Mitochondria use oxygen to convert the energy from food into a form cells can use through a process called . The idea of three parent babies previously sparked criticism from some groups, which claimed it could pave the way for "designer babies". Hopefully, this is too low to cause any problems; generally it is thought to take around 18 per cent of mitochondria to be affected before problems start. Thus, another "three parent" technique, known as spindle nuclear transfer, was used: the nucleus was first removed from the mother's egg and inserted into a donor's egg, after removing its own nucleus. The egg is then fertilised by the father's sperm 
 
 Both the mother's and donor's eggs are fertilised with the father's sperm to create two embryos 
 
 The pronuclei, the nuclei during the process of fertilisation, contain the majority of the genetic material. The team avoided destroying embryos, and used a male embryo, so that the resulting child wouldn’t pass on any inherited mitochondrial DNA. Certain tissues that require large amounts of energy, such as the brain, muscles, and heart, seem especially sensitive to decreases in cellular energy. Because of this, she and her husband had already lost two children, so they asked a US-based team of scientists – at New Hope Fertility Center in New York City – for their help. “To save lives is the ethical thing to do,” he says.
– A 5-month-old born using a "revolutionary" genetic technique is said to be the world's first baby created using DNA from three parents since the technique was banned about two decades ago, New Scientist reports. The boy, IDed by the International Business Times as Abrahim Hassan, was born in Mexico to Jordanian parents, and embryologists are hoping his successful birth will hasten using the procedure elsewhere. Abrahim's mother, Shaban, carries the gene for Leigh syndrome—a severe neurological condition that decimates mental and physical capabilities and often results in a child's death before kindergarten. Although Hassan herself is healthy, her first two children died from the disease. That's when she and her husband looked for assistance from NYC's New Hope Fertility Center, where a team led by Dr. John Zhang started them off on an alternative way to parenthood. There are a couple of different ways to pull off the three-parent technique, but the one they chose to go with is called spindle nuclear transfer, in which the nucleus from the mother's egg is placed in a donor egg whose own nucleus has been taken out; that egg, which then contains nuclear DNA from the mom and mitochondrial DNA from the donor, is fertilized with the father's sperm. Five embryos were created in this case, and when just one "took," it was implanted into Hassan, who delivered Abrahim nine months later. This all had to be done in Mexico, where Zhang says "there are no rules" (the Times labels it "relatively flexible legislation"; the procedure isn't approved in the US). One concern scientists are keeping an eye on: faulty mitochondria that could replicate, a problem that may have occurred when the technique was last tried in the '90s. (The UK has OKed a controversial gene-editing method.)