> This means that they will judge the risks/harm to the benefits and make a judgement, and receive informed consent.
We should remember that it's not just the individual whose genome is edited that may be harmed, but all of their descendants.
> And can’t you just sequence or test one of the cells from the morula stage?
This isn't sufficient. It has been observed (in mice) that editing the germline by directly editing the embryo will result in chimerism in the fetus. This happens because the editing is not 100% efficient in one cell division. So while some cells have the desired modification, others do not, while others still have completely different off-target edits. The resulting fetus may have the right edits in most cells, but the wrong ones in some particular tissue. It could be perfectly healthy except that it carries some alleles that are lethal when they occur in the liver, heart, or brain. It is impossible to avoid this by sequencing a single cell from the blastocyst, and probably it can't be avoided by sequencing any small number of cells.
> There’s no reason that if the technology exists, is safe, and is regulated that it should be only used for people with a huge number of genetic defects.
This technique does not appear to be safe, and it is not easy to control. If it were, I'd think it would be pretty cool. But, I don't see how we could do one-step editing with many edits unless the efficiency of the editing process is ~100%. And, given that the technique involves cutting the genome and hoping that the repair systems of the cell correct the cuts to templates that we've provided, it is very unlikely that it ever will be, because much of the editing process is outside of our control.
I look forward to another editing technique that is more precise. Or, to growing humans from cell culture. Both of these methods would provide the precision and safety that is required.
> It has been observed (in mice) that editing the germline by directly editing the embryo will result in chimerism in the fetus.
This is an implementation detail to be overcome, not a problem with the general concept. And this study seems to have overcome it.
> The earlier Chinese publications, although limited in scope, found CRISPR caused editing errors and that the desired DNA changes were taken up not by all the cells of an embryo, only some. That effect, called mosaicism, lent weight to arguments that germline editing would be an unsafe way to create a person.
> But Mitalipov and his colleagues are said to have convincingly shown that it is possible to avoid both mosaicism and “off-target” effects, as the CRISPR errors are known.
We should remember that it's not just the individual whose genome is edited that may be harmed, but all of their descendants.
> And can’t you just sequence or test one of the cells from the morula stage?
This isn't sufficient. It has been observed (in mice) that editing the germline by directly editing the embryo will result in chimerism in the fetus. This happens because the editing is not 100% efficient in one cell division. So while some cells have the desired modification, others do not, while others still have completely different off-target edits. The resulting fetus may have the right edits in most cells, but the wrong ones in some particular tissue. It could be perfectly healthy except that it carries some alleles that are lethal when they occur in the liver, heart, or brain. It is impossible to avoid this by sequencing a single cell from the blastocyst, and probably it can't be avoided by sequencing any small number of cells.
> There’s no reason that if the technology exists, is safe, and is regulated that it should be only used for people with a huge number of genetic defects.
This technique does not appear to be safe, and it is not easy to control. If it were, I'd think it would be pretty cool. But, I don't see how we could do one-step editing with many edits unless the efficiency of the editing process is ~100%. And, given that the technique involves cutting the genome and hoping that the repair systems of the cell correct the cuts to templates that we've provided, it is very unlikely that it ever will be, because much of the editing process is outside of our control.
I look forward to another editing technique that is more precise. Or, to growing humans from cell culture. Both of these methods would provide the precision and safety that is required.