T
he health of our skeletal muscle is crucial for
everyday activities. It provides structural support
and stability to bones and joints and is also a key
powerhouse for energy production and use.
Our research team at the Murdoch Childrens Research Insti-
tute focuses on how our genes effect the ability of our skeletal
muscle to perform across the spectrum of health, including
both inherited and acquired muscle diseases. By examining
both athletes and people affected by muscle diseases we are able
to look at the contrasting role our genes play under these
extremely different settings.
In 1999 we discovered a variant of the ACTN3gene, which
encodes the protein α-actinin-3. This structural protein is found
in the fast-twitch skeletal muscle ibres that produce the rapid,
powerful movements that set elite sprinters and weightlifters
apart from the rest of us.
The ACTN3gene variant R577X is common, and results in
complete deiciency of α-actinin-3 in almost 20% of the generalpopulation (or 1.5 billion people worldwide). In contrast, we
found that α-actinin-3 deiciency is extremely rare in sprint
athletes, suggesting that this protein plays a crucial role in the
function of fast-twitch muscle ibres.
The association between ACTN3and athletic performance
has since been replicated in athletes from around the world.
The effect in sprint athletes is particularly strong: of the 74
Olympic-level sprint athletes that have so far been tested for
ACTN3, not a single one is deicient for α-actinin-3.
Hence α-actinin-3 is commonly referred to as the “gene for
speed” and is now one of the best characterised and most
frequently studied genes related to sport and exercise perform-
ance.
In our laboratory we have generated an ACTN3gene
knockout mouse to determine how α-actinin-3 inluences
muscle performance and metabolism. We are also interested
in its role in health and disease, including its interaction with
the inherited muscle disorder Duchenne muscular dystrophy.24 | MAY 2016
A Gene for Speed
PETER HOUWELING & KATHRYN NORTHA gene that may have enabled ancient humans to spread to colder climates may also be the
difference between power athletes and the rest of us, and play a role in muscle diseases.Wikimedia CommonsOlympic gold medallist Usain Bolt is regarded
as the fastest man alive. He is the first man to
hold both the 100 and 200 metre world
records, as well as the 4 x 100 metre relay.