A controversial in vitro fertilization (IVF) technique that could help prevent the transmission of certain genetic disorders is not quite ready for human clinical trials. That appeared to be the general consensus among advisers to the U.S. Food and Drug Administration (FDA) who met yesterday and today to discuss a technique that could prevent women affected by various mitochondrial diseases from passing their conditions to children. The method has provoked controversy because it involves combining genetic material from two different women’s egg cells. Crossing an ethical line that many have drawn, the genetic changes introduced by the procedure could also be passed on to future generations.
The IVF method addresses disease that occurs when the mitochondria, organelles that provide energy to cells, don’t work properly. Some devastating or fatal syndromes, for example, result when the DNA that the organelles carry suffers mutations. Mitochondria are inherited from the mother through the egg cell, and several teams of scientists have found ways to remove the normal complement of human chromosomes from an egg with mutated mitochondrial DNA and place it into a donor egg that has healthy mitochondria. The egg is then fertilized with sperm—the resulting embryo carries genetic information from the mother, the father, and the egg donor.
A group led by Shoukhrat Mitalipov of Oregon Health & Science University in Beaverton has produced a half-dozen monkeys using this IVF technique, and he told the FDA advisory panel yesterday that they seem healthy so far. But most members said they would like to see more data indicating that the procedure doesn’t have unexpected side effects before they would recommend testing in human patients.
If additional studies answer some of the outstanding questions, panelists agreed it would be best to begin clinical trials in women who have very high risk of passing a severe mitochondrial disease to their children. The women should also be younger than 35 and have mild enough symptoms that the pregnancy wouldn’t jeopardize their health.
Several panel members said they were much more cautious about testing the technique as a way to treat infertility. Some researchers think that faulty mitochondria might contribute to infertility, especially in older women. But animal data is sparse, and there is no way to tell which infertile women are candidates for the technique, said panel member Maria del Carmen Bustillo of the South Florida Institute for Reproductive Medicine in Miami.
Mitalipov told ScienceInsider by e-mail after the meeting that he is “not sure at this point” if he will ask for permission to start a trial. “But we will follow up with the FDA a bit later,” he wrote.