The COL5A1 gene is associated with increased risk of carpal tunnel syndrome

Carpal tunnel syndrome

Median neuropathy at the wrist, commonly referred to as carpal tunnel syndrome (CTS), is the most common entrapment neuropathy. It is caused by chronic compression of the median nerve at the wrist within the space-limited carpal tunnel. Risk factors that contribute to the etiology of compression include female gender, obesity, work-related factors, and underlying medical conditions, such as hypothyroidism, pregnancy, and amyloidosis. The diagnosis is made on clinical grounds, although these can be confounded by anatomical variations. Electrodiagnostic studies, which are specific and sensitive in diagnosing CTS, support the diagnosis; however, a subgroup may present with normal results. The advent of imaging techniques, including ultrasound and MRI, further assists the diagnostic process. The management of CTS is divided into the nonsurgical approaches that include hand therapy, splinting and corticosteroid injection, and surgical decompression of the carpal tunnel. Although several surgical techniques have been developed, no one method is more effective than the other. Each of these management approaches are effective at providing symptom relief and are utilized at different severities of the condition. There is, however, a lack of consensus on standardized diagnostic criteria, as well as when and to whom to refer patients for surgery.

Are commercial genetic injury tests premature?

INTRODUCTION

Several direct-to-consumer (DTC) genetic testing companies have emerged that claim to be able to test for susceptibility for musculoskeletal injuries. Although there are several publications on the emergence of this industry, none have critically evaluated the evidence for the use of genetic polymorphisms in commercial tests. The aim of this review was to identify, where possible, the polymorphisms and to evaluate the current scientific evidence for their inclusion.

RESULTS

The most common polymorphisms included COL1A1 rs1800012, COL5A1 rs12722, and GDF5 rs143383. The current evidence suggests that it is premature or even not viable to include these three polymorphisms as markers of injury risk. A unique set of injury-specific polymorphisms, which do not include COL1A1, COL5A1, or GDF5, identified from genome-wide association studies (GWAS) is used by one company in their tests for 13 sports injuries. However, of the 39 reviewed polymorphisms, 22 effective alleles are rare and absent in African, American, and/or Asian populations. Even when informative in all populations, the sensitivity of many of the genetic markers was low and/or has not been independently validated in follow-up studies.

CONCLUSIONS

The current evidence suggests it is premature to include any of the reviewed polymorphisms identified by GWAS or candidate gene approaches in commercial genetic tests. The association of MMP7 rs1937810 with Achilles tendon injuries, and SAP30BP rs820218 and GLCCI1 rs4725069 with rotator cuff injuries does warrant further investigation. Based on current evidence, it remains premature to market any commercial genetic test to determine susceptibility to musculoskeletal injuries.

β2-Microglobulin Elevates COL5A1 mRNA in the Subsynovial Connective Tissue of Patients Receiving Hemodialysis With Carpal Tunnel Syndrome

Background Although carpal tunnel syndrome (CTS) is frequently observed in patients undergoing long-term hemodialysis (HD), exactly how CTS arises is unknown. Here, we examined levels of COL5A1 in the subsynovial connective tissue (SSCT) of patients receiving HD and studied its potential regulation by β2-microglobulin (Β2-MG) in SSCT-derived cells (SSCTCs). Methods We extracted SSCT samples from 67 patients with CTS (49 non-HD and 18 HD) during carpal tunnel release. The samples were subjected to quantitative polymerase chain reaction (qPCR) to determine COL5A1 expression. Further, to examine the potential regulation of COL5A1 expression by Β2-MG, SSCTCs were stimulated in the absence (control) or presence of 10 µg/ml Β2-MG. Results The HD group showed significantly elevated COL5A1 levels compared to the non-HD group (P=0.027). Moreover, treating SSCTCs with Β2-MG for 24 h increased the mRNA expression of COL5A1 relative to control conditions (P=0.013). Conclusions Elevated COL5A1 expression may form part of the mechanism underlying the development of CTS, and Β2-MG may play a role in promoting COL5A1 expression in HD patients.

Pathophysiology, Diagnosis, Treatment, and Genetics of Carpal Tunnel Syndrome: A Review

Carpal tunnel syndrome (CTS) is a common peripheral canalicular nerve entrapment syndrome in the upper extremities. The compression of or injury to the median nerve at the wrist as it passes through a space-limited osteofibrous carpal canal can cause CTS, resulting in hand pain and impaired function. The present paper reviews the literature on the prevalence, pathology, diagnosis, treatment, and risk factors of CTS in conjunction with the role of genetic factors in CTS etiology. CTS diagnosis is primarily linked with clinical symptoms; still, it is simplified by sophisticated approaches such as magnetic resonance imaging and ultrasonography. CTS symptoms can be ameliorated through conservative and surgical strategies. The exact CTS pathophysiology needs clarification. Genetic predispositions to CTS are augmented by various variants within genes; however, CTS etiology could include risk factors such as wrist movements, injury, and specific conditions (e.g., age, body mass index, sex, and cardiovascular conditions). The high prevalence of CTS diminishes the quality of life of its sufferers and imposes costs on health systems, hence the significance of research and clinical trials to elucidate CTS pathogenesis and develop novel therapeutic targets.

Risk of de novo severe carpal tunnel syndrome after bilateral oophorectomy: a population-based cohort study

OBJECTIVE

The incidence of carpal tunnel syndrome (CTS) is higher in women, and peaks around the age of menopause. Therefore, we investigated whether bilateral oophorectomy is associated with an increased risk of severe CTS.

METHODS

We included all of the 1,653 premenopausal women who underwent bilateral oophorectomy for a nonmalignant indication between 1988 and 2007, and a random sample of 1,653 age-matched referent women who did not undergo bilateral oophorectomy in Olmsted County, MN. Diagnoses of CTS assigned to women over their entire lifetime were identified in these two cohorts. The risk of de novo severe CTS after bilateral oophorectomy (or index date) was evaluated using Cox proportional hazards models adjusted for potential confounders.

RESULTS

Bilateral oophorectomy was associated with an increased risk of severe CTS (adjusted hazard ratio 1.65, 95% confidence interval 1.20-2.25). The risk was suggestively greater in women with lower body mass index, nulliparity, and with a benign ovarian indication for oophorectomy (nonsignificant interactions). We did not observe a protective effect of estrogen therapy after the oophorectomy. The findings were similar in secondary analyses considering the incidence of CTS of any severity or idiopathic CTS.

CONCLUSIONS

The risk of severe CTS, common in perimenopausal women, is increased after bilateral oophorectomy. The association may be causal or due to confounding. Therefore, the precise biological mechanisms explaining the association and the absence of a mitigating effect of estrogen therapy should be further investigated.

Cascade of interactions between candidate genes reveals convergent mechanisms in keratoconus disease pathogenesis

Keratoconus is a progressive thinning, steepening and distortion of the cornea which can lead to loss of vision if left untreated. Keratoconus has a complex multifactorial etiology, with genetic and environmental components contributing to the disease pathophysiology. Studies have observed high concordance between monozygotic twins, discordance between dizygotic twins, and high familial segregation indicating the presence of a very strong genetic component in the pathogenesis of keratoconus. The use of genome-wide linkage studies on families and twins, genome-wide association studies (GWAS) on case-controls, next-generation sequencing (NGS)-based genomic screens on both familial and non-familial cohorts have led to the identification of keratoconus candidate genes with much greater success and increased resproducibility of genetic findings. This review focuses on candidate genes identified till date and attempts to understand their role in biological processes underlying keratoconus pathogenesis. In addition, using these genes I propose molecular pathways that could contribute to keratoconus pathogenesis. The pathways identified the presence of direct cross-talk between known candidate genes of keratoconus and remarkably, 28 known candidate genes have a direct relationship among themselves that involves direct protein-protein binding, regulatory activities such as activation and inhibition, chaperone, transcriptional activation/co-activation, and enzyme catalysis. This review attempts to describe these relationships and cross-talks in the context of keratoconus pathogenesis.

Delineation of a new fibrillino-2-pathy with evidence for a role of FBN2 in the pathogenesis of carpal tunnel syndrome

BACKGROUND

Although carpal tunnel syndrome (CTS) is the most common form of peripheral entrapment neuropathy, its pathogenesis remains largely unknown. An estimated heritability index of 0.46 and an increased familial occurrence indicate that genetic factors must play a role in the pathogenesis.

METHODS AND RESULTS

We report on a family in which CTS occurred in subsequent generations at an unusually young age. Additional clinical features included brachydactyly and short Achilles tendons resulting in toe walking in childhood. Using exome sequencing, we identified a heterozygous variant (c.5009T>G; p.Phe1670Cys) in the fibrillin-2 (FBN2) gene that co-segregated with the phenotype in the family. Functional assays showed that the missense variant impaired integrin-mediated cell adhesion and migration. Moreover, we observed an increased transforming growth factor-β signalling and fibrosis in the carpal tissues of affected individuals. A variant burden test in a large cohort of patients with CTS revealed a significantly increased frequency of rare (6.7% vs 2.5%-3.4%, p<0.001) and high-impact (6.9% vs 2.7%, p<0.001) FBN2 variants in patient alleles compared with controls.

CONCLUSION

The identification of a novel FBN2 variant (p.Phe1670Cys) in a unique family with early onset CTS, together with the observed increased frequency of rare and high-impact FBN2 variants in patients with sporadic CTS, strongly suggest a role of FBN2 in the pathogenesis of CTS.

Mutations in COMP cause familial carpal tunnel syndrome

Carpal tunnel syndrome (CTS) is the most common peripheral nerve entrapment syndrome, affecting a large proportion of the general population. Genetic susceptibility has been implicated in CTS, but the causative genes remain elusive. Here, we report the identification of two mutations in cartilage oligomeric matrix protein (COMP) that segregate with CTS in two large families with or without multiple epiphyseal dysplasia (MED). Both mutations impair the secretion of COMP by tenocytes, but the mutation associated with MED also perturbs its secretion in chondrocytes. Further functional characterization of the CTS-specific mutation reveals similar histological and molecular changes of tendons/ligaments in patients’ biopsies and the mouse models. The mutant COMP fails to oligomerize properly and is trapped in the ER, resulting in ER stress-induced unfolded protein response and cell death, leading to inflammation, progressive fibrosis and cell composition change in tendons/ligaments. The extracellular matrix (ECM) organization is also altered. Our studies uncover a previously unrecognized mechanism in CTS pathogenesis.

Familial carpal tunnel syndrome (CTS) is common, but causal genes are not characterized. Here the authors report two CTS-related mutations in two large families that impair secretion of COMP in tenocytes, leading to ER stress-induced unfolded protein response, inflammation and fibrosis in patients and mouse models.

Activation of JNK signaling in osteoblasts is inversely correlated with collagen synthesis in age-related osteoporosis

The age-related reduction in the function of osteoblasts plays a central role in the pathogenesis of bone loss and osteoporosis. Collagen synthesis is a primary function of differentiated osteoblasts, however, the mechanisms for age-related changes in collagen synthesis in human osteoblasts remain elusive. We use Gene Ontology (GO) analysis and Gene Set Enrichment Analysis (GSEA) analysis to exploit the transcriptional profiles of osteoblasts from young and old donors. A panel of collagen members was downregulated in aged osteoblasts, including COL12A1, COL5A1, COL5A3, COL8A1 and COL8A2. Co-expression analysis followed by GO analysis revealed that oxidoreductase activity and kinase activity were inversely correlated with collagen synthesis in osteoblasts. GESA analysis further showed that JNK signaling was upregulated in aged osteoblasts. Consistently, MAP3K4 and MAP4K2, upstream of JNK, were also increased in aged osteoblasts. Moreover, expression levels of MAP3K4 were significantly inversely correlated with levels of the collagen genes. Those transcriptomic results were further verified by examining clinical specimens of osteoporosis by immunohistochemistry. These results provide transcriptomic evidence that deregulated JNK signaling may impair collagen synthesis in osteoblasts and imply a therapeutic value of JNK inhibitors for treating osteoporosis and preventing skeletal aging by counteracting the age-related reduction in the function of osteoblasts.

Interactions between COL5A1 Gene and Risk of the Anterior Cruciate Ligament Rupture

Collagen alpha-1(V) chain, encoded by the COL5A1 gene, plays a crucial role in abundant fibrillar collagens supporting many tissues in the body containing type I collagen and appears to regulate the association between heterotypic fibers composed of both type I and type V collagen occurring among others in muscles, tendons and ligaments. Taking this fact into consideration we decided to examine the association between COL5A1 rs12722 and rs13946 polymorphisms, individually and as inferred haplotypes, with anterior cruciate ligament rupture risk (ACLR) in professional soccer players. A total of 134 male professional soccer players with surgically diagnosed primary anterior cruciate ligament ruptures and 211 apparently healthy male professional soccer players, who were without any self-reported history of ligament or tendon injury, were included in the study. Both the cases and the healthy controls were recruited from the same soccer teams, of a similar age category, and had a comparable level of exposure to anterior cruciate ligament injury. Genomic DNA was extracted from oral epithelial cells using GenElute Mammalian Genomic DNA MiniprepKit. All samples were genotyped for the rs12722 and rs13946 polymorphisms using a Rotor-Gene realtime polymerase chain reaction. Statistically significant differences in the genotype frequencies for the COL5A1 rs13946 polymorphisms in dominant modes of inheritance occurred (p = 0.039). Statistically significant differences were documented only in the dominant model under the representation tendency of the C-C haplotype in the ACLR group compared to controls (p = 0.038). Our results suggest that variation in the COL5A1 gene may be one of the non-modifiable factors associated with the ACL injury in professional soccer players. The C-C rs12722-rs13946 haplotype provides a protective effect against the ACL tear.

Carpal tunnel syndrome: The role of collagen gene variants

INTRODUCTION

The direct causes of idiopathic carpal tunnel syndrome (CTS) are still unknown. It is suggested that pathology of the tendons and other connective tissue structures within the carpal tunnel may play a role in its aetiology. Variants in genes encoding connective tissue proteins, such as type V collagen, have previously been associated with CTS. Since variants within other collagen genes, such as type I, XI and XII collagen, have previously been associated with modulating the risk of musculoskeletal soft tissue injuries, the aim of this study was to determine whether variants within COL1A1, COL11A1, COL11A2 and COL12A1 were associated with CTS.

METHODS

Self-reported Coloured South African participants, with a history of carpal tunnel release surgery (CTS, n=103) and matched control (CON, n=150) participants without any reported history of CTS symptoms were genotyped for COL1A1 rs1800012 (G/T), COL11A1 rs3753841 (T/C), COL11A1 rs1676486 (C/T), COL11A2 rs1799907 (T/A) and COL12A1 rs970547 (A/G).

RESULTS

The TT genotype of COL11A1 rs3753841 was significantly over-represented in the CTS group (21.4%) compared to CON group (7.9%, p=0.004). Furthermore, a trend for the T minor allele to be over-represented in the CTS group (p=0.055) with a significant association when only female participants (p=0.036) were investigated was observed. Constructed inferred pseudo-haplotypes including a previously investigated COL5A1 variant, rs71746744 (-/AGGG), suggest gene-gene interactions between COL5A1 and COL11A1 modulate the risk of CTS.

DISCUSSION

These findings provide further information of the role of the genetic risk factors and the possible role of variations in collagen fibril composition in the aetiology of CTS. Genetic factors could potential be included in models developed to identify indivisuals at risk of CTS. Strategies that target modifiable risk factors to mitigate the effect of non-modifiable risk factors, such as the genetic risk, could be also developed to reduce incidence and morbidity of CTS.

Towards an Understanding of the Genetics of Tendinopathy

To date, more than 18 genomic intervals, which underpin the complex myriad of extracellular matrix interactions of tendons, have been implicated in risk models for tendinopathy. It is these relationships that most likely regulate the tissue's response to loading and unloading, thereby dictating the overall capacity of tendons and influencing injury susceptibility. The evidence suggesting a genetic contribution to the susceptibility of sustaining a tendon injury is growing. However, only a few of the loci have been repeated in independent studies, of which some have included a range of musculoskeletal soft tissues injuries. Case-control study designs can be effective in capturing risk, provided that the cases and controls are equally well-defined and carefully considered. The genome consists of 3.6 × 10(9) sequences and therefore we realise that we are far from decoding all the genomic signatures. We are indeed fortunate to be living in such exciting times where high-throughput technologies are at our disposal. Through collaboration, our chances of harnessing these "omics" technologies to further our clinical understanding of tendinopathy will increase.

The BGN and ACAN genes and carpal tunnel syndrome

The causes of idiopathic carpal tunnel syndrome (CTS) remain unknown and the involvement of the tendons within the carpal tunnel structure in the aetiology of CTS cannot be excluded. Variants within the COL5A1 gene, an important regulator of fibril assembly in tendons, have previously been associated with modulating the risk of CTS. Furthermore, proteoglycans are also important structural components of tendons and variants within the aggrecan gene are associated with musculoskeletal soft tissue injuries. The aim of this study was to determine whether ACAN and BGN variants are associated with CTS. Self-reported Coloured participants (n=99), with a history of CTS release surgery (CTS), and 136 control participants, with no history of CTS symptoms (CON), were genotyped for ACAN rs1516797(G/T) and BGN rs1126499(C/T) variants. The BGN CC genotype was significantly over-represented (p=0.0498; OR=0.545, 95% CI=0.30-0.99) in the CON group (71.8%) versus the CTS (58.1%) group. When the previously reported associated COL5A1 genotypes were included in the analysis, COL5A1 and BGN gene-gene interactions were also shown to significantly modulate the risk of CTS in females. In conclusion this is the first study to report that variants within the BGN gene, independently and by interacting with COL5A1 variants, are associated with CTS. Further studies are required to replicate these findings.