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Updated: Jun 2, 2026

Evaluation of Exon Inclusion Induced by Splice Switching Antisense Oligonucleotides in SMA Patient Fibroblasts
Published on: May 11, 2018
Pseudoexon exclusion by antisense therapy in 6-pyruvoyl-tetrahydropterin synthase deficiency
Sandra Brasil1, Hiu Man Viecelli, David Meili
1Centro de Diagnóstico de Enfermedades Moleculares, Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Universidad Autónoma de Madrid, Madrid, Spain.
Abstract:
Antisense oligonucleotide therapy to modulate splicing mutations in inherited diseases is emerging as a treatment option also for metabolic defects. In this article, we report the effect of cellular antisense therapy to suppress pseudoexon activation in primary dermal fibroblasts from patients with mutations in the PTS gene encoding 6-pyruvoyltetrahydropterin synthase (PTPS), which leads to tetrahydrobiopterin and monoamine neurotransmitter deficiency. Pathogenic inclusion of SINE or LINE-derived cryptic exons in different PTPS patients due to the intronic mutations c.84-322A>T, c.163 + 695_163 + 751del57, or c.164-712A>T was demonstrated by transcript analysis in fibroblasts and minigene ex vivo assays. Antisense morpholino oligonucleotides (AMOs) directed to the pseudoexons 3' or 5' splice sites were designed with the aim of preventing the pathological pseudoexon inclusion. At the time of AMO transfection, we investigated patients' cells for correct PTS-mRNA splicing and functional recovery of the PTPS protein. Transcriptional profiling after 24 hr posttransfection revealed a dose- and sequence-specific recovery of normal splicing. Furthermore, PTPS enzyme activity in all three patients' fibroblasts and the pterin profile were close to normal values after antisense treatment. Our results demonstrate proof-of-concept for pseudoexon exclusion therapy using AMO in inherited metabolic disease.
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