Dr. John Zhang holding the baby boy who was conceived thanks to the new technique that incorporates DNA from three people.

The world's first "three person" baby has been born, using a new fertility technique, in which scientists added a small amount of genetic code from a donor to the baby’s parents to ensure the child is free of a condition that his mother carries in her genes.
On Tuesday, the Journal New Scientist revealed that Abrahim Hassan, born in April, doesn't have his mother's genes for Leigh syndrome, a fatal disorder that results in the failure of the central nervous system.
In order to block the Leigh syndrome gene from being transferred to the child, experts incorporated a tiny amount of DNA from a donor into his genetic makeup. The neurological disorder, which usually becomes apparent during the first year of a child's life, affects at least one in 40,000 new-born babies.

Eggs from a mother with damaged mitochondria and a donor with healthy mitochondria are collected 2) The majority of the genetic material is removed from both eggs 3) The mother's genetic material is inserted into the donor egg, which can be fertilized by sperm.
According to scientists, Abrahim’s birth heralds a new era in medicine and could help other families with various rare genetic conditions. They also warned that as the technology, named mitochondrial donation, is still new, it requires thorough testing.
A team of US doctors, headed by Dr. John Zhang, carried out the procedure in Mexico because there are no regulations prohibiting it there. They took DNA from the mother's egg and added healthy mitochondria from a donor egg to make a healthy new egg to be later fertilized with the father's sperm.  
The result is a child with 0.1 percent of its DNA being from the donor, and the reset of its genetic code from its parents, including markers for hair and eye color.