Posted on July 19, 2019 at 1:08 AM
The New England Journal of Medicine carries a brief
article about “Controlling
CRISPR-Cas9 Gene Editing” (subscription required). The upshot: RNA used as a medicine, as in the
case of “CRISPR” to edit genes, can hang around well after
administration, and alter genes other than the ones intended to be
altered. These “off-target”
effects could lead to unwanted clinical side effects. You’d like to be able to shut the RNA medicine
off. Pharmaceutical companies that make
and develop medicines from short RNA sequences have been doing just that—creating
“antidotes,” if you’ll pardon the expression (bad use of the word,
really—an antidote is to a poison, and the medicines are not poisons)—to reverse
unwanted off-target effects of their medicines, should such effects occur.
Using CRISPR for gene editing to treat known genetic disease
raises a similar concern, and the NEJM article cites a recent experiment
indicating that such a “reversing agent” for CRISPR, if needed, might
indeed be feasible. So, suppose you are
trying to treat someone with genetically-caused blindness, and there’s a risk
that other genes might be affected. You
could give the “reversing agent” to block that. Cool.
You’d want to get it into the right tissues—the right parts of the body—but
the work described in NEJM suggests that might all be reality eventually.
One challenge is: these RNA-based agents don’t always get
into the parts of the body, or into cells, all that well. The NEJM writer says that this new work into
“controlling” CRISPR-based gene editing “of course, depends on
the [reversing agent] delivery problem being solved, but that is a topic for
It’s been some time since your correspondent worked for a
drug company making RNA-based drugs, and I’m not close to the work these days,
but I would say that is most definitely a topic for another day.
So, why bring this up in a bioethics forum? Because it’s one more matter that would need
to be considered and addressed before charging into gene editing that can be inherited
from generation to generation. This, as the
present writer has repeatedly held, is something that that the human race
should never do.
But it’s bowling along.
The latest reports are that attempts to edit genes babies of deaf
couples to prevent them from being born with genetic deafness are nigh
in Russia. Understandable, laudable
goal, but we should not think that control of the process is nigh.