US takes first steps toward approving babies with three genetic parents

In this magnified image of mouse cells, the nucleus is blue, the mitochondria are green, and the cell walls are red. Every cell has hundreds or even thousands of mitochondria producing energy. (credit: D. Burnette, J. Lippincott-Schwartz/NICHD)

Today a panel of scientists released a report recommending that the US Food and Drug Administration (FDA) approve testing for a medical procedure known as mitochondrial replacement, which could prevent dangerous genetic diseases in newborns. The procedure, already approved in Great Britain, still has a long way to go before final approval in the US.

A microscopic organ transplant

Though critics say it will send us down a slippery slope of "gene editing," there is in fact no gene editing involved in mitochondrial replacement. Instead, it's more like a microscopic version of an organ transplant.

Mitochondria are called "organelles" because they play an organ-like role in the cell. A bit like a miniature stomach, mitochondria break down molecules to provide energy for the entire body. Mitochondria are also the only part of the cell that contains DNA, other than the nucleus. Some biologists believe this is because mitochondria were once separate cells, absorbed in a process called endosymbiosis during a very early phase in cellular evolution, which nevertheless retained a shred of DNA over the billions of years since that merging.

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