Bioethics Blogs

The Collapse of a Dangerous Analogy: Or, why mitochondria are much more than batteries

The editors at New Scientist have made a “U-turn” on “three-parent babies.” Their new conclusion: “It’s more messy than we thought.”

If you’ve read anything at all promoting 3-person IVF, you’ve no doubt seen the analogy that the cellular organelles called mitochondria “just” produce energy, and that the biologically extreme technique often misleadingly called “mitochondrial replacement,” which would combine genetic material from three people into an embryo, is comparable to merely “changing a battery.”

The connotation is immediate: Just as changing a battery in a computer doesn’t affect the hard disk, so too, the logic goes, would this technique – more accurately termed nuclear genome transfer – merely provide the resulting person with a healthy new source of energy (from the second woman’s mitochondria,) but not change who they are.

The mitochondria-as-batteries analogy has always been spurious, and for numerous reasons. But it has now, thankfully, collapsed.

A new article in New Scientist lays out the evidence. It reviews case after case that supports a “new paradigm” whereby mitochondria are understood not merely as energy sources, but as important actors in and of themselves, greatly influencing numerous complex traits that do in fact make people who they are.
In short, this is because mitochondrial DNA “generates thousands of distinct small non-coding RNAs,” which “are able to influence how the nuclear genetic code is expressedthrough processes such as methylation, which alters gene activity, thus modifying which proteins are produced.”

And what does this mean?

The author explains that “the picture of the enslaved organelle seems to be precisely the wrong way around – in many ways, these bacterial “slaves” are in fact “masters of our fates.” In fact, he continues, this “suggests that the mitochondrion isn’t an evolutionary bystander, but a bona fide second genome.” (Emphasis mine.)

And as the article spells out, this suggests serious trouble for the safety and efficacy of nuclear genome transfer or 3-person IVF.

The views, opinions and positions expressed by these authors and blogs are theirs and do not necessarily represent that of the Bioethics Research Library and Kennedy Institute of Ethics or Georgetown University.