Four Healthy Rhesus Monkeys Born with Mitochondrial DNA from Donor: Procedure May One Day Prevent Some Inherited Diseases

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Scientists may have found a way to prevent the transfer of serious inherited mitochondrial diseases from mother to child. By shuttling nuclear DNA from an egg cell to a donor cell, the technique enabled the birth of four healthy rhesus macaque monkey males, researchers report online August 26 in Nature.

"We consider this a big achievement," study coauthor Shoukhrat Mitalipov of the Oregon National Primate Research Center in Beaverton said in a news briefing August 25. "We believe that the technique can be applied very quickly to humans, and we believe it will work."

Mitochondria, the power-producing organelles in cells, carry their own DNA, distinct from the DNA held in cells' nuclei. Healthy or otherwise, mitochondrial DNA is passed from mother to child. In recent years, researchers have identified more than 150 harmful mutations in mitochondrial DNA, some of which can cause serious diseases (SN: 2/28/09, p. 20). There are only preimplantation and prenatal tests for some of these diseases, and most tests are unreliable.

"This whole field of mitochondria medicine is very new," says Douglas Wallace of the University of California, Irvine. "It affects lots of people, but we have very little to offer them." Some estimates report that 1 in 6,0OO people may have inherited a mitochondrial DNA disorder.

A single cell can have thousands of copies of mitochondrial DNA. Usually, all of these copies are the same, healthy type. But occasionally a cell can have a mix of normal and mutant mitochondrial DNA, a condition called heteroplasmy.

Heteroplasmy in an egg cell makes it nearly impossible to determine if a baby is going to inherit a severe mitochondrial disease, says Jo Poulton of the University of Oxford in England. "You can get quite a big range of how much mitochondrial DNA is transferred to children."

To get around the guesswork surrounding inherited mitochondrial diseases, the researchers took the mother's mitochondrial DNA completely out of the picture. …