Download Are your odds of athletic success coded in your DNA?

LIFE
Are your odds
of athletic
success coded
in your DNA?
SPORTING
CHANCE
ilary Anderson
has always been
athletic. She grew
up playing basketball, spiked her
H
way through college on a volleyball scholarship, and now works
as a personal trainer. So when
she heard about a genetic test
that could reveal which sports
she might have a natural ability
for, she was intrigued.
Anderson and her husband,
Aaron, a former competitive
weight lifter, both took the test
They also gave it to their Vyearold daughter, Ava. "A lot of it
was just for fun and curiosity,"
Hilary says. But the results may
influence what activities the
family—especially young Ava—
pursues in the future. "The
genetics of sports performance
has really just begun in the last
couple years," says Kevin Reilly,
president of Atlas Sports
Genetics, which processed the
Andersons' tests. Will genetic
tests someday predict the
sports stars of the future?
8 October 16, 2009 CURRENT SCIENCE
X'S AND R'S
The test was easy, Hilary says.
She and her husband collected
saliva samples by swabbing the
insides of their cheeks and
Ava's with cotton swabs. Then
they sent the swabs to Atlas
Sports Genetics and waited for
the results.
The $149 test analyzes a
single gene called ACTN3. A
gene Is a segment of DNA that
is the basic unit of inheritance.
ACTN3 comes in two forms:
the R form and the X form.
Everyone has two copies of
ACTN3 in each cell. Some people have two R's, some have two
X's, and some have one R and
oneX.
The R form of ACTN3 carries
instructions for the production
of the protein, aipha-actinin-3,
which is found specifically in
muscle fibers that produce
fast, short bursts of power. (See
"Which Twitch is Which? ") "That
protein taffectsl the ability of a
muscle to contract at very high
velocities," says Reilly.
The types of ACTN3 gene a
person has—R or X—is linked to
athletic ability, scientists have
found. Researchers studying
ACTN3 in hundreds of elite
athletes discovered that many
top "power" athletes, including
sprinters and weight lifters,
have two copies of the R form,
Aaron and Hilary Anderson and
daughter Ava were tested for a gene
that codes for athletic ability.
y e t "There will be other genes
that will be linked to [athletic]
performance over the next
few years," Reilly predicts.
His company has teamed up
with a lab that is searching for
those genes.
and almost all have at least one
copy. "Endurance" athletes, such
as marathon runners and crosscountry skiers, were less likely
to have the R form. In other
words, Reilly says, people with
two R forms seem best suited
for power sports, while people
with two copies of the X form
are probably better built for
endurance sports. Athletes with
one of each form of the gene
might do well in mixed-pattem"
sports, such as soccer, which
require both endurance and
bursts of power.
POWER PLAy
Ttie ACTN3 gene isn't the only
factor that determines athletic
ability, of course. Take Hilary
Anderson, for instance. She
has two X copies of ttie gene,
so is seemingly better suited
for endurance sports, y e t she
excelled at volleyball, a sport
that falls on the power end of
the spectrum. But Hilary is also
very tall, an advantage in volleyball. Obviously, many physical
factors play a part in athletic
ability-height flexibility, lung
capacity, and hand-eye coordination, to name a few.
Critics of ACTN3 testing say
not enough research has been
done to prove the link between
ACTN3 and athletic ability. And
other genes besides ACTN3
almost certainly affect the ways
that muscles work. Those genes
just haven't been discovered
In the meantime, Reilly says,
ACTN3 testing is one way to
help budding athletes Identify
the sports that might be best
for them. But when it comes to
deciding which sports a young
child should pursue, he cautions,
"a test like this may be a t o o l not the tool."
That's how the Andersons
view the test. Results showed
that Aaron Anderson has one
copy of the R fomi of the gene—
a result that fits with his success
as a weight lifter. Like her dad,
Ava has one X and one R fonn,
suggesting that she has the
potential to do well at power
and endurance sports. "Any
Which Twitch
Is Which?
Running, clapping, smiling—every time
you move, you have your skeletal tnuscles
to thank. Skeletal muscles are attached
to the skeleton and create movement by
coniract/nj (tightening) and relaxing.
Two kinds of muscle fibers make up the
skeletal muscles.
Slow-twitch muscle fibers can operate
for a long time without becoming fatigued.
They are aerobic, that is. they use oxygen
for fuel. Slow-twitch muscle fibers are
important for endurance sports, such as
marathon running and long-distance
cycling.
Fast-rwitch muscle fibers contract and
relax quickly. They produce quick, short
bursts of strength and speed, but they tire
out quickly too. Fast-twitch muscle fibers
are anaerobic, they don't need oxygen
for fuel. Athletes flex their fast-twitch
muscles in power sports, such as
weight lifting and sprinting.
Skiwtwitch
libar
n up: Vaar: CMnnphii Butkar Cnirutv of Hllatv Anderson
I1080LI
sport she plays is up to h e r /
Hilary stresses.
What if the test had suggested
that Ava were genetically suited
to just power sports or just
endurance sports? "We might
[introduce] her to sports that
are better suited for her," says
Hilary. If kids are exposed to
activities that they have a
natural aptitude for, Reilly adds,
"they might do better, enjoy it
more, and even have fewer
injuries."
Hilary Anderson is no longer
a competitive athlete, but she's
still interested in how the test
might guide her own athletic
choices. She recently became
involved in cyding, an endurance
sport "Now I might look more
seriously at doing some races,"
she says. "If I had this information
earlier, would I have done more
with cyding [rather than voHeybatl]? It makes you wonder" CS