Abstract
Professor Carbone: Yes and no. On the one hand, this involves a relatively minor genetic change: the elimination of mitochondrial DNA that might pass on a hereditary disease. The nuclear DNA that affects most of a child's characteristics is unaffected. In addition, the intended parents make a conscious decision only to eliminate the defective DNA—they are presumably not choosing a donor on the basis of the donor's characteristics. Still, this does allow creating children who will be genetically related to three people, who could not be produced through sexual intercourse alone, and who can transmit the donor's genetic characteristics to their offspring. It is therefore genetic engineering.
Professor Carbone: Before the UK Parliament approved the procedure, the UK insisted on testing in animals and use of the procedure to create human embryos that were allowed to develop to the 14-day stage permitted in the EU. In both cases, the researchers succeeded in producing seemingly healthy animals and embryos. Until the procedure is tried in humans, however, it is impossible to determine whether there are unknown risks that might materialize.
A number of children have been born worldwide using cytoplasmic transfer that produced children with mitochondrial DNA from a donor. The earlier procedure, however, simply added cytoplasm from a donor to a fertilized egg. Most of the children thus produced, who are now in their teens, appear to be healthy, but some have developmental disorders. Relatively little follow-up has been done, and it is unknown at this point whether the developmental disorders resulted from the procedure (which is somewhat different from the current procedure) or from other causes.
The only way to fully assess the safety of the procedure is to try it and to study the resulting children on a long-term basis. At this point, no one can say either that the procedure is risk free or that we have found the safest way to do it.
Professor Carbone: The problem of sterility is not fundamentally different from other possible medical conditions. First, steps can be taken to determine how great the risk is. Follow-up studies of the monkeys produced using the technique can ascertain whether they are sterile. Long-term studies of the children who were born in the nineties using cytoplasmic transfer will also indicate whether fertility is an issue. Second, if the children have trouble reproducing, the next step would be to try to find out why and whether the doctors can address the problem. Finally, even if some (or all) of the children are unable to reproduce, parents may still prefer to have the choice: risk having a child who cannot reproduce, or risk having a child with a devastating disease. Parents who know they are carriers for various diseases face difficult choices all the time. They may decide not to reproduce; to test embryos before deciding which to implant; or to reproduce naturally and let nature take its course. A decision like this is not fundamentally different from decisions prospective parents are already making. Indeed, parents now face decisions about whether to treat existing children with medicines or cancer treatments that may also limit their future fertility. Doctors, on the other hand, might elect not to participate in a procedure that would knowingly produce infertile children, and I would respect their ability to decline to perform such procedures on that basis. The question may be not so much whether such decisions are ever permissible, but who should make them.
I would emphasize, though, that I have not seen any indication that the procedure is likely to produce infertile children.
Professor Carbone: An important question to resolve is whether the procedure will be done using donor embryos or donor eggs. There is some indication that the procedure is more effective using donor embryos, which would then have their nuclei removed, and the nucleus from an embryo created by the intended parents inserted instead. If donor embryos are used, they would presumably come from embryos donated from fertility clinic patients. There are several hundred thousand extra embryos in freezers in the United States now, and it is likely that securing donation will not be a problem if the UK decides to permit such donations.
Some of the studies in monkeys use unfertilized eggs, and some ethicists may feel more comfortable using unfertilized eggs rather than donor embryos. The ability to freeze eggs is relatively new, but now that it is an option, it is likely that there will be a large number of extra eggs available in the future. These eggs may come from in vitro fertilization (IVF) patients who produce more eggs than they need, or young women who freeze their eggs to preserve their fertility and later find that they do not need to use the eggs. One question that may affect the supply from any of these sources is payment; the UK currently limits payment for egg donation while American states typically do not.
Professor Carbone: There are different ways to think about human dignity. The Catholic Church, for insistence, associates human dignity with procreation through sexual intercourse within marriage. It accordingly opposes in vitro fertilization altogether, as well as any procedures that involve manipulation or alteration of human embryos. Judaism, in contrast, views the command “to heal” as divinely ordained and associates human dignity with the use of knowledge to better the human condition. Sharon Bernardi, who lost all seven of her children to mitochondrial disease, approved the decision to authorize the procedure as essential to spare others, who like her are carriers of the disease, the agony she experienced in watching her children die. She might well associate human dignity with the ability to produce a child free from a horrible disease.