Objectives Achilles tendinopathy (AT) is a multifactorial condition for which genetic risk factors have been identified. A pathway-based approach was used to investigate genes within the inflammatory pathway.
Methods Functional polymorphisms within IL-1β (−31T→C and −511C→T), IL-1RN (variable number tandem repeat) and IL-6 (−172G→C) were investigated for associations with AT in a South African (SA) and Australian (AUS) case–control studies. A total of 369 (161 SA and 208 AUS) asymptomatic control participants (CON) and 175 (90 SA and 85 AUS) participants with AT (TEN) were genotyped. Allele combinations were constructed using the above polymorphisms in combination with the COL5A1 BstUI RFLP.
Results Independently, no associations were observed between any of the polymorphisms tested and risk of TEN. The allele combinations of five polymorphisms were, however, found to have a highly significant relationship with AT (p=0.005), after adjusting for gender and country (SA or AUS).
Conclusions Variations within the interleukin genes and the COL5A1 BstUI CC genotype are collectively significantly associated with risk of AT. This research emphasises that a pathway-based genetic association study may be a more effective approach to capture and understand the genetic risk factors underlying the multifactorial conditions, such as AT.
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EN and KO'C contributed equally to this work
Funding This study was supported in part by funds from the National Research Foundation (grant numbers SUR2008060500012 and FA2005021700015), the South African Medical Research Council, the University of Cape Town and Discovery Health. The final preparation of this study for publication was supported in part by the International Olympic Committee (IOC) Research grant to the Clinical Sports Medicine Group of the UCT/MRC Research Unit for Exercise Science and Sports Medicine of the University of Cape Town. The authors, EN and KO'C, were awarded the grantholder-linked student support from the National Research Foundation (NRF) of South Africa (Grant SUR2008060500012).
Competing interests None.
Patient consent Obtained.
Ethics approval This study was conducted with the approval of the University of Cape Town, and the University of La Trobe and Deakin University
Provenance and peer review Not commissioned; externally peer reviewed.