Feb 09 2015

Three Person IVF

The United Kingdom’s House of Commons has recently voted to allow so-called three person in vitro fertilization. This opens the door to the UK being the first country to provide such a procedure.

The purpose of three person IVF is to allow a woman who carries a genetic mutation for a mitochondrial disorder to have her own genetic children without passing on the disease.

Mitochondria are organelles in every cell that produce energy. They are essentially the power plants of the cell. Evolutionarily they are likely the result of a symbiotic relationship between a prokaryote and eukaryote, meaning that the mitochondria were once independent living cells. They carry their own genes, and in fact have their own slightly different genetic code (evidence of their ancient origin).

There are a number of genetic diseases known as mitochondrial disease because they represent mutations in the mitochondrial genes. Since mitochondria are almost completely passed down through the maternal line, so are such diseases. The female eggs contain all the cellular structures of the fertilized egg, while the sperm contributes only its packet of DNA (although a stray mitochondrion might sneak through).

If a woman is a known carrier of a mitochondrial mutation then she carries the risk of passing it down to her children. There is some complexity here, however. Some mitochondrial proteins are encoded in nuclear DNA. This new procedure will only address mutations in the mitochondrial DNA itself. Also, there is often a variable relationship between mitochondrial mutations and the resulting disease, mainly in severity. That is why a female carrier can have a very mild manifestation but her children’s can be severe.

IVF is simply the process of putting donated sperm and egg together in a “test tube” and allowing fertilization to take place there. Fertilized eggs are then implanted into the woman in the hopes that one will form a viable pregnancy.

Three person IVF adds another step, and another donor. There are essentially two techniques, which differ only in the timing of events. They both involve taking the nucleus from the donor mother and implanting it into the egg of another donor in which the nucleus was removed. You can either fertilize first then do the transfer, or transfer first then fertilize.

Either way the result is a fertilized egg with nuclear DNA from a male donor, nuclear DNA from a female donor, and mitochondria from a different female donor. This allows women with mitochondrial mutations to have their own genetic children, just without their mitochondria.

This procedure is an obvious extension of IVF. There are an estimated 2000 women in the UK alone who could benefit from this procedure.

It is interesting that this type of medical procedure would be singled out for such a high profile political vote. In the parliament 382 members voted in favor, while 128 voted against. I would not argue that new medical procedures should be completely unregulated, but it is interesting which medical procedures become morally controversial.

IVF itself was controversial when it first appeared. So-called “test tube babies” created a mini-moral panic. Now it is generally accepted, and to me seems silly that anyone would worry about where the egg and the sperm come together.

It seems to me that such controversies have more to do with our emotional reaction to the idea of a medical procedure rather than any real ethical issues (not that there aren’t sometimes real ethical issues). For example, the “girl with the baboon heart” was a major controversy with protesters objecting mostly to the idea of mixing human and animal proteins.

Parenthood and purity are both highly emotional issues as well. This new procedure would create a child with three genetic parents. Theoretically, a child could have four parents, a father and three mothers, if there were a mitochondrial donor and a surrogate mother to carry the pregnancy.

I personally see no ethical or moral problem here. Some medical procedures do require oversight, and do require some level of counseling to ensure that there is proper informed consent, that no one is being placed under any undue pressure, and that there are no psychiatric or cognitive issues that might compromise proper consent.

Assuming, however, that everyone involved is a consenting adult who is happy with the purpose and mechanism of the procedure, I see no reason to deny the procedure based upon any personal emotions that the procedure is “icky” or crosses some boundary.

I also recognize that each time medical technology takes us across a new boundary, there is likely to be some public moralizing and hand-wringing. Then we’ll get over it, and the procedure will become commonplace, like IVF.

Hopefully the process of getting over three-person IVF will be quick, and the UK decision will serve as an example. This is a technology that can allow someone to become a parent while preventing a potentially serious disease. This should be looked upon as disease prevention, which is usually a good thing.

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