A genome-wide association analysis identifies 16 novel susceptibility loci for carpal tunnel syndrome

Identifying non-genetic factors associated with trigger finger

BACKGROUND

The non-genetic factors predisposing to trigger finger (TF) have mostly been characterised in small studies from individual institutions. Here, we aimed to provide a more complete picture of TF and its associations.

METHODOLOGY

This case-control study used cross-sectional data from the UK Biobank population-based cohort to identify and determine the strength of associations of phenotypic variables with TF. We performed multivariable logistic regression of a multitude of phenotypic factors associated with TF.

RESULTS

We identified 2250 individuals with medical and surgical diagnostic codes for TF, and 398,495 controls. TF was found to be significantly associated with age (OR 1.04, 95% CI 1.03-1.04, P < 2.23×10-308), female sex (OR 1.22, 95% CI 1.08-1.39, P = 2.35×10-3), body mass index (OR 1.10, 95% CI 1.04-1.16, P = 5.52×10-4), carpal tunnel syndrome (OR 9.59, 95% CI 8.68-10.59, P < 2.23×10-308), Dupuytren's disease (OR 4.89, 95% CI 4.06-5.89, P < 2.23×10-308), diabetes mellitus without complications (OR 1.35, 95% CI 1.15-1.58, P = 2.03×10-4) and with complications (OR 2.46, 95% CI 1.90-3.17, P = 4.98×10-12), HbA1c (OR 1.01, 95% CI 1.01-1.02, P = 8.99×10-9), hypothyroidism (OR 1.24, 95% CI 1.07-1.43, P = 4.75×10-3) and rheumatoid arthritis (OR 1.33, 95% CI 1.06-1.68, P = 0.014).

CONCLUSION

Our results provide evidence supporting the well-known risk factors such as diabetes mellitus, carpal tunnel syndrome, age and female sex. Furthermore, we can confirm putative associations such as hypothyroidism, obesity and rheumatoid arthritis, while providing evidence against others such as hypertension and hyperlipidaemia. A novel finding arising from this study is the strong association with Dupuytren's disease. Our study design allowed us to identify these associations as being independent from carpal tunnel syndrome, thereby indicating a shared pathophysiology between this disease and TF.

Genetic Correlations between Migraine and Carpal Tunnel Syndrome

BACKGROUND

Surgical deactivation of extracranial nerve trigger sites is now well established as an effective treatment for migraine headache. Parallels have been drawn to median nerve decompression for carpal tunnel syndrome (CTS), and 2 previous studies have demonstrated an association between migraine and CTS. The authors sought to (1) substantiate these findings in a considerably larger UK cohort, and (2) investigate potential genetic associations between the 2 disorders.

METHODS

Nested case-control studies were conducted in the UK Biobank cohort of 401,656 individuals. Odds ratios were calculated for the association between migraine and CTS in the overall cohort and sex-stratified subsets. Genetic correlation between migraine and CTS was interrogated by linkage disequilibrium score regression, leveraging data from published genomewide association studies. Regions of genetic overlap were identified by multitrait analysis of genomewide association studies and cross-phenotype association.

RESULTS

Migraine and CTS show a significant epidemiologic association within UK Biobank (OR, 1.14, 95% CI, 1.04 to 1.25; P = 0.0058), which is specific to women (OR, 1.15; 95% CI, 1.04 to 1.28; P = 0.0057) and not men (OR, 1.07; 95% CI, 0.82 to 1.40; P = 0.61). Genetic analysis demonstrated a significant positive genetic correlation between the 2 disorders ( rg = 0.13; P = 0.0039), and implicated the TRIM32 locus on chromosome 9 as a region of genetic overlap.

CONCLUSIONS

This study replicates past reports of an epidemiologic association between CTS and migraine, albeit in women only. This association is underpinned by a genetic correlation, with shared genetic susceptibility at the TRIM32 locus. The authors' data add credibility to the notion that an element of entrapment neuropathy underlies migraine pathophysiology.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, III.

Carpal tunnel syndrome

Carpal tunnel syndrome (CTS) is the most common nerve entrapment disorder worldwide. The epidemiology and risk factors, including family burden, for developing CTS are multi-factorial. Despite much research, its intricate pathophysiological mechanism(s) are not fully understood. An underlying subclinical neuropathy may indicate an increased susceptibility to developing CTS. Although surgery is often performed for CTS, clear international guidelines to indicate when to perform non-surgical or surgical treatment, based on stage and severity of CTS, remain to be elucidated. Neurophysiological examination, using electrophysiology or ultrasonography, performed in certain circumstances, should correlate with the history and findings in clinical examination of the person with CTS. History and clinical examination are particularly relevant globally owing to lack of other equipment. Various instruments are used to assess CTS and treatment outcomes as well as the effect of the disorder on quality of life. The surgical treatment options of CTS - open or endoscopic - offer an effective solution to mitigate functional impairments and pain. However, there are risks of post-operative persistent or recurrent symptoms, requiring meticulous diagnostic re-evaluation before any additional surgery. Health-care professionals should have increased awareness about CTS and all its implications. Future considerations of CTS include use of linked national registries to understand risk factors, explore possible screening methods, and evaluate diagnosis and treatment with a broader perspective beyond surgery, including psychological well-being.

[The EAN-NeuPSIG guideline on the diagnosis of neuropathic pain-a summary]

In this joint guideline of the scientific societies and working groups mentioned in the title, evidence-based recommendations for the use of screening questionnaires and diagnostic tests in patients with neuropathic pain were developed. The systematic literature search and meta-analysis yielded the following results: Of the screening questionnaires, Douleur Neuropathique en 4 Questions (DN4), I‑DN4 (self-administered DN4), and Leeds Assessment of Neuropathic Symptoms and Signs (LANSS) received a strong recommendation, while S‑LANSS (self-administered LANSS) and PainDETECT received weak recommendations for their use in the diagnostic workup of patients with possible neuropathic pain. There was a strong recommendation for the use of skin biopsy and a weak recommendation for quantitative sensory testing and nociceptive evoked potentials. The role of confocal corneal microscopy is still unclear. Functional imaging and peripheral nerve blocks are helpful in elucidating the pathophysiology, but current literature does not support their use in diagnosing neuropathic pain. In selected cases, genetic testing in specialized centers may be considered.

Relationship of obesity indices with clinical severity and nerve conduction studies in females presenting with median nerve compression neuropathy at the wrist

Background

Carpal tunnel syndrome (CTS) is considered to be one of the most common peripheral nerve disorders with female preponderance which significantly reduces work efficacy and needs further research on its preventable factors, especially obesity. We studied the effects of obesity indices on Phalen's test duration and median nerve conduction study (NCS) parameters in patients presenting with CTS.

Methods

We examined 229 female patients presenting with clinical features of CTS. Clinical examinations including Phalen's test, median NCSs, and body composition were evaluated. Obesity indices and electrophysiological parameters were compared.

Results

There were significant associations of both body mass index (BMI) degrees and body fat percent (BF%) with clinical and NCS parameters with a linear relationship. BF% and BMI were strongly negatively correlated with Phalen's test duration (BF%; r = -0.334, BMI; r = -0.270 P = 0.001). On the other hand, BF% and BMI were positively correlated with median distal latency (BF%; r = 0.338, BMI; r = 0.372, P value = 0.001), M-latency (BF%; r = 0.264, BMI; r = 0.285, P = 0.001), median motor conduction velocity (MMCV) (BF%; r = 0.119, P = 0.072, BMI; r = 0.173, P = 0.009), median sensory conduction velocity (MSCV) (BF%; r = -0.195, P = 0.003, BMI; r = 0.327, P = 0.001), and sensory nerve action potential (SNAP amplitude) (BF%; r = -.239, BMI; r = -0.350, P = 0.001).

Conclusions

Nerve conduction parameters are significantly affected by obesity degree defined by BMI and BF%. Therefore, combining BMI and BF% assessments gives more clinical information regarding CTS severity and management. The true predictive value of these indices needs to be elucidated further.

Variant to gene mapping for carpal tunnel syndrome risk loci implicates skeletal muscle regulatory elements

BACKGROUND

Carpal tunnel syndrome (CTS) is a common disorder caused by compression of the median nerve in the wrist, resulting in pain and numbness throughout the hand and forearm. While multiple behavioural and physiological factors influence CTS risk, a growing body of evidence supports a strong genetic contribution. Recent genome-wide association study (GWAS) efforts have reported 53 independent signals associated with CTS. While GWAS can identify genetic loci conferring risk, it does not determine which cell types drive the genetic aetiology of the trait, which variants are "causal" at a given signal, and which effector genes correspond to these non-coding variants. These obstacles limit interpretation of potential disease mechanisms.

METHODS

We analysed CTS GWAS findings in the context of chromatin conformation between gene promoters and accessible chromatin regions across cellular models of bone, skeletal muscle, adipocytes and neurons. We identified proxy variants in high LD with the lead CTS sentinel SNPs residing in promoter connected open chromatin in the skeletal muscle and bone contexts.

FINDINGS

We detected significant enrichment for heritability in skeletal muscle myotubes, as well as a weaker correlation in human mesenchymal stem cell-derived osteoblasts. In myotubes, our approach implicated 117 genes contacting 60 proxy variants corresponding to 20 of the 53 GWAS signals. In the osteoblast context we implicated 30 genes contacting 24 proxy variants coinciding with 12 signals, of which 19 genes shared. We subsequently prioritized BZW2 as a candidate effector gene in CTS and implicated it as novel gene that perturbs myocyte differentiation in vitro.

INTERPRETATION

Taken together our results suggest that the CTS genetic component influences the size, integrity, and organization of multiple tissues surrounding the carpal tunnel, in particular muscle and bone, to predispose the nerve to being compressed in this disease setting.

FUNDING

This work was supported by NIH Grant UM1 DK126194 (SFAG and WY), R01AG072705 (SFAG & KDH) and the Center for Spatial and Functional Genomics at CHOP (SFAG & ADW). SFAG is supported by the Daniel B. Burke Endowed Chair for Diabetes Research. WY is supported by the Perelman School of Medicine of the University of Pennsylvania.

Modifiable Risk Factors for Prevention in Dupuytren Disease: A UK Biobank Case-Control Study

BACKGROUND

Dupuytren disease is associated with significant comorbidity and mortality, and it has no existing prevention strategies. It is unclear which modifiable risk factors are most amenable for prevention. This study aimed to determine the strength of modifiable risk factors for Dupuytren disease, and to investigate associations with other diseases.

METHODS

Using UK Biobank data, this case-control study analyzed the association between phenotypic variables and Dupuytren disease through multivariable logistic regression. Exposures assessed were age, sex, body mass index, waist-to-hip ratio, Townsend deprivation index, smoking status, alcohol intake, diabetes mellitus, hypertension, cancer, liver disease, respiratory disease, rheumatoid arthritis, epilepsy, psoriasis, and gout.

RESULTS

There were 4148 cases and 397,425 controls. Male sex (OR, 3.23; 95% CI, 2.90 to 3.60; P = 1.07 × 10 -100 ), increasing age (OR, 1.08; 95% CI, 1.07 to 1.08; P = 6.78 × 10 -167 ), material deprivation (OR, 1.01; 95% CI, 1.00 to 1.02; P = 0.0305), high-density lipoprotein cholesterol (OR, 1.76; 95% CI, 1.58 to 1.96; P = 3.35 × 10 -24 ), smoking exposure, and alcohol intake were all associated with increased odds of Dupuytren disease. With increasing obesity class, there was approximately 25% decreased odds (OR, 0.774; 95% CI, 0.734 to 0.816; P = 4.71 × 10 -21 ). Diabetes with microvascular or end-organ complications was associated with more than 2.5 times increased odds of Dupuytren disease (OR, 2.59; 95% CI, 1.92 to 3.44; P = 1.92 × 10 -10 ). Within this group, increasing hemoglobin A1c values by 10 mmol/mol, or 0.9%, increased the odds by 31% (OR, 1.31; 95% CI, 1.13 to 1.51; P = 2.19 × 10 -4 ).

CONCLUSION

Diabetes and poor glycemic control are major risk factors for Dupuytren disease, which present an opportunity for prevention.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, III.

Genetic causal association between frozen shoulder and carpal tunnel syndrome: a two-sample mendelian randomization

OBJECTIVE

Observational studies have suggested an association between frozen shoulder (FS) and carpal tunnel syndrome (CTS). However, due to challenges in establishing a temporal sequence, the causal relationship between these two conditions remains elusive. This study, based on aggregated data from large-scale population-wide genome-wide association studies (GWAS), investigates the genetic causality between FS and CTS.

METHODS

Initially, a series of quality control measures were employed to select single nucleotide polymorphisms (SNPs) closely associated with the exposure factors. Two-sample Mendelian randomization (MR) was utilized to examine the genetic causality between FS and CTS, employing methods including Inverse-Variance Weighted (IVW), MR-Egger, Weighted Median, Simple Mode, and Weighted Mode approaches. Subsequently, sensitivity analyses were conducted to assess the robustness of the MR analysis results.

RESULTS

IVW analysis results indicate a positive causal relationship between CTS and FS (p < 0.05, OR > 1), while a negative causal relationship between the two conditions was not observed. Heterogeneity tests suggest minimal heterogeneity in our IVW analysis results (p > 0.05). Multivariable MR testing also indicates no pleiotropy in our IVW analysis (p > 0.05), and stepwise exclusion tests demonstrate the reliability and stability of the MR analysis results. Gene Ontology (GO) pathway analysis reveals enrichment of genes regulated by the associated SNPs in the TGFβ-related pathways.

CONCLUSION

This study provides evidence of the genetic causal association between frozen shoulder and carpal tunnel syndrome and provides new insights into the genetics of fibrotic disorders.

Surgery for mononeuropathies

Advancement in microsurgical techniques and innovative approaches including greater use of nerve and tendon transfers have resulted in better peripheral nerve injury (PNI) surgical outcomes. Clinical evaluation of the patient and their injury factors along with a shift toward earlier time frame for intervention remain key. A better understanding of the pathophysiology and biology involved in PNI and specifically mononeuropathies along with advances in ultrasound and magnetic resonance imaging allow us, nowadays, to provide our patients with a logical and sophisticated approach. While functional outcomes are constantly being refined through different surgical techniques, basic scientific concepts are being advanced and translated to clinical practice on a continuous basis. Finally, a combination of nerve transfers and technological advances in nerve/brain and machine interfaces are expanding the scope of nerve surgery to help patients with amputations, spinal cord, and brain lesions.

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.

Screening Plasma Proteins for the Putative Drug Targets for Carpal Tunnel Syndrome

Carpal tunnel syndrome (CTS) is one of the most common work-related musculoskeletal disorders. The present study sought to identify putative causal proteins for CTS. We conducted a two-sample Mendelian randomization (MR) analysis to evaluate the causal association between 2859 plasma proteins (N = 35,559) and CTS (N = 1,239,680) based on the published GWAS summary statistics. Then we replicated the significant associations using an independent plasma proteome GWAS (N = 10,708). Sensitivity analyses were conducted to validate the robustness of MR results. Multivariate MR and mediation analyses were conducted to evaluate the mediation effects of body mass index (BMI), type 2 diabetes (T2D), and arm tissue composition on the association between putative causal proteins and CTS. Colocalization analysis was used to examine whether the identified proteins and CTS shared causal variant(s). Finally, we evaluated druggability of the identified proteins. Ten plasma proteins were identified as putative causal markers for CTS, including sCD14, PVR, LTOR3, CTSS, SIGIRR, IFNL3, ASPN, TM11D, ASIP, and ITIH1. Sensitivity analyses and reverse MR analysis validated the robustness of their causal effects. Arm tissue composition, BMI, and T2D may play a fully/partial mediating role in the causal relationships of ASIP, TM11D, IFNL3, PVR, and LTOR3 with CTS. The association of ASPN and sCD14 with CTS were supported by colocalization analysis. Druggability assessment demonstrated that sCD14, CTSS, TM11D, and IFNL3 were potential drug therapeutic targets. The present study identified several potential plasma proteins that were causally associated with CTS risk, providing new insights into the pathogenesis of protein-mediated CTS and offering potential targets for new therapies.

Big data, big consortia, and pain: UK Biobank, PAINSTORM, and DOLORisk

Chronic pain (CP) is a common and often debilitating disorder that has major social and economic impacts. A subset of patients develop CP that significantly interferes with their activities of daily living and requires a high level of healthcare support. The challenge for treating physicians is in preventing the onset of refractory CP or effectively managing existing pain. To be able to do this, it is necessary to understand the risk factors, both genetic and environmental, for the onset of CP and response to treatment, as well as the pathogenesis of the disorder, which is highly heterogenous. However, studies of CP, particularly pain with neuropathic characteristics, have been hindered by a lack of consensus on phenotyping and data collection, making comparisons difficult. Furthermore, existing cohorts have suffered from small sample sizes meaning that analyses, especially genome-wide association studies, are insufficiently powered. The key to overcoming these issues is through the creation of large consortia such as DOLORisk and PAINSTORM and biorepositories, such as UK Biobank, where a common approach can be taken to CP phenotyping, which allows harmonisation across different cohorts and in turn increased study power. This review describes the approach that was used for studying neuropathic pain in DOLORisk and how this has informed current projects such as PAINSTORM, the rephenotyping of UK Biobank, and other endeavours. Moreover, an overview is provided of the outputs from these studies and the lessons learnt for future projects.

Joint European Academy of Neurology-European Pain Federation-Neuropathic Pain Special Interest Group of the International Association for the Study of Pain guidelines on neuropathic pain assessment

BACKGROUND AND PURPOSE

In these guidelines, we aimed to develop evidence-based recommendations for the use of screening questionnaires and diagnostic tests in patients with neuropathic pain (NeP).

METHODS

We systematically reviewed studies providing information on the sensitivity and specificity of screening questionnaires, and quantitative sensory testing, neurophysiology, skin biopsy, and corneal confocal microscopy. We also analysed how functional neuroimaging, peripheral nerve blocks, and genetic testing might provide useful information in diagnosing NeP.

RESULTS

Of the screening questionnaires, Douleur Neuropathique en 4 Questions (DN4), I-DN4 (self-administered DN4), and Leeds Assessment of Neuropathic Symptoms and Signs (LANSS) received a strong recommendation, and S-LANSS (self-administered LANSS) and PainDETECT weak recommendations for their use in the diagnostic pathway for patients with possible NeP. We devised a strong recommendation for the use of skin biopsy and a weak recommendation for quantitative sensory testing and nociceptive evoked potentials in the NeP diagnosis. Trigeminal reflex testing received a strong recommendation in diagnosing secondary trigeminal neuralgia. Although many studies support the usefulness of corneal confocal microscopy in diagnosing peripheral neuropathy, no study specifically investigated the diagnostic accuracy of this technique in patients with NeP. Functional neuroimaging and peripheral nerve blocks are helpful in disclosing pathophysiology and/or predicting outcomes, but current literature does not support their use for diagnosing NeP. Genetic testing may be considered at specialist centres, in selected cases.

CONCLUSIONS

These recommendations provide evidence-based clinical practice guidelines for NeP diagnosis. Due to the poor-to-moderate quality of evidence identified by this review, future large-scale, well-designed, multicentre studies assessing the accuracy of diagnostic tests for NeP are needed.

A comparative study on efficacy of modified endoscopic minimally invasive treatment and traditional open surgery for primary carpal tunnel syndrome

BACKGROUND AND OBJECTIVE

Carpal tunnel syndrome (CTS) is the most common type of median nerve entrapment neuropathy. This study aims to comparatively assess the effectiveness and clinical efficacy of modified transforaminal endoscopic minimally invasive incision of transverse carpal ligament against traditional open incision of transverse carpal ligament in the treatment of CTS.

METHOD

The clinical data of 35 patients (57 wrists) with primary CTS treated in Shanxi Bethune Hospital, China, were retrospectively analyzed. The patients were divided into observation group (21 cases, 33 wrists) and control group (14 cases, 24 wrists), respectively, who underwent modified endoscopic minimally invasive incision of transverse carpal ligament and traditional open incision of transverse carpal ligament release. The Boston Carpal Tunnel Questionnaire (BCTQ) was assessed at for points: before the operation; 2 weeks; 1 month; and 3 months after operation. The BCTQ scores of the two groups were compared on all four points. The incidence of intraoperative and postoperative complication was used as the evaluation index. The study variables were comparatively assessed before and postoperation and also between the groups.

RESULTS

The BCTQ scores at 2 weeks, 1 month and 3 months after the operation were significantly lower than preoperative BCTQ scores (P < 0.005) for both the groups. There was no significant difference in BCTQ scores between the two groups at the four assessment points (P > 0.005). The scar size and wound healing time were significantly better with modified transforaminal endoscopic minimally invasive transverse carpal ligament incision.

CONCLUSION

The clinical effects of both modified transforaminal minimally invasive incision of transverse carpal ligament and traditional open incision of transverse carpal ligament are significant, while the treatment efficacy of modified transforaminal minimally invasive transverse carpal ligament incision is better in terms of operation time, wound size, postoperative scar size and incision healing time.

A Shared Genetic Signature for Common Chronic Pain Conditions and its Impact on Biopsychosocial Traits

The multiple comorbidities & dimensions of chronic pain present a formidable challenge in disentangling its aetiology. Here, we performed genome-wide association studies of 8 chronic pain types using UK Biobank data (N =4,037-79,089 cases; N = 239,125 controls), followed by bivariate linkage disequilibrium-score regression and latent causal variable analyses to determine (respectively) their genetic correlations and genetic causal proportion (GCP) parameters with 1,492 other complex traits. We report evidence of a shared genetic signature across chronic pain types as their genetic correlations and GCP directions were broadly consistent across an array of biopsychosocial traits. Across 5,942 significant genetic correlations, 570 trait pairs could be explained by a causal association (|GCP| >0.6; 5% false discovery rate), including 82 traits affected by pain while 410 contributed to an increased risk of chronic pain (cf. 78 with a decreased risk) such as certain somatic pathologies (eg, musculoskeletal), psychiatric traits (eg, depression), socioeconomic factors (eg, occupation) and medical comorbidities (eg, cardiovascular disease). This data-driven phenome-wide association analysis has demonstrated a novel and efficient strategy for identifying genetically supported risk & protective traits to enhance the design of interventional trials targeting underlying causal factors and accelerate the development of more effective treatments with broader clinical utility. PERSPECTIVE: Through large-scale phenome-wide association analyses of >1,400 biopsychosocial traits, this article provides evidence for a shared genetic signature across 8 common chronic pain types. It lays the foundation for further translational studies focused on identifying causal genetic variants and pathophysiological pathways to develop novel diagnostic & therapeutic technologies and strategies.

Shared genetic architecture of hernias: A genome-wide association study with multivariable meta-analysis of multiple hernia phenotypes

Abdominal hernias are common and characterised by the abnormal protrusion of a viscus through the wall of the abdominal cavity. The global incidence is 18.5 million annually and there are limited non-surgical treatments. To improve understanding of common hernia aetiopathology, we performed a six-stage genome-wide association study (GWAS) of 62,637 UK Biobank participants with either single or multiple hernia phenotypes including inguinal, femoral, umbilical and hiatus hernia. Additionally, we performed multivariable meta-analysis with metaUSAT, to allow integration of summary data across traits to generate combined effect estimates. On individual hernia analysis, we identified 3404 variants across 38 genome-wide significant (p < 5×10-8) loci of which 11 are previously unreported. Robust evidence for five shared susceptibility loci was discovered: ZC3H11B, EFEMP1, MHC region, WT1 and CALD1. Combined hernia phenotype analyses with additional multivariable meta-analysis of summary statistics in metaUSAT revealed 28 independent (seven previously unreported) shared susceptibility loci. These clustered in functional categories related to connective tissue and elastic fibre homeostasis. Weighted genetic risk scores also correlated with disease severity suggesting a phenotypic-genotypic severity correlation, an important finding to inform future personalised therapeutic approaches to hernia.

Characterization of Genetic Risk of End-Stage Knee Osteoarthritis Treated with Total Knee Arthroplasty: A Genome-Wide Association Study

BACKGROUND

End-stage knee osteoarthritis (OA) is a highly debilitating disease for which total knee arthroplasty (TKA) serves as an effective treatment option. Although a genetic component to OA in general has been described, evaluation of the genetic contribution to end-stage OA of the knee is limited. To this end, we present a genome-wide association study involving patients undergoing TKA for primary knee OA to characterize the genetic features of severe disease on a population level.

METHODS

Individuals with the diagnosis of knee OA who underwent primary TKA were identified in the U.K. Biobank using administrative codes. The U.K. Biobank is a data repository containing prospectively collected clinical and genomic data for >500,000 patients. A genome-wide association analysis was performed using the REGENIE software package. Logistic regression was also used to compare the total genetic risk between subgroups stratified by age and body mass index (BMI).

RESULTS

A total of 16,032 patients with end-stage knee OA who underwent primary TKA were identified. Seven genetic loci were found to be significantly associated with end-stage knee OA. The odds ratio (OR) for developing end-stage knee OA attributable to genetics was 1.12 (95% confidence interval [CI], 1.10 to 1.14), which was lower than the OR associated with BMI (OR = 1.81; 95% CI, 1.78 to 1.83) and age (OR = 2.38; 95% CI, 2.32 to 2.45). The magnitude of the OR for developing end-stage knee OA attributable to genetics was greater in patients <60 years old than in patients ≥60 years old (p = 0.002).

CONCLUSIONS

This population-level genome-wide association study of end-stage knee OA treated with primary TKA was notable for identifying multiple significant genetic variants. These loci involve genes responsible for cartilage development, cartilage homeostasis, cell signaling, and metabolism. Age and BMI appear to have a greater impact on the risk of developing end-stage disease compared with genetic factors. The genetic contribution to the development of severe disease is greater in younger patients.

LEVEL OF EVIDENCE

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

Shared genetic susceptibility between trigger finger and carpal tunnel syndrome: a genome-wide association study

Background

Trigger finger and carpal tunnel syndrome are the two most common non-traumatic connective tissue disorders of the hand. Both of these conditions frequently co-occur, often in patients with rheumatoid arthritis. However, this phenotypic association is poorly understood. Hypothesising that the co-occurrence of trigger finger and carpal tunnel syndrome might be explained by shared germline predisposition, we aimed to identify a specific genetic locus associated with both diseases.

Methods

In this genome-wide association study (GWAS), we identified 2908 patients with trigger finger and 436579 controls from the UK Biobank prospective cohort. We conducted a case-control GWAS for trigger finger, followed by co-localisation analyses with carpal tunnel syndrome summary statistics. To identify putative causal variants and establish their biological relevance, we did fine-mapping analyses and expression quantitative trait loci (eQTL) analyses, using fibroblasts from healthy donors (n=79) and tenosynovium samples from patients with carpal tunnel syndrome (n=77). We conducted a Cox regression for time to trigger finger and carpal tunnel syndrome diagnosis against plasma IGF-1 concentrations in the UK Biobank cohort.

Findings

Phenome-wide analyses confirmed a marked association between carpal tunnel syndrome and trigger finger in the participants from UK Biobank (odds ratio [OR] 11·97, 95% CI 11·1-13·0; p<1 × 10^-300). GWAS for trigger finger identified five independent loci, including one locus, DIRC3, that was co-localised with carpal tunnel syndrome and could be fine-mapped to rs62175241 (0·76, 0·68-0·84; p=5·03 × 10^-13). eQTL analyses found a fibroblast-specific association between the protective T allele of rs62175241 and increased DIRC3 and IGFBP5 expression. Increased plasma IGF-1 concentrations were associated with both carpal tunnel syndrome and trigger finger in participants from UK Biobank (hazard ratio >1·04, p<0·02).

Interpretation

In this GWAS, the DIRC3 locus on chromosome 2 was significantly associated with both carpal tunnel syndrome and trigger finger, possibly explaining their co-occurrence. The disease-protective allele of rs62175241 was associated with increased expression of long non-coding RNA DIRC3 and its transcriptional target, IGBP5, an antagonist of IGF-1 signalling. These findings suggest a model in which IGF-1 is a driver of both carpal tunnel syndrome and trigger finger, and in which the DIRC3-IGFBP5 axis directly antagonises fibroblastic IGF-1 signalling.

Funding

Wellcome Trust, National Institute for Health Research, Medical Research Council.

Endothelial nitric oxide synthase Asp298Glu (894G/T) gene polymorphism as a possible risk factor for the coronary slow flow phenomenon among Iranians

Background

Mounting evidence indicates an association between endothelial dysfunction and the coronary slow flow phenomenon (CSFP). In the present study, we aimed to evaluate the possible role of endothelial nitric oxide synthase (eNOS) 894G/T and interleukin-1β (IL-1β) 315C/T polymorphisms as possible risk factors for CSFP.

Methods

This prospective study enrolled patients with CSFP and individuals with normal coronary arteries. Genotypes were assessed using regular polymerase chain reaction and direct Sanger-sequencing techniques.

Results

The study population consisted of 267 individuals: 180 patients with CSFP (49 women [27.2%]) at a median age of 55 (48–62) years and 87 controls with normal coronary arteries (56 women [64.4%]) at a median age of 47 (41–58) years. The allelic distribution of eNOS 894G/T was significantly associated with CSFP (odds ratio [OR], 1.58; 95% confidence interval (CI), 1.04–2.42; P = 0.03). This polymorphism increased the risk of CSFP under the dominant model (OR 1.73; 95% CI I.02–2.95; P = 0.04). However, the allelic frequencies (1.05; 95% CI 0.68–1.59; P = 0.83) and genotypic frequencies (0.88; 95% CI 0.52–1.49; P = 0.63) of the IL-1β 315C/T polymorphism were not associated with the incidence of CSFP in the Iranian population.

Conclusions

The CSFP and control groups were statistically different regarding the eNOS 894G/T polymorphism. Our findings also demonstrated that the IL-1β 315C/T polymorphism was not a risk factor for CSFP.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-022-02736-0.

Genome-wide association analysis and replication in 810,625 individuals with varicose veins

Varicose veins affect one-third of Western society, with a significant subset of patients developing venous ulceration, costing $14.9 billion annually in the USA. Current management consists of either compression stockings, or surgical ablation for more advanced disease. Most varicose veins patients report a positive family history, and heritability is ~17%. We describe the largest two-stage genome-wide association study of varicose veins in 401,656 individuals from UK Biobank, and replication in 408,969 individuals from 23andMe (total 135,514 cases and 675,111 controls). Forty-nine signals at 46 susceptibility loci were discovered. We map 237 genes to these loci, several of which are biologically plausible and tractable to therapeutic targeting. Pathway analysis identified enrichment in extracellular matrix biology, inflammation, (lymph)angiogenesis, vascular smooth muscle cell migration, and apoptosis. Using a polygenic risk score (PRS) derived in an independent cohort, we demonstrate its predictive utility and correlation with varicose veins surgery.

A genome-wide meta-analysis identifies 50 genetic loci associated with carpal tunnel syndrome

Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy and has a largely unknown underlying biology. In a genome-wide association study of CTS (48,843 cases and 1,190,837 controls), we found 53 sequence variants at 50 loci associated with the syndrome. The most significant association is with a missense variant (p.Glu366Lys) in SERPINA1 that protects against CTS (P = 2.9 × 10^-24, OR = 0.76). Through various functional analyses, we conclude that at least 22 genes mediate CTS risk and highlight the role of 19 CTS variants in the biology of the extracellular matrix. We show that the genetic component to the risk is higher in bilateral/recurrent/persistent cases than nonrecurrent/nonpersistent cases. Anthropometric traits including height and BMI are genetically correlated with CTS, in addition to early hormonal-replacement therapy, osteoarthritis, and restlessness. Our findings suggest that the components of the extracellular matrix play a key role in the pathogenesis of CTS.

Carpal Tunnel Syndrome and Diabetes—A Comprehensive Review

Carpal tunnel syndrome (CTS) is the most common compression neuropathy in the general population and is frequently encountered among individuals with type 1 and 2 diabetes. The reason(s) why a peripheral nerve trunk in individuals with diabetes is more susceptible to nerve compression is still not completely clarified, but both biochemical and structural changes in the peripheral nerve are probably implicated. In particular, individuals with neuropathy, irrespective of aetiology, have a higher risk of peripheral nerve compression disorders, as reflected among individuals with diabetic neuropathy. Diagnosis of CTS in individuals with diabetes should be carefully evaluated; detailed case history, thorough clinical examination, and electrophysiological examination is recommended. Individuals with diabetes and CTS benefit from surgery to the same extent as otherwise healthy individuals with CTS. In the present review, we describe pathophysiological aspects of the nerve compression disorder CTS in relation to diabetes, current data contributing to the explanation of the increased risk for CTS in individuals with diabetes, as well as diagnostic methods, treatment options, and prognosis of CTS in diabetes.

Systemic inflammatory markers in neuropathic pain, nerve injury, and recovery

ABSTRACT

The role that inflammation plays in human nerve injury and neuropathic pain is incompletely understood. Previous studies highlight the role of inflammation in the generation and maintenance of neuropathic pain, but the emerging evidence from the preclinical literature for its role in the resolution of neuropathic pain remains to be explored in humans. Here, we use carpal tunnel syndrome (CTS) as a human model system of nerve injury and neuropathic pain to determine changes in serum cytokine protein levels and gene expression levels before (active stage of disease) and after carpal tunnel decompression surgery (recovery). Fifty-five patients with CTS were studied, and 21 healthy age-matched and gender-matched participants served as controls. In the active stage of the disease (CTS before surgery vs healthy controls), PTGES2 mRNA was decreased in patients (adjusted P = 0.013), while transforming growth factor-β and C-C motif chemokine ligand 5 protein levels were increased (adjusted P = 0.016 and P = 0.047, respectively). In the resolution phase (CTS before surgery vs after surgery), IL-9 mRNA was increased after surgery (adjusted P = 0.014) and expression of IL-6 mRNA and IL-4 protein levels were increased before surgery (adjusted P = 0.034 and P = 0.002, respectively). IL-9 mRNA expression negatively correlated with several (neuropathic) pain scores. By contrast, protein levels of IL-4 positively correlated with pain scores. In conclusion, we demonstrate specific dysregulation of systemic cytokine expression in both the active and resolution phases of nerve injury and neuropathic pain. IL-9 represents an interesting candidate associated with resolution of nerve injury and neuropathic pain.

Identifying Risk Factors for Recurrence After Cubital Tunnel Release

PURPOSE

This study investigated specific risk factors for recurrent surgery of ulnar nerve entrapment (ie, ipsilateral clinical symptoms within 5 years after initial cubital tunnel release [CuTR]) in a large cohort. We hypothesized that recurrence is associated with lifestyle variables (eg, smoking, drinking alcohol, a high body mass index [BMI]) or comorbidities).

METHODS

A retrospective cohort study was performed using the Current Procedural Terminology codes for all patients who underwent CuTR between January 2012 and November 2018. Demographic data, including sex, age, weight, height, BMI, comorbidities, smoking, and alcohol consumption, were collected. The primary outcome was the need for revision surgery after initial CuTR. Univariate and multivariate analyses were performed to identify potential risk factors for revision surgery.

RESULTS

Of the 678 patients who underwent CuTR, 120 patients (18%) needed revision surgery within 5 years. Sixty-six patients required subfascial transposition (55%) and 47 patients (39%) received in situ releases. Also, sex, BMI, smoking, alcohol consumption, and comorbidities (except for spinal disc herniation) were similar between the primary and revision subgroup. Age at first occurrence was significantly lower in the revision group (48 years for revision vs 52 years for primary surgery). Moreover, cervical spinal disc herniation was associated with revision surgery (13% vs 6% in the primary group).

CONCLUSIONS

Age and medical history of cervical spinal disc herniation are associated with an increased risk of revision surgery. More importantly, BMI, smoking, alcohol consumption, and other comorbidities are not associated with increased risk of revision surgery within our sample.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognostic IV.

Update on Efficacy of Conservative Treatments for Carpal Tunnel Syndrome

Carpal tunnel syndrome (CTS) is the most common upper extremity compression neuropathy. Non-operative interventions are usually the first-line treatments, and surgery is reserved for those that do not achieve a satisfactory symptom state by non-operative means. This narrative review summarizes the current evidence regarding the efficacy of orthoses, corticosteroid injections, platelet-rich plasma injections, Kinesio taping, neurodynamic techniques, gabapentin, therapeutic ultrasound, and extracorporeal shockwave therapy in people with CTS. While many trials suggest small short-term benefits, rigorous evidence of long-term patient-important benefits is limited. To improve the utility of healthcare resources, research in this area should focus on establishing efficacy of each treatment instead of comparing various treatments with uncertain benefits.

Genetic basis to structural grey matter associations with chronic pain

Structural neuroimaging studies of individuals with chronic pain conditions have often observed decreased regional grey matter at a phenotypic level. However, it is not known if this association can be attributed to genetic factors. Here we employed a novel integrative data-driven and hypothesis-testing approach to determine whether there is a genetic basis to grey matter morphology differences in chronic pain. Using publicly available genome-wide association study summary statistics for regional chronic pain conditions (n = 196 963) and structural neuroimaging measures (n = 19 629-34 000), we applied bivariate linkage disequilibrium-score regression and latent causal variable analyses to determine the genetic correlations (rG) and genetic causal proportion (GCP) between these complex traits, respectively. Five a priori brain regions (i.e. prefrontal cortex, cingulate cortex, insula, thalamus and superior temporal gyrus) were selected based on systematic reviews of grey matter morphology studies in chronic pain. Across this evidence-based selection of five brain regions, 10 significant negative genetic correlations (out of 369) were found (false discovery rate < 5%), suggesting a shared genetic basis to both reduced regional grey matter morphology and the presence of chronic pain. Specifically, negative genetic correlations were observed between reduced insula grey matter morphology and chronic pain in the abdomen (mean insula cortical thickness), hips (left insula volume) and neck/shoulders (left and right insula volume). Similarly, a shared genetic basis was found for reduced posterior cingulate cortex volume in chronic pain of the hip (left and right posterior cingulate), neck/shoulder (left posterior cingulate) and chronic pain at any site (left posterior cingulate); and for reduced pars triangularis volume in chronic neck/shoulder (left pars triangularis) and widespread pain (right pars triangularis). Across these negative genetic correlations, a significant genetic causal proportion was only found between mean insula thickness and chronic abdominal pain [rG (standard error, SE) = -0.25 (0.08), P = 1.06 × 10-3; GCP (SE) = -0.69 (0.20), P = 4.96 × 10-4]. This finding suggests that the genes underlying reduced cortical thickness of the insula causally contribute to an increased risk of chronic abdominal pain. Altogether, these results provide independent corroborating evidence for observational reports of decreased grey matter of particular brain regions in chronic pain. Further, we show for the first time that this association is mediated (in part) by genetic factors. These novel findings warrant further investigation into the neurogenetic pathways that underlie the development and prolongation of chronic pain conditions.

A single-cell atlas of chromatin accessibility in the human genome

Current catalogs of regulatory sequences in the human genome are still incomplete and lack cell type resolution. To profile the activity of gene regulatory elements in diverse cell types and tissues in the human body, we applied single-cell chromatin accessibility assays to 30 adult human tissue types from multiple donors. We integrated these datasets with previous single-cell chromatin accessibility data from 15 fetal tissue types to reveal the status of open chromatin for ∼1.2 million candidate cis-regulatory elements (cCREs) in 222 distinct cell types comprised of >1.3 million nuclei. We used these chromatin accessibility maps to delineate cell-type-specificity of fetal and adult human cCREs and to systematically interpret the noncoding variants associated with complex human traits and diseases. This rich resource provides a foundation for the analysis of gene regulatory programs in human cell types across tissues, life stages, and organ systems.

Replication of epidemiological associations of carpal tunnel syndrome in a UK population-based cohort of over 400,000 people

Introduction

Several phenotypic factors are associated in the literature with an increased risk of carpal tunnel syndrome (CTS). Along with female sex and older age, certain systemic diseases show an association with CTS, with varying degrees of evidence.

Methods

This study was performed using the UK Biobank resource – a cohort study of over 500,000 participants who have allowed linkage of phenotypic data with their medical records. We calculated the prevalence of CTS and a sex-specific prevalence ratio and compared the body mass index (BMI) between cases and controls. We performed a series of nested case-control studies to compute odds ratios for the association between CTS and three systemic diseases.

Results

There were 12,312 CTS cases within the curated UK Biobank dataset of 401,656 (3.1% prevalence), and the female:male ratio was 1.95:1. CTS cases had, on average, a BMI > 2.0 kg/m² greater than controls. Odds ratios for the association with CTS for three systemic diseases were 2.31 (95% CI 2.17–2.46) for diabetes, 2.70 (95% CI 2.44–2.99) for rheumatoid arthritis, and 1.47 (95% CI 1.38–1.57) for hypothyroidism. Adjusted for BMI, these odds ratios fell to 1.75 (95% CI 1.65–1.86), 2.43 (95% CI 2.20–2.69), and 1.35 (95% CI 1.26–1.43), respectively.

Discussion

We harnessed the size and power of UK Biobank to provide robust replication of evidence for the associations between CTS and female sex, raised BMI, and three systemic diseases, which are only mediated in part by raised BMI.

Mapping the proteo-genomic convergence of human diseases

Characterization of the genetic regulation of proteins is essential for understanding disease etiology and developing therapies. We identified 10,674 genetic associations for 3892 plasma proteins to create a cis-anchored gene-protein-disease map of 1859 connections that highlights strong cross-disease biological convergence. This proteo-genomic map provides a framework to connect etiologically related diseases, to provide biological context for new or emerging disorders, and to integrate different biological domains to establish mechanisms for known gene-disease links. Our results identify proteo-genomic connections within and between diseases and establish the value of cis-protein variants for annotation of likely causal disease genes at loci identified in genome-wide association studies, thereby addressing a major barrier to experimental validation and clinical translation of genetic discoveries.

Lessons from Injury: How Nerve Injury Studies Reveal Basic Biological Mechanisms and Therapeutic Opportunities for Peripheral Nerve Diseases

Since Waller and Cajal in the nineteenth and early twentieth centuries, laboratory traumatic peripheral nerve injury studies have provided great insight into cellular and molecular mechanisms governing axon degeneration and the responses of Schwann cells, the major glial cell type of peripheral nerves. It is now evident that pathways underlying injury-induced axon degeneration and the Schwann cell injury-specific state, the repair Schwann cell, are relevant to many inherited and acquired disorders of peripheral nerves. This review provides a timely update on the molecular understanding of axon degeneration and formation of the repair Schwann cell. We discuss how nicotinamide mononucleotide adenylyltransferase 2 (NMNAT2) and sterile alpha TIR motif containing protein 1 (SARM1) are required for axon survival and degeneration, respectively, how transcription factor c-JUN is essential for the Schwann cell response to nerve injury and what each tells us about disease mechanisms and potential therapies. Human genetic association with NMNAT2 and SARM1 strongly suggests aberrant activation of programmed axon death in polyneuropathies and motor neuron disorders, respectively, and animal studies suggest wider involvement including in chemotherapy-induced and diabetic neuropathies. In repair Schwann cells, cJUN is aberrantly expressed in a wide variety of human acquired and inherited neuropathies. Animal models suggest it limits axon loss in both genetic and traumatic neuropathies, whereas in contrast, Schwann cell secreted Neuregulin-1 type 1 drives onion bulb pathology in CMT1A. Finally, we discuss opportunities for drug-based and gene therapies to prevent axon loss or manipulate the repair Schwann cell state to treat acquired and inherited neuropathies and neuronopathies.

[Entrapment neuropathies: a contemporary approach to pathophysiology, clinical assessment, and management : German version]

Entrapment neuropathies such as carpal tunnel syndrome, radiculopathies, or radicular pain are the most common peripheral neuropathies and also the most common cause for neuropathic pain. Despite their high prevalence, they often remain challenging to diagnose and manage in a clinical setting. Summarising the evidence from both preclinical and clinical studies, this review provides an update on the aetiology and pathophysiology of entrapment neuropathies. Potenzial mechanisms are put in perspective with clinical findings. The contemporary assessment is discussed and diagnostic pitfalls highlighted. The evidence for the noninvasive and surgical management of common entrapment neuropathies is summarised and future areas of research are identified.

Carpal tunnel syndrome in patients with arteriovenous fistula for haemodialysis: A narrative review of the current literature

The ideal choice of vascular access in patients requiring haemodialysis is an arteriovenous fistula. However, an important often under-reported complication encountered at follow-up is symptoms of tingling or numbness in the hand. This may represent carpal tunnel syndrome, impairment of the median nerve as it traverses through the carpal tunnel at the wrist by focal compression of this nerve. Contributory factors in the presence of an arteriovenous fistula may include venous hypertension and varying steal syndrome phenomena provoking micro-ischaemia. Studies that investigated the evolution of carpal tunnel syndrome in haemodialysis patients with an arteriovenous fistula revealed that the frequency of carpal tunnel syndrome associated with an arteriovenous fistula on haemodialysis ranged from 10.4% to 42.6%. An association between duration of haemodialysis with arteriovenous fistula and carpal tunnel syndrome development was also observed. Surgical release of carpal tunnel provided complete relief of paraesthesia in all treated patients in the examined, demonstrating an alleviation of symptoms and improved function of hand and quality of life in patients with an arteriovenous fistula. However, the aetiology and risk factors for development of carpal tunnel syndrome remain unclear and further studies should attempt to elucidate the pathophysiology of this occurrence in the presence of arteriovenous fistulas.

Utility of EFEMP1 in the Prediction of Oncologic Outcomes of Urothelial Carcinoma

Urothelial carcinoma (UC) of the upper tract (UTUC) and urinary bladder (UBUC) is a heterogeneous malignancy. Through transcriptomic profiling of the Gene Expression Omnibus UBUC dataset (GSE31684), we discovered that epidermal growth factor-containing fibulin-like extracellularmatrix protein 1 (EFEMP1) was the most upregulated gene during metastatic development. EFEMP1 is an important component of basement membranes and acts as an enzyme regulator in extracellular matrix biology. Initially, evaluation of EFEMP1 mRNA expression in 50 UBUCs showed significantly upregulated levels in high stage UC. We further validated the clinical significance of EFEMP1 in 340 UTUC and 295 UBUC using immunohistochemistry, evaluated by H-score. High EFEMP1 immunoexpression significantly correlated with high pathologic stage, high histological grade, lymph node metastasis, vascular invasion, perineural invasion and high mitosis (all p < 0.05). After adjusting for established clinicopathological factors, EFEMP1 expression status retained its prognostic impact on disease-specific survival and metastasis-free survival in UTUC and UBUC (all p < 0.01). Furthermore, Ingenuity Pathway Analysis showed that actin cytoskeleton signaling, tumor microenvironment pathway and mitochondrial dysfunction were significantly enriched by EFEMP1 dysregulation. In conclusion, high EFEMP1 expression was associated with adverse pathological features in UC and independently predicted worse outcomes, suggesting its roles in clinical decision-making and risk stratification.

Cardiac cell type-specific gene regulatory programs and disease risk association

Misregulated gene expression in human hearts can result in cardiovascular diseases that are leading causes of mortality worldwide. However, the limited information on the genomic location of candidate cis-regulatory elements (cCREs) such as enhancers and promoters in distinct cardiac cell types has restricted the understanding of these diseases. Here, we defined >287,000 cCREs in the four chambers of the human heart at single-cell resolution, which revealed cCREs and candidate transcription factors associated with cardiac cell types in a region-dependent manner and during heart failure. We further found cardiovascular disease-associated genetic variants enriched within these cCREs including 38 candidate causal atrial fibrillation variants localized to cardiomyocyte cCREs. Additional functional studies revealed that two of these variants affect a cCRE controlling KCNH2/HERG expression and action potential repolarization. Overall, this atlas of human cardiac cCREs provides the foundation for illuminating cell type-specific gene regulation in human hearts during health and disease.

Spatio-temporal correlates of gene expression and cortical morphology across lifespan and aging

Evidence from neuroimaging and genetic studies supports the concept that brain aging mirrors development. However, it is unclear whether mechanisms linking brain development and aging provide new insights to delay aging and potentially reverse it. This study determined biological mechanisms and phenotypic traits underpinning brain alterations across the lifespan and in aging by examining spatio-temporal correlations between gene expression and cortical volumes using datasets d with the age range from 2 to 82 years. We revealed that a large proportion of genes whose expression was associated with cortical volumes across the lifespan were in astrocytes. These genes, which showed up-regulation during development and down-regulation during aging, contributed to fundamental homeostatic functions of astrocytes. Included among these genes were those encoding components of cAMP, Ras, and retrograde endocannabinoid signaling pathways. Genes associated with cortical volumes in the same data aged above 55 years were also enriched for the sphingolipid, renin-angiotensin system (RAS), proteasome, and TGF-β signaling pathway, which is linked to senescence-associated secretory phenotypes. Neuroticism, drinking, and smoking were the common phenotypic traits in the lifespan and aging, while memory was the unique phenotype associated with aging. These findings provide biological mechanisms mirroring development and aging as well as unique to aging.

The Pathophysiological Significance of Fibulin-3

Fibulin-3 (also known as EGF-containing fibulin extracellular matrix protein 1 (EFEMP1)) is a secreted extracellular matrix glycoprotein, encoded by the EFEMP1 gene that belongs to the eight-membered fibulin protein family. It has emerged as a functionally unique member of this family, with a diverse array of pathophysiological associations predominantly centered on its role as a modulator of extracellular matrix (ECM) biology. Fibulin-3 is widely expressed in the human body, especially in elastic-fibre-rich tissues and ocular structures, and interacts with enzymatic ECM regulators, including tissue inhibitor of metalloproteinase-3 (TIMP-3). A point mutation in EFEMP1 causes an inherited early-onset form of macular degeneration called Malattia Leventinese/Doyne honeycomb retinal dystrophy (ML/DHRD). EFEMP1 genetic variants have also been associated in genome-wide association studies with numerous complex inherited phenotypes, both physiological (namely, developmental anthropometric traits) and pathological (many of which involve abnormalities of connective tissue function). Furthermore, EFEMP1 expression changes are implicated in the progression of numerous types of cancer, an area in which fibulin-3 has putative significance as a therapeutic target. Here we discuss the potential mechanistic roles of fibulin-3 in these pathologies and highlight how it may contribute to the development, structural integrity, and emergent functionality of the ECM and connective tissues across a range of anatomical locations. Its myriad of aetiological roles positions fibulin-3 as a molecule of interest across numerous research fields and may inform our future understanding and therapeutic approach to many human diseases in clinical settings.

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.

Genetic Risk of Trigger Finger: Results of a Genomewide Association Study

BACKGROUND

Trigger finger, or stenosing tenosynovitis, is one of the most common conditions affecting the hand, yet its pathophysiology remains poorly understood, and genetic association studies of trigger finger are lacking. The purpose of this study was to identify single-nucleotide polymorphisms associated with trigger finger through a genomewide approach.

METHODS

The authors performed a case-control genomewide association study in the Partners HealthCare Biobank. Single-nucleotide polymorphism- and gene-based association analyses were carried out after quality control, imputation, and filtering.

RESULTS

Among 942 trigger finger cases and 24,472 controls, the authors tested 7,846,471 single-nucleotide polymorphisms for association with trigger finger. In the single-nucleotide polymorphism-based analysis, a single locus on chromosome 13 corresponding to KLHL1 met the genomewide significance threshold (lead single-nucleotide polymorphism rs59988404; OR, 1.74; 95 percent CI, 1.47 to 2.07; p = 1.99 × 10). After mapping, gene-based analysis demonstrated a significant association with POLE2 (p = 7.53 × 10) on chromosome 14. Among trigger finger cases, rs59988404 genotype was significantly associated with the total number of trigger finger procedures performed (p = 0.026).

CONCLUSIONS

In the first reported genomewide association study of trigger finger, the authors report significant associations of KLHL1 and POLE2 with risk of trigger finger. The authors' results may help to elucidate the pathophysiology of trigger finger and facilitate an individualized, precision-medicine treatment approach.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, III.

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.

Entrapment neuropathies: a contemporary approach to pathophysiology, clinical assessment, and management

Entrapment neuropathies such as carpal tunnel syndrome, radiculopathies, or radicular pain are the most common peripheral neuropathies and also the most common cause for neuropathic pain. Despite their high prevalence, they often remain challenging to diagnose and manage in a clinical setting. Summarising the evidence from both preclinical and clinical studies, this review provides an update on the aetiology and pathophysiology of entrapment neuropathies. Potential mechanisms are put in perspective with clinical findings. The contemporary assessment is discussed and diagnostic pitfalls highlighted. The evidence for the noninvasive and surgical management of common entrapment neuropathies is summarised and future areas of research are identified.

Assessing Digital Phenotyping to Enhance Genetic Studies of Human Diseases

Population-scale biobanks that combine genetic data and high-dimensional phenotyping for a large number of participants provide an exciting opportunity to perform genome-wide association studies (GWAS) to identify genetic variants associated with diverse quantitative traits and diseases. A major challenge for GWAS in population biobanks is ascertaining disease cases from heterogeneous data sources such as hospital records, digital questionnaire responses, or interviews. In this study, we use genetic parameters, including genetic correlation, to evaluate whether GWAS performed using cases in the UK Biobank ascertained from hospital records, questionnaire responses, and family history of disease implicate similar disease genetics across a range of effect sizes. We find that hospital record and questionnaire GWAS largely identify similar genetic effects for many complex phenotypes and that combining together both phenotyping methods improves power to detect genetic associations. We also show that family history GWAS using cases ascertained on family history of disease agrees with combined hospital record and questionnaire GWAS and that family history GWAS has better power to detect genetic associations for some phenotypes. Overall, this work demonstrates that digital phenotyping and unstructured phenotype data can be combined with structured data such as hospital records to identify cases for GWAS in biobanks and improve the ability of such studies to identify genetic associations.

The ADAMTS/Fibrillin Connection: Insights into the Biological Functions of ADAMTS10 and ADAMTS17 and Their Respective Sister Proteases

Secreted adisintegrin-like and metalloprotease with thrombospondin type 1 motif (ADAMTS) proteases play crucial roles in tissue development and homeostasis. The biological and pathological functions of ADAMTS proteases are determined broadly by their respective substrates and their interactions with proteins in the pericellular and extracellular matrix. For some ADAMTS proteases, substrates have been identified and substrate cleavage has been implicated in tissue development and in disease. For other ADAMTS proteases, substrates were discovered in vitro, but the role of these proteases and the consequences of substrate cleavage in vivo remains to be established. Mutations in ADAMTS10 and ADAMTS17 cause Weill–Marchesani syndrome (WMS), a congenital syndromic disorder that affects the musculoskeletal system (short stature, pseudomuscular build, tight skin), the eyes (lens dislocation), and the heart (heart valve abnormalities). WMS can also be caused by mutations in fibrillin-1 (FBN1), which suggests that ADAMTS10 and ADAMTS17 cooperate with fibrillin-1 in a common biological pathway during tissue development and homeostasis. Here, we compare and contrast the biochemical properties of ADAMTS10 and ADAMTS17 and we summarize recent findings indicating potential biological functions in connection with fibrillin microfibrils. We also compare ADAMTS10 and ADAMTS17 with their respective sister proteases, ADAMTS6 and ADAMTS19; both were recently linked to human disorders distinct from WMS. Finally, we propose a model for the interactions and roles of these four ADAMTS proteases in the extracellular matrix.

[Carpal tunnel syndrome: Rare causes and associated forms behind a common and stereotyped affection]

Carpal tunnel syndrome (CTS) is too common a condition not to daily interact with the practitioner, if only because of its entanglement to other pathologies, causal or chance association. The typical symptomatology, with hand paresthesia and morning pain upon waking, is related to a median nerve injury in the confined space of the carpal tunnel, more often by local inflammation and tenosynovitis of the finger flexors (repetitive activity of the hands). SCC may be secondary to situations (pregnancy) or conditions (edema, hypothyroidism…), which exaggerate the ordinary pathophysiology or cause deposits in the channel (amyloidosis, mucopolysaccharidoses, etc.). Otherwise, SCC is favored by all neuropathies that cause nerve fragility (especially diabetes). It is sometimes the first sign of these various affections of which it can allow early diagnosis. Electroneuromyographic examination (ENMG) is a key examination to confirm the diagnosis (slowing of sensitive and motor conduction of the median nerve through the carpal tunnel, due to local demyelination), to look for a predisposing neuropathy and for signs of seriousness (amplitude reduction of electrophysiological signals) that indicate axonal loss. In SCC forms with only slowed conduction without sign of seriousness, a splint or infiltration treatment may be attempted. If this medical treatment does not bring healing, or if there are signs of seriousness or unbearable pains, a decompression surgery is indicated. Whether it is performed traditionally or endoscopically, it provides fast relief, even immediate.

Etiopathogenetic Mechanisms in Diverticular Disease of the Colon

This article reviews epidemiological evidence of heritability and putative mechanisms in diverticular disease, with greatest attention to 3 recent studies of genetic associations with diverticular disease based on genome-wide or whole-genome sequencing studies in large patient cohorts. We provide an analysis of the biological plausibility of the significant associations with gene variants reported and highlight the relevance of ANO1, CPI-17 (aka PPP1R14A), COLQ6, COL6A1, CALCB or CALCA, COL6A1, ARHGAP15, and S100A10 to colonic neuromuscular function and tissue properties that may result in altered compliance and predispose to the development of diverticular disease. Such studies also identify candidate genes for future studies.