele. Proof of concept was obtained that gapmer antisense oligonucleotides (AONs), directed against the c.151C>T mutation or mutant allele-specific intronic variants, are able to induce mutant transcript degradation when delivered to transgenic cells expressing minigenes. The most potent AON, directed against the c.151C>T mutation, was able to induce a 60% decrease in mutant transcripts without affecting wild-type transcript levels. Allele specificity decreased when increasing concentrations of AON were delivered to the cells. With the proven safety of AONs in humans, and rapid advancements in inner ear drug delivery, our studies indicate that AONs offer a promising treatment modality for DFNA9.