What Risks Should We Accept in Disease Prevention?

by Jennifer Lahl, CBC President on July 11, 2013

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I read with much interest Marcy Darnvosky’s article in Nature, “A Slippery Slope to Human Germline Modification.” The article focuses on the ethics of the technology used to create “three-parent embryos.” This new technique has been given the green light for trial by the Human Fertilization and Embryology Authority (HFEA) in the U.K. and will be used with women who have a genetic mitochondrial disease they don’t wish to pass onto future children.

The technique involves replacing the defective gene found in the mother’s mitochondria with the healthy gene from a donor egg, and then fertilizing the “new” egg with the male sperm – the three-parents being DNA from mother, egg donor, and biological father.

Darnovsky does a good job of talking about the ethics of this technology writing,

Mitochondrial-replacement procedures would constitute germline modification. Were the United Kingdom to grant a regulatory go-ahead, it would unilaterally cross a legal and ethical line on this issue that has been observed by the entire international community. This consensus holds that genetic-engineering tools may be applied, with appropriate care and safeguards, to treat an individual’s medical condition, but should not be used to modify gametes or early embryos and so manipulate the characteristics of future children.

While she does not want to accept the risks of manipulating future children (and I agree) and she expresses sympathy to women with such a defect (as do I), she offers this as the solution:

. . . these women have much safer alternatives, including pre-implantation genetic diagnosis (PGD)and the use of third-party eggs with conventional IVF.

I would argue that these alternatives are not necessarily safer. PGD is not without risks, and in fact raises concerns about the genetic manipulation of future children. While mitochondrial modification removes defective DNA, PGD removes DNA without consideration of what that removal does for the developing embryo.

The use of third-party eggs can come at the risk of women undergoing ovarian hyper stimulation. Conventional IVF too is not without risk (e.g. cancers, OHSS).

And of course, no mention is made of the children born to one mother but biologically related to the woman who donated her eggs. Children created via third party reproduction, no matter the method, are still future children created via technologies with inherent risk.

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