View Full Version : DNA surgery on embryos removes disease

09-28-2017, 02:47 PM
not sure how I feel about this...on the one hand, progress... on the other, can humans be trusted with this power?

"Precise "chemical surgery" has been performed on human embryos to remove disease in a world first, Chinese researchers have told the BBC."



09-28-2017, 04:02 PM
The answer to the "trust" question is, "probably not". But we've had to deal with many inventions that have implications far beyond what their inventors possibly foresaw.

But over a period of years I watched a very sweet young lady waste away from a mitochondrial disorder known as MELAS. That stands for "Mitochondrial Encephalopathy, Lactic acidosis, and Stroke-like episodes", and as painful as it was for her friends and acquaintances to see what was happening to her, I can't imagine what it was like for her parents and sister.

But the world of the numerous mitochondrial disorders that are out there is where the so-called "three person babies" come in. The idea is to replace mitochondria which have a dangerous mutation with mitochondria that don't.
The child's nuclear DNA comes from the parents, but the mitochondrial DNA is from a third party.

Here's an article from the BBC that talks about an actual use of the technique last year. http://www.bbc.com/news/health-37485263

Until now, every person receives his or her mitochondria from the same woman who gave birth to us. This makes it possible to use mtDNA to trace one of our lines back through time. Of course, that no longer will be true in any meaningful way for someone whose mtDNA has been donated like this.

But in reality, the connection between mtDNA and nuclear DNA is tenuous, anyway. Obviously, you get both from your mother, and your mother's mother, and even your mother's mother's mother. But eventually, if you keep going up the line you'll run into a woman from whom you only received mtDNA.

In fact, at Ancestry I'm in a DNA Circle that involves my 4th great grandmother in this line, Rosalie Fayard. At one time, the "connection confidence" was only "weak", but it has now increased to "some". Now, "circle confidence" is largely a function of how many others are in the circle, and how much DNA you share with how many; but "circle confidence" is also going to depend on how much nuclear DNA you share with an ancestor. If you don't share much with the ancestor, you can't share much with any other relatives -- and you'll likely also have fewer that you share with (on this line).

So as always, advancing technology may be be a double-edged sword.