• Question: Is it possible to remove a gene containing something like caber from passing from a mother to her child?

    Asked by to Claire, Ian, Sergey, Vicky, Zena on 23 Jun 2014. This question was also asked by .
    • Photo: Claire Shooter

      Claire Shooter answered on 23 Jun 2014:

      Is ‘caber’ a typo of ‘cancer’? I’m going to assume it is because I just got sport videos when I googled caber….
      It is possible to prevent a mother from passing a bad gene onto their child in several different ways: it depends a little bit on the disease.
      A lot of diseases are caused by mutations we are very familiar with, and good at spotting. Sickle cell disease, for instance, is always caused by the same mutation, so if two people have a family history of sickle cell disease and want a baby, we check if they carry the gene and then, if they do, we also check the pregnancy. You only get sickle cell disease if you have two copies of the mutation – one from your mum and one from your dad. The majority of genetic diseases work like this. The most common way we deal with these sorts of diseases is to test the fetus, and if it is affected let the parents decide if they want to have an abortion. If they both only have one copy of the gene (which is what we see most often, because people who are affected are very sick) they only have a 25% chance of having an affected baby, so many parents will choose to have the abortion and try again for an unaffected pregnancy later.
      Some diseases aren’t down to the DNA in the nucleus of the cell, but the DNA in mitochondria which are the bits of your cells which produce energy, and have their own DNA. If a mother has this disease she is very likely to pass it onto her child in the body of her egg cell, rather than in her DNA. In this situation we take the nucleus (which contains your genomic DNA) out of the egg cell and transplant it into a healthy cell instead.
      Actually removing genes is a lot more complicated: scientists have done it successfully for some diseases but only in really rare cases, because it currently has a high failure rate and is very time consuming and expensive.
      Cancer can be caused by lots and lots of different mutations and most of the time genes you inherit from your parents may increase your risk of getting cancer slightly, but you won’t find a single mutation that means you will definitely get cancer, or definitely not get cancer. For the most part, we just hope for the best in these situations because we don’t know enough about it to remove all the right genes, like you suggested. A few very specific cancers are caused by simple mutations we do understand, and these can be identified with the tests I mentioned earlier if necessary

    • Photo: Sergey Lamzin

      Sergey Lamzin answered on 23 Jun 2014:

      Absolutely!
      And I bet there are people working on it as we speak. The major problem there is often not the practical possibility, but governments blocking it because they don’t believe it’s safe or ethical to do so.

    • Photo: Ian Simpson

      Ian Simpson answered on 25 Jun 2014:

      I’d have to answer no here.

      You can certainly “screen” in utero (during pregnancy) for known mutations and this would be done if there were a high expectation of the child inheriting a serious condition. For cancer there are very very few mutations that absolutely definitely will cause cancer although some have a high probability. Even in this case what you are doing is screening and having the option at an early stage of choosing to abort a foetus based on the result. You’re not removing the cancer gene.

      In the really excellent example Claire gave of mitochondrial disease (I did my doctorate in the lab that was the Northern hemisphere hub for inherited metabolic diseases, which are very rare and pretty much all mitochondrial). There are indeed rarely used IVF procedures whereby you can isolate mitochondria carrying severe mutations. I don’t know how often these are used, but again not cancer. The mitochondrial genome only encodes genes involved in energy transduction which are absolutely essential for life in most cases, but in some of the genes cases babies carrying mutations can be born, but with pretty harrowing conditions and they sadly normally have very short life expectancies.

      In the future of course I believe this kind of intervention may well be possible and Sergey could be right. There may well be labs working on this somewhere right now.

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