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Progress Made In Creating Babies With Three Biological Parents

IVF of human egg
The embryos produced were indistinguishable from standard IVF embryos. Monkey Business Images/Shutterstock

Researchers have moved a step closer to creating babies that contain DNA from three people. The technique, which is aimed at stopping the inheritance of genetic diseases passed onto children by their mother, has been met with controversy. But it has also been found to produce healthy embryos that were indistinguishable to standard IVF embryos. While none of these have been implanted yet, it is expected that they are viable, and will implant if placed in a womb.  

Known as “mitochondrial donation”, the procedure replaces the natural but faulty DNA found in the mitochondria in a mother's egg, with healthy DNA from a second woman. This prevents the infant from inheriting certain genetic diseases that are passed on through the mitochondria, such as one that means that the body has insufficient energy to keep the heart beating and the brain functioning.


The latest research, led by the Wellcome Trust Centre for Mitochondrial Research in Newcastle, UK and published in Nature, worked by fertilizing a healthy egg with sperm in the usual way, and then removing the chromosomes from the egg before it had started to divide, placing them in a healthy egg taken from a second woman. By doing this, the researchers were able to able to create embryos that contained only 5 percent of the original mother's faulty mitochondrial DNA (as small bits of it are also transferred with the bulk of the chromosomes). In most cases, the embryos contained as little as 2 percent of the faulty DNA.

They then went on to compare the newly created embryos with those formed through standard IVF, and found no differences between them. While these signs are promising, it does not mean that things are now clear. Other experiments have shown that the tiny bit of original mitochondrial DNA that is also transferred can increase in proportion in developing fetuses, which could suggest that the genetic disease may persist, something that will now have to be tested.

There has been a lot of controversy surrounding the creation of children who technically contain DNA from three “parents.” There have been concerns about the safety of such a procedure, and more worry about the legality of it. Some argued that the technique might not be permissible in the EU under their regulations. The Catholic Church has also been vocal on the subject, saying that it is neither safe nor ethical, mainly on the grounds that it will involve the destruction of embryos. Others claim that it will open the door to allow other genetic modifications of children.

Either way, these arguments didn’t sway British politicians, who last year voted by a large majority to allow scientists to create three-parent babies, becoming the first country in the world to approve of the procedure. This has been followed by other countries, such as the US, but over there the authorities have added a caveat. Three-parent babies will be allowed, but only if the resulting children are male, as this will ensure that the added mitochondria are not passed on to the next generation, should there be any unforeseen consequences.  


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