Cone cell gene therapy

Hi all!

We’ve written a post on color blindness before, but there’s still a lot to say, so here’s another one! In 2009, researchers at the University of Washington in Seattle developed a cure for color blindness in squirrel monkeys, that can also be possibly applicable to humans. They cured Daltonism, red-green color blindness, in the monkeys by injecting them with a virus that had the corrective gene for their defective cone cells (photoreceptors in the retina) as a payload.

Squirrel monkeys

Due to a large amount of time they spent training the monkeys to react to colors, they could finally determine that they were as a matter of fact aware of colors, as opposed to their actions before the treatment.

Wy is this so important though? Daltonism is by far the most occuring vision defect in humans, and it stems from similar defective cone cells. Considering about 5% of male humans suffers from it, a cure like this could make a huge difference once it is made available for humans. But it has even more potential than that. Many other human eye-diseases stem from problems with these same cone cells, and these diseases are the cause of partial -or complete- blindness. If it is possible to cure one cone cell disease by using gene therapy, solutions for these even more severe problems might come into range.

We are not there yet though, as the therapy is still in its testing phase for humans, and for that it has to go through the many legislative procedures required for testing medicines. Once that is done though, and if it is considered safe for humans, we can look forward to a very potent new weapon in humanity’s ever increase disease-combatting arsenal.

For more info, see this article from The Guardian, or go to the website of (one of the) authors!



5 responses to “Cone cell gene therapy

  1. Yo, cool stuff! If this gets optimized and tested, it’s actually a nice and minimally invasive way of curing vision defects. Colour blindness is indeed something that can even shatter dreams. Some years ago, I worked with this guy who, as a child, always wanted to be an electrician; not being able to distinguish between the different colour codes that were used, put him in his current situation. He’s now working (reluctantly) as a truck driver. Not even the cool big trucks, nope, those petty small oversized vans.

    Anyway, I’m curious where the project is now in terms of success. They submitted their paper to Nature 19/06/2009, so that already gives some time for exiting changes to develop.

    I fear however, that the application of this technique probably won’t be focussed on daltonism. Would the government refund a operation for a disease such as this? If no, only the richer classes will be able to benefit, putting the treatment in an expensive niche and people like the guy above, who are probably more likely to miss out on an interesting life because of the disease, won’t be able to benefit.

    • koenraadvanhoutte

      I’m sorry to hear about your friend, the genetic lottery can be awful at times. Especially when it comes to vision, where something as common as having to wear glasses can already keep you out of certain career paths.

      The treatment has not been translated to humans as of yet, but the researchers still continue working on it. Most of the hold-up is the cause of the legislative requirements that come with human testing, so nothing really that they can do about it apart from waiting.

      The treatment being cheap will indeed not happen soon either, and I don’t expect we’ll be seeing “Do-it-yourself-put-needles-in-your-eye-kits”, but there might be hope for your friend. Since the vast amount of people that suffer from Daltonism, the treatment, once finished, will have a huge possible audience. This might inspire hospitals to have specialized doctors for it, and for many hospitals to make the treatments a common thing, since they can make a lot of profit by doing so. Then it’s just hoping for capitalism to do the rest, and lower the prices.
      And if that is too far into the future, their department has an application form for human test persons. You would even get payed to receive the treatment (in its current form), but you will have to risk the concequence of maybe going blind alltogether.

  2. I for one suffer from Red & green color blindness, I am probably not the worst case out there but I lack enough to always ask professors to write in black on whiteboards, i’ve learned to live with it though and in my case contrasts help a lot to distinguish things. One thing i do like to think about is that its a genetic “disease”. If your treatment cures the genes, in that manner of speaking, won’t you get rid of colour-blindness in the end? 1 generation of treatments and the next one won’t suffer from the same problem! Not sure if this reasoning is correct though.

    • koenraadvanhoutte

      I’m afraid not, or at least not in this case. There are two types of gene therapy: this one is an example of what’s called ‘Somatic gene therapy”, where the genes are modified in the non-sex cells of the body. This means the patient will carry the consequences of the therapy, but it cannot be passed on to their progeny. In this case, the viruses are directly injected into the patient’s eyes.

      The other one, which would have the effect you describe, is called “germ-line gene therapy”. In this case, the therapeutic genes are inserted into the sex cells, so the changes will be passed on. There are some legislations prohibiting the use of this type of therapy though, since the consequences, good or bad, will be passed on to the next generations. Seems like a safe approach for gene altering, but when it comes to possibly genetically preventing your offspring of being blind, I think the rewards outweigh the risk.

      • I see! Well the legislations speak for themselves off course but it’s like you say, once the technology is more refined and safe. The reward will be great, if it is right now, i’m not sure.

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