Investigation of
Variants within the COL27A1 and TNC Genes and Achilles Tendinopathy in
Two Populations

CJ., van der Merwe L., Posthumus M., Cook J., Handley CJ., Collins M.,
September AV. Journal of Orthopaedic Research Month. 2012;

risk of developing Achilles tendinopathy is strongly related to intrinsic
factors such as an individual’s genes (genotype).  Previous research has found that 2 genes,
which encode proteins in the composition of tissue, may be associated to
Achilles tendinopathy (COL5A1 and TNC). COL27A1 is another gene in close
in proximity to both of those genes and provides instructions for a type of collagen.
Therefore, the purpose of this study was to view the association between the
risk of Achilles tendinopathy and several genetic variants (specifically, single nucleotide polymorphisms;SNPs),
including COL27A1 and TNC genes. The authors explored these
associations in two populations. The first population consisted of 131 South
African asymptomatic control participants and 94 South African participants
with diagnosed Achilles tendinopathy. The second population was 208 Australian
asymptomatic control participants and 85 Australian participants diagnosed with
Achilles tendinopathy. The authors evaluated (genotyped) four SNPs (rs4143245,
rs1249744, rs753085, rs946053) within COL27A1
and 3 SNPs (rs13321, rs 2104772, rs1330363) within TNC. The South African and Australian populations had similar genotypes
so the data from both cohorts were combined for further analysis. After that,
the authors found the presence of two SNPs in the TNC gene were different between participants diagnosed with
Achilles tendinopathy compared to the controls (rs2104772 and rs1330363). Specifically,
athletes that carry one variation within the TNC SNP rs2104772 (an A instead of the T allele) may be almost 10
times more likely to sustain an Achilles tendinopathy than those carrying the T
allele. This variant may change the amount of protein that is produced that is
responsible for tissue healing. 
Conversely, those carrying one variation within the TNC SNP rs1330363 (G instead of the C allele) were found to be 15
times less likely to develop Achilles tendinopathy compared to those carrying
the C allele. Furthermore, the inheritance of a cluster of SNPs (haplotype; rs946053-rs13321-rs2104772)
occurred more frequently in those diagnosed with Achilles tendinopathy compared
to controls. The authors found no other differences between those with and
without Achilles tendinopathy.

study helps to establish genetic factors that could increase the risk of
Achilles tendinopathy. These variations may influence how much protein is made
as well as the quality of the protein being produced. Due to the differences in
the proteins these variations could also lead to changes in how the proteins
interact with one another as well as protein-environmental interactions. These changes
could also compromise the wound healing and remodeling. This study further
implicates a specific region of the genome as contributing factor to one’s risk
for Achilles tendinopathy. If we can understand the functional implications of
these genetic variations we may be able to identify mechanisms of disease and
patients at increased risk for Achilles tendinopathy. This knowledge could also
help us develop individual programs for prevention and rehabilitation. This
study is a good example of genetic research being conducted in areas related to
sports medicine. Do you feel that genotyping may play an important role in
prevention and treatment of injuries?

by: Jane McDevitt, MS, ATC, CSCS
Jeffrey Driban

Related Posts:

Saunders CJ, van der Merwe L, Posthumus M, Cook J, Handley CJ, Collins M, & September AV (2012). Investigation of variants within the COL27A1 and TNC genes and Achilles tendinopathy in two populations. Journal of Orthopaedic Research PMID: 23192621