Third-party DNA can erase birth defects

Technique Involves Replacing Nucleus Of Egg Cell With Another Before Fertilization

Mixing in genetic material from one monkey at the point when two others conceive helped replace defective DNA to produce healthy babies, and may one day keep humans from passing on rare flaws, scientists said.

The experiment by researchers at the Oregon Primate Research Center in Beaverton is designed to replace defective DNA in the mitochondria, energy-producing elements of cells necessary for metabolic processes. The scientists reported the findings on Thursday in the journal Nature.

The new technique might provide a way for women with mitochondrial disease to have children without passing on their defective genetic material, according to scientists. Because the technique permanently alters part of the offspring’s DNA, it also may open a path to modifying a baby’s DNA to select desired traits. That raises ethical concerns, scientists said.

“It’s a very exciting experiment that would give parents the option of being able to have their own genetic children,” said Arthur Caplan, director of the University of Pennsylvania’s Center for Bioethics in Philadelphia. “It’s also the classic example of the road to hell being paved with good intentions.”

Defective mitochondria are passed only from mother to child, not from the father. About 1 in 4,000 births produce babies with defective mitochondria and can lead to a variety of diseases, said Vamsi Mootha, an associate professor of systems biology and medicine at Harvard Medical School in Boston who studies mitochondrial disorders. Nerve and muscle cells deprived of energy are particularly vulnerable to breakdown, leading to conditions like Kearns-Sayre syndrome that can cause progressive muscle weakness and death.

The genes that determine the traits of individuals, from their hair and eye color to their risk for many diseases, are found in the nucleus of each cell. Mitochondria are located outside the nucleus of cells and have their own DNA.

The team at the Oregon Primate Research Center led by Shoukhrat Mitalipov took the egg cells of a rhesus macaque monkey, plucked out the nucleus and inserted it into an another egg cell whose nucleus had been removed. The second cell was then fertilized by another monkey’s sperm and implanted in a surrogate mother who gave birth to twins named Mito and Tracker. Subsequent experiments led to the birth of two more single babies named Spindler and Spindy.

“We believe this technique can be applied very quickly to humans and it will work,” Mitalipov said. BLOOMBERG