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Biotech Technology Science

Researchers Use CRISPR To Repair Genetic Defect That Causes Blindness (dispatchtribunal.com) 46

hypnosec writes: In what has been claimed to be the first use of gene editing technique CRISPR for replacement of a defective gene associated with a sensory disease, researchers have repaired a genetic defect that causes blindness. The research that led to successful editing of defective genes responsible for retinitis pigmentosa (RP) – an inherited condition that causes the retina to degrade and leads to blindness in at least 1.5 million cases worldwide – was carried out using stem cells derived from a patient's tissue. Published in Scientific Reports, the study paves the way for using CRIPSR therapeutically to treat eye diseases.
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Researchers Use CRISPR To Repair Genetic Defect That Causes Blindness

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  • Curing blindness sounds admirable - but at what cost?
    Don't forget the unseen side effects!
    The first Google hit on CRISPR side effects is:
    http://phys.org/news/2015-10-c... [phys.org]

    • Re:Side Effects (Score:5, Insightful)

      by Applehu Akbar ( 2968043 ) on Thursday January 28, 2016 @08:10PM (#51392699)

      The whole point of using GMO technology in an application like this is the 'exceptional specificity' cited in the article.

      "The primary advantage of CRISPR over previous technologies is the ability to use a genetic scalpel rather than a sledgehammer," said Charles Gersbach, associate professor of biomedical engineering at Duke University.

      • Re:Side Effects (Score:4, Interesting)

        by Immerman ( 2627577 ) on Thursday January 28, 2016 @09:08PM (#51392903)

        I think you're both right. CRISPR allows for extremely precise gene editing, which is great. (though the wording leaves me unclear on whether they can sometimes cause unintended edits as well - that could be a real problem)

        The problem though, is that we very rarely understand everything those gene edits will do. Very often making a small and specific change in one area may cause a host of unintended side effects as the chain of causality cascades through the many feedback loops of the organism. Maybe you just edited a gene to increase the production of protein X that has some beneficial effect. Well, that means you necessarily reduce the production of at least some other proteins dependent on the same raw materials and production equipment, and that will have its own consequences. And of course there's the direct effect of elevated protein X on the bodies systems, but that part is probably relatively well researched.

        And of course there's also the risk of major and direct unintended consequences. From what I've read we're barely beginning to scratch the surface of understanding how DNA does its thing, but it potentially puts to shame the most convoluted and obscure spaghetti-code ever written by man. There's a very real chance that what looks to be a simple gene to code for X also interacts with other apparently unrelated DNA to do something completely unforseen. Now, if that causes the individual to die horribly then, well, sucks to be the guy to discovers that firsthand, but not really a big problem. What is a big problem is the edit that has only minor obvious effects, or even individually beneficial ones, but also causes long-term environmental issues. Because that's going to inevitably spread through the population, and we'll all have to deal with the consequences. That's more of an issue for our edited food stock contaminating it's wild relatives, but you could imagine things that would have dire effects within the human population as well. To be silly, say we modified a gene that tended to make its carriers far more attractive to the opposite sex, but also caused a serious drop in intelligence.

        • All of which side effects are much worse when we fire the hybridization shotgun, mixing and matching many genes at once. Which is why we have never been able to apply this traditional technique to human diseases of the type referenced here. When we hybridize plants we can just toss out the culls. But with genetic engineering, we have a whole new class of disease treatments we never had before.

        • Re:Side Effects (Score:5, Insightful)

          by cheater512 ( 783349 ) <nick@nickstallman.net> on Thursday January 28, 2016 @09:45PM (#51393075) Homepage

          How can there be side effects if the only modification is changing a specific already damaged gene back to it's known healthy setting?

          If you are just stabbing around changing random stuff sure there will be random consequences.
          But if you can change specific genes and you know what the damaged state and the healthy states are, you are good to go.

          • by jedidiah ( 1196 )

            Also, this is a very limited edit. It's not something that is meant to be grown across the surface of the entire planet and released into the wild. It really is quite "surgical" when compared to other forms of "GMO".

            • "t's not something that is meant to be grown across the surface of the entire planet and released into the wild."

              Exactly! We can't have all the blind seeing again, their one-eyed king objects to that.

          • by Anonymous Coward

            There are six reading frames to DNA. Changing a sequence of DNA to fix the ability to make one protein, can potentially mess up things that were working properly in the other 5 frames. It is unlikely though, and if we sequence the genomes of patients before applying therapy, mostly avoidable.

          • Re:Side Effects (Score:4, Informative)

            by Pharmboy ( 216950 ) on Friday January 29, 2016 @05:36AM (#51394743) Journal

            I have a friend with Friedrich's Ataxia, and CRISPR is one of the silver bullets she's praying for. FA cripples then kills you: wheel chair by 25, dead by 40 is often the case (it hardens the heart so it can't pump). While CRISPR has some unknowns and risks, having FA is a certainty. FA affects a single gene pair, so if you can replace either side of that gene, you have solved the problem, the mitochondria will start producing frataxin again, and the nerves will stop being slowly destroyed.

            There are no treatments and since it is so rare (1 in 50,000 have it in the US, 1 in 30k in Europe, almost no one in Africa or Asia), few are investing in finding a cure or treatment. FA isn't the only orphan disorder like this. So yes, I'm quite happy to see CRISPR move forward.

          • Re:Side Effects (Score:4, Interesting)

            by quantaman ( 517394 ) on Friday January 29, 2016 @05:41AM (#51394755)

            How can there be side effects if the only modification is changing a specific already damaged gene back to it's known healthy setting?

            If you are just stabbing around changing random stuff sure there will be random consequences.
            But if you can change specific genes and you know what the damaged state and the healthy states are, you are good to go.

            It's a lot better but I don't think it's risk free. Consider a bad variant A and the good variant B.

            B may have also had a developmental role. Only adding B as an adult and missing out on the developmental aspects might mean B functions improperly and causes bad things to happen.

            Also the body may have adapted to A, for instance A is supposed to generate some hormone X and because A generates a crappy version of X your body is hypersensitive to X. Swapping in B and getting the right version of X means your hyper-sensitive body is suddenly overwhelmed by the effects of X and bad things happen.

            Now CRISPR is awesome and revolutionary, but the body is really really complex, and it's hard to do something to a really complex system without having some sort of side effect.

        • by Mal-2 ( 675116 )

          If the edits are localized (performed in vitro, then the cells re-implanted where they belong), the edits won't make it into the germ line. They won't with females regardless.

          • True. There still may be unexpected side effects, but so long as they are limited to an individual willing to take the risk, I say pursue it. I think that's actually the reasonable and responsible approach to genetic engineering our own germ line.

            And hopefully we'll understand things a lot better before we decide to proactively cure all our future descendants. After all that's not any more difficult in principle, and absolutely seems to be a reasonable and responsible thing to do, so long as we're actuall

        • by tibit ( 1762298 )

          This is true, but it relates to GMO concerns, not to fixing mutations that cause genetic diseases. In generic diseases, we know exactly what's broken, and we know that fixing it won't break anything either: after all, the rest of us, who don't suffer from the mutation, have the "fix" already!

          • So long as you're able to *only* edit the intended gene with 100% accuracy, you're probably right. It sounds like that might be under debate.

            And assuming that starting out with the "bad" gene didn't modify your epigenome in some way that alters the way the "good" gene gets expressed.

    • by tlambert ( 566799 ) on Friday January 29, 2016 @01:03AM (#51393963)

      The article you reference does not demonstrate any side effects.

      However, it is a valid concern, in that in vitro CRISPR/CAS9 and CRISPR/CPF1 edits has historically hit identical palindromic sequences that happened to be outside the target edit area, since the palindromes in question are only 24 or so base pairs in length. You have to expect that there will be other instances elsewhere in the genome.

      If you read the article, the experiment was conducted on pluripotent stem cells created from skin cells taken from the patient, and done in vitro.

      The eventual hope in this case is implantation of the in vitro stem cells in order to correct the defect.

      This means that any side effects can be avoid by separating the edited cells into individual cells, and then culturing each batch to the point some of the batch can be taken and fully sequenced to verify that the only change in the gene sequences relative to the (fully sequenced) parent organisms genome, is the target gene sequence alone. This would be done before implantation, which would guarantee that the gene sequence causing the disease was the only one impacted by the therapy.

      Practically speaking, we have AAVV/AAV-2 techniques -- utilizing Adeno-associated virus vectors, in other words -- that tend to be much more accurate. This is the type of vector that was utilized by the CEO of BioViva, Elizabeth "Liz" Parrish:

      https://www.youtube.com/watch?... [youtube.com]

      • by T.E.D. ( 34228 )

        However, it is a valid concern, in that in vitro CRISPR/CAS9 and CRISPR/CPF1 edits has historically hit identical palindromic sequences that happened to be outside the target edit area, since the palindromes in question are only 24 or so base pairs in length. You have to expect that there will be other instances elsewhere in the genome.

        I guess they need to use a larger CRC.

    • Curing blindness sounds admirable - but at what cost?
      Don't forget the unseen side effects!
      The first Google hit on CRISPR side effects is:
      http://phys.org/news/2015-10-c... [phys.org]

      Without a suitable blindness cure, the side effects will remain literally unseen.

    • Don't worry, manufacturers of walking sticks will do fine - there are still plenty of other ways to go blind.
    • "Curing blindness sounds admirable - but at what cost?
      Don't forget the unseen side effects!"

      Since they're blind, all the side effects are unseen.

    • by jbengt ( 874751 )
      I, for one, welcome our new naked mole rat visionary overlords.
  • That is... so cool. I thought it was essentially too late for alterations to an adult's DNA to have much effect, but I suppose that depends on what you're changing.
  • Nice article
  • Interesting

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