Designer Baby breakthrough this is not- it is actually much cooler

The article “Chinese researchers announce designer baby breakthrough” published by FoxNews.com attempts to sell the idea of designer babies being the end goal of genetic editing. Not the case.

As with many kinds of these articles, their citation links to an article on the New Scientist covering the journal article. This article has done a much better job of covering the nuances of the method used by these Chinese researchers.

The article, “CRISPR/Cas9-mediated gene editing in human zygotes using Cas9 protein” published in Molecular Genetics and Genomics.

In short the study was building off of the previous body of work showing that the CRISPR/CAS9 system techniques could be used to edit tripronuclear zygotes by applying it to dual pronuclear zygotes.

So what are tripronuclear and dual pronuclear zygotes anyway?

First lets start with zygote. A zygote is a fertilized egg, in this case we are talking about human eggs. So a Tripronuclear zygote is an egg that was extracted for invitrofertliziation that was fertilized by 2 sperm at the same time. This means the zygote has 1/3 more chromosomes than it should. It has 3 copies of each chromosome when it should only have 2. A dual pronuclear zygote is a normal zygote, where 1 egg was fertilized by a single sperm.

This distinction is important because due to certain ethical issues surrounding science’s use of fertilized embryos, normally scientists don’t get to use eggs that could be considered normally fertilized zygotes.  This is because usually the research being done using what basically becomes unusable for implantation into a human female would normally be discarded. Thus these tripronuclear zygotes find a purpose other than ending up in the garbage.

 

That means the Chinese researchers were using something that could have become a person… if it wasn’t also going to be garbage. The researchers found an excellent use for an excess of sperm and ovum samples given to the clinic by the patients.  These researchers are great to put forth a plan to make this kind of research more possible. It is in this that their meaningful contribution can be found.  These researchers recieved consent from the donors of the sperm and egg samples that were not used for their IVF treatment to be used in further research.  They then tell us what they did after injecting each egg with a single sperm to keep it alive, and dividing.  Then they drop the big bomb, not only did they have normal zygotes dividing, they did a CRISPR/CAS9 experiment to show that gene editing works a good bit better than it does in a tripronuclear zygote!

In other studies looking at gene editing to remove or decrease diseases in the zygote’s genome could only use tripronuclear zygotes, and they saw what the paper’s authors quote at being 10% effective. In their sample size of 2 (I know, we will get to it) they saw of these zygotes both went either half or all cells after the division were repaired. So that’s why the fox article makes sure to quote it as “encouraging”, and not with stronger language.

Now let’s talk about the sample size of 2 thing. Normally, this wouldn’t hardly indicate a study. In this case, they are really just publishing a paper to say some very basic, but important statements. The sample size of 2 is from the criteria they set up the study with. First they had to find IVF patients that had fathers that had a specific blood disorder. This meant, when they started with 10 zygotes after selecting for ones where the fertilized eggs were female (a necessity of the experimental design) and that CRISPR/CAS9 had worked on the  region it was intended to, they had 2. But if this were a situation where the family wanted to do this to fix their potential offspring ahead of time is not a bad amount to work with.

What the author’s are contributing to the scientific community-

1. Normal Chinese people who underwent IVF treatment agreed to give the researchers their left over samples for scientific research- even when those samples could produce potentially viable eggs.
2. That there isn’t anything keeping from CRISPR/CAS9 from working in a normal zygote.
3. This would make doing more specific research into easily reparable diseases possible by showing that there is proof that it can work.