Quoted TextThe prevalence of rupture of the Achilles tendon has been shown to be greater in patients who have blood group O, at least among Hungarians80 and in some Finns99. These findings have not been confirmed in other studies128 even when the same ethnic groups were involved105. We were not able to prove an association with blood group in our area of Scotland, which has a high incidence of rupture of the Achilles tendon152.
The Guanine-Thymine Dinucleotide Repeat Polymorphism Within the Tenascin-C Gene Is Associated With Achilles Tendon Injuries
Gaonyadiwe G. Mokone, BSc(Med)(Hons)*, Mamta Gajjar, BSc , , Alison V. September, PhD , Martin P. Schwellnus, MBChB, MD*, Jacquie Greenberg, PhD , Timothy D. Noakes, MBChB, MD, DSc(Med)* and Malcolm Collins, PhD ,||
From the * UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa, the Division of Human Genetics, Department of Clinical Laboratory Sciences, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa, and the || Medical Research Council of South Africa, Tygerberg, South Africa
Address correspondence to Malcolm Collins, PhD, UCT/MRC Research Unit for Exercise Science and Sports Medicine, University of Cape Town, PO Box 115, Newlands 7725, South Africa (e-mail: email@example.com ).
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.
Hypothesis: The tenascin-C gene is associated with Achilles tendon injury.
Study Design: 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 ( 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.
Clinical Relevance: 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.
Key Words: genetics • tendinopathy • rupture • risk factor