By Samuel W. Anderson

from GeneWatch 27-3 | Sept-Nov 2014

Although it isn't specifically named on the cover, this issue of GeneWatch focuses on a particular reproductive technology (or "technique," or "procedure," or "set of procedures," depending on how you look at it and who you ask). Already you may have noticed me being oblique about this technique/technology/procedure - there, I did it again! - and throughout the issue you may notice that even those who are intimately familiar with it have some trouble knowing quite what to call it. As you can imagine, the popular press hasn't agreed on a term yet, either. A few of the ones you'll see most often:

Mitochondrial transfer
Mitochondrial replacement
Three-parent (or three-person) babies
Three-parent/three-person embryos
Three-parent/three-person IVF
Nuclear genome transfer

Before getting any further into that mess: What is this mitochondrial nuclear three-parent whatever-you-call it? The rest of this issue contains plenty of explanation, as you might imagine, but the short version is that nuclear genome transfer (this publication's preferred term) involves removing the nucleus from one  woman's egg and replacing it with the nucleus from another woman's egg.

The goal is to allow a woman with mitochondrial disease to have a healthy child. That's where terms like "mitochondrial replacement" come in: Mitochondria have their own DNA distinct from nuclear DNA, so by removing the nucleus from an egg with problematic mitochondria and swapping it into a donor egg with healthy mitochondria, you are in effect replacing the "bad" mitochondria with "good" mitochondria. (See Stuart Newman's article in this issue for numerous reasons that terms like "mitochondrial replacement" can be misleading, at times perhaps purposely so.)

If this is the first you've heard of all this and you have nonetheless managed to stick with me so far, you may be wondering: What's the big deal? Who would this really affect? And what does this have to do with human genetic engineering? For that, I'll turn you over to the experts - read on.


Cover photo credit: Angie Garrett (

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