Scientists: new genomic editor is causing «hundreds» of bugs when you change the DNA

© Fotolia / Dan RaceУченый with a model DNA in a test tubeScientists: new genomic editor is causing «hundreds» of bugs when you change the DNA© Fotolia / Dan Race

. Popular today the genomic editor CRISPR/Cas9 causes hundreds of random mutations in editing DNA, say scientists investigating the full results of his work, and published an article in the journal Nature Methods.

«The researchers, analyzing the genomes of fully for possible side effects of gene therapy, may be missing a small but important mutations. Changing even a single «letter» in certain genes can cause a powerful change. We hope that our results will force other scientists to conduct genome-wide analysis and to explore alternative versions of CRISPR/Cas9 for safe editing of the genome,» said Stephen Tsang (Stephen Tsang) of Columbia University in new York (USA).

Genomic editor CRISPR/Cas9, named chief scientific breakthrough 2015, was created by American scientist Feng Zhang (Feng Zhang) and several other molecular biologists about four years ago. Since then it has undergone several upgrades that allow scientists to use it to edit even a single «letter» in the DNA strands and RNA.

In 2013, the rapid development of this technology, and today its time to use to edit the genomes of dozens of living beings, including human embryos, what is confessed Chinese geneticists in April of this year. These experiments revealed the lack of CRISPR/Cas9 – editor, especially when you change multiple genes, sometimes were wrong and delete the unwanted segments of DNA.

Such behavior is permissible in genetic experiments in the laboratory, but is unacceptable in medical practice, where such a typo can cost a human life, the DNA of which is «surgery». Two years ago, Zhang and his colleagues have created a new, more reliable version of CRISPR/Cas9, which, according to their calculations, had to make just one mistake in a billion editable «letters»-nucleotides.

Tsang and his colleagues have drawn attention to the fact that Zhang and other developers editors CRISPR/Cas9 receive such assessments are not experimentally by the complete decoding of the genome, and using complex mathematical models based on data about the structure of short DNA segments. The authors, doctors by training, decided to see how justified such an approach.

To do this, scientists analyzed the DNA of mice, which they recently rescued from the development of blindness, after fixing a single typo in RPGR gene causing a massive loss of photoreceptors in the retina.

The results of this analysis were very unexpected and disturbing – in the genome of mice was attended by hundreds of «spot» typos in other genes, and two rodents in the DNA contained over a thousand of single mutations, and over 100 segments of DNA were or removed, or duplicated.

Despite such a large amount of damage, mice do not suffer from any apparent issues and was completely healthy. However, as scholars have noted, experimenters and doctors in China and the United States, which already carried out or intend to carry out experiments on volunteers on the use of CRISPR/Cas9 for cancer treatment and control of congenital diseases, you should think about what the side effects can cause this therapy and what it will cost the patient.

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