A 6-month-old baby boy may have opened the door to a new world of reproductive medicine. He is the first person born from a controversial new technique for preventing mitochondrial diseases by creating a “three-parent baby” — a child in which the vast majority of DNA comes from the mother and father and a small amount of DNA comes from a female donor.
Mitochondria are organelles inside cells that, among other tasks, generate energy. The organelles are passed from mother to child. Mutations in the 37 genes housed inside mitochondria can lead to fatal inherited diseases that affect organs that need lots of energy, such as the brain and muscles. There is no cure or effective treatment for many of the mitochondrial diseases.
Some of the mitochondria in the baby boy’s mother’s cells have a mutation that causes Leigh syndrome, a fatal neurological disorder. Most of her mitochondria function properly, so she doesn’t have the syndrome. But she can pass the disease on to her children: Two have died of the disease and she has had four miscarriages.
Her son’s birth in April caps nearly three decades of efforts to manipulate mitochondria and produce healthy eggs — initially to overcome fertility problems and now to avoid passing on disease. Although it takes three people to make these fertilized eggs, some researchers take issue with the moniker “three-parent baby”. Pioneering clinical embryologist Jacques Cohen calls the term erroneous. Mitochondrial DNA doesn’t contribute to a person’s traits, so a mitochondrial donor hardly constitutes a parent, he says.
The procedure was done in Mexico by American doctors because it is not currently legal in the United States.