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BABIES WITH TWO MOTHERS, IS IT WRONG?

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Part I

Last March the Institute for Reproductive Medicine and Science of Saint Barnabas in West Orange, New Jersey, reported in the Journal of Human Reproduction, in the paper: “Mitochondria in human offspring derived from ooplasmic transplantation: Brief communication,”, that they had produced 16 babies that had two biological mothers and that there were already 30 worldwide. This information caused concern in the medical community because it implicated the modification of the human genome. Before discussing the implications of this fact, let me tell you why and how it was done.

The procedure was done to solve an infertility problem that these women in the experiment had due to a deficiency in their mitochondria, which are structures whose major role is to produce energy for the cell to function. Mitochondria contain its own DNA (mtDNA).

All of us inherit our mitochondria from our mothers. That is so because during fecundation, spermatozoids loose their tails, which is where their mitochondria are. In consequence, the fecundated egg is left with the mitochondria of the female reproductive cell, the ovule. Since through mtDNA you can tell if two people are related, it is used in forensic analysis.

The experimenters used a technique called ooplasmic transfer, which is somewhat the opposite of what is done to clone animals. Instead of transferring the nucleus of the animal to be cloned to an enucleated cell, they transfer the mitochondria-containing cytoplasm to the ovule of the infertile woman, which is then fecundated with the father's sperm and implanted in the biological mother's uterus. Thus, the fecundated egg has nuclear DNA from both biological parents and mtDNA from both women; the scientists ascertained this using a genetic engineering technique known as fingerprinting.

In this way couples that previously could not have children now can. Thus, you can ask, what is the problem?

Well, the biggest one is that the researchers state, "The basis for this work is the supposition that embryonic failure may be related to hitherto unknown cytoplasmic pathology." In other words, the experiments were not based on any scientific finding but under the assumption that the problem is in the mitochondria. There is no evidence that it is so. Since the women were able to conceive, it seems obvious that they solved the infertility problem but it could be due to any other cytoplasm component.

But there may be problems associated with this type of experimentation. Since very little is understood about the relationship between mtDNA and nuclear DNA and there are not enough experimental data to support the use of ooplasmic transfer in humans, it is obvious that nobody knows what are the long term consequences, if any, of babies with two different sets of mtDNA. It will not necessarily have adverse effects on the kids, but since they were not confronting a life-or-death situation, why hurry?

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