The MMP3 gene in musculoskeletal soft tissue injury risk profiling: A study in two independent sample groups.

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.

Are genes encoding proteoglycans really associated with the risk of anterior cruciate ligament rupture?

Proteoglycans are considered integral structural components of tendon and ligament and have been implicated in the resistance of compressive forces, collagen fibrillogenesis, matrix remodelling and cell signalling. Several sequence variants within genes encoding proteoglycans were recently implicated in modulating anterior cruciate ligament ruptures (ACLR). This study aimed to test the previously implicated variants in proteoglycan and vascular epithelial growth factor encoding genes with risk of ACLR in a population from Poland. A case control genetic association study was conducted using DNA samples from 143 healthy participants without a history of ACL injuries (99 male and 44 females) (CON group) and 229 surgically diagnosed ACLR participants (158 males and 71 females). All samples were genotyped for the ACAN: rs1516797, BGN: rs1042103, rs1126499, DCN: rs516115 and VEGFA: rs699947 variants. Main findings included the (i) ACAN rs1516797 G/T genotype which was underrepresented in the CON group (CON: 36%, n=52, ACLR: 49%, n=112, p=0.017, OR=1.68, 95% CI 1.09 to 2.57) when all participants were investigated and (ii) the BGN rs1042103 A allele was significantly under-represented in the male CON group compared to the male ACLR group (CON: 39%, n=78, ACLR: 49%, n=156, p=0.029, OR=1.5, 95% CI 1.05 to 2.15). Furthermore, BGN inferred haplotypes were highlighted with altered ACLR susceptibility. Although the study implicated the ACAN and BGN genes (combination of genotype, allele and haplotype) in modulating ACLR susceptibility, several differences were noted with previous published findings.

AVPR2 gene and weight changes during triathlons.

The arginine vasopressin receptor 2 (AVPR2) plays an important antidiuretic role in regulating water balance to maintain osmotic equilibrium. The aim of this study was to determine if there were any associations between single nucleotide polymorphisms (SNPs), within the AVPR2 gene, and changes in serum sodium concentrations and/or body weight (BW) in Ironman triathletes. Caucasian male triathletes who completed either the 2000, 2001 or 2006 South African Ironman Triathlons were genotyped (n=570) for at least one SNP. Pre- and post-race serum [Na+] (pre n=514; post n=423) and BWs (pre n=556; post n=552) were measured. Triathletes were divided into 3 groups according to their relative BW loss during the triathlon (BW loss of 0-3, 3-5 and >5%). There was a significant linear trend (p=0.010, x2=6.7) for the distribution of minor haplotypes GCT, GTC and GCC across the 3 BW loss groups. The >5% group had the highest percentage (4.7%) of triathletes with minor haplotypes followed by the 3-5% (3.6%) and 3-0% (0%) groups. In conclusion, the minor haplotype constructs of AVPR2 SNPs were associated with larger BW losses during the Ironman Triathlons. This finding supports a possible genetic contribution to BW loss during endurance exercise events acting through the argine vasopression system.

Expression levels of selected cytokines and microRNAs in response to vitamin D supplementation in ultra-marathon runners.

Ultra-marathon (UM) running is an extreme endurance exercise. However, the mechanisms triggered with its practice remain unclear. While it is documented that strenuous physical activity activates immune responses and vitamin D plays a role in immune system suppression, data on the relationship between vitamin D status and cytokine profile in athletic populations are limited. To analyse the relative mRNA expression levels of selected pro-inflammatory cytokines (IL-1ß, IL-6, IL-8, IL-17, TNF-α), COX-2, vitamin D receptor and abundance of selected inflammatory microRNAs (Hsa-miR-21, -miR-146a, -miR-150, -miR-155, -miR-222, -miR-223) before and after a 100 km race in amateur runners in the presence or absence of vitamin D supplementation. Twenty runners aged 36-40years were divided into two groups: with and without vitamin D3 supplementation (10,000units daily). Blood samples were collected before and 12 h after the UM. The mRNA expression levels of selected cytokines, COX-2 and VDR in peripheral blood and abundance of serum exosomal miRNAs were investigated using q-RT-PCR. After UM, the significant up-regulation of TNF-α and hsa-miR-155 and down-regulation of IL-1ß were observed in the group with vitamin D supplementation. In its absence, hsa-miR-155 and -miR-223 were significantly up-regulated. Additionally, a reverse correlation was observed between IL-6 expression level and abundance of hsa-miR-155 and -miR-223 in both groups. No statistical differences were noted when the other miRNAs and genes were examined in the groups and at the time points. The UM-induced mRNA expression pattern of pro-inflammatory cytokines could be influenced by vitamin D supplementation and/or miRNA.

The COL5A1 genotype is associated with range of motion measurements.

There is an interest in identifying the intrinsic risk factors, including altered musculotendinous flexibility, that may be associated with musculotendinous injuries. We have recently shown that a sequence variant, namely the BstUI restriction fragment length polymorphism (RFLP), within the COL5A1 gene is associated with chronic Achilles tendinopathy. Mutations within COL5A1 have been implicated in Ehlers Danlos syndrome, a condition that is characterized by joint hypermobility. The aim of this study was to investigate the association of sequence variants within COL5A1 and musculotendinous range of motion (ROM). The sit and reach (SR) and the passive straight leg raise (SLR) were measured on 119 Caucasian subjects with either a past, current or no history of Achilles tendon injuries. The subjects were genotyped for four sequence variants within the 3'-UTR of the COL5A1 gene. Gender (P=0.016), age (P=0.011) and the BstUI RFLP (P=0.010) jointly contributed significantly to the optimal SLR model which accounted for 19.3% of the variance. The factors contributing significantly to SR, which accounted for 28.8% of the variance, were weight (P=0.004), age (P<0.001) and the BstUI RFLP (P=0.001). These data suggest that the COL5A1 BstUI RFLP is independently associated with lower limb ROM within the cohort investigated in this study.

Variants within the COL5A1 gene are associated with Achilles tendinopathy in two populations.

OBJECTIVES: A COL5A1 gene variant was shown to be associated with chronic Achilles tendinopathy in a South African population. The aim of this case-control genetic association study was to investigate the BstUI and DpnII restriction fragment length polymorphisms (RFLP) in a second population from Australia and to identify a predisposing haplotype for Achilles tendinopathy in both populations. METHODS: 85 Australian and 93 South African patients with tendinopathy, as well as 210 Australian and 132 white South African control subjects were genotyped for the BstUI (rs12722) and DpnII (rs13946) RFLP, as well as markers rs10858286, rs3196378, rs11103544, rs4504708 and rs3128575. RESULTS: The BstUI RFLP (p<0.001) and marker rs3196378 (p = 0.016) were associated with chronic Achilles tendinopathy in Australian subjects. Individuals within both populations with a CC genotype for the BstUI RFLP had a significantly decreased risk of developing tendinopathy versus any other genotypes (Australian odds ratio 0.42, 95% CI 0.20 to 0.86, p = 0.017). The TC inferred haplotype (rs12722, rs3196378) was found to be overrepresented (global p = 0.008) in the South African tendinopathy group compared with all other haplotypes. CONCLUSION: The BstUI RFLP is associated with chronic Achilles tendinopathy in a second population and a region within the COL5A1 3' untranslated region may predispose individuals to an increased risk of developing chronic Achilles tendinopathy.

Genetic risk factors for anterior cruciate ligament ruptures: COL1A1 gene variant.

BACKGROUND: Anterior cruciate ligament (ACL) ruptures are considered the most severe injury sustained in sports. Although various intrinsic and extrinsic risk factors have been identified, the exact aetiology of the injury is not yet fully understood. Recently, the gene encoding for the alpha1 chain of type I collagen (COL1A1) has been shown to be associated with cruciate ligament ruptures and shoulder dislocations. OBJECTIVE: To determine whether the functional Sp1 binding site polymorphism within intron 1 of the COL1A1 gene is associated specifically with ACL ruptures in an independent population. METHODS: 117 Caucasian participants with surgically diagnosed ACL ruptures, and 130 Caucasian physically active controls without any history of previous ligament or tendon injuries were recruited for this case-control genetic association study. All participants were genotyped for the COL1A1 Sp1 binding site polymorphism (G/T; rs1800012). RESULTS: The rare TT genotype was significantly (p = 0.031, OR = 0.08, 95% CI <0.01 to 1.46) under-represented in the ACL group (0 out of 117, 0%), compared with the controls (6 out of 130, 4.6%). CONCLUSION: The TT genotype of the COL1A1 Sp1 binding site polymorphism was significantly under-represented in South African participants with ACL ruptures. We propose that this sequence variant be the first specific genetic element to be included in multifactorial models developed to understand the aetiology and risk factors for ACL rupture.

Inherited retinal disorders in South Africa and the clinical impact of evolving technologies.

Retinal degenerative disorders (RDDs) encompass a group of inherited diseases characterised by vision loss. The genetic and clinical complexity poses a challenge in unravelling the molecular genetic aetiology of this group of disorders. Furthermore, the population diversity in South Africa (SA) presents researchers with a particularly complicated task. Rapid advances in the development of cutting-edge technological platforms over the past two decades, however, have assisted in overcoming some of the challenges. The RDD research team has utilised these escalating technologies, which has facilitated a corresponding increase in molecular diagnoses. A biorepository has been established and comprises ~3 200 patient DNA samples archived with many forms of RDD (including retinitis pigmentosa, macular dystrophies, Stargardt disease, Leber congenital amaurosis, Usher syndrome and Bardet Biedl syndrome). A comprehensive review is presented of the SA journey spanning 25 years, into elucidating the molecular genetic basis of various forms of RDD in SA.

Application of genomics in the prevention, treatment and management of Achilles tendinopathy and anterior cruciate ligament ruptures.

Musculoskeletal soft tissue injuries such as Achilles tendinopathy and anterior cruciate ligament ruptures are common among elite athletes, recreational athletes and physically active individuals. The consequences of injury may be devastating and prevent the recreational or competitive athlete from reaching their potential or lead to a premature end to their careers. Although these injuries have been well described at a clinical level, the biological mechanisms causing these injuries are poorly understood. A further understanding of the biological mechanisms underlying the injury will assist the treatment and management of these injuries. In addition, understanding the biology is an important prerequisite in developing models that can be used to effectively identify risk, as well as, implement personalized prevention, treatment and rehabilitation programmes. Both intrinsic, including genetic variants, and extrinsic risk factors have nevertheless been implicated in the aetiology of these injuries. To date, several patents have been filed which involve the use of specific polymorphisms and regions within specific genes to be used in a genetic test for either tendon or ligament injury risk. The objective of this manuscript will be to review the evidence for the genetic predisposition to soft tissue injury, as well as the application of this data in the prevention, treatment and management of musculoskeletal soft tissue injuries.

The COL12A1 and COL14A1 genes and Achilles tendon injuries.

Genes encoding for tenascin C and a subunit of type V collagen have previously been reported to be associated with Achilles tendon injuries. Types XII and XIV collagen may be involved in similar biological processes as these proteins in tendons. The aim of this study was therefore to test the association between polymorphisms within COL12A1 and COL14A1 and Achilles tendon injuries. Restriction fragment length polymorphism (RFLP) analysis was used to identify the relative frequencies of two polymorphisms within each of the COL12A1 and COL14A1 genes within 137 subjects with clinical symptoms of Achilles tendon injuries, consisting of 93 with Achilles tendinopathy and 44 with Achilles tendon rupture, and 131 asymptomatic control subjects. No statistically significant differences were identified in the genotype, allele or haplotype distributions between the affected and control subjects. The findings from this study suggest that although COL12A1 and COL14A1 are involved in similar biological processes as TNC and COL5A1, the polymorphisms tested are not associated with clinical symptoms of Achilles tendon injury within the investigated population.

No association of the ACTN3 gene R577X polymorphism with endurance performance in Ironman Triathlons.

Alpha-actinins are major structural components of the Z-discs in skeletal muscle. Alpha-actinin 3 is encoded by the ACTN3 gene and is expressed only in type II muscle fibres. Homozygosity for the nonsense mutation, 577X, within ACTN3 results in deficiency of alpha-actinin-3 but does not result in an abnormal muscular phenotype. Previous research has found an association of the 577R allele with sprinting and/or power performance. It has also been suggested that the 577X allele may confer an advantage during endurance events. Four hundred and fifty seven Caucasian male triathletes who completed either the 2000 and/or 2001 226 km South African Ironman Triathlons, and 143 Caucasian controls, were genotyped for the R577X mutation within the ACTN3 gene. There were no significant differences in either the genotype (P = 0.486) or allele (P = 0.375) frequencies within the fastest, middle of the field or slowest Caucasian male finishers and the control population. In conclusion, the R577X polymorphism within the ACTN3 gene was not associated with ultra-endurance performance in the 2000 and 2001 South African Ironman Triathlons.