Angiogenesis-associated signaling is a fundamental component in the remodeling of the extracellular matrix in response to loading. Genes encoding protein components within this signaling cascade are therefore suitable candidates for investigation into ACL injury susceptibility: namely, vascular endothelial growth factor A isoform (VEGFA), kinase insert-domain receptor (KDR), nerve growth factor (NGF), and hypoxia inducible factor-1α (HIF1A). A case-control genetic association study was conducted on 227 asymptomatic control participants and 227 participants with surgically diagnosed ACL ruptures of which 126 participants reported a non-contact mechanism of rupture. All participants were genotyped for seven polymorphisms within the four genes. The VEGFA rs699947 CC genotype (p = 0.010, OR: 1.92, 95% CI: 1.17–3.17) was significantly over-represented within participants with non-contact ACL ruptures. The VEGFA rs1570360 GA genotype was significantly over-represented in the CON group (p = 0.007, OR: 1.70, 95% CI: 1.16–2.50). Furthermore, the KDR rs2071559 GA genotype was significantly over-represented in the female controls (p = 0.023, OR: 2.16, 95% CI: 1.11–4.22). Inferred haplotype analyses also implicated genomic regions spanning the VEGFA and KDR genes. These novel findings suggest that regions within VEGFA and KDR may be implicated in the pathophysiology of ACL ruptures; highlighting the potential biological significance of angiogenesis-associated signaling in the aetiology of ACL ruptures. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:1612–1618, 2014.

Achilles tendinopathy (AT) is a degenerative condition for which several risk factors have been implicated including components of the inflammatory pathway. The aim was to assess functional variants within genes encoding components of the apoptosis signaling cascade and the effectiveness of a polygenic apoptosis profile to capture tendinopathy (TEN) risk. A total of 358 unaffected control (CON) participants [159 South Africa (SA CON) and 199 Australia (AUS CON)] and 166 affected AT (TEN) participants (87 SA TEN and 79 AUS TEN) were genotyped for four variants [CASP8 (rs384129), CASP8 (rs1045485), NOS3 (rs1799983), and NOS2 (rs2779249)]. Logistic regression was used to derive risk models for AT. A receiver operator characteristic (ROC) curve was plotted to determine the effectiveness of a model to capture AT risk. This study indicates the independent association of CASP8_rs1045485 and CASP8_rs3834129 as well as their haplotype with AT risk and the identification of an optimal model which included genetic loci CASP8_rs384129 and CASP8_rs1045485 together with sex to capture AT risk in both SA and AUS. Collectively, these results further implicate the apoptosis signaling cascade as one of the biological pathways involved in the development of AT. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1719–1724, 2012

The TNC gene has previously been associated with Achilles tendinopathy (AT) in a South African population. The aims of this study were (i) to investigate the association of single nucleotide polymorphisms within the TNC gene, and the additional candidate gene, COL27A1, with AT in two populations, and (ii) to identify if there is a risk haplotype for AT in both populations. Three hundred and thirty nine healthy control participants (CON) and 179 participants clinically diagnosed with AT (TEN) from South Africa and Australia, were genotyped for variants: rs4143245, rs1249744, rs753085, rs946053 (COL27A1) and rs13321, rs2104772, rs1330363 (TNC). Haplotypes were inferred using the genotype data. The rs2104772 (p = 0.017) and rs1330363 (p = 0.020) variants within TNC showed a significant allele association with AT. The GCA haplotype (rs946053‐rs13321‐rs2104772) occurred significantly more frequently in TEN participants compared to CON (27% vs. 18%; p = 0.019). This study further implicates the genomic region containing the TNC and COL27A1 genes in influencing risk of AT, and maps the potential risk allele to a genetic interval flanked by rs946053 and rs2104772. This region may have functional effects on the transcription, structure and properties of tenascin‐C and the alpha‐1 chain of type XXVII collagen. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31: 632–637, 2013

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 withinIL-1β(−31T→C and −511C→T),IL-1RN(variable number tandem repeat) andIL-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 theCOL5A1 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 theCOL5A1 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.

Matrix metalloproteinase-3 (MMP3) is a mediator of matrix remodelling and a proposed susceptibility locus in the genetic profile of musculoskeletal soft tissue injuries. Therefore, this study aimed to validate the MMP3 gene as a risk marker for these injuries by conducting a case control genetic association study in two independent samples groups. Three previously investigated MMP3 variants (rs679620, rs591058 and rs650108) in addition to the functional promoter variant (rs3025058) were genotyped in 195 Australian control participants and 79 Australian individuals with chronic Achilles tendinopathy. Similarly, 234 South African individuals with acute anterior cruciate ligament ruptures and 232 matched control participants were also analysed. Based on high linkage with the previously associated MMP3 variant rs679620, rs3025058 was inferred and found to be associated with increased risk for Achilles tendinopathy within the South African group (P = 0.012; OR: 2.88; 95% CI: 1.4 to 6.1). Lastly, the 6A-G-C-G haplotype, constructed from the investigated variants, was significantly associated with reduced risk for Achilles tendinopathy (29% CON vs. 20% TEN, P = 0.037) in the Australian group. In conclusion, a signal surrounding MMP3 is apparent with respect to Achilles tendinopathy. However, whether the investigated variants are contributing to injury susceptibility or whether they are merely linked to the risk conferring variants mapping elsewhere within the MMP gene cluster on chromosome 11, still requires refining.

Several genetic loci have been associated with risk of Achilles tendon pathology (ATP) within South African and Australian populations. The aim of this study was, therefore, to evaluate eight previously implicated genetic variants in an independent British population. A total of 130 asymptomatic controls (CON) and 112 participants clinically diagnosed with ATP comprising 87 individuals with chronic Achilles tendinopathy (TEN) and 25 with Achilles tendon ruptures (RUP) were included. All participants were genotyped for variants within the COL5A1, MIR608, IL-1β, IL-6 and CASP8 genes. Primary findings implicated COL5A1 and CASP8. Three inferred allele combinations constructed from COL5A1 rs12722, rs3196378 and rs71746744 were identified as risk modifiers. The T–C–D combination was associated with increased risk of ATP (P = 0.023) and RUP (P < 0.001), the C–A–I combination was associated with increased risk of ATP (P = 0.011), TEN (P = 0.011) and RUP (P = 0.011) and the C–C–D combination was associated with decreased risk of ATP (P = 0.011) and RUP (P = 0.004). The CASP8 rs3834129 DD genotype was associated with decreased risk of TEN (P = 0.020, odds ratio: 0.45, 95% confidence interval: 0.22–0.90) and the CASP8 I–G (rs3834129–rs1045485) inferred allele combination was associated with increased risk of TEN (P = 0.031). This study further highlights the importance of polymorphisms within COL5A1 and CASP8 in the aetiology of ATP.