As counter-intuitive as it may sound, a baby has been born that has the DNA of three separate people. While we’re quite familiar with the traditional combination of genetic material from two reproductive cells — ovum and sperm — this combination came from the DNA of the baby’s mother, father, and a separate egg donor.
This new procedure was employed because the baby’s mother carries the gene for Leigh syndrome, a neurological disorder that can be fatal to the infant within a few years after birth. Two previous children born to this individual succumbed to the disease, prompting her to seek help in avoiding passing the deadly gene on to yet another child.
DNA is carried in two main parts of the cell: nuclear DNA, found in the cell’s nucleus, and mitochondrial DNA (mDNA), found in the cell’s mitochondria. The process involved using only the nuclear DNA from one of the mother’s eggs, discarding the mDNA, where the genetic code for Leigh syndrome would be carried. This healthy portion of DNA was then added to the ovum of the egg donor, containing the third person’s healthy mDNA, making for a healthy egg that could then be fertilized by the father’s sperm.
The procedure was carried out by a US-based fertility clinic, treating the two Jordanian parents at a facility in Mexico, although it has not been disclosed as to what country the baby was actually born in. This technique, currently not approved for use in the United States, has drawn criticism for its use in producing the child in question — while the procedure is considered ethical in some regions for research purposes, this baby will have to be monitored for decades to ensure that this novel DNA combination doesn’t produce health complications.