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IntroductionWhen assessing kidney biopsies, pathologists use light microscopy, immunofluorescence, and electron microscopy to describe and diagnose glomerular lesions and diseases. These methods can be laborious, costly, fraught with inter-observer variability, and can have delays in turn-around time. Thus, computational approaches can be designed as screening and/or diagnostic tools, potentially relieving pathologist time, healthcare resources, while also having the ability to identify novel biomarkers, including subvisual features.MethodsHere, we implement our recently published biomarker feature extraction (BFE) model along with 3 pre-trained deep learning models (VGG16, VGG19, and InceptionV3) to diagnose 3 glomerular diseases using PAS-stained digital pathology images alone. The BFE model extracts a panel of 233 explainable features related to underlying pathology, which are subsequently narrowed down to 10 morphological and microstructural texture features for classification with a linear discriminant analysis machine learning classifier. 45 patient renal biopsies (371 glomeruli) from minimal change disease (MCD), membranous nephropathy (MN), and thin-basement membrane nephropathy (TBMN) were split into training/validation and held out sets. For the 3 deep learningmodels, data augmentation and Grad-CAM were used for better performance and interpretability.ResultsThe BFE model showed glomerular validation accuracy of 67.6% and testing accuracy of 76.8%. All deep learning approaches had higher validation accuracies (most for VGG16 at 78.5%) but lower testing accuracies. The highest testing accuracy at the glomerular level was VGG16 at 71.9%, while at the patient-level was InceptionV3 at 73.3%.DiscussionThe results highlight the potential of both traditional machine learning and deep learning-based approaches for kidney biopsy evaluation.

Background Podocyte dysfunction is the main pathologic mechanism driving the development of FSGS and other morphologic types of steroid-resistant nephrotic syndrome (SRNS). Despite significant progress, the genetic causes of most cases of SRNS have yet to be identified. Methods Whole-genome sequencing was performed on 320 individuals from 201 families with familial and sporadic NS/FSGS with no pathogenic mutations in any known NS/FSGS genes. Results Two variants in the gene encoding regulator of calcineurin type 1 (RCAN1) segregate with disease in two families with autosomal dominant FSGS/SRNS. In vitro, loss of RCAN1 reduced human podocyte viability due to increased calcineurin activity. Cells expressing mutant RCAN1 displayed increased calcineurin activity and NFAT activation that resulted in increased susceptibility to apoptosis compared with wild-type RCAN1. Treatment with GSK-3 inhibitors ameliorated this elevated calcineurin activity, suggesting the mutation alters the balance of RCAN1 regulation by GSK-3β, resulting in dysregulated calcineurin activity and apoptosis. Conclusions These data suggest mutations in RCAN1 can cause autosomal dominant FSGS. Despite the widespread use of calcineurin inhibitors in the treatment of NS, genetic mutations in a direct regulator of calcineurin have not been implicated in the etiology of NS/FSGS before this report. The findings highlight the therapeutic potential of targeting RCAN1 regulatory molecules, such as GSK-3β, in the treatment of FSGS.

Although the clinical benefit of obtaining a remission in proteinuria in nephrotic patients with focal and segmental glomerulosclerosis (FSGS) is recognized, the long-term value of maintaining it and the impact of relapses on outcome are not well described.We examined the impact of remissions and relapses on either a 50% decline in kidney function or ESKD (combined event) using time-dependent and landmark analyses in a retrospective study of all patients from the Toronto Glomerulonephritis Registry with biopsy-proven FSGS, established nephrotic-range proteinuria and at least one remission.In the 203 FSGS individuals with a remission, 89 never relapsed and 114 experienced at least one relapse. The first recurrence was often followed by a repeating pattern of remission and relapse. The 10-year survival from a combined event was 15% higher in those with no relapse versus those with any relapse. This smaller than anticipated difference was related to the favorable outcome in individuals whose relapses quickly remitted. Relapsers who ultimately ended in remission (n = 46) versus in relapse (n = 68) experienced a 91% and 32% 7-year event survival (p0.001). Using time-varying survival analyses that considered all periods of remission and relapse in every patient and adjusting for each period's initial eGFR, the state of relapse was associated with a 2.17 (95%CI,1.32-3.58, p = 0.002) greater risk of experiencing a combined event even in this FSGS remission cohort.In FSGS, unless remissions are maintained and relapses avoided, long-term renal survival remains poor. Treatment strategies addressing remission duration remain poorly defined and should be an essential question in future trials.

Specific variants in genes that encode the α3α4α5 chains of type IV collagen cause Alport syndrome (AS), which encompass a clinical spectrum from isolated hematuria to multisystem disease affecting sight, hearing and kidney function. The commonest form is X-linked Alport syndrome (XLAS; COL4A5) with autosomal AS (COL4A3 and COL4A4) comprising a minority of cases. While historic data estimates the frequency of AS at 1:5000-10,000, recent population-based genetic studies suggest the prevalence is considerably higher. Genome-wide association studies (GWAS) have been performed in the Icelandic (deCODE) and UK (UK Biobank) populations, demonstrating an association of type IV collagen gene variants with AS relevant kidney traits. In the Icelandic population, 1 in 600 carries a 2.5-kb COL4A3 coding deletion or a COL4A3 missense variant (rs200287952[A], Gly695Arg), both of which are strongly associated with hematuria and albuminuria (P values = 1.9 × 10-5 to 2.5 × 10-20). In the UK Biobank, COL4A4 rs35138315 (Ser969X; carrier frequency 0.13%) is strongly associated with both hematuria and albuminuria (P = 1.5 × 10-73). Thus, the frequency for autosomal AS is 5-16 times higher than the historic prevalence of all forms of the disorder. Furthermore, COL4A4 rs3518315 (Ser969X) is also a reported founder mutation in families with autosomal dominant focal and segmental glomerulosclerosis and autosomal recessive forms of AS. This supports an additive mode of inheritance for specific variants, wherein a number of copies of a mutation influence disease severity in a cumulative fashion. These studies did not include the X chromosome, excluding analysis of COL4A5, which represents an area for future study.

BACKGROUND AND OBJECTIVES: Glomerular hematuria has varied causes but can have a genetic basis, including Alport syndrome and IgA nephropathy. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We used summary statistics to identify genetic variants associated with hematuria in White British UK Biobank participants. Individuals with glomerular hematuria were enriched by excluding participants with genitourinary conditions. A strongly associated locus on chromosome 2 (COL4A4-COL4A3) was identified. The region was reimputed using the Trans-Omics for Precision Medicine Program followed by sequential rounds of regional conditional analysis, conditioning on previous genetic signals. Similarly, we applied conditional analysis to identify independent variants in the MHC region on chromosome 6 using imputed HLA haplotypes. RESULTS: In total, 16,866 hematuria cases and 391,420 controls were included. Cases had higher urinary albumin-creatinine compared with controls (women: 13.01 mg/g [8.05–21.33] versus 12.12 mg/g [7.61–19.29]; P

Pathologists use multiple microscopy modalities to assess renal biopsy specimens. Besides usual diagnostic features, some changes are too subtle to be properly defined. Computational approaches have the potential to systematically quantitate subvisual clues, provide pathogenetic insight, and link to clinical outcomes. To this end, a proof-of-principle study is presented demonstrating that explainable biomarkers through machine learning can distinguish between glomerular disorders at the light-microscopy level. The proposed system used image analysis techniques and extracted 233 explainable biomarkers related to color, morphology, and microstructural texture. Traditional machine learning was then used to classify minimal change disease (MCD), membranous nephropathy (MN), and thin basement membrane nephropathy (TBMN) diseases on a glomerular and patient-level basis. The final model combined the Gini feature importance set and linear discriminant analysis classifier. Six morphologic (nuclei-to-glomerular tuft area, nuclei-to-glomerular area, glomerular tuft thickness greater than ten, glomerular tuft thickness greater than three, total glomerular tuft thickness, and glomerular circularity) and four microstructural texture features (luminal contrast using wavelets, nuclei energy using wavelets, nuclei variance using color vector LBP, and glomerular correlation using GLCM) were, together, the best performing biomarkers. Accuracies of 77% and 87% were obtained for glomerular and patient-level classification, respectively. Computational methods, using explainable glomerular biomarkers, have diagnostic value and are compatible with our existing knowledge of disease pathogenesis. Furthermore, this algorithm can be applied to clinical datasets for novel prognostic and mechanistic biomarker discovery.

Rationale & Objective Pathogenic variants in type IV collagen have been reported to account for a significant proportion of chronic kidney disease. Accordingly, genetic testing is increasingly used to diagnose kidney diseases, but testing also may reveal rare missense variants that are of uncertain clinical significance. To aid in interpretation, computational prediction (called in silico) programs may be used to predict whether a variant is clinically important. We evaluate the performance of in silico programs for COL4A3/A4/A5 variants. Study Design, Setting, & Participants Rare missense variants in COL4A3/A4/A5 were identified in disease cohorts, including a local focal segmental glomerulosclerosis (FSGS) cohort and publicly available disease databases, in which they are categorized as pathogenic or benign based on clinical criteria. Tests Compared & Outcomes All rare missense variants identified in the 4 disease cohorts were subjected to in silico predictions using 12 different programs. Comparisons between the predictions were compared with: (1) variant classification (pathogenic or benign) in the cohorts and (2) functional characterization in a randomly selected smaller number (17) of pathogenic or uncertain significance variants obtained from the local FSGS cohort. Results In silico predictions correctly classified 75% to 97% of pathogenic and 57% to 100% of benign COL4A3/A4/A5 variants in public disease databases. The congruency of in silico predictions was similar for variants categorized as pathogenic and benign, with the exception of benign COL4A5 variants, in which disease effects were overestimated. By contrast, in silico predictions and functional characterization classified all 9 pathogenic COL4A3/A4/A5 variants correctly that were obtained from a local FSGS cohort. However, these programs also overestimated the effects of genomic variants of uncertain significance when compared with functional characterization. Each of the 12 in silico programs used yielded similar results. Limitations Overestimation of in silico program sensitivity given that they may have been used in the categorization of variants labeled as pathogenic in disease repositories. Conclusions Our results suggest that in silico predictions are sensitive but not specific to assign COL4A3/A4/A5 variant pathogenicity, with misclassification of benign variants and variants of uncertain significance. Thus, we do not recommend in silico programs but instead recommend pursuing more objective levels of evidence suggested by medical genetics guidelines.

Background: Focal and segmental glomerulosclerosis (FSGS) is a histologic pattern of injury that characterizes a wide spectrum of diseases. Many genetic causes have been identified in FSGS but even in families with comprehensive testing, a significant proportion remain unexplained. Results: In one FSGS family with 6 affected relatives, we performed linkage analysis and whole exome sequencing (WES). Linkage analysis narrowed the disease gene(s) to within 3% of the genome. Whole exome sequencing revealed 5 heterozygous rare variants, which were sequenced in 11 relatives where DNA was available. Two of these variants, in LAMA2 and LOXL4, remained as candidates after segregation analysis and encode extracellular matrix proteins of the glomerulus. Renal biopsies showed classic segmental sclerosis/hyalinosis lesion on a background of mild mesangial hypercellularity. Examination of basement membranes with electron microscopy showed regions of dense mesangial matrix in one individual and wider glomerular basement membrane (GBM) thickness in two individuals compared to historic control averages. Conclusions: Based on our findings, we postulate that the additive effect of digenic inheritance of heterozygous variants in LAMA2 and LOXL4 leads to adult-onset FSGS. Limitations to our study includes the absence of functional characterization to support pathogenicity. Alternatively, identification of additional FSGS cases with suspected deleterious variants in LAMA2 and LOXL4 will provide more evidence for disease causality. Thus, our report will be of interest to clinicians and genetic groups as sequencing in renal disease becomes more widespread. Overall, our results provide an example of more complicated genetic inheritance patterns that underlie glomerular disorders in unexplained families.

An upgraded finite control set model predictive control strategy (MPC) for a multilevel inverter is introduced in this paper. A 3-level neutral point clamped (NPC) inverter is presented. The control strategy ensures current control with a narrow spectrum and unwanted harmonics reduction. The designed model predicts system behavior for all probable switching states of the multilevel inverter and uses a cost function to generate the expected operation. This cost function is frequency weighted as it employs a discrete-time filter for current errors. The current drawn by load as well as voltage spectrum is modified by precisely designing the filter resulting in the reduction of undesirable harmonic components. The proposed strategy is corroborated by plausible simulation results. The simulation result shows a narrower load current spectrum after the addition of a 2kHz filter component in the cost function.

Specific variants in genes that encode the α3α4α5 chains of type IV collagen cause Alport syndrome (AS), which encompass a clinical spectrum from isolated hematuria to multisystem disease affecting sight, hearing and kidney function. The commonest form is X-linked Alport syndrome (XLAS; COL4A5) with autosomal AS (COL4A3 and COL4A4) comprising a minority of cases. While historic data estimates the frequency of AS at 1:5000-10,000, recent population-based genetic studies suggest the prevalence is considerably higher. Genome-wide association studies (GWAS) have been performed in the Icelandic (deCODE) and UK (UK Biobank) populations, demonstrating an association of type IV collagen gene variants with AS relevant kidney traits. In the Icelandic population, 1 in 600 carries a 2.5-kb COL4A3 coding deletion or a COL4A3 missense variant (rs200287952[A], Gly695Arg), both of which are strongly associated with hematuria and albuminuria (P values = 1.9 × 10

BACKGROUND: Podocyte dysfunction is the main pathologic mechanism driving the development of FSGS and other morphologic types of steroid-resistant nephrotic syndrome (SRNS). Despite significant progress, the genetic causes of most cases of SRNS have yet to be identified. METHODS: Whole-genome sequencing was performed on 320 individuals from 201 families with familial and sporadic NS/FSGS with no pathogenic mutations in any known NS/FSGS genes. RESULTS: Two variants in the gene encoding regulator of calcineurin type 1 (RCAN1) segregate with disease in two families with autosomal dominant FSGS/SRNS. In vitro, loss of RCAN1 reduced human podocyte viability due to increased calcineurin activity. Cells expressing mutant RCAN1 displayed increased calcineurin activity and NFAT activation that resulted in increased susceptibility to apoptosis compared with wild-type RCAN1. Treatment with GSK-3 inhibitors ameliorated this elevated calcineurin activity, suggesting the mutation alters the balance of RCAN1 regulation by GSK-3β, resulting in dysregulated calcineurin activity and apoptosis. CONCLUSIONS: These data suggest mutations in RCAN1 can cause autosomal dominant FSGS. Despite the widespread use of calcineurin inhibitors in the treatment of NS, genetic mutations in a direct regulator of calcineurin have not been implicated in the etiology of NS/FSGS before this report. The findings highlight the therapeutic potential of targeting RCAN1 regulatory molecules, such as GSK-3β, in the treatment of FSGS.

Background and objectives FSGS and nephrotic syndrome studies have shown that single gene causes are more likely to be found in pediatric cases than adults. Consequently, many studies have examined limited gene panels in largely pediatric cohorts. Design, setting, participants, & measurements Whole-exome sequencing was performed in adults with FSGS diagnosed between 1976 and 2017 in the Toronto GN Registry. An expanded panel of 109 genes linked to FSGS, glomerular basement membrane abnormalities, as well as causes of pediatric ESKD including congenital abnormalities of the kidney and urinary tract (CAKUT) and nephronophthisis, were examined. Results The cohort was composed of 193 individuals from 179 families. Nearly half (49%) developed ESKD at a mean age of 47±17 years. The genetic diagnostic rate was 11%. Of definitely pathogenic variants, 55% were in COL4A (A3/A4/A5), 40% were in podocyte genes, and 5% were in CAKUT genes. Many, but not all individuals with COL4A definitely pathogenic variants had some evidence of glomerular basement membrane abnormalities. The estimated mean survival/age of kidney failure for individuals with COL4A definitely pathogenic variants was 58 years (95% confidence interval, 49 to 69), far later than what has been reported in the literature. Likely pathogenic variants were identified in an additional 9% of the cohort, with most in COL4A. Correlation with glomerular basement membrane morphology suggested a causal role for at least some of these likely pathogenic variants. Conclusions Even with an expanded gene panel, we find that COL4A disorders are the leading monogenic cause in adults diagnosed with FSGS. Podcast This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2019_01_15_CJASNPodcast_19_02_.mp3

Purpose of review The widespread adoption of next-generation sequencing by research and clinical laboratories has begun to uncover the previously unknown genetic basis of many diseases. In nephrology, one of the best examples of this is seen in focal and segmental glomerulosclerosis (FSGS) and nephrotic syndrome. We review advances made in 2017 as a result of human and molecular genetic studies as it relates to FSGS and nephrotic syndrome. Recent findings There are more than 50 monogenic genes described in steroid-resistant nephrotic syndrome and FSGS, with seven reported in 2017. In individuals presenting with FSGS or nephrotic syndrome before or at the age of 18 years, the commonest genes in which a mutation is found continues to be limited to only a few including NPHS1 and NPHS2 based on multiple studies. For FSGS or nephrotic syndrome that presents after 18 years, mutations in COl4A3/4/5, traditionally associated with Alport syndrome, are increasingly being reported. Despite the extensive genetic heterogeneity in FSGS, there is evidence that some of these genes converge onto common pathways. There are also reports of in-vivo models exploring apolipoprotein 1 biology, variants in which account for part of the increased risk of nondiabetic kidney disease in African-Americans. Finally, genetic testing has several clinical uses including clarification of diagnosis and treatment; identification of suitable young biologic relatives for kidney donation; and preimplantation genetic diagnosis. CRISPR gene editing is currently an experimental tool only, but the recent reports of excising mutations in embryos could be a therapeutic option for individuals with any monogenic disorder in the future. Summary Sequencing efforts are bringing novel variants into investigation and directing the efforts to understand how these lead to disease phenotypes. Expanding our understanding of the genetic basis of health and disease processes is the necessary first step to elaborate the repertoire of therapeutic agents available for patients with FSGS and nephrotic syndrome.

Alport syndrome is experiencing a remarkable increase in preclinical investigations. To proactively address the needs of the Alport syndrome community, as well as offer clarity for future clinical research sponsors, the Alport Syndrome Foundation hosted a workshop to generate consensus recommendations for prospective trials for conventional drugs. Opinions of key stakeholders were carefully considered, including those of the biopharmaceutical industry representatives, academic researchers, clinicians, regulatory agency representatives, and—most critically—patients with Alport syndrome. Recommendations were established for preclinical researchers, the use and selection of biomarkers, standards of care, clinical trial designs, trial eligibility criteria and outcomes, pediatric trial considerations, and considerations for patient engagement, recruitment, and treatment. This paper outlines their recommendations.

Extreme obesity (EO) (BMI >50 kg/m2) is frequently associated with neuropsychiatric disease (NPD). As both EO and NPD are heritable central nervous system disorders, we assessed the prevalence of protein-truncating variants (PTVs) and copy number variants (CNVs) in genes/regions previously implicated in NPD in adults with EO (n = 149) referred for weight loss/bariatric surgery. We also assessed the prevalence of CNVs in patients referred to University College London Hospital (UCLH) with EO (n = 218) and obesity (O) (BMI 35–50 kg/m2; n = 374) and a Swedish cohort of participants from the community with predominantly O (n = 161). The prevalence of variants was compared with control subjects in the Exome Aggregation Consortium/Genome Aggregation Database. In the discovery cohort (high NPD prevalence: 77%), the cumulative PTV/CNV allele frequency (AF) was 7.7% vs. 2.6% in control subjects (odds ratio [OR] 3.1 [95% CI 2–4.1]; P < 0.0001). In the UCLH EO cohort (intermediate NPD prevalence: 47%), CNV AF (1.8% vs. 0.9% in control subjects; OR 1.95 [95% CI 0.96–3.93]; P = 0.06) was lower than the discovery cohort. CNV AF was not increased in the UCLH O cohort (0.8%). No CNVs were identified in the Swedish cohort with no NPD. These findings suggest that PTV/CNVs, in genes/regions previously associated with NPD, may contribute to NPD in patients with EO.

Alport syndrome is a rare hereditary disorder caused by rare variants in 1 of 3 genes encoding for type IV collagen. Rare variants in COL4A5 on chromosome Xq22 cause X-linked Alport syndrome, which accounts for ∼80% of the cases. Alport syndrome has a variable clinical presentation, including progressive kidney failure, hearing loss, and ocular defects. Exome sequencing performed in 2 affected related males with an undefined X-linked glomerulopathy characterized by global and segmental glomerulosclerosis, mesangial hypercellularity, and vague basement membrane immune complex deposition revealed a COL4A5 sequence variant, a substitution of a thymine by a guanine at nucleotide 665 (c.T665G; rs281874761) of the coding DNA predicted to lead to a cysteine to phenylalanine substitution at amino acid 222, which was not seen in databases cataloguing natural human genetic variation, including dbSNP138, 1000 Genomes Project release version 01-11-2004, Exome Sequencing Project 21-06-2014, or ExAC 01-11-2014. Review of the literature identified 2 additional families with the same COL4A5 variant leading to similar atypical histopathologic features, suggesting a unique pathologic mechanism initiated by this specific rare variant. Homology modeling suggests that the substitution alters the structural and dynamic properties of the type IV collagen trimer. Genetic analysis comparing members of the 3 families indicated a distant relationship with a shared haplotype, implying a founder effect.

Patient engagement in research is increasingly recognized as an important component of the research process and may facilitate translation of research findings. To heighten awareness on this important topic, this review presents opportunities and challenges of patient engagement in research, drawing on specific examples from 4 areas of Canadian kidney research conducted by New Investigators in the Kidney Research Scientist Core Education and National Training (KRESCENT) Program.Research expertise, published reports, peer-reviewed articles, and research funding body websites.In this review, the definition, purpose, and potential benefits of patient engagement in research are discussed. Approaches toward patient engagement that may help with translation and uptake of research findings into clinical practice are highlighted. Opportunities and challenges of patient engagement are presented in both basic science and clinical research with the following examples of kidney research: (1) precision care in focal and segmental glomerulosclerosis, (2) systems biology approaches to improve management of chronic kidney disease and enhance kidney graft survival, (3) reducing the incidence of suboptimal dialysis initiation, and (4) use of patient-reported outcome measures (PROMs) and patient-reported experience measures (PREMs) in kidney practice.Clinical research affords more obvious opportunities for patient engagement. The most obvious step at which to engage patients is in the setting of research priorities. Engagement at all stages of the research cycle may prove to be more challenging, and requires a detailed plan, along with funds and infrastructure to ensure that it is not merely tokenistic. Basic science research is several steps removed from the clinical application and involves complex scientific concepts, which makes patient engagement inherently more difficult.This is a narrative review of the literature that has been partly influenced by the perspectives and experiences of the authors and focuses on research conducted by the authors. The evidence base to support the suggested benefits of patient engagement in research is currently limited.The formal incorporation of patients' priorities, perspectives, and experiences is now recognized as a key component of the research process. If patients and researchers are able to effectively work together, this could enhance research quality and efficiency. To effectively engage patients, proper infrastructure and dedicated funding are needed. Going forward, a rigorous evaluation of patient engagement strategies and their effectiveness will be needed.La participation des patients au processus de recherche tend à se généraliser; elle peut en effet faciliter l’application des résultats à la pratique clinique. Afin de sensibiliser la communauté scientifique à ce sujet, notre revue présente diverses occasions d’intégrer les patients au processus de recherche, de même que les défis posés par cette intégration. Nos constats sont tirés d’exemples issus de quatre domaines de recherche en néphropathologie conduite au Canada par les nouveaux chercheurs du programme KRESCENT (Kidney Research Scientist Core Education and National Training).Nous avons consulté des chercheurs, des rapports, des articles évalués par les pairs et des sites Web d’organisations finançant la recherche.Sont discutés dans la présente revue la définition, l’objectif et les bienfaits potentiels de la participation de patients à la recherche. On a mis l’accent sur certaines stratégies susceptibles de favoriser la transposition et l’application des résultats de recherche dans la pratique clinique. Les occasions et défis inhérents à cette pratique sont présentés tant en recherche fondamentale qu’en recherche clinique, et ce, dans quatre domaines de la recherche en néphropathologie : 1) les soins de précision en hyalinose segmentaire et focale, 2) les approches de la biologie systémique qui améliorent la gestion des maladies rénales chroniques et les chances de survie du greffon, 3) la diminution de l’incidence des amorces de dialyse suboptimales, et 4) la prise en compte des résultats et expériences déclarés par les patients (MRDP et MEDP) dans la pratique en néphrologie.La recherche clinique offre les occasions les plus concevables d’intégrer les patients au processus. L’étape de l’établissement des priorités de recherche est la plus opportune à l’incorporation du patient au projet. L’intégration des patients à un moment ou à un autre du cycle de recherche peut se révéler difficile; elle requiert un plan détaillé, des infrastructures adéquates et des ressources financières convenables pour que sa portée dépasse la simple symbolique. La recherche fondamentale se trouve quant à elle plus éloignée de l’application clinique; et comme elle repose sur des concepts scientifiques complexes, l’incorporation des patients y est plus épineuse.Il s’agit d’une revue narrative de la littérature en partie influencée par les recherches menées par les auteurs, leurs expériences et leurs points de vue. Qui plus est, les données probantes confirmant les bienfaits plausibles de la participation des patients à la recherche sont à ce jour limitées.L’incorporation formelle des priorités, du point de vue et du vécu des patients au processus de recherche se voit désormais considérée comme un élément clé de celui-ci. Une collaboration resserrée entre patients et chercheurs ne pourra qu’accroître la qualité et l’efficacité de la recherche. Par contre, l’intégration opérante des patients au processus de recherche requiert infrastructures et financement appropriés. À l’avenir, il faudra évaluer rigoureusement des stratégies d’intégration des patients au processus de recherche et en mesurer l’efficacité.

In the article cited above, affiliations for the authors below were listed incorrectly. The correct affiliations are given here. Timothy Jackson: Division of General Surgery, University Health Network, Toronto, Ontario, Canada, and Bariatric Surgery Department, Toronto Western Hospital, Toronto, Ontario, Canada David R. Urbach: Bariatric Surgery Department, Toronto Western Hospital, Toronto, Ontario, Canada Allan Okrainec: Division of General Surgery, University Health Network, Toronto, Ontario, …

The haploid human genome is composed of three billion base pairs, about one percent of which consist of exonic regions, the coding sequence for functional proteins, also now known as the ‘exome'. The development of next-generation sequencing makes it possible from a technical and economic standpoint to sequence an individual's exome but at the cost of generating long lists of gene variants that are not straightforward to interpret. Various public consortiums such as the 1000 Genomes Project and the NHLBI Exome Sequencing Project have sequenced the exomes and a subset of entire genomes of over 2500 control individuals with ongoing efforts to further catalog genetic variation in humans. 1 The use of these public databases facilitates the interpretation of these variant lists produced by exome sequencing and, as a result, novel genetic variants linked to the disease are being discovered and reported at a record rate. However, the interpretation of these results and their bearing on diagnosis, prognosis, and treatment is becoming even more complicated. Here, we discuss the application of genetic testing to individuals with focal and segmental glomerulosclerosis (FSGS), taking a historical perspective on gene identification and its clinical implications along with the growing potential of next-generation sequencing.

Our understanding of focal and segmental glomerulosclerosis (FSGS) has advanced significantly from the studies of rare, monogenic forms of the disease. These studies have demonstrated the critical roles of multiple aspects of podocyte function in maintaining glomerular function. A substantial body of research has suggested that the integral membrane protein podocalyxin (PODXL) is required for proper functioning of podocytes, possibly by preserving the patency of the slit diaphragm by negative charge–based repulsion. Exome sequencing of affected cousins from an autosomal dominant pedigree with FSGS identified a cosegregating private variant, PODXL p.L442R, affecting the transmembrane region of the protein. Of the remaining 11 shared gene variants, two segregated with disease, but their gene products were not detected in the glomerulus. In comparison with wild type, this disease-segregating PODXL variant facilitated dimerization. By contrast, this change does not alter protein stability, extracellular domain glycosylation, cell surface expression, global subcellular localization, or interaction with its intracellular binding partner ezrin. Thus, a variant form of PODXL remains the most likely candidate causing FSGS in one family with autosomal dominant inheritance, but its full effect on protein function remains unknown. Our work highlights the challenge faced in the clinical interpretation of whole-exome data for small pedigrees with autosomal dominant diseases.

Importance International nephrology societies advise against nonsteroidal anti-inflammatory drug (NSAID) use in patients with hypertension, heart failure, or chronic kidney disease (CKD); however, recent studies have not investigated the frequency or associations of use in these patients. Objectives To estimate the frequency of and variation in prescription NSAID use among high-risk patients, to identify characteristics associated with prescription NSAID use, and to investigate whether use is associated with short-term, safety-related outcomes. Design, Setting, and Participants In this retrospective cohort study, administrative claims databases were linked to create a cohort of primary care visits for a musculoskeletal disorder involving patients 65 years and older with a history of hypertension, heart failure, or CKD between April 1, 2012, and March 31, 2016, in Ontario, Canada. Exposure Prescription NSAID use was defined as at least 1 patient-level Ontario Drug Benefit claim for a prescription NSAID dispensing within 7 days after a visit. Main Outcomes and Measures Multiple cardiovascular and renal safety-related outcomes were observed between 8 and 37 days after each visit, including cardiac complications (any emergency department visit or hospitalization for cardiovascular disease), renal complications (any hospitalization for hyperkalemia, acute kidney injury, or dialysis), and death. Results The study identified 2 415 291 musculoskeletal-related primary care visits by 814 049 older adults (mean [SD] age, 75.3 [4.0] years; 61.1% female) with hypertension, heart failure, or CKD, of which 224 825 (9.3%) were followed by prescription NSAID use. The median physician-level prescribing rate was 11.0% (interquartile range, 6.7%-16.7%) among 7365 primary care physicians. Within a sample of 35 552 matched patient pairs, each consisting of an exposed and nonexposed patient matched on the logit of their propensity score for prescription NSAID use (exposure), the study found similar rates of cardiac complications (288 [0.8%] vs 279 [0.8%]), renal complications (34 [0.1%] vs 33 [0.1%]), and death (27 [0.1%] vs 30 [0.1%]). For cardiovascular and renal-safety related outcomes, there was no difference between exposed patients (308 [0.9%]) and nonexposed patients (300 [0.8%]) (absolute risk reduction, 0.0003; 95% CI, −0.001 to 0.002; P = .74). Conclusions and Relevance While prescription NSAID use in primary care was frequent among high-risk patients, with widespread physician-level variation, use was not associated with increased risk of short-term, safety-related outcomes.

Summary: Autosomal-dominant polycystic kidney disease (ADPKD) is the most common Mendelian disorder of the kidney and accounts for approximately 5% of end-stage renal disease in developed countries. It is characterized by focal and sporadic development of renal cysts that increase in number and size with age. Mutations of 2 genes (ie, PKD1 and PKD2) account for most of the cases. Although the clinical manifestations of both gene types overlap completely, PKD1 is associated with more severe disease than PKD2, with bigger kidneys and earlier onset of end-stage renal disease. In general, the diagnosis of ADPKD is commonly made by renal ultrasonography. Age-dependent ultrasound criteria have been established for both diagnosis and disease exclusion in subjects at risk of PKD1. However, the utility of these criteria in the clinic setting is unclear because their performance characteristics have not been defined for the milder PKD2 and the gene type for most test subjects is unknown. Recently, highly predictive ultrasound diagnostic criteria have been derived for at-risk subjects of unknown gene type. In addition, molecular genetic testing is now available for the diagnosis of ADPKD, especially in subjects with equivocal imaging results, with a negative or indeterminate family history, or in younger at-risk individuals with a negative ultrasound study being evaluated as potential living-related kidney donor. Here, we review the clinical utilities and limitations of these imaging- and molecular-based diagnostic tests, and outline our approach for the evaluation of individuals suspected to have ADPKD.

FSGS is characterized by segmental scarring of the glomerulus and is a leading cause of kidney failure. Identification of genes causing FSGS has improved our understanding of disease mechanisms and points to defects in the glomerular epithelial cell, the podocyte, as a major factor in disease pathogenesis. Using a combination of genome-wide linkage studies and whole-exome sequencing in a kindred with familial FSGS, we identified a missense mutation R431C in anillin (ANLN), an F-actin binding cell cycle gene, as a cause of FSGS. We screened 250 additional families with FSGS and found another variant, G618C, that segregates with disease in a second family with FSGS. We demonstrate upregulation of anillin in podocytes in kidney biopsy specimens from individuals with FSGS and kidney samples from a murine model of HIV-1-associated nephropathy. Overexpression of R431C mutant ANLN in immortalized human podocytes results in enhanced podocyte motility. The mutant anillin displays reduced binding to the slit diaphragm-associated scaffold protein CD2AP. Knockdown of the ANLN gene in zebrafish morphants caused a loss of glomerular filtration barrier integrity, podocyte foot process effacement, and an edematous phenotype. Collectively, these findings suggest that anillin is important in maintaining the integrity of the podocyte actin cytoskeleton.

Immunoglobulin A nephropathy (IgAN) is the most common primary glomerular disease worldwide and a significant cause of end-stage renal disease [1]. Although dysregulation of mucosal immunity is a notable feature of this disease, the pathogenesis of IgAN remains poorly understood and its treatment is limited. Familial clustering of patients with IgAN suggests a genetic predisposition [2–5]. Recent genome-wide studies of multiplex families with IgAN have identified two loci with significant linkage on chr. 6q22 [6] and chr. 2q36 [7], and two loci (see the Appendix) with suggestive linkage on chr. 4q26–31 and chr. 17q12–22 [8]. Moreover, the absence of linkage to these loci in a large family with multiple affected members suggests additional genetic heterogeneity (see the Appendix) [5]. Taken together, these data indicate that IgAN is a complex disease likely influenced by multiple genetic and environmental factors. The identification of susceptibility genes for IgAN has the potential to improve risk prediction and may yield novel insights into the primary pathogenesis of this disease. The latter knowledge is essential for future development of mechanism-based therapeutics. However, none of these putative susceptibility genes for IgAN has been identified thus far. To map these susceptibility genes, a candidate gene or genome-wide approach can be taken [9–12]. The former requires a conscious effort to select and then test polymorphic markers (see the Appendix) from one or more candidate gene loci among ∼25 000 genes in the human genome [13] for association or linkage with the disease. In contrast, the latter tests a dense set of equally spaced polymorphic markers across the entire genome for association or linkage with the disease and is agnostic for any underlying assumptions. To date, the candidate gene approach has been used exclusively for sporadic IgAN [1,14–18], while three genome-wide linkage studies have been employed for familial IgAN [6–8]. Candidate gene association studies

FSGS is characterized by the presence of partial sclerosis of some but not all glomeruli. Studies of familial FSGS have been instrumental in identifying podocytes as critical elements in maintaining glomerular function, but underlying mutations have not been identified for all forms of this genetically heterogeneous condition. Here, exome sequencing in members of an index family with dominant FSGS revealed a nonconservative, disease-segregating variant in the PAX2 transcription factor gene. Sequencing in probands of a familial FSGS cohort revealed seven rare and private heterozygous single nucleotide substitutions (4% of individuals). Further sequencing revealed seven private missense variants (8%) in a cohort of individuals with congenital abnormalities of the kidney and urinary tract. As predicted by in silico structural modeling analyses, in vitro functional studies documented that several of the FSGS-associated PAX2 mutations perturb protein function by affecting proper binding to DNA and transactivation activity or by altering the interaction of PAX2 with repressor proteins, resulting in enhanced repressor activity. Thus, mutations in PAX2 may contribute to adult-onset FSGS in the absence of overt extrarenal manifestations. These results expand the phenotypic spectrum associated with PAX2 mutations, which have been shown to lead to congenital abnormalities of the kidney and urinary tract as part of papillorenal syndrome. Moreover, these results indicate PAX2 mutations can cause disease through haploinsufficiency and dominant negative effects, which could have implications for tailoring individualized drug therapy in the future.

Focal and segmental glomerulosclerosis (FSGS) is a pathologic diagnosis characterized by a signature pathologic lesion, grossly defined by the pathologic finding of sclerosis in parts of the tufts involving some but not all glomeruli. It can be primary or due to secondary causes. The incidence of FSGS has been increasing for unclear reasons and now it is the commonest glomerulonephritis underlying ESRD in the USA. Genetic studies have advanced our understanding of disease pathogenesis, pointing to injury in the podocyte as central to the disease. Despite this, our therapeutic options for primary FSGS remain limited and there is a lack of rigorous studies supporting current treatment practices. The mainstay of treatment for primary FSGS is glucocorticosteroids. Individuals who relapse are challenging to treat and there is very little data to guide practice. Regimens for these individuals include cyclophosphamide and cyclosporine.

Identification of single-gene causes of steroid-resistant nephrotic syndrome (SRNS) has furthered the understanding of the pathogenesis of this disease. Here, using a combination of homozygosity mapping and whole human exome resequencing, we identified mutations in the aarF domain containing kinase 4 (ADCK4) gene in 15 individuals with SRNS from 8 unrelated families. ADCK4 was highly similar to ADCK3, which has been shown to participate in coenzyme Q(10) (CoQ(10)) biosynthesis. Mutations in ADCK4 resulted in reduced COQ(10). levels and reduced mitochondrial respiratory enzyme activity in cells isolated from individuals with SRNS and transformed lymphoblasts. Knockdown of adck4 in zebrafish and Drosophila recapitulated nephrotic syndrome-associated phenotypes. Furthermore, ADCK4 was expressed in glomerular podocytes and partially localized to podocyte mitochondria and foot processes in rat kidneys and cultured human podocytes. In human podocytes, ADCK4 interacted with members of the CoQ(10) biosynthesis pathway, including COQ6, which has been linked with SRNS and COQ7. Knockdown of ADCK4 in podocytes resulted in decreased migration, which was reversed by CoQ(10) addition. Interestingly, a patient with SRNS with a homozygous ADCK4 frameshift mutation had partial remission following CoQ(10) treatment. These data indicate that individuals with SRNS with mutations in ADCK4 or other genes that participate in CoQ(10) biosynthesis may be treatable with CoQ(10).

Mutations of PKD1 and PKD2 account for 85 and 15% of cases of autosomal dominant polycystic kidney disease (ADPKD), respectively. Clinically, PKD1 is more severe than PKD2, with a median age at ESRD of 53.4 versus 72.7 yr. In this study, we explored whether a family history of renal disease severity predicts the mutated gene in ADPKD. We examined the renal function (estimated GFR and age at ESRD) of 484 affected members from 90 families who had ADPKD and whose underlying genotype was known. We found that the presence of at least one affected family member who developed ESRD at age ≤55 was highly predictive of a PKD1 mutation (positive predictive value 100%; sensitivity 72%). In contrast, the presence of at least one affected family member who continued to have sufficient renal function or developed ESRD at age >70 was highly predictive of a PKD2 mutation (positive predictive value 100%; sensitivity 74%). These data suggest that close attention to the family history of renal disease severity in ADPKD may provide a simple means of predicting the mutated gene, which has prognostic implications.

Background and objectives: Women of childbearing age on conventional hemodialysis (CHD) have decreased fertility when compared with the general population. Even in women who conceived, maternal morbidity and fetal mortality remained elevated. We hypothesized that nocturnal hemodialysis (NHD) (3 to 6 sessions per week, 6 to 8 h per treatment), by augmenting uremic clearance, leads to a more hospitable maternal environment and therefore superior outcomes in fertility and pregnancy compared with CHD. Design, setting, participants, and measurements: This is a descriptive cohort study of all female patients achieving pregnancy and delivering a live infant while on NHD at the University Health Network, St. Michael9s Hospital, and Humber River Regional Hospital from 2001 to 2006 in Toronto, Canada. Our primary objective was to describe maternal and fetal outcomes in addition to the changes in biochemical parameters after conception in our cohort. Results: Our cohort included five patients (age range, 31 to 37 yr) who had seven pregnancies while on NHD and delivered six live infants. All had previously been on CHD, but none conceived during that time. In all patients, the amount of hemodialysis was increased (from a weekly mean of 36 ± 10 to 48 ± 5 h; P Conclusions: NHD may allow for improved fertility. Delivering a live infant at a mature gestational age is feasible for patients on NHD. Our cohort tended to have fewer maternal and fetal complications compared with historical controls. Hemoglobin and phosphate levels must be monitored with treatment adjusted accordingly.

The majority of prostate cancers (PCa) that relapse after androgen deprivation therapy (androgen-independent PCa) continue to express androgen receptor (AR). To study the functional importance of AR in these tumors, we derived androgen-independent CWR22 PCa xenografts in castrated mice and generated a cell line from one of these xenografts (CWR22R3). Similarly to androgen-independent PCa in patients, the relapsed xenografts and cell line expressed AR and were resistant to treatment with bicalutamide. However, expression of the AR-regulated PSA gene in the CWR22R3 cell line was markedly decreased compared to the relapsed xenografts in vivo. Transfections with androgen-regulated reporter genes further indicated that the cells lacked androgen-independent AR transcriptional activity and were not hypersensitive to low androgen concentrations despite constitutive activation of the Erk/MAP kinases. Nonetheless, AR remained essential for androgen-independent growth because retroviral shRNA-mediated AR down-regulation resulted in marked long-term growth suppression. This was associated with increased levels of p27(kip1) and hypophosphorylation of retinoblastoma protein but not with decreases in D-type cyclin levels or MAP kinase activation. These results reveal a potentially critical function of AR in androgen-independent PCa that is distinct from its previously described transcriptional or nontranscriptional functions.

T cell factor (Tcf) proteins bind beta-catenin and are downstream effectors of Wnt/beta-catenin signals. A recently demonstrated interaction between beta-catenin and the androgen receptor (AR) ligand binding domain has suggested that AR may be a Tcf-independent Wnt/beta-catenin effector. This study demonstrates that there is a direct interaction between the AR DNA binding domain (DBD) and Tcf4. Tcf4 bound specifically to a glutathione S-transferase-ARDBD fusion protein and could be coimmunoprecipitated with beta-catenin and transfected AR or endogenous AR in prostate cancer cells. Transfected Tcf4 repressed the transcriptional activity of full-length AR and a VP16-ARDBD fusion protein, and this repression was only partially reversed by transfected beta-catenin. AR activation by cyproterone acetate, a partial agonist that did not support beta-catenin binding to the AR, was also repressed by Tcf4, further indicating that repression was not due to beta-catenin sequestration. Tcf4 could recruit beta-catenin to the AR DBD in vitro and to the cyproterone acetate-liganded AR in vivo. Chromatin immunoprecipitation experiments in LNCaP prostate cancer cells showed that endogenous AR was bound to a Tcf4-responsive element in the c-myc promoter. These findings indicate that AR and Tcf4 can interact directly and that this interaction may occur on the promoters or enhancers of particular genes. The direct AR-Tcf4 interaction, in conjunction AR- and Tcf4-beta-catenin binding, provides a mechanism for cooperative and selective gene regulation by AR and the Wnt/beta-catenin-Tcf pathway that may contribute to normal and neoplastic prostate growth.