A U.S. doctor treating infertility in New York City made possible the birth of a baby who has the DNA of three genetic parents.
John Zhang of the New Hope Fertility Center in Manhattan performed the procedure to help a couple from Jordan who had already lost two children to an inherited neurological disorder called Leigh syndrome. The goal was to help the couple give birth to a healthy baby.
The baby's mother has genes for the Leigh syndrome, which is characterized by progressive loss of mental and movement abilities that often become apparent in the first year of life. The condition often results in death within two or three years usually because of respiratory failure.
The DNA for this severe neurological condition resides in the mitochondria, the cell's energy source. Mitochondrial DNA is only passed to the children through their mother.
The woman already had four pregnancy losses and while she has successfully given birth to two children, they also died because of the syndrome. Tests revealed that while the woman was healthy, about a quarter of her mitochondria carry genes for Leigh syndrome so the couple asked help from Zhang, who decided to use mitochondrial transfer procedure.
The procedure involved taking nucleus from one of the mother's eggs and then inserting this into another woman's egg that had its own nucleus removed. The egg is then fertilized using the husband's sperm.
Zhang's team produced five embryos but only one of these developed normally. This embryo was then implanted into the mother. Nine months later, the woman gave birth to a baby boy.
"Without much ado, it appears the first mitochondrial donation baby was born three months ago. This was an ice-breaker. The baby is reportedly healthy," said Dusko Ilic, from King's College London.
Zhang had to go to Mexico to perform the procedure because it is not yet approved in the United States. Nonetheless, some health experts are optimistic that the procedure offers hope to parents who risk transmitting to their children genetic disorders that are potentially deadly.
"This work represents an important advancement in reproductive medicine," American Society for Reproductive Medicine president Owen Davis said in a statement. "We look forward to it being an option for patients who risk transmitting mitochondrial diseases to their children."
Some fertility experts, however, raised concern saying the boy needs to be monitored to ensure that the faulty DNA does not multiply and eventually cause problems.