Genetic Polymorphisms
Associated With the Risk of Concussion in 1056 College Athletes: A Multicenter
Prospective Cohort Study
Terrell
TR, Abramson R, Barth JT, Bennett E, Cantu RC, Sloane R, Laskowitz DT, Erlanger
DM, McKeag D, Nichols G, Valentine V, Galloway L. Br J Sports Med. 2017. Ahead
of print
Take Home Message: A
college athlete with a specific genetic variation at IL-6R has almost 3.5 times
greater risk of concussion and an athlete with a genetic variation at APOE4 had
a 40% lower risk.
Several
of the concussion sport guidelines highlight the need to
identify athletes at risk for poor outcomes, and suggests one way to do so is
through genetic testing; however, these statements also point out that
there are significant biases and a need for more studies in this area. Therefore,
the authors evaluated the association between the risk of concussion in college
sports and 8 genetic variations from 4 genes that are related to structural
neuronal integrity (APOE, MAPT) and release of pro
inflammatory signals (IL-6R). The authors included
1056 college athletes (~20 years of age; 80% male; 65% football, 20% soccer)
from 23 sites that had genotyping for one or more of these variations. Overall,133
athletes sustained a concussion during an average of 3-year surveillance per
athlete. The authors found that an athlete with a specific variation in IL-6R was at almost 3.5 times greater
risk for a concussion. Additionally, an athlete with a specific variation in APOE4 had almost a 40% lower risk for a
concussion.
This
analysis was the largest cohort to investigate the association between genetic
association and sport concussion. However, there were still large differences
between groups, and the number of athletes with a concussion was low, which
prevented the authors from verifying these results in another study sample. Nevertheless,
it is still interesting to note that even after controlling for confounding factors
(sex and years of experience) that IL-6R
was associated with a 3 times greater risk of concussion. It was surprising to
see APOE4 was associated with a
decreased risk of concussion, since previous researchers found it to be
associated with an increased risk of suffering from Alzheimer’s. Genetic
testing could allow medical professionals to determine if an athlete may be at
risk for poorer outcomes following a concussion. While this study had many
strengths it would be helpful if everyone was tested for the same genes/variations
and if they could verify these results in another cohort. Genetic testing in
athletes at risk for concussion should remain as part of research protocol, and
not for clinical decision making or guidance. In the meantime, clinicians can
use studies like this to educate patients about why some people may be more
susceptible to concussions.
Questions for Discussion:
Would you consider the use of genotypes
to provide athletes with information about his/her risk of injury or potential
outcomes following an injury?  If an athlete disclosed that he/she had a
genotype that made them more susceptible to an injury, what clinical course of
action might you take?
Written by: Jane McDevitt, PhD
Reviewed
by: Jeff Driban
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