Candidate gene approach identifies six SNPs in tenascin-C (TNC) associated with degenerative rotator cuff tears

The Envelope of Function: Revisiting the Theory With New Concepts-A Narrative Review

Musculoskeletal injuries are a complex multifactorial phenomenon, and several factors can contribute to their occurrence. This review aimed to discuss some relevant and often unexpected elements involved in musculoskeletal injuries and rehabilitation. One of the main factors discussed is the role of physiological adaptation to training in musculoskeletal injury susceptibility. This is probably the most modifiable factor in preventing and treating musculoskeletal injuries. Other factors discussed are the role of genetics in injury susceptibility; the effect of stressors and environmental factors and the way we deal with setbacks; anabolic steroid use as aesthetic and performance-enhancement drugs; nutrition, sleeping, and the imbalance between rest, energy intake, and training; anatomic and biomechanical factors; and the role of systemic disease. Moreover, the topic of unknown factors keeps an open door for future discoveries. This review highlights the importance of understanding the various factors contributing to musculoskeletal injuries and the need for an individualized approach to injury prevention and rehabilitation, from both a historical and a physiological point of view.

Identification of rare genetic variants for rotator cuff tearing and repair in high-risk pedigrees

Background

Common genetic variants with small effect sizes have been associated with rotator cuff tearing although very few rare, highly penetrant variants have been identified. The purpose of this pilot study was to identify dominant coding variants that segregated with affected individuals in pedigrees at high risk for rotator cuff tears (RCTs). We hypothesize that rare variants contribute to symptomatic RCTs and that they can be identified in related cases with a full-thickness tear requiring surgical management.

Methods

We used the Utah Population Database to identify pedigrees that exhibited a significant excess of individuals who had undergone surgical repair of a full-thickness RCT. We analyzed whole exome sequence analysis to identify rare coding variants in 9 independent affected cousin pairs (first or second cousins) who had undergone arthroscopic surgery for repair of a full-thickness RCT (mean age at diagnosis 68 years). Validation of association of the candidate variants with risk for rotator cuff tearing was accomplished utilizing data from the UK Biobank and a separate cohort of unrelated cases of full-thickness RCTs.

Results

A total of 82 rare (minor allele frequency <0.005) coding variants were identified as shared in at least one cousin pair affected with full-thickness rotator cuff tearing belonging to a high-risk pedigree, which included variants in RUNX1, ADAM12, TGFBR2, APBB1, PDLIM7, LTBP1, MAP3K4, and MAP3K1. Analysis of 39 of these variants with data available in the UK Biobank (3899 cases with rotator cuff injury and 11,697 matched controls; mean case age 59.9 years) identified a significant association with the APBB1 gene (OR = 2.37, P = .007, uncorrected). The PDLIM7 allele was found to be in significant excess in RCT cases in a separate cohort of Utah patients with full-thickness RCTs (10 carriers out of 458 independent, unrelated patients; minor allele frequency of 0.022) compared to a minor allele frequency of 0.0058 for the European (non-Finnish) control population rate (749 carriers out of 128612 tested) (chi-square test: 19.3 [P < .001]).

Discussion

The analysis of closely related individuals with confirmed full-thickness RCTs from high-risk pedigrees has identified 82 rare, shared candidate genetic predisposition coding variants. Association of the PDLIM7 allele with risk for tear was confirmed in an independent cohort of RCTs. Further analysis of the variant alleles is required for confirmation of these genes in rotator cuff tearing.

Factors associated with genetic markers for rotator cuff disease in patients with atraumatic rotator cuff tears

For atraumatic rotator cuff tears, genetics contributes to symptomatic tear risk and may influence rotator cuff healing after surgical repair. But little is known about how genetic factors influence rotator cuff tear patient characteristics at presentation. We collected saliva samples for genotyping from atraumatic rotator cuff tear patients. We examined nine single nucleotide polymorphisms (SNPs) associated with cuff tears in prior literature. We estimated associations of SNP dosage with (1) age at tear diagnosis, (2) bilateral atraumatic tear prevalence, and (3) tear size. Linear regression was used to estimate associations with diagnosis age adjusted for sex and principal components. Logistic regression and ordinal logistic regression were used to estimate associations with bilateral tear prevalence and tear size category, respectively, adjusting for age, sex, and principal components. Of 344 eligible patients, 336 provided sufficient samples for genotyping. Median age at tear diagnosis was 61, 22% (N = 74) had bilateral atraumatic tears, and 9% (N = 29) had massive tears. SNP rs13107325 in the SLC39A8 gene and rs11850957 in the STXBP6 gene were associated with younger diagnosis age even after accounting for multiple comparisons (rs13107325: -4 years, 95% CI = -6.5, -1.4; rs11850957: -2.7 years, 95% CI = -4.3, -1.1). No other significant associations were observed with diagnosis age, tear size, or bilateral tear prevalence. SLC39A8 encodes a Mn transporter. STXBP6 may play a role in inflammatory responses by altering phagocytosis and antigen presentation of monocytes and macrophages. Further research is needed to determine if genetic markers can be used alongside patient characteristics to aid in identifying optimal surgical repair candidates.

The Study of the Influence of IL5RA Variants on Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a complex disease, and its pathogenesis is influenced by genetic factors. This study aimed to evaluate the role of IL5RA genetic variation in the risk of COPD. In this study, 498 patients with COPD and 498 normal controls were recruited. Subsequently, five SNPs (rs3804795, rs2290610, rs13097407, rs334782, and rs3856850) in the IL5RA gene were genotyped. Logistic analysis examined the association of five single nucleotide polymorphisms (SNPs) in IL5RA with the risk of COPD under various genetic models. Furthermore, the association between IL5RA and susceptibility to COPD was comprehensively analyzed with stratification based on age, sex, smoking, and alcohol consumption. Our study showed that IL5RA rs13097407 reduced susceptibility to COPD (OR = 0.43, p < 0.001, p (FDR)< 0.001). On the other hand, rs3856850 was associated with an increased risk of COPD (OR = 1.71, p = 0.002, p (FDR) = 0.002). Interestingly, the effect of IL5RA SNPs on susceptibility to COPD was found to be influenced by factors such as sex and smoking. IL5RA gene variants were significantly associated with susceptibility to COPD.

Genetic Determinants of the Anterior Cruciate Ligament Rupture in Sport: An Up-to-Date Systematic Review

Anterior cruciate ligament injuries (ACLIs) are one of the most common knee injuries in sports. Although numerous factors have been related to the risk of ACLIs, it is still unclear why some individuals are more susceptible than others due to the intricate etiology of ACLIs. Several genetic factors have been identified as contributing to ACLIs. This systematic review summarizes the current evidence regarding the genetic causes of ACLIs based on the available literature. Five electronic databases were searched from 2017 to 2022. All titles, abstracts, and full texts were reviewed in detail to determine the inclusions and exclusions. The Newcastle-Ottawa Scale was used to evaluate the risk of bias. The studies' characteristics and results are presented in both narrative and tabular formats. A total of 24 studies examined 31 genes and 62 variants associated with ACLIs in the global population. Ten studies investigated seven collagens and ten SNPs for the ACL injury. The majority of studies found no significant difference in the association of the COL1A1 rs1800012, COL5A1 rs12722, VEGFA rs1570360, IL6R rs2228145, IL6 rs1800795, IL1B rs16944 and rs1143627, however, contrary results were found when nationality and gender were considered together. Conflicting evidence was found for polymorphisms rs2010963, rs699947 of the VEGFA gene in different studies. Due to a lack of data, it was impossible to determine the relationship between the anterior cruciate ligament rupture (ACLR) and the other polymorphisms. More research is required to establish a clear relationship between the ACLR and genetic variants, particularly when gender and nationality are taken into account separately.

Association between the rs820218 Variant within the SAP30BP Gene and Rotator Cuff Rupture in an Amazonian Population

BACKGROUND

Rotator cuff disease is one of the leading causes of musculoskeletal pain and disability, and its etiology is most likely multifactorial but remains incompletely understood. Therefore, the objective of this research was to investigate the relationship of the single-nucleotide rs820218 polymorphism of the SAP30-binding protein (SAP30BP) gene with rotator cuff tears in the Amazonian population.

METHODS

The case group consisted of patients who were operated on due to rotator cuff tears in a hospital in the Amazon region between 2010 and 2021, and the control group was composed of individuals who were selected after negative physical examinations for rotator cuff tears. Genomic DNA was obtained from saliva samples. For the genotyping and allelic discrimination of the selected single nucleotide polymorphism (rs820218) in the SAP30BP gene, real-time PCR was performed.

RESULTS

The frequency of the A allele in the control group was four times as high as that in the case group (AA homozygotes); an association of the genetic variant rs820218 of the SAP30BP gene with rotator cuff tears was not established (p = 0.28 and 0.20), as the A allelic frequency is ordinarily low in the general population.

CONCLUSIONS

The presence of the A allele indicates protection against rotator cuff tears.

Genetic Characterization in Familial Rotator Cuff Tear: An Exome Sequencing Study

Background: multiple gene variants seem to contribute to rotator cuff (RC) tear susceptibility. The aim of the study is to perform an exome sequencing analysis within a family to identify rare gene variants predisposing to the development of RC tear. Material and methods: the exome sequencing was conducted in a family consisting of four individuals, two healthy and the remaining ones with bilateral RC tears. Variants in common among the two affected subjects were selected, and those in common with the healthy subject and those with a frequency >1% were removed. The potential pathogenicity of the variants was investigated using the predictions of several in silico tools from VarSome. Results: the exome sequencing yielded approximately 600,000 variants per patient, subsequently filtered according to frequency <1% and absence of association with other diseases. Removing variants common with the healthy subject, 348 rare variants among 248 genes were identified. Based on the risk of damaging, three candidate genes for RC tear were found: COL23A1, EMILIN3, and HDAC10. Conclusion: this is the first whole-exome sequencing analysis within a family to explore genetic predisposition in RC tear. The results reveal the presence of common damaging variants among affected individuals in the COL23A1, EMILIN3, and HDAC10 genes.

Genome-Wide Association Study Identifies Genetic Variants Associated with Rotator Cuff Tear-A Pilot Study

A rotator cuff is a muscle and tendon surrounding the shoulder joint, and a rotator cuff tear can be caused by overuse or injury, which leads to great pain in affected individuals. However, rotator cuff tear is a multifactorial process whose underlying mechanism is still unclear. Many previous studies have suggested an important role of genetic predisposition, such as single-nucleotide polymorphisms (SNPs), in explaining the genesis of tendinopathy. This study aimed to identify specific genes or genetic variants associated with rotator cuff tears by performing a genome-wide association study (GWAS) using an independent case of rotator cuff tears. GWAS was performed using data from CHA Bundang Medical Center with 20 cases of rotator cuff tears, and 20 cases of healthy controls genotyped on the Illumina HiSeq 2500. Tests of association were performed using the Burrows−Wheeler Aligner (BWA) software at 284,246 SNPs. Data were filtered based on sequence ontology, minor allele frequency, and Hardy−Weinberg equilibrium values, and SNPs were considered significant if the p-value was <0.05. The tests of association revealed more than 20 significantly associated SNPs. SNPs showing the highest significance occurred in candidate genes, including LAIR2 (rs2287828, OR 9.116, p-value 5.49 × 10−4) on chromosome 19 and CRIPAK (rs9328733, OR 6, p-value 1.11 × 10−3) and REST (rs2228991, OR 8.222, p-value 1.20 × 10−3) on chromosome 4. This study attempted to identify genetic variants influencing rotator cuff tears through a genome-wide association study using a dense set of SNPs. More than 20 SNPs were significantly associated with rotator cuff tears. The major limitation of this study is that it was conducted on a small study group and requires further validation. Nevertheless, the identification of potential genetic variants related to rotator cuff injury would aid in the early detection of individuals at risk for the development of tendinopathy and will provide insight into future gene therapies.

Tendon and Ligament Genetics: How Do They Contribute to Disease and Injury? A Narrative Review

A significant proportion of patients requiring musculoskeletal management present with tendon and ligament pathology. Our understanding of the intrinsic and extrinsic mechanisms that lead to such disabilities is increasing. However, the complexity underpinning these interactive multifactorial elements is still not fully characterised. Evidence highlighting the genetic components, either reducing or increasing susceptibility to injury, is increasing. This review examines the present understanding of the role genetic variations contribute to tendon and ligament injury risk. It examines the different elements of tendon and ligament structure and considers our knowledge of genetic influence on form, function, ability to withstand load, and undertake repair or regeneration. The role of epigenetic factors in modifying gene expression in these structures is also explored. It considers the challenges to interpreting present knowledge, the requirements, and likely pathways for future research, and whether such information has reached the point of clinical utility.

The effect of estrogen-like compound on rotator cuff tendon healing in a murine model

Estrogen deficiency has been shown to negatively influence rotator cuff tendon healing. Therefore, the addition of an estrogen-like-compound (ELC) in a nonestrogen-deficient animal may improve the quality of a rotator cuff repair. The purpose of this study was to evaluate the effects of an ELC, diethylstilbestrol (DES), on tendon healing in a murine rotator cuff repair model. Thirty-three male wild-type mice (C57BL/6NJ) were randomly divided into three study groups. Group 1-unoperated mice with normal rotator cuff tendons. Groups 2 and 3 consisted of surgically repaired rotator cuff tendons; Group 2 (repair-only) was the standard repair group (no DES injected), whereas Group 3 (repair + DES) was the experimental repair group (injected with DES). Comparing the maximal thickness of calcified fibrocartilage to uncalcified fibrocartilage, the ratios for the control (intact tendon), repair-only, and repair + DES groups were 2:1, 0.9:1, and 1.7:1. RNA expression data demonstrated upregulation of chondrogenic, angiogenic, and tendon modulation genes in the repair- only group compared to the control (intact tendon) group (p < 0.04 for all), and that addition of DES further increased the osteogenic, angiogenic, and tendon modulation gene expression compared to the repair-only group (p < 0.02). Immunohistochemical analysis indicated that the addition of DES further increased osteogenic, angiogenic, and tendon maturation protein expression at the enthesis compared to standard repairs.

Tendon and multiomics: advantages, advances, and opportunities

Tendons heal by fibrosis, which hinders function and increases re-injury risk. Yet the biology that leads to degeneration and regeneration of tendons is not completely understood. Improved understanding of the metabolic nuances that cause diverse outcomes in tendinopathies is required to solve these problems. 'Omics methods are increasingly used to characterize phenotypes in tissues. Multiomics integrates 'omic datasets to identify coherent relationships and provide insight into differences in molecular and metabolic pathways between anatomic locations, and disease stages. This work reviews the current literature pertaining to multiomics in tendon and the potential of these platforms to improve tendon regeneration. We assessed the literature and identified areas where 'omics platforms contribute to the field: (1) Tendon biology where their hierarchical complexity and demographic factors are studied. (2) Tendon degeneration and healing, where comparisons across tendon pathologies are analyzed. (3) The in vitro engineered tendon phenotype, where we compare the engineered phenotype to relevant native tissues. (4) Finally, we review regenerative and therapeutic approaches. We identified gaps in current knowledge and opportunities for future study: (1) The need to increase the diversity of human subjects and cell sources. (2) Opportunities to improve understanding of tendon heterogeneity. (3) The need to use these improvements to inform new engineered and regenerative therapeutic approaches. (4) The need to increase understanding of the development of tendon pathology. Together, the expanding use of various 'omics platforms and data analysis resulting from these platforms could substantially contribute to major advances in the tendon tissue engineering and regenerative medicine field.

A genome-wide association study for shoulder impingement and rotator cuff disease

BACKGROUND

The purpose of the study was to identify genetic variants associated with rotator cuff disease by performing a genome-wide association study (GWAS) for shoulder impingement using the UK Biobank (UKB) cohort and then combining the GWAS data with a prior GWAS for rotator cuff tears. The loci identified by the GWAS and meta-analysis were examined for changes in expression following rotator cuff tearing using RNA sequencing.

METHODS

A GWAS was performed using data from UKB with 3864 cases of shoulder impingement. The summary statistics from shoulder impingement and a prior study on rotator cuff tears were combined in a meta-analysis. Also, the previous association of 2 single-nucleotide polymorphisms (SNPs) with shoulder impingement from a published GWAS using the UKB was tested. Rotator cuff tendon biopsies were obtained from 24 patients with full-thickness rotator cuff tears who underwent arthroscopic rotator cuff repair (cases) and 9 patients who underwent open reduction internal fixation for a proximal humeral fracture (controls). Total RNA was extracted and differential gene expression was measured by RNA sequencing for genes with variants associated with rotator cuff tearing.

RESULTS

The shoulder impingement GWAS identified 4 new loci: LOC100506457, LSP1P3, LOC100506207, and MIS18BP1/LINC00871. Combining data with a prior GWAS for rotator cuff tears in a meta-analysis resulted in the identification of an additional 7 loci: SLC39A8/UBE2D3, C5orf63, ASTN2, STK24, FRMPD4, ACOT9/SAT1, and LINC00890/ALG13. Many of the identified loci have known biologic functions or prior associations with diseases, suggesting possible biologic pathways leading to rotator cuff disease. RNA sequencing experiments show that expression of STK24 increases whereas expression of SAT1 and UBE2D3 decreases following rotator cuff tearing. Two SNPs previously reported to show an association with shoulder impingement from a prior UKB GWAS were not validated in our study.

CONCLUSION

This is the first GWAS for shoulder impingement in which new data from UKB enabled the identification of 4 loci showing a genetic association. A meta-analysis with a prior GWAS for rotator cuff tearing identified an additional 7 loci. The known biologic roles of many of the 11 loci suggest plausible biologic mechanisms underlying the etiology of rotator cuff disease. The risk alleles from each of the genetic loci can be used to assess the risk for rotator cuff disease in individual patients, enabling preventative or restorative actions via personalized medicine.

Identification of a Novel Genetic Marker for Risk of Degenerative Rotator Cuff Disease Surgery in the UK Biobank

BACKGROUND

While evidence indicates that familial predisposition influences the risk of developing degenerative rotator cuff disease (RCD), knowledge of specific genetic markers is limited. We conducted a genome-wide association study of RCD surgery using the UK Biobank, a prospective cohort of 500,000 people (40 to 69 years of age at enrollment) with genotype data.

METHODS

Cases with surgery for degenerative RCD were identified using linked hospital records. The cases were defined as an International Classification of Diseases, Tenth Revision (ICD-10) code of M75.1 determined by a trauma/orthopaedic specialist and surgery consistent with RCD treatment. Cases were excluded if a diagnosis of traumatic injury had been made during the same hospital visit. For each case, up to 5 controls matched by age, sex, and follow-up time were chosen from the UK Biobank. Analyses were limited to European-ancestry individuals who were not third-degree or closer relations. We used logistic regression to test for genetic association of 674,405 typed and >10 million imputed markers, after adjusting for age, sex, population principal components, and follow-up.

RESULTS

We identified 2,917 RCD surgery cases and 14,158 matched controls. We observed 1 genome-wide significant signal (p < 5 × 10-8) for a novel locus tagged by rs2237352 in the CREB5 gene on chromosome 7 (odds ratio [OR] = 1.17, 95% confidence interval [CI] = 1.11 to 1.24). The single-nucleotide polymorphism (SNP) rs2237352 was imputed with a high degree of confidence (info score = 0.9847) and is common, with a minor allele frequency of 47%. After expanding the control sample to include additional unmatched non-cases, rs2237352 and another SNP in the CREB5 gene, rs12700903, were genome-wide significant. We did not detect genome-wide significant signals at loci associated with RCD in previous studies.

CONCLUSIONS

We identified a novel association between a variant in the CREB5 gene and RCD surgery. Validation of this finding in studies with imaging data to confirm diagnoses will be an important next step.

CLINICAL RELEVANCE

Identification of genetic RCD susceptibility markers can guide understanding of biological processes in rotator cuff degeneration and help inform disease risk in the clinical setting.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Genetic variants associated with rotator cuff tearing utilizing multiple population-based genetic resources

BACKGROUND

The etiology of rotator cuff tearing is likely multifactorial, including a potential genetic predisposition. The purpose of the study was to identify genetic variants associated with rotator cuff tearing utilizing the UK Biobank (UKB) cohort, confirm variants using a separate genetic database, and evaluate tissue expression of genes with associated variants following rotator cuff tearing using RNA sequencing.

METHODS

Genome-wide association study (GWAS): A GWAS was performed using data from UKB with 5701 cases of rotator cuff injury. RNA sequencing analyses: rotator cuff biopsies were obtained from 24 patients with full-thickness rotator cuff tears who underwent arthroscopic rotator cuff repair (cases) and 9 patients who underwent open reduction internal fixation for a proximal humerus fracture (controls). Total RNA was extracted and differential gene expression was measured by RNAseq for genes with variants associated with rotator cuff tearing.

RESULTS

The results of the UKB GWAS identified 3 loci that reached genome-wide statistical significance: 2 loci on chromosome 7 in GLCCI1 (rs4725069; P = 5.0E-09) and THSD7A (rs575224171; P = 5.3E-09), and 1 locus on chromosome 2 in ZNF804A (rs775583810; P = 3.9E-09). The association with rotator cuff injury of the GLCCI1 single-nucleotide polymorphism (SNP; rs4725069) was confirmed in the Kaiser Permanente Research Bank cohort (P = .008). Twenty previously reported SNPs in 12 genes were evaluated using summary statistics from the UKB GWAS, which confirmed 3 SNPs in TNC with rotator cuff injury (rs1138545, rs72758637, and rs7021589; all P < .0024). Of 17 genes with variants associated with rotator cuff injury (14 previously from literature plus 3 new genes from current UKB GWAS), TIMP2, Col5A1, TGFBR1, and TNC were upregulated (P < .001 for all) and THSD7A was downregulated (P = .005) in tears vs. controls in the RNA sequencing data set.

CONCLUSION

The UKB GWAS has identified 3 novel loci associated with rotator cuff tearing (ZNF804A, GLCCI1, THSD7A). Expression of the THSD7A gene was significantly downregulated in rotator cuff tears vs. controls supporting a potential functional role. Three previously reported SNPs in the TNC gene were validated in the UKB GWAS, supporting a role for this gene in rotator cuff tearing. Finally, TIMP2, Col5A1, TGFBR1, and TNC genes were found to have significantly upregulated tissue expression in cases vs. controls supporting a biologic role in tearing for these genes.

Polymorphisms and alterations in gene expression associated with rotator cuff tear and healing following surgical repair: a systematic review

BACKGROUND

Rotator cuff tears (RCTs) are a common cause of shoulder disability, yet both conservative and surgical treatment strategies can lead to poor results in some patient populations. Enhanced understanding of the genetic processes associated with RCTs can assist in the development of more effective management options and help predict individual responses to surgical treatment. This systematic review analyzes the current literature on the genetic footprint associated with RCTs and interprets these findings to enhance the current understanding of RCT pathogenesis, potential treatment regimens, and prognostic biomarkers of outcomes after surgical repair.

METHODS

A systematic search of the Embase, PubMed, and Web of Science electronic databases was performed. Medical Subject Headings (MeSH) and Emtree index terms were formulated from the concept terms "rotator cuff tear," "genetics," and "human," and synonyms of these concepts were applied to the Web of Science search. Articles were screened against predefined inclusion and exclusion criteria. Eligible studies compared gene expression patterns and genetic polymorphisms between cases (with RCTs) and controls (without RCTs). Quality assessment was performed with studies being rated as high, moderate, or poor quality. A modified best-evidence synthesis was applied, and studies were determined to be of strong, moderate, or limited evidence.

RESULTS

The search identified 259 articles. Of these studies, 26 were eligible for review. Two studies were considered poor quality; 15 studies, moderate quality; and 9 studies, high quality. Analysis of these articles found that RCTs were associated with alterations in genes that code for the extracellular matrix, cell apoptosis, immune and inflammatory responses, and growth factor pathways. In particular, there was strong evidence of a significant association between RCTs and the genes MMP3, TNC, and ESRRB. Strong evidence of an association between BMP5 upregulation and successful healing after surgical repair was also found.

CONCLUSION

This review provides strong evidence of an genetic association with RCTs. The genotype and gene expression patterns detailed within this review can assist in deciphering the biological mechanisms resulting in RCTs, as well as predicting an individual's response to surgical repair. Future research could investigate whether manipulating these genes-or their associated signaling pathways-could assist in RCT healing and whether genetic biomarkers could be used clinically to predict patient outcomes after surgical repair of RCTs.

Genetic Aspects in Shoulder Disorders

The influence of genetic inheritance has been increasingly investigated in shoulder disorders, such as rotator cuff injury, instability and frozen shoulder. Although the initial findings are enlightening, it is necessary to progressively build a database of genetic markers to catalog genomic profiles that, later, may contribute for predicting the risk of the disease, as well as to the development of better diagnostic and treatment tools. The present article seeks to update what is evidence of genetic studies in the literature for these diseases, from polymorphism analyses, expression of candidate genes in tissues and broad genomic association studies (GWAS). However, it is necessary to point out that there is great difficulty in replicating and using the findings, mainly due to the lack of statistical power, the high rate of false-positive results and the large number of variables involved.

Family Predisposition for Rotator Cuff Tear and Other Tendinopathies - A Case-Control Study

Objective  To evaluate the prevalence of family history of rotator cuff tear and the presence of tendinopathy in other joints in patients with rotator cuff tears and to compare them with paired controls. To estimate the odds ratio for rotator cuff tear for these two risk factors. Methods  We performed a case-control study comparing patients submitted to treatment for rotator cuff tear with asymptomatic controls. All cases and controls were evaluated by imaging exams and matched by age (±2 years) and gender. We conducted an interview using a standardized questionnaire, and collected data on various risk factors. Results  We evaluated 144 patients, 72 per group. Patients with rotator cuff tears reported a higher number of consanguineous relatives who underwent treatment for the same disease and tendon injuries in other joints compared to the controls ( p  = 0.005 and p  = 0.045 respectively). Individuals with a family history of treatment for rotator cuff tear or with tendinopathies in other joints were more likely to present a rotator cuff tear, with odds ratios of 3.3 (95% confidence interval [95%CI] = 1.4-7.7) and 2.7 (95%CI = 1.1-6.9) respectively. Conclusions  Patients with rotator cuff tear have a higher prevalence of family members with the same disease and tendinopathies or tendon injuries in other joints. The presence of consanguineous relatives with treatment for rotator cuff and tendinopathies in other joints are risk factors for the presence of rotator cuff tears.

Gene Expression in Torn Rotator Cuff Tendons Determined by RNA Sequencing

Background:

Although the cause of rotator cuff tearing is likely multifactorial and a genetic predisposition has been proposed, the biochemical basis remains unknown.

Purpose:

To determine gene expression profiles in torn rotator cuff tendon tissue through use of RNA sequencing.

Study Design:

Controlled laboratory study.

Methods:

The supraspinatus tendon edge was biopsied in 24 patients undergoing arthroscopic rotator cuff repair for full-thickness supraspinatus rotator cuff tears. The supraspinatus tendon was also biopsied in 9 patients undergoing open reduction and internal fixation for a proximal humeral fracture (controls). Total RNA was extracted and sequenced. Differential gene expression was analyzed between the tear and control groups, and a secondary analysis was conducted between groups defined by an unbiased clustering.

Results:

Tear and control transcriptomes demonstrated significant differential expression in more than 3000 genes. The identified differential genes were highlighted in pathways involved in inflammation in control patients and extracellular matrix generation in patients with tears. Secondary analysis using unsupervised and thus unbiased hierarchical clustering revealed 2 clusters (c2 and c3). Cluster c3 contained smaller (P < .001) and less retracted (P = .018) tears (ie, tears earlier in the progression of rotator cuff disease) with increased expression of hypoxia target genes. Cluster c2 contained larger, more retracted tears (ie, tears further in the progression of rotator cuff disease) with increased expression of endothelial cell markers and chronic inflammation target genes. Tears in c2 had significantly worse healing rates compared with tears in c3 (0% vs 89%; P = .007).

Conclusion:

Smaller, less retracted tears had increased expression of hypoxia target genes and improved healing, whereas larger, more retracted tears were associated with endothelial cell markers and worse healing. Thus, hypoxia may be the inciting event for tear development, whereas with tear enlargement, a chronic, inflammatory, angiogenic process may predominate.

Clinical Relevance:

Identification of differential gene expression in rotator cuff tears may be a reliable tool to predict repair healing in the future.

Genetic factors in rotator cuff pathology: potential influence of col 5A1 polymorphism in outcomes of rotator cuff repair

Background

Investigations in genetics have provided valuable information about the correlation between gene variants and tendinopathy. Single Nucleotide Polymorphisms of COL5A1 gene are reported to be involved in Achilles tendinopathy, chronic degenerative tendon changes at the elbow, and other tendinopathies. The influence of Single Nucleotide Polymorphisms of COL5A1 was previously analyzed in rotator cuff disease with confounding results. Moreover, the rs12722 polymorphism in COL5A1 gene has been implicated in the aetiology of musculoskeletal soft tissue injuries in several association studies. This study aims to analyse the possible influence of rs12722 polymorphism in COL5A1 in the outcomes of rotator cuff repair.

Methods

Seventy-nine patients were included in the study. DNA was extracted from 1.2 ml of venous blood and genotyped for COL5A1 SNPs rs12722. Rotator cuff muscle strength and range of motion (ROM) in anterior elevation, external and internal rotation of the shoulder were evaluated.

Results

Patients presenting COL5A1 SNP rs12722 CC showed a ROM of passive external rotation statistically significantly higher compared to patients with CT genotype and TT genotype.

Conclusions

COL5A1 SNP rs12722 may influence the functional outcomes of RCRs, even though further studies are required to confirm these preliminary results.

The "other" 15-40%: The Role of Non-Collagenous Extracellular Matrix Proteins and Minor Collagens in Tendon

Extracellular matrix (ECM) determines the physiological function of all tissues, including musculoskeletal tissues. In tendon, ECM provides overall tissue architecture, which is tailored to match the biomechanical requirements of their physiological function, that is, force transmission from muscle to bone. Tendon ECM also constitutes the microenvironment that allows tendon-resident cells to maintain their phenotype and that transmits biomechanical forces from the macro-level to the micro-level. The structure and function of adult tendons is largely determined by the hierarchical organization of collagen type I fibrils. However, non-collagenous ECM proteins such as small leucine-rich proteoglycans (SLRPs), ADAMTS proteases, and cross-linking enzymes play critical roles in collagen fibrillogenesis and guide the hierarchical bundling of collagen fibrils into tendon fascicles. Other non-collagenous ECM proteins such as the less abundant collagens, fibrillins, or elastin, contribute to tendon formation or determine some of their biomechanical properties. The interfascicular matrix or endotenon and the outer layer of tendons, the epi- and paratenon, includes collagens and non-collagenous ECM proteins, but their function is less well understood. The ECM proteins in the epi- and paratenon may provide the appropriate microenvironment to maintain the identity of distinct tendon cell populations that are thought to play a role during repair processes after injury. The aim of this review is to provide an overview of the role of non-collagenous ECM proteins and less abundant collagens in tendon development and homeostasis. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:23-35, 2020.

Rotator Cuff Tear Susceptibility Is Associated With Variants in Genes Involved in Tendon Extracellular Matrix Homeostasis

Rotator cuff tears (RCT) is a multifactorial disease with genetic factors contributing for the disease etiology. We hypothesized that genetic variants in genes involved in extracellular matrix (ECM) homeostasis may alter susceptibility to RCT. We evaluated 20 polymorphisms of genes involved in ECM homeostasis in 211 cases of full-thickness tears of the supraspinatus (N_females  = 130; N_males  = 81) and 567 age-matched controls (N_females  = 317; N_males  = 250). Multivariate logistic regressions were carried out with age, gender, genetic ancestry (based on the analysis of 61 biallelic short insertion/deletion polymorphisms), and common co-morbidities (diabetes, dyslipidemia, and smoking habits) as covariates. We observed that carriers of the rare allele of both studied variants of TGFB1, as well as their G/A (rs1800470/rs1800469) haplotype, were less susceptible to RCT (p < 0.05). In contrast, carriers of the G allele of MMP9 rs17576 (p = 0.014) or G/G haplotype (rs17576/rs17577; p < 0.001) had an increased risk for tendon tears. The presence of the T allele of MMP2 rs2285053 (p = 0.033), the T allele of MMP3 rs679620 (p = 0.024), and the TT-genotype of TIMP2 rs2277698 (p = 0.01) was associated with susceptibility to tears, especially in females. In males, the A allele of COL5A1 rs3196378 (p = 0.032) and the G allele of TGFBR1 rs1590 (p = 0.039) were independent risk factors for RCT. The C/T COL5A1 (rs3196378/rs11103544) haplotype was associated with a reduced risk of tears in males (p = 0.03). In conclusion, we identified the genetic variants associated with RCT susceptibility, thereby reinforcing the role of genes involved in the structure and homeostasis of the ECM of tendons in disease development. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:192-201, 2020.

Genetic basis of rotator cuff injury: a systematic review

Background

Rotator cuff disease is a widespread musculoskeletal pathology and a major cause of shoulder pain. Studies on familial predisposition suggest that genetic plays a role in the pathogenesis of rotator cuff disease. Several genes are responsible for rotator cuff disease. The aim of this study was to perform a systematic review on genetic association between rotator cuff disease and genes variations.

Methods

A systematic review of the literature was performed, in accordance with the PRISMA guidelines. PubMed, Medline, CINAHL, Cochrane, Embase and Google Scholar databases were searched comprehensively using the keywords: “Rotator cuff”, “Gene”, “Genetic”, “Predisposition”, “Single-nucleotide polymorphism” and “Genome-wide association”.

Results

8 studies investigating genes variations associated with rotator cuff tears were included in this review. 6 studies were case-control studies on candidate genes and 2 studies were GWASs. A significant association between SNPs and rotator cuff disease was found for DEFB1, FGFR1, FGFR3, ESRRB, FGF10, MMP-1, TNC, FCRL3, SASH1, SAP30BP, rs71404070 located next to cadherin8. Contradictory results were reported for MMP-3.

Conclusion

Further investigations are warranted to identify complete genetic profiles of rotator cuff disease and to clarify the complex interaction between genes, encoded proteins and environment. This may lead to individualized strategies for prevention and treatment of rotator cuff disease.

Level of evidence

Level IV, Systematic Review.

Intra-articular treatment with corticosteroids increases apoptosis in human rotator cuff tears

PURPOSE

The aim of this study is to evaluate in vivo the level of apoptosis in human rotator cuff tears and the relationship it might have with tendon degeneration.

METHODS

Rotator cuff biopsies from 19 male and female patients, ages between 38 and 68 years, with and without previous corticosteroid infiltrations were collected via arthroscopy. Biopsies from seven patients with healthy rotator cuffs were used as a control group. An in situ terminal deoxynucleotidyl transferase dUTP nick end labeling assay was performed to detect the level of apoptosis, which was expressed as a percentage of apoptotic cells (PAC).

RESULTS

PAC in patients with corticosteroid infiltrations was 76.97 ± 16.99 in all tendon rupture zones, in non-infiltrated patients was 35.89 ± 22.96, whereas in control patients was 14.48 ± 8.15. Likewise, the tendency of PAC reveals that apoptosis in control and non-infiltrated groups was different and dispersed in all tear zones; while in corticosteroid treated patients, the tendency was similar in all rupture sites.

CONCLUSIONS

This investigation leads us to conclude that the administration of corticosteroid is associated with a higher amount of apoptosis at the insertion site of the rotator cuff (rupture edge).

Rotator Cuff Degeneration: The Role of Genetics

BACKGROUND

The literature is certain regarding the multifactorial etiology of rotator cuff degeneration. However, it remains unclear if rotator cuff degeneration exclusively depends on intrinsic and extrinsic factors or if it is also genetically determined. We compared the health status of cuff tendons, evaluated with a magnetic resonance imaging (MRI) study, between elderly monozygotic and dizygotic twins with the aim of separating the contributions of genetics from shared and unique environments.

METHODS

The rotator cuff tendon status was assessed using the Sugaya classification by MRI. Heritability, defined as the proportion of total variance of a specific characteristic in a particular population due to a genetic cause, was calculated as twice the difference between the intraclass correlation coefficients for monozygotic and dizygotic pairs. The influence of shared environment, which contributes to twin and sibling similarity, was calculated as the difference between the monozygotic correlation coefficient and the heritability index.

RESULTS

We identified 33 pairs of elderly twins: 17 monozygotic pairs and 16 dizygotic pairs, with a mean age (and standard deviation) of 64.62 ± 3.32 years. The polychoric correlation was 0.62 in monozygotic twins and 0.53 in dizygotic twins. The calculated heritability index was 0.18 (18%), and the contribution was 0.44 (44%) for the shared environment and 0.38 (38%) for the unique environment.

CONCLUSIONS

The role of genetics in rotator cuff degeneration is quantified by our study on elderly monozygotic and dizygotic twins; however, it is only partial with respect to the contribution of shared and unique environments.

Genetics of rotator cuff tears: no association of col5a1 gene in a case-control study

Background

The incidence of RC tears increases with aging, affecting approximately 30 to 50% of individuals older than 50 years, and more than 50% of individuals older than 80 years. Intrinsic factors (age or gender), extrinsic factors (sports activity or occupation), and biological factors were identified in the onset and progression of RC tears. The attention in the study of aetiology of RC tendinopathy has shifted to the identification of gene variants. Genes encoding for proteins regulating the concentration of pyrophosphate in the extracellular matrix and genes encoding for fibroblastic growth factors, defensin beta 1 and estrogen-related receptor-beta were analyzed. However, only in one study the role of variants of collagen type V alpha 1 (col5a1) gene in RC tears was assessed. The objective of this study was to determine whether a col5a1 DNA sequence variant, rs12722 (C/T) was associated with rotator cuff (RC) tears in a case-control study.

Methods

The study included 93 Caucasian patients undergoing surgery for RC tears and 206 patients with no history and sign of RC disease as evaluated by MRI. Patients were divided into two groups. Group 1 included patients with RC tear diagnosed on clinical and imaging grounds and confirmed at the time of surgery. Group 2 (control group) included patients without history or clinical symptoms of RC disorders and with a MRI negative for RC disease. DNA was obtained from approximately 1.2 ml of venous blood using the MagCore extractor system H16 with a MagCore Genomic DNA Large Volume Whole Blood Kit (RBC Bioscience Corp., Taiwan). All study participants were genotyped for SNPs rs12722.

Results

We first estimated that our study had 92% power at p < 0.05 to detect a genetic effect size of 2.05 in the RT tears (93 individuals) and healthy population (206 individuals) cohorts, assuming a minor allele frequency for col5a1 variant rs12722 of 0.5707 in the Italian population (gnomAD frequency). No significant difference in allele and genotype frequencies was observed between RT tears patients and healthy controls. Similarly, no significant association was seen between the RT tears and healthy controls participants in the combined genotype distributions.

Conclusion

In conclusion, no correlations between the SNP rs12722 of col5a1 gene and RC tears susceptibility was found.

Defining the molecular signatures of Achilles tendinopathy and anterior cruciate ligament ruptures: A whole-exome sequencing approach

Musculoskeletal soft tissue injuries are complex phenotypes with genetics being one of many proposed risk factors. Case-control association studies using the candidate gene approach have predominately been used to identify risk loci for these injuries. However, the ability to identify all risk conferring variants using this approach alone is unlikely. Therefore, this study aimed to further define the genetic profile of these injuries using an integrated omics approach involving whole exome sequencing and a customised analyses pipeline. The exomes of ten exemplar asymptomatic controls and ten exemplar cases with Achilles tendinopathy were individually sequenced using a platform that included the coverage of the untranslated regions and miRBase miRNA genes. Approximately 200 000 variants were identified in the sequenced samples. Previous research was used to guide a targeted analysis of the genes encoding the tenascin-C (TNC) glycoprotein and the α1 chain of type XXVII collagen (COL27A1) located on chromosome 9. Selection of variants within these genes were; however, not predetermined but based on a tiered filtering strategy. Four variants in TNC (rs1061494, rs1138545, rs2104772 and rs1061495) and three variants in the upstream COL27A1 gene (rs2567706, rs2241671 and rs2567705) were genotyped in larger Achilles tendinopathy and anterior cruciate ligament (ACL) rupture sample groups. The CC genotype of TNC rs1061494 (C/T) was associated with the risk of Achilles tendinopathy (p = 0.018, OR: 2.5 95% CI: 1.2-5.1). Furthermore, the AA genotype of the TNC rs2104772 (A/T) variant was significantly associated with ACL ruptures in the female subgroup (p = 0.035, OR: 2.3 95% CI: 1.1-5.5). An inferred haplotype in the TNC gene was also associated with the risk of Achilles tendinopathy. These results provide a proof of concept for the use of a customised pipeline for the exploration of a larger genomic dataset. This approach, using previous research to guide a targeted analysis of the data has generated new genetic signatures in the biology of musculoskeletal soft tissue injuries.

Some patients (and some of us) respond better to some biological therapies: the as yet unsolved conundrum

Very often, treatment for many common musculoskeletal conditions is only palliative, or involves surgery with major shortcomings. Biological interventions—in particular, platelet-rich plasma (PRP) therapies—may well provide more effective treatments, but their actual efficacy is under scrutiny. PRP is biologically unique to each individual depending on endogenous and exogenous factors, including, but not limited to, demographic factors (i.e. age), immune status (i.e. microbiota), metabolic diseases and concomitant medications. All these potential modifiers of the ultimate effects of PRP have been poorly explored, and their relationship with efficacy has not been established.

GWAS-based machine learning approach to predict duloxetine response in major depressive disorder

Major depressive disorder (MDD) is one of the most prevalent psychiatric disorders and is commonly treated with antidepressant drugs. However, large variability is observed in terms of response to antidepressants. Machine learning (ML) models may be useful to predict treatment outcomes. A sample of 186 MDD patients received treatment with duloxetine for up to 8 weeks were categorized as "responders" based on a MADRS change >50% from baseline; or "remitters" based on a MADRS score ≤10 at end point. The initial dataset (N = 186) was randomly divided into training and test sets in a nested 5-fold cross-validation, where 80% was used as a training set and 20% made up five independent test sets. We performed genome-wide logistic regression to identify potentially significant variants related to duloxetine response/remission and extracted the most promising predictors using LASSO regression. Subsequently, classification-regression trees (CRT) and support vector machines (SVM) were applied to construct models, using ten-fold cross-validation. With regards to response, none of the pairs performed significantly better than chance (accuracy p > .1). For remission, SVM achieved moderate performance with an accuracy = 0.52, a sensitivity = 0.58, and a specificity = 0.46, and 0.51 for all coefficients for CRT. The best performing SVM fold was characterized by an accuracy = 0.66 (p = .071), sensitivity = 0.70 and a sensitivity = 0.61. In this study, the potential of using GWAS data to predict duloxetine outcomes was examined using ML models. The models were characterized by a promising sensitivity, but specificity remained moderate at best. The inclusion of additional non-genetic variables to create integrated models may improve prediction.

Genome-wide association study identifies a locus associated with rotator cuff injury

Rotator cuff tears are common, especially in the fifth and sixth decades of life, but can also occur in the competitive athlete. Genetic differences may contribute to overall injury risk. Identifying genetic loci associated with rotator cuff injury could shed light on the etiology of this injury. We performed a genome-wide association screen using publically available data from the Research Program in Genes, Environment and Health including 8,357 cases of rotator cuff injury and 94,622 controls. We found rs71404070 to show a genome-wide significant association with rotator cuff injury with p = 2.31x10-8 and an odds ratio of 1.25 per allele. This SNP is located next to cadherin8, which encodes a protein involved in cell adhesion. We also attempted to validate previous gene association studies that had reported a total of 18 SNPs showing a significant association with rotator cuff injury. However, none of the 18 SNPs were validated in our dataset. rs71404070 may be informative in explaining why some individuals are more susceptible to rotator cuff injury than others.

Targeting Inflammation in Rotator Cuff Tendon Degeneration and Repair

Rotator cuff degeneration is a common affliction that results in pain and disability. Tendinopathy was historically classified with or without the involvement of the immune system. However, technological advancements in screening have shown that the immune system is both present and active in all forms of tendinopathy. During injury and healing, the coordinated effort of numerous immune cell populations work with the resident stromal cells to break down damaged tissues and stimulate remodeling. These cells deploy a wide array of tools, including phagocytosis, enzyme secretion, and chemotactic gradients to direct these processes. Yet, there remains a knowledge gap in our understanding of the sequence of critical events and regulatory factors that mediate this is process in injury and healing. Furthermore, current treatments do not specifically target inflammation at the molecular level. Typical regimens include non-steroidal anti-inflammatory drugs or corticosteroids; however, researchers have found irrevocable functional deficits following treatment, and have disputed their long-term efficacy. Therefore, developing therapeutics that specifically consider the nuances of the immune system are necessary to improve patient outcomes.

Matrix Metalloproteases 1 and 3 Promoter Gene Polymorphism Is Associated With Rotator Cuff Tear

BACKGROUND

Studies suggest that the collagen degeneration and disordered arrangement of collagen fibers in rotator cuff tears are associated with an increase in activity of matrix metalloproteases 1 and 3 (MMP-1 and MMP-3), and that MMP activity may be in part genetically mediated. The degree to which this might be clinically relevant in patients with rotator cuff tears has not been well characterized.

QUESTIONS/PURPOSES

(1) Is genetic polymorphism of MMP-1 and MMP-3 associated with rotator cuff tears? (2) Are there haplotypes of MMP-1 and MMP-3 correlated with rotator cuff tears? (3) Compared with control subjects, do patients with rotator cuff tears have a higher proportion of relatives with the same disease?

METHODS

We evaluated 64 patients with full-thickness rotator cuff tears and 64 asymptomatic control subjects. Patients younger 65 years, with nontraumatic tears, were included. The tear or integrity of the rotator cuff tear was evaluated by MRI or ultrasonography in all individuals. The patients and control subjects were paired by age. MMP-1 and MMP-3 genotypes were determined using the PCR-restriction fragment length polymorphism assays.

RESULTS

Genetic polymorphisms in MMP-1 and MMP-3 are associated with rotator cuff tear, in which individuals with rotator cuff tears have associated genotypes 1G/2G (patients, 32 of 64 [50%], control subjects, 16 of 64 [25%]; odds ratio [OR], 4.8; 95% CI, 2.1-11.0; p < 0.001) and 2G/2G were at great risk (patients, 15 of 64 [23%], control subjects, seven of 64 [11%]; OR, 5.2; 95% CI,1.8-14.9; p < 0.001), and patients with rotator cuff tears were associated with a higher proportion of 2G allele distribution (62 of 128 [48%] versus 30 of 128 [23%]; p < 0.001). Patients with the 5A/5A genotype are at greater risk of rotator cuff tear (patients, 15 of 64 [23%]; control subjects, four of 64 [6%]; OR, 5.5; 95% CI, 1.4-20.9; p = 0.021), and there was higher 5A allele distribution in patients with rotator cuff tears (patients, 68 of 128 [53%]; control subjects, 52 of 128 [41%]; p = 0.045). Individuals with the haplotype 2G/5A were more likely to have rotator cuff tears develop (patients, 42 of 64 [66%]; control subjects, 17 of 64 [27%]; OR, 5.3; 95% CI, 2.5-11.3; p < 0.001). Patients with rotator cuff tears reported, in higher number, the existence of relatives who previously had treatment for rotator cuff tears (19 of 64 [30%] versus four of 64 [6%]; OR, 6.3; 95% CI, 2.0-19.9; p = 0.001).

CONCLUSIONS

The genetic polymorphism of MMP-1 and MMP-3 is associated with rotator cuff tear. Individuals with haplotype 2G/5A were more susceptible to rotator cuff tears in the population studied.

CLINICAL RELEVANCE

Knowledge of the genetic markers related to rotator cuff tears can enable identification of susceptible individuals and increase understanding of the pathogenesis of tendon degeneration.