L van der Merwe

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.

Variants within the MMP3 gene are associated with Achilles tendinopathy: possible interaction with the COL5A1 gene

Objectives: Sequence variation within the COL5A1 and TNC genes are known to associate with Achilles tendinopathy. The primary aim of this case-control genetic association study was to investigate whether variants within the matrix metalloproteinase 3 (MMP3) gene also contributed to both Achilles tendinopathy and Achilles tendon rupture in a Caucasian population. A secondary aim was to establish whether variants within the MMP3 gene interacted with the COL5A1 rs12722 variant to raise risk of these pathologies. Methods: 114 subjects with symptoms of Achilles tendon pathology and 98 healthy controls were genotyped for MMP3 variants rs679620, rs591058 and rs650108. Results: As single markers, significant associations were found between the GG genotype of rs679620 (OR = 2.5, 95% CI 1.2 to 4.90, p = 0.010), the CC genotype of rs591058 (OR = 2.3, 95% CI 1.1 to 4.50, p = 0.023) and the AA genotype of rs650108 (OR = 4.9, 95% CI 1.0 to 24.1, p = 0.043) and risk of Achilles tendinopathy. The ATG haplotype (rs679620, rs591058, and rs650108) was under-represented in the tendinopathy group when compared to the control group (41% vs 53%, p = 0.038). Finally, the G allele of rs679620 and the T allele of COL5A1 rs12722 significantly interacted to raise risk of AT (p = 0.006). No associations were found between any of the MMP3 markers and Achilles tendon rupture. Conclusion: Variants within the MMP3 gene are associated with Achilles tendinopathy. Furthermore, the MMP3 gene variant rs679620 and the COL5A1 marker rs12722 interact to modify the risk of tendinopathy. These data further support a genetic contribution to a common sports related injury.

Matrix metalloproteinase genes on chromosome 11q22 and the risk of anterior cruciate ligament (ACL) rupture.

As matrix metalloproteinases (MMPs) are critical to ligament homeostasis and integrity, the aim of this study was to investigate whether four functional polymorphisms within four MMP genes, which cluster on chromosome 11q22 associate with risk of ACL ruptures. Three hundred and forty‐five [129 with ACL ruptures (ACL group) and 216 asymptomatic controls (CON group)] unrelated Caucasians were recruited for this case‐control study. Fifty‐four participants reported non‐contact mechanisms of ACL rupture (NON subgroup). All participants were genotyped for the MMP10 C/T rs486055, MMP1 1G/2G rs1799750, MMP3 G/A rs679620 and MMP12 A/G rs2276109 variants. After adjusting for sex, age and weight, the AG and GG genotypes of the MMP12 rs2276109 variant were significantly (P=0.030) under‐represented among the NON subgroup (14%), when compared with the CON group (26%). No other variants were significantly different between groups. Adjusted for the same confounders, the two four‐variant haplotypes T‐1G‐A‐A (CON 14%, ACL 9%, P=0.033) and C‐2G‐G‐G (CON 14%, NON 5%, P=0.021) were significantly different between the CON and the ACL groups, and the CON group and the NON subgroup, respectively. This is the first report that indicates an association between the chromosomal region 11q22 and the risk of ACL rupture.

Complete deficiency of the sixth complement component (C6Q0), susceptibility to Neisseria meningitidis infections and analysis of the frequencies of C6Q0 gene defects in South Africans

Complete complement component 6 deficiency (C6Q0) is a co‐dominant genetic disease presenting as increased susceptibility to invasive Neisseria meningitidis infections. Affected individuals have two affected alleles which can be homozygous or compound heterozygous for the particular gene defects they carry. This disorder has been diagnosed relatively frequently in Western Cape South Africans. Affected patients are prescribed penicillin prophylaxis. In 2004 we commenced a clinical follow‐up study of 46 patients. Of these, 43 had family age‐matched C6 sufficient controls. Participants were classified as either (i) well, or (ii) having a serious illness (SI) or died (D). An SI was a long‐term illness that did not allow the performance of normal daily activities. Among 43 patients, 21 were well and 22 were SI/D, while among 43 matched controls, 35 were well and eight were SI/D. This difference is highly significant. Among all 46 C6Q0 patients, those who had had recurrent infection had significantly more SI/D than those who had suffered none or one infection. Thus, this work demonstrates the long‐term serious outcome of repeated meningococcal disease (MD) episodes. We investigated the frequencies of four C6Q0 pathogenic mutations known to affect Cape patients (828delG, 1138delC, 821delA and 1879delG) in 2250 newborns. A total of 103 defective alleles (2·28%) and three affected C6Q0 individuals were detected. For all defects combined, 5·24 affected subjects (C6Q0) are expected among 10 000 individuals. What is still unknown is the number of C6Q0 individuals who suffer MD or other infectious diseases.

Investigation of glucocorticoid receptor polymorphisms in relation to metabolic parameters in Addison's disease

BACKGROUND Uncertainty exists whether glucocorticoid receptor (GCR) polymorphisms play a role in steroid-related side effects in Addisons disease (AD) patients on hydrocortisone. The polymorphisms Bcll and N363S appear to increase sensitivity to cortisol, while the ER22/23EK polymorphism has been associated with resistance to cortisol. METHOD One hundred and forty seven AD patients, and gender, and ethnicity-matched controls were recruited in South Africa. Three polymorphisms in the GCR were studied, using PCR followed by restriction fragment length analysis. Associations with BMI, lipids, glucose and inflammatory markers were investigated. RESULTS In both patients and controls, the Bcll polymorphism occurred more frequently in whites than in other ethnic groups studied but was not associated with any of the metabolic parameters tested. The ER22/23EK polymorphism was associated with an increased BMI in both patients (29.4 vs 24.7  kg/m²) and control subjects (26.3 vs 24.2  kg/m²). The ER22/23EK polymorphism was also associated with lower LDL cholesterol in control subjects (3.46 vs 3.93  mmol/l) and in patients (3.52 vs 4.10  mmol/l). N363S was associated with increased BMI in controls 29.9  kg/m² vs wild type 24.8  kg/m². Median hydrocortisone doses were greater in patients heterozygous for either ER22/23EK 30.0  mg or N363S 25.0  mg polymorphisms than in wild type patients 20.0  mg (both comparisons). CONCLUSION Alterations in lipids, BMI and hydrocortisone dose were associated with two polymorphisms. Further larger studies are warranted to corroborate these findings.

Matrix metalloproteinase genes on chromosome 11q22 and the risk of anterior cruciate ligament (ACL) rupture

Background Anterior cruciate ligament (ACL) rupture is a complex disorder for which several risk factors, including genetic factors, have been established. Objective As matrix metalloproteinases (MMPs) are critical to ligament homeostasis and integrity, the primary aim of this study was to investigate if four selected polymorphisms within four MMP genes, which cluster on chromosome 11q22, associate with risk of ACL ruptures. Methods 343 (138 individuals with ACL ruptures (ACL group) and 215 asymptomatic controls (CON group)) unrelated Caucasians were recruited for this case-control genetic association study. The ACL group included 54 participants with a non-contact mechanism of ACL rupture (NON- subgroup). All participants were genotyped using fluorescence-based assays, for the four selected functional polymorphisms; namely the MMP10 C/T rs486055, MMP1 1G/2G rs1799750, MMP3 G/A rs679620 and MMP12 A/G rs2276109 variants. Results When adjusted for sex, age and weight, the AG and GG genotypes of the MMP12 rs2276109 variant were significantly (p=0.030) under-represented among the NON-subgroups (14%), when compared to the CON group (26%). No other variants were significantly different between groups. In addition, when adjusted for the same confounders, the four variant haplotypes T-1G-A-A (CON 14%, ACL 9%, p=0.033) and C-2G-G-G (CON 14%, NON 5%, p=0.021) were significantly different between the CON group and the ACL group, as well as the CON and NON sub-group, respectively. Conclusion This study reports for the first time that the chromosomal region 11q22 is associated with risk of ACL rupture. The genetic risk profile reported in this study, together with genetic risk factors previously associated, and those yet to be identified, should in the future be included in multifactorial models designed to reduce the incidence of ACL rupture within ‘at-risk’ populations. Further research is required to replicate these findings in an independent population.

AN ASSOCIATION BETWEEN COMPONENTS OF THE APOPTOSIS PATHWAY AND THE GENETIC PREDISPOSITION TO ACHILLES TENDINOPATHY

Introduction Achilles tendinopathy is a degenerative condition for which several risk factors have been implicated including components of the inflammatory pathway. The aims of this study was to evaluate (i) several functional variants within genes encoding components of the apoptosis signalling cascade and (ii) the effectiveness of a polygenic apoptosis profile to capture Achilles tendinopathy (TEN) risk. Methods A total of 358 unaffected control (CON) participants (159 South Africa (SA CON) and 199 Australia (AUS CON)) and 166 affected 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 TEN and a receiver operator characteristic (ROC) curve was plotted to determine the effectiveness of the models to capture TEN risk. Results An independent association of CASP8_rs1045485 and CASP8_rs3834129, together with their haplotype was observed with TEN risk. The optimal risk model identified from the study included the two CASP8 genetic loci investigated (CASP8_rs384129 and CASP8_rs1045485) together with sex to capture TEN risk in both SA and AUS participants collectively. Conclusions These findings further implicate the apoptosis signalling cascade as one of the important biological pathways involved in the development of Achilles tendinopathy.