once in a while there's a development in
science that gets an unusual amount of
press often that's a good thing we
discover a new subatomic particle or
detect gravitational waves for the first
time or land something on Mars this time
is different
last week a researcher in China
announced that he had used the gene
editing technique known as CRISPR to
change the DNA of human embryos created
via in vitro fertilization and that
these two embryos had been successfully
implanted in their mom and developed
into twin baby girls that were born last
month the experiment has been
universally condemned by scientists and
according to practically every expert on
medical ethics should never have been
done in the first place here's why
CRISPR is a revolutionary gene editing
technique that's been used for a ton of
research in the last few years it allows
scientists to delete genes turn off
genes or insert genes all more easily
cheaply and accurately than ever before
in this latest experiment Huijin quai a
scientist at the Southern University of
Science and Technology in Shenzhen China
used CRISPR to disable a gene called
ccr5 in human embryos ccr5 is involved
in the immune system and the HIV virus
exploits it in order to infect human
cells so by disabling this gene he aimed
to make the babies resistant to HIV
we don't know many of the details of
this experiment because who's Jean qui
hasn't published the research and a
peer-reviewed scientific journal but
according to reports the parents of the
babies went through IVF and shortly
after the eggs were fertilized her used
the CRISPR technique to cause a genetic
mutation that would disable the ccr5
gene the embryos were then implanted
into their mother's uterus and were
carried to term the twin girls were born
around the beginning of November and so
far they seem healthy there's been
speculation that the parents may have
decided to participate in this
experiment because the father is HIV
positive but there are other less risky
ways to ensure that a baby with an HIV
positive parent doesn't contract the
virus and then episode we did on CRISPR
back in 2016 we mentioned that
scientists are aware of that just
because you can doesn't mean you should
principle but it seems like who's Jean
qui was not CRISPR had been used to edit
genes in human embryos before now but
only
for research purposes and never with the
intention of implanting the embryos or
allowing them to develop and the
consensus among both scientists and
policy makers was that we were nowhere
near ready to implant genetically edited
embryos we needed more research first
ethically there are still some open
questions about the implications of
editing someone's entire genome before
they're born whether it will lead to
so-called designer babies for example or
if it's okay to alter the course of
human evolution in this way no matter
how you feel about those questions we're
not ready for CRISPR edited babies
because of some pretty basic safety
concerns CRISPR isn't perfect yet and
sometimes it will change a gene in
unexpected ways
causing an unintended mutation and the
last thing you want is an accidental
potentially dangerous change in every
single cell in someone's body the few
approved gene therapies that involved
directly editing someone's DNA inside of
their body use older better studied
techniques not CRISPR there are a few
CRISPR based treatments in trials right
now but they work by taking certain
types of cells out of the patient
modifying them and then putting them
back in and no matter what technique
they use all these treatments have
something in common they don't touch the
germline germline cells are the ones
that divide to produce eggs or sperm and
by making sure they stay unmodified you
can't pass on the edited DNA to a child
so even if something goes wrong you
avoid the risk of introducing that
problem to future generations
who's Jean quiet basically took all
those precautions and threw them out the
window for the experiment he used CRISPR
to edit DNA and very early embryos
consisting of only a few cells at most
at that stage CRISPR can alter genes in
every cell of the embryo which
eventually generate every cell in the
fetuses body including their germline
cells even if everything had gone
exactly as planned this research would
have been controversial because it
skipped so many steps in the usual
careful process that goes into
developing new treatments especially new
gene editing treatments but it didn't
all go exactly as planned the babies are
healthy right now but the mutations in
their ccr5 genes are slightly different
from the naturally occurring ones who
was trying to reproduce you have no idea
if those new mutations will have other
effects and now the girls are stuck with
them for the
to their lives it also seems like in at
least one of the babies only half of the
ccr5 genes were edited depending on how
the edited genes are distributed that
could mean that she didn't even get the
HIV resistance after all that so yeah it
turns out there are reasons we are
cautious about research like this but
it's not just about the fact that hood
tried a treatment and it didn't work out
exactly as expected that happens all the
time it's that he went against
scientific consensus so strong that
there are laws to enforce it the Chinese
government now seems to be investigating
him although the details of that are not
yet clear either way this was not a good
strategy for pushing scientific progress
scientists said pretty much agreed that
if they ever used CRISPR on a human
embryo that would be carried to term
they would use it to correct a genetic
disease for which there was no other
reasonable treatment in a youtube video
he posted because of course this all
came out via a YouTube video who
explained that he'd show us the gene
because it's extremely well studied
thanks to years of HIV research but
there was no medical need for this the
goal was just to make the babies more
resistant to HIV infection which they
didn't have and again could have
prevented in a number of less expensive
and much less controversial ways
scientists are all for progress that's
kind of their job and gene editing has
the potential to completely transform
the face of medicine but if there's
anything scientists have learned from
past mistakes it's that we need to be
careful about how we wield that type of
power because it can be dangerous too
and with CRISPR being such an amazing
potential treatment the last thing we
want to do is sour the whole world on
its use because of some mistakes made
early in the process here at scishow we
believe the more you know about the
universe and how scientists come to
understand it the easier it is to
recognize good research and realize when
science has gone astray it's one reason
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