Fine Mapping of the NRG1 Hirschsprung's Disease Locus

The primary pathology of Hirschsprung's disease (HSCR, colon aganglionosis) is the absence of ganglia in variable lengths of the hindgut, resulting in functional obstruction. HSCR is attributed to a failure of migration of the enteric ganglion precursors along the developing gut. RET is a key regulator of the development of the enteric nervous system (ENS) and the major HSCR-causing gene. Yet the reduced penetrance of RET DNA HSCR-associated variants together with the phenotypic variability suggest the involvement of additional genes in the disease. Through a genome-wide association study, we uncovered a ∼350 kb HSCR-associated region encompassing part of the neuregulin-1 gene (NRG1). To identify the causal NRG1 variants contributing to HSCR, we genotyped 243 SNPs variants on 343 ethnic Chinese HSCR patients and 359 controls. Genotype analysis coupled with imputation narrowed down the HSCR-associated region to 21 kb, with four of the most associated SNPs (rs10088313, rs10094655, rs4624987, and rs3884552) mapping to the NRG1 promoter. We investigated whether there was correlation between the genotype at the rs10088313 locus and the amount of NRG1 expressed in human gut tissues (40 patients and 21 controls) and found differences in expression as a function of genotype. We also found significant differences in NRG1 expression levels between diseased and control individuals bearing the same rs10088313 risk genotype. This indicates that the effects of NRG1 common variants are likely to depend on other alleles or epigenetic factors present in the patients and would account for the variability in the genetic predisposition to HSCR

RET Mutational Spectrum in Hirschsprung Disease: Evaluation of 601 Chinese Patients

Rare (RVs) and common variants of the RET gene contribute to Hirschsprung disease (HSCR; congenital aganglionosis). While RET common variants are strongly associated with the commonest manifestation of the disease (males; short-segment aganglionosis; sporadic), rare coding sequence (CDS) variants are more frequently found in the lesser common and more severe forms of the disease (females; long/total colonic aganglionosis; familial)

A Comprehensive Appraisal of Meta-Analyses of Exercise-Based Stroke Rehabilitation with Trial Sequential Analysis

Meta-analysis is a common technique used to synthesise the results of multiple studies through the combination of effect size estimates and testing statistics. Numerous meta-analyses have investigated the efficacy of exercise programmes for stroke rehabilitation. However, meta-analyses may also report false-positive results because of insufficient information or random errors. Trial sequential analysis (TSA) is an advanced technique for calculating the required information size (RIS) and more restrictive statistical significance levels for the precise assessment of any specific treatment. This study used TSA to examine whether published meta-analyses in the field of stroke rehabilitation reached the RIS and whether their overall effect sizes were sufficient. A comprehensive search of six electronic databases for articles published before May 2022 was conducted. The intervention methods were divided into four primary groups, namely aerobic or resistance exercise, machine-assisted exercise, task-oriented exercise, and theory-based exercise. The primary outcome measure was gait speed and the secondary outcome measure was balance function. The data were obtained either from the meta-analyses or as raw data from the original cited texts. All data analysis was performed in TSA software. In total, 38 articles with 46 analysable results were included in the TSA. Only 17 results (37.0%) reached the RIS. In conclusion, meta-analysis interpretation is challenging. Clinicians must consider the RIS of meta-analyses before applying the results in real-world situations. TSA can provide accurate evaluations of treatment effects, which is crucial to the development of evidence-based medicine

Multi-energy spectral photon-counting computed tomography (MARS) for detection of arthroplasty implant failure

To determine whether state-of-the-art multi-energy spectral photon-counting computed tomography (MARS) can detect knee arthroplasty implant failure not detected by standard pre-operative imaging techniques. A total knee arthroplasty (TKA) removed from a patient was reviewed. The extracted prosthesis [NexGen Legacy Posterior Stabilized (LPS) TKA] was analyzed as were pre-operative imaging examination and compared with a MARS-CT examination obtained of the extracted TKA prosthesis. Radiographs, fuoroscopy, ultrasound and MRI preoperatively did not reveal the cause of the implant failure. MARS CT images of the extracted prosthesis clearly showed the presence of posteromedial polyethylene and tibial tray wear which is compatible with the clinical appearance of the extracted TKA. MARS can identify polyethylene insert and metallic tibial tray wear as a cause of TKA failure, that could not be identifed with on standard pre-operative imaging. Although clinical MARS CT system is still under development, this case does illustrate its potential clinical usefulness. This is the frst study to document how MARS CT imaging can detect orthopedic implant failure not detected by standard current imaging techniques. This system has a potential clinical application in orthopedic patients

Clinical and manometric evaluations of anorectal function in patients after transanal endorectal pull-through operation for Hirschsprung's disease: A multicentre study

© 2015 College of Surgeons of Hong Kong. Aim: Transanal endorectal pull-through (TEPT) operation is one the most popular operations for Hirschsprung's disease. This aim of the present study was to evaluate its outcome by clinical and manometric assessments. Patients and Methods: This study was a multicentred study involving all three paediatric surgical centres under the Hospital Authority in Hong Kong. All patients, over the age of 3years, who had undergone primary TEPT operation for more than 1year, were included in the present study. Clinical evaluation with bowel function score (BFS) and anorectomanometry were carried out. A BFS >18 and sphincter resting pressure between 30mmHg and 60mmHg were considered normal. Those with concomitant anorectal/neurological anomaly or who could not cooperate were excluded. Results: A total of 37 patients were enrolled in this study. The median age was 60months (range: 36-144months), and the median age at the time of operation was 3months (range: 0.5-60months). With respect to functional outcomes, six patients (16.2 per cent) suffered from constipation, but more than two-thirds of patients had satisfactory stool consistency, as well as frequency. Sixteen patients (43.2 per cent) had no report of any soiling. For the BFS, 26 patients had a BFS above 18, with the median value being 16 (range: 7-20). Manometric assessment revealed that 27 patients (72.9 per cent) had sphincteric resting pressure within the normal value, and the median value was 45mmHg (range: 14-79mmHg). Rectoanal inhibitory reflex was present in six patients (16.2 per cent), and the median value for the volume of air to elicit the first anal sensation was 41mL (range: 18-126mL). Using univariate analysis, long segment disease was identified as a risk factor for developing soiling of more than two times per week [relative risk (RR): 1.87, 95 per cent confidence interval (CI):1.03-2.22, P=0.05], whereas the creation of stoma (RR: 1.69, 95 per cent CI: 1.41-2.14, P=0.04) and occurrence of postoperative enterocolitis (RR: 1.58, 95 per cent CI: 1.36-1.0, P=0.04) were risk factors for abnormal bowel function score. There was no significant risk factor identified for abnormal manometric results. Lastly, patients with abnormal sphincter resting pressure detected in the anorectomanometry study were also more likely to have an abnormal BFS. Conclusion: Most patients have satisfactory clinical and manometric outcomes after primary TEPT operation. Anorectomanometry findings can predict clinical outcomes. Patients with long segment disease, development of enterocolitis and stoma creation before operation will need more attention, as they are prone to develop abnormal bowel function. Early interventions, such as manometric assessment and proper bowel management, are recommended in order to correct bowel dysfunction, as well enabling patients to have a better quality of life.Link_to_subscribed_fulltex

Genome-wide association study identifies a susceptibility locus for biliary atresia on 10q24.2

Biliary atresia (BA) is characterized by the progressive fibrosclerosing obliteration of the extrahepatic biliary system during the first few weeks of life. Despite early diagnosis and prompt surgical intervention, the disease progresses to cirrhosis in many patients. The current theory for the pathogenesis of BA proposes that during the perinatal period, a still unknown exogenous factor meets the innate immune system of a genetically predisposed individual and induces an uncontrollable and potentially self-limiting immune response, which becomes manifest in liver fibrosis and atresia of the extrahepatic bile ducts. Genetic factors that could account for the disease, let alone for its high incidence in Chinese, are to be investigated. To identify BA susceptibility loci, we carried out a genome-wide association study (GWAS) using the Affymetrix 5.0 and 500 K marker sets. We genotyped nearly 500 000 single-nucleotide polymorphisms (SNPs) in 200 Chinese BA patients and 481 ethnically matched control subjects. The 10 most BA-associated SNPs from the GWAS were genotyped in an independent set of 124 BA and 90 control subjects. The strongest overall association was found for rs17095355 on 10q24, downstream XPNPEP1, a gene involved in the metabolism of inflammatory mediators. Allelic chi-square test P-value for the meta-analysis of the GWAS and replication results was 6.94 × 10−9. The identification of putative BA susceptibility loci not only opens new fields of investigation into the mechanisms underlying BA but may also provide new clues for the development of preventive and curative strategies

Genome-Wide Copy Number Analysis Uncovers a New HSCR Gene: <em>NRG3</em>

<div><p>Hirschsprung disease (HSCR) is a congenital disorder characterized by aganglionosis of the distal intestine. To assess the contribution of copy number variants (CNVs) to HSCR, we analysed the data generated from our previous genome-wide association study on HSCR patients, whereby we identified <em>NRG1</em> as a new HSCR susceptibility locus. Analysis of 129 Chinese patients and 331 ethnically matched controls showed that HSCR patients have a greater burden of rare CNVs (<em>p</em> = 1.50×10⁻⁵), particularly for those encompassing genes (<em>p</em> = 5.00×10⁻⁶). Our study identified 246 rare-genic CNVs exclusive to patients. Among those, we detected a <em>NRG3</em> deletion (<em>p</em> = 1.64×10⁻³). Subsequent follow-up (96 additional patients and 220 controls) on <em>NRG3</em> revealed 9 deletions (combined <em>p</em> = 3.36×10⁻⁵) and 2 <em>de novo</em> duplications among patients and two deletions among controls. Importantly, <em>NRG3</em> is a paralog of <em>NRG1</em>. Stratification of patients by presence/absence of HSCR–associated syndromes showed that while syndromic–HSCR patients carried significantly longer CNVs than the non-syndromic or controls (<em>p</em> = 1.50×10⁻⁵), non-syndromic patients were enriched in CNV number when compared to controls (<em>p</em> = 4.00×10⁻⁶) or the syndromic counterpart. Our results suggest a role for <em>NRG3</em> in HSCR etiology and provide insights into the relative contribution of structural variants in both syndromic and non-syndromic HSCR. This would be the first genome-wide catalog of copy number variants identified in HSCR.</p> </div

CNV burden for syndromic (Syn) and non-syndromic (Non-syn) HSCR patients relative to controls (Ctrl).

<p>The burden was measured with reference to the (A) size, (B) rate and (C) gene count of CNVs. Red and blue bars denote the mean value of the corresponding test for deletion and duplication respectively. Summary statistics as well as conditional permutation <i>p</i>-value was shown in (D).</p