The guanine-thymine dinucleotide repeat polymorphism within the tenascin-C gene is associated with achilles tendon injuries.
BACKGROUND
Although there is a high incidence of tendon injury as a result of participation in physical activity, the mechanisms responsible for such injuries are poorly understood. Investigators have suggested that some people may have a genetic predisposition to develop tendon injuries; in particular, genes on the tip of the long arm of chromosome 9 might, at least in part, be associated with this condition. The tenascin-C gene, which has been mapped to chromosome 9q32-q34, encodes for a structural component of tendons.


OBJECTIVE
The tenascin-C gene is associated with Achilles tendon injury.


METHODS
Case control study; Level of evidence, 3.


METHODS
A total of 114 physically active white subjects with symptoms of Achilles tendon injury and 127 asymptomatic, physically active white control subjects were genotyped for the guanine-thymine dinucleotide repeat polymorphism within the tenascin-C gene.


RESULTS
A significant difference in the allele frequencies of this polymorphism existed between the 2 groups of subjects (chi(2) = 51.0, P = .001). The frequencies of the alleles containing 12 repeats (symptomatic group, 18.9% vs control group, 10.2%) and 14 repeats (symptomatic group, 9.2% vs control group, 0.8%) were significantly higher in the symptomatic group, while the frequencies of the alleles containing 13 repeats (symptomatic group, 8.8% vs control group, 24.0%) and 17 repeats (symptomatic group, 7.5% vs control group, 20.1%) were significantly lower in this same group. Subjects who were homozygous or heterozygous for the underrepresented alleles (13 and 17 repeats) but who did not possess an overrepresented allele (12 and 14 repeats) may have a lower risk of developing Achilles tendon injuries (odds ratio, 6.2; 95% confidence interval, 3.5-11.0; P < .001).


CONCLUSIONS
The guanine-thymine dinucleotide repeat polymorphism within the tenascin-C gene is associated with Achilles tendon injury. Alleles containing 12 and 14 guanine-thymine repeats were overrepresented in subjects with tendon injuries, while the alleles containing 13 and 17 repeats were underrepresented.


CONCLUSIONS
Persons who have variants of the tenascin-C gene with 12 and 14 guanine-thymine repeats appear to have a 6-fold risk of developing Achilles tendon injuries.
UCT/MRC Research Unit for Exercise Science and Sports Medicine, University of Cape Town, PO Box 115, Newlands 7725, South Africa.
Gaonyadiwe G
GG
Mokone
Mamta
M
Gajjar
Alison V
AV
September
Martin P
MP
Schwellnus
Jacquie
J
Greenberg
Timothy D
TD
Noakes
Malcolm
M
Collins
D000125:Achilles Tendon / Q000293:injuries*; D000328:Adult; D015415:Biomarkers; D016022:Case-Control Studies; D018900:Dinucleotide Repeats / Q000235:genetics; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease; D006147:Guanine; D006801:Humans; D008875:Middle Aged; D011110:Polymorphism, Genetic; D012421:Rupture; D019063:Tenascin / Q000235:genetics*; D013941:Thymine
D015415:Biomarkers; D019063:Tenascin; D006147:Guanine; D013941:Thymine