A baby boy was born to three biological parents. The birth took place in Mexico due to a U.S. law that is being applied to cases of genetic mutations caused by mitochondrial diseases. These diseases afflict between 1,000 and 4,000 people in the U.S. each year. Mitochondria are inherited only from the mother and have their own DNA. In this case, the mother carried genes for Leigh syndrome, which is fatal.
The doctors manipulated the genetic material from two mothers before fertilizing the resulting egg with the father’s sperm. Doctors also made sure the child was a male to prevent passing on the genes to future generations. Outside scientists commenting on the work said they believed that the team behaved ethically.