Scientists Create Human Embryo with 3 Parents

Debates in bioethics range from stem cell research to genetically altered foods and everything in between. British scientists may have given us something new to debate.

Scientists from Newcastle University in the UK have created human embryos with three parents. The “test-tube” embryos, made from in vitro fertilization (IVF) were created using DNA from one man and two women.

During fertilization, the mitochondria in the sperm are destroyed, leaving only the mitochondria from the female to be passed on to the offspring. Mitochondria are, essentially, the power plants that provide energy in the cell. Faulty genetics in the mitochondria can result in a build up of poisons responsible for more than forty different diseases. Somewhere around one in 4,000 children develops a mitochondrial disease by age 10. Such diseases include fatal liver, heart, and brain disorders, deafness, muscular problems, and epilepsy. These diseases are often debilitating or even fatal, and until now, there was no cure in sight.

The idea of this research was to prevent women with errors in their mitochondrial DNA from passing diseases onto their children. The UK scientists believe that these diseases could be avoided all together if at-risk embryos were given an effective mitochondrial transplant.


Scientists use IVF to create a zygote and then remove the nucleus from said fertilized egg. The nucleus is then placed in a donor egg whose DNA has been removed. The resulting fetus inherits its genes (from the nuclear DNA) from the original sperm/egg pairing, but its mitochondrial DNA would come from a third party.

Image: from Nature

Patrick Chinnery, a member of the Newcastle team is quoted as saying, “The idea is to swap the bad diseased mitochondria – give a transplant, if you like – for good healthy ones from a donor.”

Presently, this technique has only been used in a laboratory, using abnormal embryos left over from regular IVF therapy. The eight three-parent embryos that were successfully created were destroyed within six days, after reaching a blastocyst stage of about 100 cells.

Although these six day old blastocysts are the only examples of human embryos with 3 parents, scientists first used this technique on mice and then later on rhesus monkeys. The mice grown from these 3 parent embryos have successfully reached adulthood and reproduced themselves. The monkeys, however, are only one year old.

Even though the effects of this research aren’t yet known, strict opposition is already appearing.

The US’s Family Research Council says “This technology…is a further step toward tampering with the very essence of humanity, and demonstrates not just a contempt for life itself – all the embryos in this experiment were destroyed for science – but a profoundly dangerous and arrogant belief that we can tamper with the genetic makeup of our fellow human beings.” Members of the team, and the scientific community at large, is somewhat exasperated by such claims, saying “We’re trying to prevent kids being born with fatal diseases.”

The more common objection is that of “designer children” created from altering heritable traits. The general public opinion is that altering DNA is perfectly fine when its changes aren’t inherited, such as gene therapy to repair eyes, but altering heritable DNA is extremely troubling. Countries like France and Germany have banned germline genetic engineering due to fears of designer babies and unknown health problems. Although the US has not banned germline genetic engineering, it does not currently provide any support for IFV research.

Doug Wallace, mitochondrial geneticist from the University of California looks at the ethical dilemmas in a different way. “Is it fair for society to make it impossible for a woman who has a high percentage of mutant mitochondrial issues to have a healthy baby?”

From fear of designer children, critics to the UK techniques could be preventing mitochondrial troubled parents from having children at all. The British scientists report that if the program moves ahead as planned, they may be able to offer this medical technique within the next three to five years.