GM Watch
  • Main Menu
    • Home
    • News
      • Newsletter subscription
      • News Reviews
      • News Languages
        • Notícias em Português
        • Nieuws in het Nederlands
        • Nachrichten in Deutsch
      • Archive
    • Articles
      • GM Myth Makers
      • GM Reports
      • GM Quotes
      • GM Myths
      • Non-GM successes
      • GM Firms
        • Monsanto: a history
        • Monsanto: resources
        • Bayer: a history
        • Bayer: resources
    • Videos
      • Latest Videos
      • Must see videos
      • Agriculture videos
      • Labeling videos
      • Animals videos
      • Corporations videos
      • Corporate takeover videos
      • Contamination videos
      • Latin America videos
      • India videos
      • Asia videos
      • Food safety videos
      • Songs videos
      • Protests videos
      • Biofuel myths videos
      • Index of GM crops and foods
      • Index of speakers
      • Health Effects
    • Contact
    • About
    • Donations
News and comment on genetically modified foods and their associated pesticides    
  • News
    • Newsletter subscription
    • News Reviews
    • News Languages
      • Notícias em Português
      • Nieuws in het Nederlands
      • Nachrichten in Deutsch
    • Archive
      • 2022 articles
  • Articles
    • GM Myth Makers
    • GM Reports
    • GM Quotes
    • GM Myths
    • Non-GM successes
    • GM Firms
      • Monsanto: a history
      • Monsanto: resources
      • Bayer: a history
      • Bayer: resources
  • Donations
  • Videos
    • Index of speakers
    • Glyphosate Videos
    • Latest Videos
    • Must see videos
    • Health Effects
    • Agriculture videos
    • Labeling videos
    • Animals videos
    • Corporations videos
    • Corporate takeover videos
    • Contamination videos
    • Latin America videos
    • India videos
    • Asia videos
    • Food safety videos
    • Songs videos
    • Protests videos
    • Biofuel myths videos
    • Index of GM crops and foods
  • Contact
  • About

GMWatch Facebook cornfield banner

INTRODUCTION TO GM

GMO Myths and Facts front page.jpg

SCIENCE SUPPORTS REGULATION OF GENE EDITING

Plant tissue cultures

GENE EDITING: UNEXPECTED OUTCOMES AND RISKS

Damaged DNA on fire

GENE EDITING MYTHS AND REALITY

A guide through the smokescreen

Gene Editing Myths and Reality

ON-TARGET EFFECTS OF GENE EDITING

Damaged DNA

Yet more problems with CRISPR – with consequences for food safety

  • Print
  • Email
Details
Published: 22 February 2020
Twitter

Genetic alphabet sequence

Things go wrong "more often than you would think" – scientist commenting on unwanted duplications of genetic insertions

Adding to the list of problems that can occur with CRISPR, a new study shows that when the CRISPR/Cas system was used in an SDN-2 ("gene modification") gene editing procedure aimed at engineering insertion of genetic material in mice, a high frequency was found of insertions of multiple copies of the DNA molecules used as a template for bringing about the desired gene modifications. The researchers were concerned by the fact that the insertions could not be detected using standard PCR analysis. This in turn led to what they called "a high rate of falsely claimed precisely edited alleles" (gene variants).

In other words, scientists have been unduly hyping the precision of CRISPR when in reality it isn't precise at all.

The researchers used an extended PCR analytical method and found that in most cases, there were multiple head-to-tail insertions of the template DNA molecule.

The lead authors of the study, Boris Skryabin and Timofey Rozhdestvensky, told The Scientist magazine that their findings could have relevance for gene editing across all kingdoms of life, from plants to human cells. They warned that duplications could lead to dangerous frameshift mutations, resulting in misshapen proteins.

GMWatch points out that this could have unpredictable consequences for the food safety of gene-edited crops and foods – for example, producing unexpected toxicity or allergenicity.

According to The Scientist, Katharina Boroviak, a genetic engineer at the Sanger Institute in the UK who wasn’t involved in the new research, isn’t surprised by the findings. She too has observed duplications of inserted sequences in her lab while generating transgenic mouse models.

Commenting on the new study, she said, “[The publication] makes smaller labs that haven’t really quite thought about it that much aware of it. Everybody keeps talking about how great CRISPR is and how wonderful, and so easy. But if you start delving into the details... you can see what is actually going wrong and how often it is actually going wrong — it’s more often than you would think.”

Amid the virtually complete silence from plant genetic engineers about the problems with CRISPR, it's increasingly clear that far more honesty and caution is voiced by those scientists using the gene-editing tool in human cell and animal research for medical purposes.
---

Pervasive head-to-tail insertions of DNA templates mask desired CRISPR-Cas9–mediated genome editing events
Boris V. Skryabin,, Delf-Magnus Kummerfeld, Leonid Gubar, Birte Seeger, Helena Kaiser1, Anja Stegemann, Johannes Roth, Sven G. Meuth, Hermann Pavenstädt, Joanna Sherwood, Thomas Pap, Roland Wedlich-Söldner, Cord Sunderkötter, Yuri B. Schwartz, Juergen Brosius and Timofey S. Rozhdestvensky
Science Advances  12 Feb 2020: Vol. 6, no. 7, eaax2941
DOI: 10.1126/sciadv.aax2941
https://advances.sciencemag.org/content/6/7/eaax2941

Abstract

CRISPR-Cas9–mediated homology-directed DNA repair is the method of choice for precise gene editing in a wide range of model organisms, including mouse and human. Broad use by the biomedical community refined the method, making it more efficient and sequence specific. Nevertheless, the rapidly evolving technique still contains pitfalls. During the generation of six different conditional knockout mouse models, we discovered that frequently (sometimes solely) homology-directed repair and/or nonhomologous end joining mechanisms caused multiple unwanted head-to-tail insertions of donor DNA templates. Disturbingly, conventionally applied PCR analysis, in most cases, failed to identify these multiple integration events, which led to a high rate of falsely claimed precisely edited alleles. We caution that comprehensive analysis of modified alleles is essential and offer practical solutions to correctly identify precisely edited chromosomes.

Menu

Home

Subscriptions

News Archive

News Reviews

Videos

Articles

GM Myth Makers

GM Reports

GM Myths

GM Quotes

Non-GM Successes

Contacts

Contact Us

About

Facebook

Twitter

Donations

Content 1999 - 2023 GMWatch.
Web Development By SCS Web Design