A baby boy was born to a couple from Jordan this year who is being called a ‘three-parent baby’- to the dismay of some scientists. He has two mothers and one father.
The controversial technique that led to the healthy birth involved moving the DNA from an egg of the mother, who had mutated mitochondria, and placing it in the egg of a healthy egg donor after removing the donor’s nuclear DNA from her egg cell. Then that egg, with its healthy mitochondria and the mother’s DNA, was fertilized.
The technique is banned in many countries because it uses genetic material from a donor in addition to that of the couple trying to conceive, though it overcomes flaws in a parent’s mitochondria that can cause grave illnesses in babies. The Jordanian parents were treated by a US-based team in Mexico and the baby was born in New York. Britain recently allowed research on mitochondrial transfers to proceed. Embryologists feel the ban should now be lifted.
Mitochondria, the cell’s energy factories, are separate from the DNA that determines a child’s inherited traits. But mutations in mitochondria results in fatal diseases involving the nerves, muscles, brain, heart, liver, skeletal muscles, kidney and the endocrine and respiratory systems that often kill babies in the first few years of life.
New York Times reported that in 2011, the Jordanian couple first came to see Dr. James Grifo, a professor of obstetrics and gynecology at New York University who pioneered the method in studies with mice. He referred the couple to his former student Dr. John Zhang, medical director of the New Hope Fertility Center in New York. Dr. Zhang had tried the method in China but the 30-year-old woman’s twins were born prematurely and died, though their mitochondria were normal. The first baby died at age 6; the second baby at 8 months.
When Dr. Zhang told the Jordanian couple about the technique, they hesitated at first. They already had a child who was terribly ill with Leigh syndrome – a mitochondrial disease. But there was a chance they could have a normal baby on their own. A quarter of the woman’s mitochondria were mutated, but mitochondria are distributed at random in eggs. If an egg with mostly good mitochondria happened to be fertilized, the baby would be fine. They decided to take their chances.
The couple returned to Jordan and had a baby. But the baby had the same mitochondrial disease, Leigh syndrome and progressively lost its ability to move and breathe. It had a tracheotomy and a feeding tube. The parents had to suction the baby’s lungs every hour.
The couple then came back to Dr. Zhang, ready to try the mitochondrial transfer technique. New Hope Fertility Center has a clinic in Mexico, so he suggested doing the procedure there because it is effectively banned in the United States.
By six months of pregnancy, the woman said she knew this baby was different. It kicked constantly — the others, affected even in the womb, had hardly moved. Now the boy is six months old and healthy and has normal mitochondria. The birth was first reported by New Scientist magazine.
Specialists in reproductive medicine say they hope this success will change attitudes toward mitochondrial transfers. They blame in part the term three-parent baby. That name is misleading, they believe since mitochondria do not define who you are. The genes for traits that make up a person’s appearance and other characteristics are carried in the nuclear DNA.
‘Three-parent’ babies were born before. According to New Scientist, in the 1990s, Jacques Cohen and his colleagues at the Institute for Reproductive Medicine and Science at Saint Barnabas in New Jersey were the first to inject fluid from healthy eggs – including their mitochondria – into eggs from women who had been through several rounds of failed IVF. The hope was that the donated mitochondria would boost the flagging eggs.
The team tried their technique 30 times in 27 people and 17 babies were born. But two fetuses developed a genetic disorder, in which they lacked an X chromosome. One of these pregnancies resulted in a miscarriage, the other was aborted. This led to safety concerns. In 2001, the US Food and Drug Administration wrote to fertility clinics in the US, asking them to stop using the method and to instead apply for approval from FDA in all cases. The method, called ooplasmic transfer, fell out of favour at that point.