Can you modify the gene to have a baby without HD?
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Q. Hi, my mother-in-law has HD, is 60, her late father too, my husband had symptoms and is in his 30’s. We decided not to have a baby for this reason. Now someone told my husband is possible kind of “modify the gene” in the embryo/fetus to have a baby without HD, but this procedure is very expensive and not so common….is it true???
BA, Young Adult, USA
A. Dear BA
Many thanks for your question. I think what they are referring to is a process called ‘preimplantation genetic diagnosis’ (PGD), which is a way of trying to avoid passing on a known genetic change (in this case the gene expansion that causes HD) to a child.
PGD is a process that aims to select embryos that do not carry the gene expansion (it does not modify the gene itself). The process initially works in a similar way to standard in vitro fertilisation (IVF), where embryos are created outside the body using sperm and egg cells collected from each member of the couple. The extra step for PGD involves testing the embryos before they are replaced to the womb (they do this by removing one cell from each developing embryo when it is still very small, usually around 16 cells in size) to see if the gene change is present or not. They would then plan to only replace embryos to the womb that do not carry the gene change.
Unfortunately, due to the drugs and specialised techniques involved, and the fact that it involves multiple clinic appointments, PGD is expensive. A cycle costs around $15000, and it is not usually covered by health insurance. Also, sadly not all cycles of PGD result in a successful pregnancy (the success rates are usually an average of around 1 pregnancy for every 3 or 4 cycles) and this means that as well as the financial costs, it can often be quite physically and emotionally demanding. If you would like to know more about PGD, as well as other prenatal options, I would recommend that you see a Genetic Counselor who could provide further information and support. If you wish, this website may help you to find your local Genetics service.
There is also some useful information about prenatal options including PGD in this HDYO article
I hope you find this answer useful, and please do not hesitate to get back in touch of you have any further questions, or if you have any difficulty accessing your local Genetics service.