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Alpha-actinin 3 (ACTN3) is
one of a family of actin genes and together with ACTN2 is one of the
myofibrillar proteins located at the Z-disk. ACTN3 is expressed in a
subset of type 2, fast twitch, muscle fibres. A number of studies
showed that a common non-sense mutation that results in stop codon
replacing arginine at position 577, will affect athletic performance
in different ways. The frequency of homozygous individuals with the
mutation in European populations is estimated to be of approximately
18%.
Effects of R577X
Variant
A study in Olympian athletes [1] showed that:
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The null mutation was found at a very low frequency in sprint
athletes when compared to population. No female athletes were
observed to have the null mutation.
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Endurance athletes had a slightly higher incidence of the null
mutation.
Another study [2] showed that the null mutation
is of an advantage for women to develop a dynamic muscular strength
in reponse to progressive resistance training. This mutation had a
negative effect to produce high force isometric strength in women.
No differential effects were observed in males.
Test Methodology
DNA is extracted from peripheral blood and the
region of the ACTN3 gene is amplified by PCR. Testing is done by
RFLP and confirmed by direct DNA sequencing.
Sample
Requirements
a) Peripheral whole blood collected by
venipuncture in an EDTA container. Please send the sample to the
laboratory at ambient temperature.
alternatively
b) A buccal swab can also be sent for testing.
This is a non-invasive procedure and the sample can be sent in an
envelop to the laboratory. We can send a free testing kit upon
request.
Benefits from Test
Knowing the athlete's genetic makeup will help in
personal training. Training can be addressed to improve the
athlete's genetic potential and to overcome its weaknesses.
The results can help to determine which type of
sports you will be most likely to succeed.
It is important to note that genetics are
only a part of the success story of an athlete and
importance should be given to proper nutrition, training and all the
other aspects of sports.
References
[1] Yang N., MacArthur DG., Gulbin JB. ACTN3
genotype is associated with human elite athletic performance. (2003)
American Journal of Human Genetics 73: 627
- 631.
[2] Clarkson PM., Devaney JM., Gordish-Dressman
H. ACTN3 genotype is associated in muscle strength in response to
resistance training in women. (2005) Journal of Applied
Physiology 99: 154 - 163.
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