[MUSIC PLAYING]
LUKE GROSKIN: This is Sam.
He's a pretty special monkey.
You see, unlike all other
male squirrel monkeys,
Sam can see the color
red and happily proves it
in exchange for a sugar pellet.
MAUREEN NEITZ: In
squirrel monkeys,
all the males have
color vision deficiency.
So they're all colorblind.
LUKE GROSKIN: But not
Sam here, whose ability
to smoosh his face against the
pink dots on a touch screen
represents a culmination
of color vision research
by Jay and Maureen Neitz.
JAY NEITZ: Maureen is a
geneticist and genetic engineer
and I'm a neuroscientist and so
we put together our expertise.
LUKE GROSKIN: Not to bring
male squirrel monkeys up
to par with females.
JAY NEITZ: Our whole
goal was eventually
be able to do this in people.
LUKE GROSKIN: Colorblind
people, many of whom
might be green with envy
watching a monkey see red.
There are a lot
of misperceptions
about color blindness.
JAY NEITZ: Oh, you must see
only in black and white,
like a black and
white television,
but almost everybody
who is colorblind
is not completely colorblind.
LUKE GROSKIN: 99%
of colorblind people
have the red-green variety.
This doesn't mean they
can't see red or green.
They just experience
red or green
differently from normal
people and this small gap
in the color spectrum
can taint even
the most basic experiences.
JAY NEITZ: A red pepper
and a green pepper almost
look identical.
A green banana and a
yellow banana, again,
very, very hard to tell.
LUKE GROSKIN: A
similar frustration
can occur at the
butcher's counter.
JAY NEITZ: A colorblind
person is pretty lost
at being able to tell the
nice, bright red meats using
their color vision.
As a matter of fact, you
can't be a USDA meat inspector
unless you have
perfect color vision.
LUKE GROSKIN: Other jobs
are difficult or impossible.
JAY NEITZ: People
want to be a pilot
or they want to be a nurse.
A nurse cannot
really be colorblind.
There's all those pills that
are all those different colors.
If the patient's turning
blue or if they're flushed
and they're red.
LUKE GROSKIN: Or if you're a
colorblind videographer trying
to make a video
about color vision.
JAY NEITZ: It just makes your
life extremely different.
LUKE GROSKIN: Preach
on, Dr. Neitz.
JAY NEITZ: Oh honey, let's
take a vacation to Vermont
and see the beautiful
autumn colors, the sunset.
Oh sweetheart, isn't
it so romantic?
Yeah, the color of the sky
looks pretty much the same.
LUKE GROSKIN: You
can start to see
why one in 12 men or one in 200
women affected by the disorder
might be interested in a cure.
MAUREEN NEITZ: So
in 1999, we decided
that we would give
it a shot and try
to see if we could do the cure.
LUKE GROSKIN: Easier
said than done.
Colorblind isn't an illness.
It's 100% genetic.
BOTH: Right.
JAY NEITZ: So
that-- Well, that--
LUKE GROSKIN: Let's
back up for a second.
At the back of your eye
is your retina and inside
that are three types of
photoreceptor cells called
cones.
JAY NEITZ: There's one
most sensitive to red,
one most sensitive to blue, and
one most sensitive to green.
LUKE GROSKIN: And
each of these cones
and their corresponding pigments
are encoded by specific genes.
MAUREEN NEITZ: So humans
and other Old World primates
have two genes on
the X chromosome
that encode visual pigments.
One encodes the red cone
pigment and the other one
encodes the green cone pigment.
LUKE GROSKIN: But if
you're colorblind.
MAUREEN NEITZ: Only one type--
red or green-- is expressed.
LUKE GROSKIN: Finding
that faulty gene
was relatively simple.
Replacing those genes
inside the cone cells
with the right genes, well,
that's a bit trickier.
MAUREEN NEITZ: You have to
have some way of delivering
a gene to the cells that
you're trying to treat and not
into other cells.
LUKE GROSKIN:
Fortunately, nature
has crafted a really powerful
method of forcing DNA
into a very specific cell.
A virus.
MAUREEN NEITZ: The
virus that we use
is called Adeno Associated
Virus and people call it AAV.
Its main advantage is that you
don't get an immune response
against the virus.
LUKE GROSKIN: So
while researching
how to load the therapeutic
gene into the virus,
the Neitzes trained a pair
of colorblind male squirrel
monkeys-- Sam and Dalton-- to
take a color blindness test.
JAY NEITZ: Every single
morning, the monkeys wake up
and before they
have breakfast, they
go OK, it's time to
have our color vision
tested, and the monkey
is trained to touch
the place where they
see that color blob
and then they get a treat.
They can be most efficient
and gets the most rewards
if they're-- just touch with
their nose and then they get
down and get their little treat.
LUKE GROSKIN: And
just to be thorough.
JAY NEITZ: We also
ran untreated animals.
Occasionally, they might just
by chance touch the right spot
but over trials you know that
they can only really get it
right all the time if they
have normal color vision.
LUKE GROSKIN: Once the
monkeys were trained
and the virus was
ready, Sam and Dalton
underwent a fairly
elaborate procedure.
JAY NEITZ: A vitro retinal
surgeon slipped the needle
underneath the retina.
Then the fluid is
infused in order
to treat the whole
entire back of the eye.
LUKE GROSKIN: It wasn't
immediately obvious
that it worked.
MAUREEN NEITZ:
And we didn't know
how long it was going
to take for them
to change their behavior after
the pigment was expressed
robustly.
JAY NEITZ: Now
when you look back
and you see the difference
between the animals,
it's so dramatic.
It's an amazing thing
and it amazed us.
LUKE GROSKIN: Although
the FDA has yet
to approve the procedure
for human trials,
recently the Neitzes
have developed a one shot
version of the cure.
JAY NEITZ: It's like
a every day shot
that would take one second.
Just a shot right into the eye.
LUKE GROSKIN: And while
getting a shot in your eye
sounds terrifying to
some, it's a small price
to pay for living out
a dream or getting
to see a sunset in all
its glory or maybe just
not leaving your house
dressed like this.
For Science Friday,
I'm Luke Groskin.
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