In 2011, scientists created
glow-in-the-dark cats.
The researchers took a gene from glowing jellyfish
and inserted it into the unfertilized eggs of house cats.
It was a neat trick, but they had a bigger goal in mind.
They also made the cats more likely
to be resistant to a feline form of AIDS,
by, again, manipulating their DNA.
And cats aren't that different than humans.
In fact, we share around 90% of our DNA with them.
So why can't we engineer humans in the same way?
Well, we can --
engineer ourselves to be resistant
to life-threatening illnesses, that is.
In fact, one scientist claims
that he's genetically engineered two babies
using a revolutionary tool called CRISPR.
But what exactly is a CRISPR baby, anyway?
Would you like to be 6 feet tall or never bald?
The secret to traits like these
lies in the 6 billion letters of your genetic code.
But there could be something else in there as well:
mutations.
Genetic mutations are linked
to at least 6,000 medical conditions
from sickle cell anemia to Huntington's disease.
But what if you could make those mutations simply disappear?
That's where the gene-editing tool CRISPR comes in.
CRISPR is made from specialized proteins
and other compounds found in certain bacteria.
Normally, these proteins protect the bacteria
by destroying enemy invaders like viruses.
But the inventors of CRISPR figured out
how to turn those proteins against genetic mutations
and other genes linked to disease.
First, they give the proteins
coordinates of the wanted gene.
Then, CRISPR runs a seek-and-destroy function.
After that, other molecules are dispatched
to repair the gene with new, healthy DNA.
And just like that, you can edit the human genome.
But while the edits may be quick,
their changes can last for centuries,
especially if you're editing the DNA in an embryo.
Embryos start out with a single cell
that eventually replicates into millions
and then trillions more.
So if you alter that initial cell first,
you're manipulating the ingredients
for every cell that follows later in life,
and those same altered cells can be passed on
from generation to generation.
That's one reason why most experiments
on human embryos haven't left the lab.
That is, except for the work of Dr. He Jiankui.
He claims to have used CRISPR
to target and knock out the CCR5 gene in human embryos,
which is linked to HIV infection.
And then he did something
that shocked the scientific community.
He implanted the embryos into several women,
one of whom gave birth to genetically modified twins.
Resistance to HIV aside, most scientists say
the procedure was too risky.
At least two studies suggest that edited cells
might actually trigger cancer.
And another found that CRISPR
can accidentally take aim at healthy DNA.
So while CRISPR could make us immune to disease,
who knows what else we might get on the side?