Abstract
Autosomal dominant optic atrophy (ADOA) is frequently caused by mutations in the optic atrophy 1 (OPA1) gene, with haploinsufficiency being the major genetic pathomechanism. Almost 30% of the OPA1-associated cases suffer from splice defects. We identified a novel OPA1 mutation, c.1065+5G>A, in patients with ADOA. In patient-derived fibroblasts, the mutation led to skipping of OPA1 exon 10, reducing the OPA1 protein expression by approximately 50%. We developed a molecular treatment to correct the splice defect in OPA1 using engineered U1 splice factors retargeted to different locations in OPA1 exon 10 or intron 10. The strongest therapeutic effect was detected when U1 binding was engineered to bind to intron 10 at position +18, a position predicted by bioinformatics to be a promising binding site. We were able to significantly silence the effect of the mutation (skipping of exon 10) and simultaneously increase the expression level of normal transcripts. Retargeting U1 to the canonical splice donor site did not lead to a detectable splice correction. This proof-of-concept study indicates for the first time the feasibility of splice mutation correction as a treatment option for ADOA. Increasing the amount of correctly spliced OPA1 transcripts may suffice to overcome the haploinsufficiency.
Highlights
Mutations in the optic atrophy type 1 gene (OPA1; OMIM: 605290) cause autosomal dominant optic atrophy (ADOA; OMIM: 165500), which is characterized by slowly progressive bilateral loss of visual acuity, centrocecal visual field defects, and color vision disturbances
In this study, we characterized a family with several members suffering from ADOA caused by a novel splice-site mutation in OPA1 and developed a therapeutic genetic approach to treat the mutation-induced splice defect
The novel OPA1: c.1065+5G>A mutation affects the consensus splice donor site of exon 10 and causes exon 10 skipping during splicing
Summary
Mutations in the optic atrophy type 1 gene (OPA1; OMIM: 605290) cause autosomal dominant optic atrophy (ADOA; OMIM: 165500), which is characterized by slowly progressive bilateral loss of visual acuity, centrocecal visual field defects, and color vision disturbances. The disease typically starts during early childhood, and most patients present with optic disc pallor indicating bilateral atrophy of the optic nerve due to degeneration of retinal ganglion cells. High intra- and interfamilial variability in the degree of visual impairment in ADOA occurs, ranging from normal vision to legal blindness. With a disease prevalence of about 1:10,000 to 1:30,000, ADOA is one of the most common inherited optic neuropathies.[1]. Correct splicing of nuclear pre-mRNA depends on a complex interplay of different splicing factors.[16] The first steps require the identification of the exonic sequences within the large pre-mRNA and the
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