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U.K. Government Plans to Allow Mitochondrial Replacement

A human oocyte


The U.K. government is moving toward allowing a new type of in vitro fertilization that would enable patients with mitochondrial diseases to avoid passing the condition to their children. The technique is controversial, because it involves introducing new DNA into a human embryo. But a public consultation earlier this year found broad support for the technique.

The Department of Health announced today that it would draw up draft guidelines to allow fertility clinics to offer the technique. The proposed guidelines would be released for public comment later this year, and Parliament could vote on a final version next year.

Mitochondria are the cell's power generators, and they carry their own DNA, called mtDNA. Mutations in those genes cause mitochondrial diseases, which can affect various organs, including the heart, liver, eyes, and brain. Such diseases are passed from mother to child, because the egg provides most of an embryo's mtDNA. (Sperm have mitochondria, but most disintegrate after fertilization.)

The techniques in question transfer the nuclear DNA from the sperm and egg of the potential parents into a second egg, provided by a donor who has healthy mitochondria, from which the nuclear DNA has been removed. The technique is still under development and isn't yet considered ready to try in humans. But the potential is promising enough that the government has decided move forward, said Chief Medical Officer Sally Davies in a statement. "It's only right that we look to introduce this life-saving treatment as soon as we can," Davies said.