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Fixing Faulty Genes On the Cheap

Posted by Soulskill on from the what-if-i-like-the-worn-out-look dept.

An anonymous reader sends an article about CRISPR, a system for modifying genes and moving them from cell to cell. It's notable because the cost to do so is dropping to the point where it's becoming viable to use on a patient-by-patient basis. CRISPR is one of those interesting inventions that comes, not from scientists explicitly trying to cure a disease, but from researchers trying to understand something fundamental about nature. Jennifer Doudna's research at the University of California, Berkeley has focused on how bacteria fight the flu. It turns out bacteria don't like getting flu any more than the rest of us do. Doudna says the way bacteria fight off a flu virus gave her and her colleagues an idea. Bacteria have special enzymes that can cut open the DNA of an invading virus and make a change in the DNA at the site of the cut — essentially killing the virus. Doudna and other scientists figured out how this defense system works in bacteria; that was interesting all by itself. But then they realized that they could modify these enzymes to recognize any DNA sequence, not just the DNA sequence of viruses that infect bacteria.

11 of 105 comments (clear)

  1. How long before... by tchdab1 · · Score: 3, Interesting

    ... you can go to a local independent chop shop and tell them "my phone says I have an extra guanine in my 14 chromosome and it's causing my food allergy to modified mangoes - can you get it out this afternoon?"

    1. Re:How long before... by Wonko+the+Sane · · Score: 5, Interesting

      Did you know human livers are a single broken gene away from maufacturing vitamin C from glucose, just like almost every other mammal?

      The liver perform every step in the process except the final one, because of a single transacription error that was introduced into the germline back in ancient times

      It would be cool to see what happens when they fix that.

    2. Re:How long before... by BenSchuarmer · · Score: 3, Interesting

      It's more efficient to get Vitamin C from food. If it wasn't, that mutation would have been selected out of existence a long time ago.

    3. Re:How long before... by NEDHead · · Score: 3, Insightful

      There is some evidence that the appendix acts as a reservoir of the gut biota to repopulate when the need arises due to illness (or excessive antibiotics, etc).

    4. Re:How long before... by WrongMonkey · · Score: 3, Funny

      You have the question backwards: what is the evolutionary advantage for intelligence? The smartest people certainly don't have the most kids.

    5. Re:How long before... by morgauxo · · Score: 3, Interesting

      In developed countries stupid people tend to have more children.
      Running a brain takes a lot of calories. In places where people have to worry about starvation I wonder if IQ might even be a liability.
      We are really lucky that humanity ever even achieved inteligence. It will be extremely lucky if we actually manage to keep it.

    6. Re:How long before... by radtea · · Score: 3, Interesting

      Why is there a whole raft of genetic diseases in the human population now? Shouldn't they have been "selected out" a long time ago?

      Many genetic diseases are the result of optimizations for other things (anemia is related to malaria resistance, there is some problematic gene in a Jewish sub-population that is related to plague resistance, etc.)

      Evolution is continuously running an extremely complex multi-dimensional optimization problem with a time-varying objective function. Local minima abound, and it's easy for organisms to get trapped in them.

      Furthermore, kin selection and possibly group selection play a role in human evolution, which makes the whole thing even more complex and non-linear. So looking at specific genes and saying, "That doesn't make sense!" as if there was some obligation for the universe to "make sense" to our naive pre-scientific intuition is fairly silly.

      The human genome is a Rube Goldberg apparatus that manages to make hundreds of thousands of products out of 40,000 strongly interacting templates plus a bunch of ridiculously inefficient secondary control mechanisms like micro-RNAs (which in some typically degrade already-transcribed mRNA). Pointing to one step as if it can be considered in isolation from everything else is not a good move.

      Loss of vitamin C manufacture could well have to do with the development of some other pathway that was more important at the time, and may well continue to be more important today. The only way to really find out is to either a) understand the genetic trade-offs in detail or b) ask some volunteer to have their vitamin C production turned back on by a technique like this. Personally, I'd recommend the former.

      Given how weird humans are developmentally, some things like this may be important when we're young and not so much when we're older, so in the fullness of time we may find we can turn on vitamin C production only after people mature, for example. The possible range of futures, given how little we know now, is large.

      In the meantime, we have plenty of people with genetic diseases that we know the cure will not significantly disrupt their cellular machinery, because we have lots of examples of people without those diseases who are just fine.

      --
      Blasphemy is a human right. Blasphemophobia kills.
    7. Re:How long before... by ShanghaiBill · · Score: 3, Insightful

      OK, smartass, what is the evolutionary advantage for stupidity?

      Smart people innovate. Dumb people follow routines because "we have always done it that way." So in a desert dwelling hunter-gather tribe enduring a drought, the smart guy innovates by digging for water and building a still. It comes up dry, and he dies of thirst. The dumb people follow the trail through the desert that their grandmother showed them decades ago, and find a waterhole.

      In an urbanized society, innovation has limited risk, and generous rewards. In a primitive society, innovation has big risks and limited reward. So people that have a long history of urbanization, such as the Chinese and Ashkenazi Jews, tend to have high IQs, while the desert dwelling San Bushmen have the lowest measured. In both cases, they have adapted to the environmental conditions.

  2. Re:Biofurs: the next generation of furry fandom by Kaenneth · · Score: 4, Funny

    As a trans-offended person, I'm offended by your reluctance to allow people to be offended.

    Some of us enjoy being shocked, offended, and triggered so stop cis-comfort-zone oppressing us.

  3. Confused about how this works by timrod · · Score: 4, Informative

    From the Wikipedia article, it seems like CRISPR works by injecting a strand of "neutral" genetic material into a genome and cause genes to not be transcribed - so you can "turn off" an improperly expressed gene, but can't actually replace it with a normal one. The NPR article, however, has people mentioning the idea of replacing improperly expressed genes with normal ones.

    From what I understand, the difference between the two is that if Wikipedia is correct, CRISPR would only be useful in humans (once they get it to be accurate) to cure diseases that arise from a gene being expressed when it shouldn't be, for things like sickle cell or Huntington's. However, if NPR is correct, CRISPR can also cure diseases that arise from a gene not being expressed when it should, such as hemophilia.

    Which one of these is correct? What is CRISPR actually good for?

    1. Re:Confused about how this works by paskie · · Score: 4, Informative

      CRISPR is a tool that allows you to cut the DNA in two disjoint pieces at a specific point (specification of this point is a parameter of a particular CRISPR instance). What happens then depends on your setup; bacteria will just insert some junk at that break point, or you can pack your custom DNA sequences along the CRISPRs and they will be spliced in, connecting to each of the two disjoint pieces by one end. Thanks to this, at that specific point, you can disable a gene or modify or add an extra sequence.

      We had tools to do this before - restriction enzymes or TALENs. They weren't really usable for therapeutic purposes, though, due to much less reliable targetting, more laborous engineering (parametrizing your instance for a specific sequence) and low effectivity (the break happens only in a a few percents of cases). CRISPRs are easily parametrized, can be precisely taretted, and have effectivity in tens of percents (in general; can vary organism by organism). It's still a work in progress, but looks pretty promising!

      --
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