Genetic modification

With the help of new technology, mothers may be able to avoid passing deadly genes to children

Ruby Washington/The New York Times

For thousands of U.S. women of childbearing age, a rare flaw in the mitochondrial DNA of their eggs means their children run significant risks of birth defects that can result in lives that are short and painful. Recent breakthroughs in biochemistry however may provide a controversial means of allowing these women to have healthy children. Mitochondria produce energy — and humans inherit all of their mitochondrial DNA from mothers. Mitochondria contain many copies of their DNA, so a mother can have faulty mitochondrial DNA but still have enough good DNA to keep her own cells functioning and healthy. For her eggs, however, it’s a different story: some of her eggs will acquire more good DNA, some of her eggs will acquire more bad DNA. The health of her child is decided, essentially, by a roulette wheel. Biochemist Ipisua Belmonte of the Salk Institute in La Jolla, Calif., has developed a technique that deletes the flaws in an egg’s mitochondrial DNA, but the technique has not yet been proved safe enough to be used on would-be mothers. If the technique is proved safe, it could soon be put into practice. Genetic manipulation that involves combining material from the eggs of two different women is controversial and not yet allowed in the United States, but it was recently legalized in the United Kingdom. More advanced techniques that would delete bad DNA and replace it with good DNA from a donor have been used successfully on the eggs of rhesus monkeys by researchers from the Oregon Health & Science University. In England, Newcastle’s Doug Turnbull has performed this procedure on human eggs, but as of now no human has ever been born from an egg that received such a mitochondrial transfer. There is potential danger in these techniques — if the DNA is modified incorrectly it would cause additional birth defects. But for potential mothers facing terrible or impossible odds of having children, this technology provides a new hope.

Read the full story at The Washington Post.

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