The journal Nature reports that scientists advising the U.K.’s Human Fertilization and Embryology Authority (HEFA) have judged that attempts to bring so-called “3-parent babies” to birth is “ready for limited clinical testing.” Presumably this means that the underlying technology, mitochondrial replacement, has been tested enough in the laboratory that it’s ready to try for human procreation. Also presumably, HEFA will promulgate rules or guidelines to address safety and other ethical issues.
I posted on mitochondrial replacement technology, or MRT, most recently this past February 25. Follow the link for further background. Other contributors to this blog have also written about it over the last couple of years.
As described in the report in Nature, the most salient worry seems to involve the effectiveness of the technology. In a favored approach, a woman affected with a potentially serious genetic disease involving genes in her mitochondria has the nucleus of one of her eggs, which has most of her genes which in turn are normal, transferred into a fully healthy egg from another woman donor. The resulting egg is then fertilized in the lab (i.e., fairly standard IVF), and would then be implanted into the mom for pregnancy, and so on it goes. The worry? That some of the abnormal mitochondria come along for the ride, so that the transfer is not “pure,” as it were. In that case, the disease could still be handed down to the offspring if enough abnormal mitochondria stowed away.
This has been tested in the lab by doing the egg nuclear transfer and fertilization, creating human embryos (i.e., tiny new human beings) and then growing up cells from them to see what happens, and indeed the abnormal mitochondria persist at least some of the time. This research necessarily involves the destruction of the human embryos.