MMP-8 polymorphism is genetic
marker to tendinopathy primary posterior tibial tendon

A, Ortiz RT, Mattar Junior R, Fernades TD, Santos MCL. Scand J Med Sci Sports .
2012; 39(11): 2319-2324
Posterior tibial

effects many people, especially females, and has several distinctive
predisposing risk factors (e.g., flat foot, presence of accessory navicular
bone, or impact of osteofibrous tunnel). However, many patients present with
posterior tibial tendinopathy without any of the distinctive risk factors,
which suggests there could be a genetic influence associated with patients being
more prone to this injury. For example, if there is a genetic variation within
the gene for MMP-8 (a proteinase that
stimulates protein degradation) then the quantity or quality of the MMP-8
protein could be altered. Godoy-Santos et al. examined whether a specific
genetic variation of the MMP-8 gene (-799 polymorphism in the promoter region of the gene)
was associated with posterior tibial tendinopathy. This study included 150
women patients that were divided into 2 groups: 1) a control group (n = 100),
which consisted of women who had normal posterior tibial tendons (based on
magnetic resonance imaging) with no signs of degeneration, and 2) a test group
(n = 50) with women who were undergoing a surgical procedure due posterior
tendon degeneration. Every participant gave a DNA sample via buccal cells (cells
on the cheek), which was genotyped for their MMP-8 polymorphism. They could
have had the C/C, T/T or C/T genotype
(which means there could be three genetic patterns at this location)
. Furthermore, the
researchers assessed the distribution of specific alleles (genotype data
explains the genetic sequence or code for a gene or protein, where allelic
variation can measure the frequency of a polymorphism at a specific site). The
analysis showed that T/T genotype was more frequent in the test group (46% vs 23%)
and the C/C genotype was more frequent in the control group (67% vs 19%). There
was no significant difference between the 2 groups in regards to the C/T
genotype. There was also a significant difference in the frequency of the
alleles. The T allele was significantly more frequent in the test group (54% vs
28%) and the C allele was significantly more frequent in the control group (72%
vs 46%). This suggests that there may be a genetic association to posterior
tibial tendinopathy.

are some people more susceptible to injuries than others? This question could
be answered via intrinsic factors such as genetics. If a patient carries a
different allele (genetic variation) this could alter their proteins. This
could then make the patient more susceptible to an injury (or it could protect
against an injury as well). In this study, participants with the T/T genotype
were more likely to have a posterior tibial tendinopathy, whereas those
carrying the C/C genotype were not as susceptible. This suggests that the T allele
could be a risk factor for developing degenerative posterior tibial tendinopathy
and the C allele could be a potential protective factor against developing
degenerative posterior tibial tendinopathy. While this MMP-8 promoter
polymorphism may be associated with posterior tibial tendinopathy it cannot be
ruled out that there are many other genes that may be associated to posterior
tibial tendinopathy. Knowing the genotype of a person could assist medical
personnel in more specific treatment leading to better outcomes such as better exercise/rehabilitation
programs to prevent degeneration. Do you think knowing genetic variations associated
to injuries and diseases will help us develop more specific therapeutic agents
and rehabilitation plans to promote patient recovery?

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

Related Posts:

Godoy-Santos A, Ortiz RT, Junior RM, Fernandes TD, & Santos MC (2012). MMP-8 polymorphism is genetic marker to tendinopathy primary posterior tibial tendon. Scandinavian Journal of Medicine & Science in Sports PMID: 22487237