Gene 'Fix' in Egg Prevents Inherited Diseases in Monkeys

Aug. 27 -- WEDNESDAY, Aug. 26 (HealthDay News) -- A genetic tweak of the unfertilized eggs of macaque monkeys effectively prevented the transmission of diseases typically passed down through the maternal line, U.S. scientists reported.

The hope is that the method could prevent inherited diseases passed from human mothers to their children through mutated DNA in cell "power plants" called mitochondria. Mitochondria play a basic role by producing energy for each cell, but they also contain their own genes, called mitochondrial DNA (mtDNA), the researchers say.

"Mitochondrial genes are very vulnerable to mutations that cause numerous human diseases," noted lead researcher Shoukhrat Mitalipov, from the Division of Reproductive Sciences and the Oregon National Primate Research Center and the Oregon Stem Cell Center, part of Oregon Health & Science University. "Mitochondrial genes are passed to the next generation through the maternal lineage or through the female's eggs," he added.

The study demonstrates that mtDNA can be safely removed and replaced in the egg, Mitalipov said. "We show that such experimentally created eggs can be fertilized by sperm and develop into healthy monkeys. This approach can be used in humans to prevent birth defects in patients carrying mitochondrial gene mutations," he said.

The report is published in the Aug. 26 online edition of Nature.

In their experiments, Mitalipov's team collected unfertilized eggs from two female macaque monkeys. They removed the chromosomes -- which contain the genes found in the cell nucleus -- from one female's egg and transplanted this material into the other monkey's egg, from which the nuclear DNA had already been removed. The recipient female's egg retained its original mtDNA.

The eggs were then fertilized and as they developed into embryos they were implanted in other monkeys.

That implantation resulted in the birth of healthy twin monkeys, nicknamed Mito and Tracker. These monkeys are the world's first animals derived by this "spindle transfer" process, the researchers say.