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posted by martyb on Thursday July 27 2017, @03:35PM   Printer-friendly
from the baby-steps dept.

U.S. scientists have genetically modified human embyros using CRISPR and have apparently avoided the worst of the off-target effects that have plagued previous efforts. The results are unpublished and the team is not commenting yet:

The first known attempt at creating genetically modified human embryos in the United States has been carried out by a team of researchers in Portland, Oregon, Technology Review has learned.

The effort, led by Shoukhrat Mitalipov of Oregon Health and Science University, involved changing the DNA of a large number of one-cell embryos with the gene-editing technique CRISPR, according to people familiar with the scientific results.

Until now, American scientists have watched with a combination of awe, envy, and some alarm as scientists elsewhere were first to explore the controversial practice. To date, three previous reports of editing human embryos were all published by scientists in China.

Now Mitalipov is believed to have broken new ground both in the number of embryos experimented upon and by demonstrating that it is possible to safely and efficiently correct defective genes that cause inherited diseases.

Although none of the embryos were allowed to develop for more than a few days—and there was never any intention of implanting them into a womb—the experiments are a milestone on what may prove to be an inevitable journey toward the birth of the first genetically modified humans.

Also at STAT News.

Previously: Chinese Scientists Have Genetically Modified Human Embryos
NIH Won't Fund Human Germline Modification
Group of Scientists and Bioethicists Back Genetic Modification of Human Embryos
The International Summit on Human Gene Editing
UK Scientist Makes the Case for Editing Human Embryos
Second Chinese Team Reports Gene Editing in Human Embryos
Scientists Keep Human Embryos Alive Longer Outside of the Womb
Francis Collins Retains Position as Director of the National Institutes of Health


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  • (Score: 0) by Anonymous Coward on Thursday July 27 2017, @10:52PM (2 children)

    by Anonymous Coward on Thursday July 27 2017, @10:52PM (#545502)

    unless the orderly progression of the hierarchy is disturbed by inflammation, ulceration or trauma

    That is a very big "unless" when used in the context of cancer.

    Figure 2 is looking at adult mouse tissue (some of which are heavily exposed to the external environment or have a very different internal environment), so it makes sense that the estimates exceed the ideal error rate of DNA polymerase and the error correction machinery of the cell.

    The paper probably isn't the best for an estimate, but I came across it while I was looking for the maximum tolerated mutation rate for mammals. If you're interested: It seems that ~100x is tolerated (though the mice die around 3 months compared to 27), while 10000X is embryonically lethal (some random citation that I came across) for mice.

  • (Score: 0) by Anonymous Coward on Friday July 28 2017, @03:46AM (1 child)

    by Anonymous Coward on Friday July 28 2017, @03:46AM (#545590)

    He goes into carcinogenesis later, and discusses how the "multi-stage" theory requires much higher mutation rates. If you get epidemiological data from seer and plot age specific incidence, there is a "turnover" for many cancers where they become less common. This also requires many more divisions and/or much higher mutation rates than usually assumed.

    Anyway, the best would be if they take a sample of cells before doing any of this "gene modification", and see how many are "modified", then send the rest on to be treated, but that doesn't seem to be a thing. So all we have are their controls. Apparently when someone publishes a paper about this, its is usually 0.1% to 1% are mutated at the target site either before anything happens or due to environmental factors. I couldn't find it earlier, but there is a paper that reports for one situation it was as high as 10%, and low as .001% for another.

    • (Score: 0) by Anonymous Coward on Friday July 28 2017, @11:55AM

      by Anonymous Coward on Friday July 28 2017, @11:55AM (#545724)

      take a sample of cells before doing any of this "gene modification", and see how many are "modified", then send the rest on to be treated, but that doesn't seem to be a thing

      Yes, I've always found it frustrating that lots of studies skip controls or have few biological and technical replicates. This is more true for expensive techniques (whole genome/transcriptions, ChIP-seq, IP-MS, micro-array, animal models, etc.) as there is little incentive to produce good quality data at the expense of novel, positive data.

      was as high as 10%, and low as .001% for another

      Since most quantifications in biology are relative and the systems and techniques can be extremely noisy, most baseline numbers reflect the noise and error instead of being an accurate value (excepting studies that set out to specifically determine this).