Genes encoding proteoglycans are
associated with the risk of anterior cruciate ligament ruptures

S, Mtintsilana A, Posthumus M, van der Merwe W, Hobbs H, Collins M, &
Septemeber AV.  British Journal of Sports Medicine. 
2014 Published Online First: doi: 10.1136/bjsports-2013-093201

Take Home Message: Individuals with
a history of an anterior cruciate ligament injury are more likely to have
certain genetic variations compared with individuals without a history of a
knee injury. While these findings are novel and interesting, researchers need
to conduct more research to understand the multifactorial genetic risk behind
anterior cruciate ligament injuries.  

If we could identify factors that may
predict who is at an increased risk for anterior cruciate ligament (ACL) rupture
then we may be able to implement individualized injury prevention programs.  Genetic variants may change ligamentous
properties, predispose an individual to an ACL rupture, and thus be an
important risk factor for an ACL rupture. 
Mannion and colleagues compared the presence of genetic variations between
227 individuals with an ACL rupture history and 234 healthy controls.  All of the participants were physically
active and Caucasian. The authors also analyzed a subset of 126 individuals
with a history of a noncontact ACL rupture. 
They evaluated 10 genetic variants (single nucleotide polymorphisms)
among 5 genes that encode proteoglycans, which influence the structural
integrity of ligaments. Individuals with a history of ACL injury (34%) were
more likely to have a genetic variation in a gene encoding aggrecan, a
proteoglycan, compared with healthy controls (28%).  Females with a history of an ACL injury were
also more likely to have variations in the gene encoding decorin, another
proteoglycan, compared with female healthy controls. 

This is one of the first studies to
investigate and identify genetic variations that may be related to a history of
an ACL injury.  These findings help us understand
that an ACL may be at more risk for injury due to changes in proteoglycans,
which may alter the ligament’s tensile threshold.  At this point in time, this does not directly
affect clinical treatments; however, these findings could inspire new
interventions to address changes in proteoglycans and eventually help us
identify individuals “at-risk” for an ACL injury.  This may help us prevent injuries by
identifying athletes at risk and offering them individualized injury prevention
programs.  While the authors showed that
genetics may influence the risk of ACL injuries, it only focused on 10
variations of 5 genes.  Since the risk of
an ACL injury is likely influenced by many genes, it may be advantageous to
conduct genome-wide studies to encompass all of the possible genes and
variations that influence the risk of ACL injury. We have repeatedly seen that
genetic variations may influence the risk of injury and that it could influence
how we practice but we’ll need to watch this area of research carefully to see how
it unfolds.    

Questions for Discussion:  Do
you think that genetic testing will change the future of athletic participation
(e.g., prevention programs, withheld from certain sports)?  What if you had a patient or family member
who tested positive for a genetic variation that made them more susceptible to
an injury – would you still permit them to participate in activities that made
the risk higher? 
by: Nicole Cattano
by: Jeffrey Driban

Related Posts:

Mannion, S., Mtintsilana, A., Posthumus, M., van der Merwe, W., Hobbs, H., Collins, M., & September, A. (2014). Genes encoding proteoglycans are associated with the risk of anterior cruciate ligament ruptures British Journal of Sports Medicine DOI: 10.1136/bjsports-2013-093201