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A child of many parents: a new way to have two mothers

The Guardian and Telegraph, are today reporting that British scientists have created ten human embryos which each include DNA from one man and two women. This was done by taking a one day old IVF embryo and removing its pronuclei (the parts containing the chromosomes from the parents). These were then inserted into an egg cell from the second woman, which has had its nucleus removed. The result is a new embryo with its primary DNA coming from a man and a woman, and the body of its cell coming from the second woman. This is an amazing experiment, and comes hot on the heels of other multi-parent experiments, but why has it been performed and what are the ethical implications?

The research was performed as a way of avoiding mitochondrial disease. While it is well known that we inherit DNA from our parents, fewer people are aware that we have two types of DNA: the DNA in each cell’s nucleus, which determines our inherited traits, and the DNA in each cell’s mitochondria which plays almost no role in trait inheritance, but is required for proper cell functioning. The familiar nuclear DNA is received equally from both the mother and the father, being present in the nuclei of the sperm and egg. The mitochondrial DNA, however, comes only from the mother, being present in the body of the egg. If a woman has defective mitochondrial DNA, then she could pass on a serious mitochondrial disease to her children, but if the new procedure is used, the couple can combine their nuclear DNA with the mitochondrial DNA from another woman.

An obvious concern about this procedure is that of safety: it should not be used if the risks outweigh the benefits of avoiding mitochondrial disease and we won’t know this for some time. However, people have already attacked the procedure on more specific grounds, namely that it threatens the family unit. This is a very poor criticism. Firstly, while it may seem astounding to have a child with three parents, this is not so new. Currently, we have ‘parents’ of four types:

(1) The man whose sperm took part
(2) The woman whose egg took part
(3) The woman in whose womb the embryo developed
(4) The primary carer(s)

This new development splits the second of these into two subparts:

(2a) The woman whose autosomal DNA took part
(2b) The woman whose mitochondrial DNA took part

The possibility of having different women involved in (2a) and (2b) seems much less important than that of having adoptive parents, or even a surrogate mother. Indeed, it seems to be on a similar level to:

(5) Any organ or blood donor(s)

and we don’t normally consider these to be ‘parents’ at all.

Moreover, this new procedure won’t affect families who do not use it, and for those few who could benefit from it, the benefits would clearly outweigh any potential confusion for the child. No-one would choose to suffer from the avoidable mitochondrial disease rather than have the mild confusion of ‘two mothers’.

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