Washington Week: Student Voices (O)

British scientists create embryo from 3 parents
By Paul Symansky
The Heights (Boston College)
02/07/2008

(U-WIRE) CHESTNUT HILL, Mass. — For as long as humans can remember, it takes one man and one woman to create a child. Many animals follow suit, with those reproducing asexually as exceptions. Either way, two parents seem to be the natural maximum for parenting one child. British scientists are challenging our notions of normalcy, though, as they claim to have created embryos from two women and one man: three parents. The bioethics of genetically modified babies is a touchy subject, but this group of researchers claims that the embryos are still primarily the result of a single man and woman. The impetus of this project was to help prevent the occurrence of debilitating diseases caused by mishaps in mitochondrial DNA.

Mitochondria are the cell's power supplies. They supply energy for all the cell's normal activities and their DNA follows a path of matrilineal inheritance. Thus, regardless of the father's mitochondrial DNA, the child will develop according to the genes encoded in the mother's mitochondria. Mistakes in this type of DNA can cause very serious disorders including muscular dystrophy, epilepsy, and strokes. Very often, these diseases are fatal with out cures or other treatments.

The British group of scientists begins by creating an embryo from the egg of a woman with defective mitochondria and the sperm of her partner. Then, they obtain an egg from a woman with healthy mitochondria and empty it of its nucleus.

Finally, the embryo is transplanted into the new egg with healthy mitochondria. The process is seemingly simple in concept, but very technically complex, while superbly elegant.

Mitochondrial DNA only accounts for a very small portion of the overall DNA in an organism. Nucleic DNA, which accounts for the rest, is what makes a person unique. These scientists are not modifying the nucleic DNA in any way. They hope to show that this new technique does not compromise the offspring's individuality and is strictly for therapeutic purposes.

While many opponents disdain any sort of unnatural conception, it's hard to argue with the motive of preventing insufferable living conditions for many who would have otherwise been afflicted by mitochondrial diseases. Furthermore, the scientists emphasize that they're not altering or modifying any particular genes, they're simply exchanging defective ones for working ones.

The therapy has been tested on mice in Japan, and has been shown to work effectively. More research to identify safety risks and to confirm effectiveness is needed. These specific embryos have not been allowed to develop for more than five days, but their results will hopefully lead to fully functional treatments in just a few years. A law is expected to be proposed in Britain to allow mitochondrial swapping as a suitable remedy for couples who might bear children with such diseases.

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