A baby containing the DNA from three different people was born, New Scientist reports.
The baby boy, born five months ago, is the first baby born using a particular technique, called spindle nuclear transfer.
Three-parent in-vitro fertilization (IVF) was approved in the UK back in 2015, but the team from the New Hope Fertility Center in New York performed the procedure in Mexico. The team told New Scientist they did it in Mexico because "there are no rules," unlike in the US, where it is still up for consideration but hasn't yet been approved.
Some diseases — including Leigh syndrome, which is the fatal neurological condition this particular baby's parents were trying to avoid — are passed through the DNA of the mitochondria, the part of the cell responsible for generating energy. These genes only get passed down from the mother.
The idea is to substitute that faulty mitochondrial DNA in a mother's egg with a third set of DNA from a donor's egg to avoid these inherited conditions. That's where you get the "three parents": the father (sperm), mother (egg, with faulty mitochondrial DNA removed), female donor (mitochondrial DNA).
Three different techniques to do this have been studied so far:
The second is called pronuclear transfer, and it involves swapping nuclei after both the mother's eggs and donor's eggs have been fertilized. The scientists discard the donor egg's nuclei and put the mother-father nuclei into the donor's egg. This newly combined embryo is the only one to mature.
The one these parents used is called "spindle nuclear transfer," a way of combining the donor's mitochondrial DNA with the mother's nucleus so that an embryo doesn't have to be destroyed.
1st March 1969: Dr Robert Edwards with his team at Cambridge in the early days of research into in vitro fertilisation. (Photo by Central Press/Getty Images)
NEW YORK - AUGUST 15: Doctors perform a laparoscopy on a woman August 15, 1988 in preparation for in vitro fertilization. (Photo by Yvonne Hemsey/Getty Images)
Louise Brown (top) from England, the first in-vitro baby born 15 years ago, hugs other children born with the help of in-vitro fertilization during a get together at Columbia-Presbyterian Hospital to promote the program 05 October 1993. With Brown, from L to R, are Laura Valenti, 2, Phoebe Maddox, 2, and Monica Hendricks, 5. (Photo credit should read RACHEL COBB/AFP/Getty Images)
Nepalese nurses care for the countries first test-tube twin babies (C) at the In-Vitro Fertilization Centre of Om Hospital near Kathmandu 04 March 2005. Kumudini Koirala gave birth to twince baby boys weighing 2.7kg and 3kg respectively. The births came as good news for Nepal, which has been in a state of crisis since King Gyanendra seized power on 01February, and launched a crackdown on the independent media amid an increasingly deadly Maoist insurgency. AFP PHOTO/DEVENDRA M SINGH (Photo credit should read DEVENDRA M SINGH/AFP/Getty Images)
Lehman Best holds a photo of the couple's two healthiest embryos before in vitro fertilization at North Carolina Center for Reproductive Medicine in Cary on Friday, October 12, 2007. Best jokes about 'little Lehman and Lanelle' as he cradles the photo of the embryos. (Photo by Juli Leonard/Raleigh News & Observer/MCT via Getty Images)
NANTES, FRANCE - MARCH 23: Staff work in a hospital on March 23, 2011 in Nantes, France. The center of medically assisted procreation Hospital of Nantes is the first center in France to benefit from renting an Embryoscope for conducting an international collaborative study. The Embryoscope consists of an incubator to receive the embryo; in the incubator a microscope is installed to continuously visualize the development of the embryo on the computer screen. Instead of leaving the embryo in the incubator for observation under the microscope as it is today, this very high-tech equipment meets all the conditions necessary for its cultivation by guaranteeing a stable environment. Embryoscope is developed by the Danish company Unisense Fertilitech and should improve the chances of success of IVF. The center of medically assisted procreation from Nantes hospital performs each year about 1,100 attempts at in vitro fertilization, which places it among the top ten French centers. (Photo by Alain DENANTES/Gamma-Rapho via Getty Images)
A technician works on in vitro fertilization (IVF) for livestock in the genetic research and development center at the Blanca From The Pyrenees dairy farm, partnered with Ponderosa Holsteins, in Els Hostalets de Tost, Spain, on Thursday, June 4, 2015. Global production of milk, cheese and butter will rise to records this year, according to the U.S. Department of Agriculture. Photographer: Pau Barrena/Bloomberg via Getty Images