Researchers at Newcastle University in northern England have created human embryos with three parents. The research, which has already produced healthy micelets in the laboratory, involves taking the nucleus of a ferilized egg (two parents) and inserting it into a donor egg cell (third parent) that has had its nucleus removed. The resulting child would have chromosomal DNA from the primary parents and mitochondrial DNA from the donor egg. The research was done in the hopes of being able to treat hereditary illnesses such as muscular dystrophy or certain forms of epilepsy within the next five years by eliminating the carrier (mitochondria) from the equation.
Of the 20000 to 25000 genes in humans, 37 are found in the mitochondrial DNA, which is generally inherited from the mother. That represents approximately 0.2% of all genetic material in a human being, which, while not a significant percentage, is still a contribution to the overall makeup. 80% of mitochondrial DNA handles functional mitochondial proteins, so mutations are likely to be manifested as functional problems such as muscular disorders.
The findings are being met with concern from proponents of reproductive ethics, who worry that this is another step towards designer babies.
The ethics of genetic research when it comes to embryos is, at best, grey. Is it ethical to avoid certain genetic markers by replacing them with other ones if the resulting child will be healthy instead of ill? Is preserving 99.8% of a couple's genetic creation and substituting the missing components with non-mutated variants still producing that couple's offspring?
Ultimately, the entirety of our genetic material is comprised of basic sequences in various combinations. Those basic sequences exist in every human being; it's just the order that differs. So really, a child produced from this method is no different than any other child on the planet: they are comprised of the same genetic makeup. It's just that they weren't conceived via intercourse (and realistically these days that is becoming more common as fertility treatments improve) and instead of the fertilization method leading directly to mitosis, there is a deviation in the path (to place the chromosome-laden nucleus into a different egg).
Admittedly, it is not the way of nature, but then again, neither is using invitro-fertilization, a technique that has enabled many childless couples to have a baby.
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