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Our gene editing off target paperI like this guy's thoroughness and objectivity. No b.s. in other words. "Nelson and Gersbach have previously investigated the potential of off-target editing by CRISPR/Cas9 to unintentionally modify other sites in the genome and reported minimal activity at likely off-target sites. Other recent studies, however, have reported that CRISPR can sometimes make genetic edits at the correct site but not in the intended manner. For example, some studies have shown that CRISPR can cut out genetic sections much larger than intended or that pieces of DNA can embed at the site of the cut. These types of edits had previously been unreported in genome editing studies because the methods being used only detected the intended edit. To comprehensively map all the edits occurring in the dystrophin gene, Nelson used a DNA sequencing approach that agnostically reports any type of edit. Surprisingly, there were many types of edits being made in addition to the intended removal of the targeted exon, including a high level of insertion of DNA sequences from the viral vector encoding the CRISPR/Cas9 system. Depending on the type of tissue and the dosage of CRISPR delivered, as many as half of the on-target edits resulted in these alternative sequence changes. Although this result was surprising, the unintended sequence changes do not appear to impact the safety or efficacy of this CRISPR/Cas9 gene editing approach for DMD. “None of these edits would necessarily be a cause for concern in this case because the dystrophin gene is already defective,” said Nelson. “That being said, any unintended results could potentially take away from the efficiency of the gene editing you’re trying to achieve, which supports the importance of designing ways to objectively identify and mitigate alternative edits in future studies.” “Previous studies suggested that some of these other types of edits could happen,” Gersbach said. “But this is one of the first comprehensive measurements of these events in an animal model using a therapeutically relevant approach. Moving forward, this phenomenon needs to be monitored carefully and better understood. Methods that avoid these alternative edits and increase the frequency of the intended edit will be important to maximizing the potential of genome editing to treat disease.” This research was supported by Sarepta Therapeutics, Inc., the Paul G. " https://pratt.duke.edu/about/news/single-crispr-treatment |
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