DNA-swap technology almost ready for fertility clinic

Figure 1: Mitochondria

Researchers at the Oregon Health and Science University in Beaverton say that their technology to shuffle genetic material between unfertilized eggs is ready to make healthy babies. This could greatly reduce or prevent a range of diseases caused by defects in the mitochondria of cells. While they are relatively rare, affecting only 1 in 4000 children, mitochondrial diseases are often fatal. Mitochondria also seem to play a role in many degenerative disorders, such as multiple sclerosis and Parkinson's disease. Since mitochondria have their own DNA (inherited solely from the mother), replacing defective mitochondria in oocytes could completely eliminate the risk of many diseases. 

In 2009, the researchers, led by Shoukhrat Mitalipov, created eggs with donor mitochondria that developed into healthy rhesus monkeys. This same team now reports that they have created human embryos in which all the mitochondria came from a donor. To accomplish this task, the nucleus was removed from an unfertilized egg, leaving behind all of that cell's mitochondria. The nucleus was then injected into another unfertilized egg that had had its nucleus removed. The egg was then fertilized in vitro.

To evaluate the results in the human cells, the researchers developed the embryos to the blastocyst stage - a ball of about 100 cells. They used cells from the blastocysts to produce embryonic cell lines, carrying out various tests on them. The cells appeared to be exactly like those from normal embyros, but with mitochondria exclusively from the donor.

The technique still requires some alterations to improve consistency and to minimize the abnormalities (some 50% of the human eggs underwent abnormal fertilization, in which excess maternal nuclear DNA remained). Another potential issue with the technology is that in order to be used in fertility clinics, it must be approved by the FDA. However, the FDA is weary to approve techniques utilizing "three-parent babies", because of the mixing of mitochondria from a donor, the nucleus from the mother, and a father.

This article was particularly interesting to me because of its potential ramifications on the world of reproductive physiology. If DNA can be swapped between donors, it means that the risk of certain diseases in children could be eliminated in the future. Using gene mapping and familial history, people could determine their risk for producing offspring with disorders and then utilize this technique to instead have perfectly healthy children.

Link to this Article in Nature