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the Anglo-American the latest research alert:a human embryo in CRISPR gene editing will cause chromosomal chaos

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introduction: previous studies have shown that CRISPR–Cas9 gene editing technology may be at the target site point other than to cause“off-target”mutations. Close paragraph of time, there is a range of using the CRISPR–Cas9 technology modification of the human embryo research that reveals the process of how the target site or its vicinity in the genome resulting in unnecessary significant effects.< br>gene editing gene editing is a method capable of more accurately the organism the genome of a particular target gene can be modified to an emerging genetic engineering technology. The CRISPR technology is in the 20th century, early 90’s discovered, and quickly became the human biology, agriculture, and Microbiology and other areas of the most popular gene-editing tools.< br>these recent study this month published in the Preprint bioRxiv。 The study found that the human embryo in CRISPR gene editing will cause chromosomal chaos, the standard assessment method may miss the target near the point of change. In General, these studies allowed the scientists to learn more about the CRISPR–Cas9 editing is underestimate of risk.< br>

Canberra, the Australian National University geneticist Gaétan Burgio said:“the target effect is more important, and eliminating them will be more difficult.”< br>these security issues may be caused by the relevant scientists as to whether it should be edited in human embryos to prevent genetic diseases of the debate, which is very controversial, because of its genome resulting in a permanent change, you can from generation to generation. The University of California Fyodor Urnov says:“if used for reproductive purposes of human embryos to edit or reproductive system edit is space flight, then the new data is equivalent to the rocket before take-off in the launch pad explosion.”< br>unwanted effects
researchers in 2015 to use CRISPR to edit the human embryos of the first experiment. Since then, the world of the few teams to start out this process, the purpose is the gene for precise editing. But such studies are still few, and subject to strict specifications.< br>United Kingdom University of Newcastle reproductive biologist Mary Herbert said:“the latest research shows, we for human embryonic how to fix those is genome editing tools cutting DNA little is known, which is the CRISPR–Cas9 editing of the key steps. At the beginning of the use of DNA cutting enzymes before, we need to know what would happen to the change.”< br>in London’s Francis Crick Institute for Developmental Biology home Kathy Niakan and colleagues study, they used CRISPR–Cas9 in the POU5F1 gene generated mutation, the embryonic development is very important. In the 18 months after genome editing of the embryo, about 22% contains unwanted changes, these changes affect POU5F1 around a lot of DNA. They include DNA rearrangement and thousands of DNA bases is missing, which significantly exceeded the researchers used this method intentions.< br>another team of researchers, from New York City, Columbia University stem cell biologist Dieter Egli leadership of scientists, studied by sperm produced embryos, the sperm in the EYS gene in a blinding mutations. The team used CRISPR–Cas9 to try to correct the mutation, but about half of the tested embryos lost EYS where the chromosome of most of the fragments, sometimes even entire chromosomes to.< br>the third study group, Portland Oregon Health and Science University reproductive biologist Shoukhrat Mitalipov led the scientists, the study has lead to heart disease mutations in sperm incubation of embryos. This team found some indications that gene editing had affected the chromosome containing the mutant gene of large area.< br>unpredictable repair
these changes are genome editing tools to control the DNA repair process of the results. CRISPR–Cas9 using a small segment of RNA, the Cas9 enzyme is oriented in the genome with similar sequence���Sites. Then, this enzyme cut the parts of the two DNA chains, and then by the cell repair system to repair this gap.< br>gene editing occurs in the repair process: in most cases, cells use an error-prone mechanism to the closed incision, this mechanism will insert or delete small amounts of DNA bases. If researchers provide a DNA template, the cell may sometimes follow this sequence to patch the wound, so as to achieve real genetic re-write. However, breakage of DNA also leads to chromosome a large area of confusion or loss.< br>previously in mouse embryos and other human cells using the CRISPR research has demonstrated that the edited chromosomal cause huge, unnecessary effects. But Urnov said that in human embryos prove that this work is also very important because different cell types for genome editing reactions may be different.< br>in many experiments, such a rearrangement may be ignored, such as a single DNA base change, or only the insertion or deletion of several bases. However, the latest research directed specifically to the target site in the vicinity of large deletions and chromosomal rearrangements were studied. Urnov says:“from now on, we in the scientific community that all people should be better than before more serious about this thing. This is not a momentary Fluke.”< br>gene change
the three studies on the DNA changes of produce provides a different explanation. Egli and Niakan’s team will be its embryo observed in most of the changes are attributable to large deletions and rearrangements. Mitalipov’s team said they found that 40% of the variation is by a technique called gene conversion caused by the phenomenon, in this phenomenon, the DNA repair process from the pair of chromosomes in a chromosomal copy of a sequence, to thereby cure the other chromosomes.< br>Mitalipov and his colleagues in the 2017 reported similar findings, but some researchers on the embryo that may occur in frequent gene conversion skeptical. They noted that, in the gene conversion occurs, the parent present and the parent of the chromosome and not adjacent, the research team used to identify gene conversion analysis may be in the detection of other chromosomal changes, including deletions.< br>Egli and his colleagues in the latest study, the direct detection of gene conversion, but did not find, Burgio noted that Mitalipov use of analytical methods and by 2017 they use methods similar. Seoul National University geneticist Kim Soo-Jin(Jin Soo Kim, said that one possibility is to break the DNA in the chromosomes in different locations on the healing in different ways.< br>reference:

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Published at Wed, 08 Jul 2020 09:25:48 +0000