Antisense oligonucleotides targeting exon 11 are able to partially rescue the Neurofibromatosis Type 2 phenotype in vitro

Neurofibromatosis type 2 (NF2) is an autosomal dominant condition characterized by the development of multiple tumours of the nervous system caused by loss of function variants in the NF2 gene. The clinical presentation of the disease is variable and related to the type of the inherited constitutional mutation. Here, we evaluated the use of antisense oligonucleotides, specifically phosphorodiamidate morpholino oligomers (PMOs), to reduce the severity of the effects of NF2 truncating variants by converting them to milder hypomorphic forms in vitro. Our results showed that the PMOs designed for variants located at +/- 13 from the intron-exon boundary region interfered with the correct splicing signalling of both NF2 wild-type and mutated alleles. On the other hand, we were able to specifically induce the skipping of exons 4, 8 and 11 of both the mutated and the WT allele maintaining the NF2 gene reading frame at cDNA level. Only the skipping of exon 11 produced a hypomorphic Merlin (Merlin-e11) able to partially rescue the phenotype observed in primary fibroblast cultures from NF2 patients harbouring a germline loss of function variant. This encouraging result is an in vitro proof of concept of the use of antisense therapy to develop personalized therapies for NF2.