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Krall P, Pineda C, Ruiz P, Ejarque L, Vendrell T, Camacho JA, Mendizábal S, Oliver A, Ballarín J, Torra R, Ars E. Cost-effective PKHD1 genetic testing for autosomal recessive polycystic kidney disease. Pediatr Nephrol 2014; 29:223-34. [PMID: 24162162 DOI: 10.1007/s00467-013-2657-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 09/30/2013] [Accepted: 10/04/2013] [Indexed: 12/22/2022]
Abstract
BACKGROUND Genetic diagnosis of autosomal recessive polycystic kidney disease (ARPKD) is challenging due to the length and allelic heterogeneity of the PKHD1 gene. Mutations appear to be clustered at specific exons, depending on the geographic origin of the patient. We aimed to identify the PKHD1 exons most likely mutated in Spanish ARPKD patients. METHODS Mutation analysis was performed in 50 ARPKD probands and nine ARPKD-suspicious patients by sequencing PKHD1 exons arranged by their reported mutation frequency. Haplotypes containing the most frequent mutations were analyzed. Other PKD genes (HNF1B, PKD1, PKD2) were sequenced in PKHD1-negative cases. RESULTS Thirty-six different mutations (concentrated in 24 PKHD1 exons) were detected, giving a mutation detection rate of 86%. The screening of five exons (58, 32, 34, 36, 37) yielded a 54% chance of detecting one mutation; the screening of nine additional exons (3, 9, 39, 61, 5, 22, 26, 41, 57) increased the chance to 76%. The c.9689delA mutation was present in 17 (34%) patients, all of whom shared the same haplotype. Two HNF1B mutations and one PKD1 variant were detected in negative cases. CONCLUSIONS Establishing a PKHD1 exon mutation profile in a specific population and starting the analysis with the most likely mutated exons might significantly enhance the efficacy of genetic testing in ARPKD. Analysis of other PKD genes might be considered, especially in suspicious cases.
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Affiliation(s)
- Paola Krall
- Molecular Biology Laboratory, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau (IIB-Sant Pau), Universitat Autònoma de Barcelona, REDinREN, Instituto de Investigación Carlos III, C/Cartagena, 340-350, 08025, Barcelona, Spain
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Targeted exome sequencing integrated with clinicopathological information reveals novel and rare mutations in atypical, suspected and unknown cases of Alport syndrome or proteinuria. PLoS One 2013; 8:e76360. [PMID: 24130771 PMCID: PMC3794937 DOI: 10.1371/journal.pone.0076360] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Accepted: 08/25/2013] [Indexed: 12/18/2022] Open
Abstract
We applied customized targeted next-generation exome sequencing (NGS) to determine if mutations in genes associated with renal malformations, Alport syndrome (AS) or nephrotic syndrome are a potential cause of renal abnormalities in patients with equivocal or atypical presentation. We first sequenced 4,041 exons representing 292 kidney disease genes in a Caucasian woman with a history of congenital vesicoureteral reflux (VUR), recurrent urinary tract infections and hydronephrosis who presented with nephrotic range proteinuria at the age of 45. Her biopsy was remarkable for focal segmental glomerulosclerosis (FSGS), a potential complication of longstanding VUR. She had no family history of renal disease. Her proteinuria improved initially, however, several years later she presented with worsening proteinuria and microhematuria. NGS analysis revealed two deleterious COL4A3 mutations, one novel and the other previously reported in AS, and a novel deleterious SALL2 mutation, a gene linked to renal malformations. Pedigree analysis confirmed that COL4A3 mutations were nonallelic and compound heterozygous. The genomic results in conjunction with subsequent abnormal electron microscopy, Collagen IV minor chain immunohistochemistry and progressive sensorineural hearing loss confirmed AS. We then modified our NGS approach to enable more efficient discovery of variants associated with AS or a subset of FSGS by multiplexing targeted exome sequencing of 19 genes associated with AS or FSGS in 14 patients. Using this approach, we found novel or known COL4A3 or COL4A5 mutations in a subset of patients with clinically diagnosed or suspected AS, APOL1 variants associated with FSGS in African Americans and novel mutations in genes associated with nephrotic syndrome. These studies demonstrate the successful application of targeted capture-based exome sequencing to simultaneously evaluate genetic variations in many genes in patients with complex renal phenotypes and provide insights into etiology of conditions with equivocal clinical and pathologic presentations.
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Joshi S, Andersen R, Jespersen B, Rittig S. Genetics of steroid-resistant nephrotic syndrome: a review of mutation spectrum and suggested approach for genetic testing. Acta Paediatr 2013; 102:844-56. [PMID: 23772861 DOI: 10.1111/apa.12317] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Revised: 05/21/2013] [Accepted: 06/10/2013] [Indexed: 01/03/2023]
Abstract
UNLABELLED Identification of genes, associated mutations and genotype-phenotype correlations in steroid-resistant nephrotic syndrome (SRNS) is being translated to clinical practice through genetic testing. This review provides an update on the genes and mutations associated with SRNS along with a suggested approach for genetic testing in patients with SRNS. CONCLUSION The number of indentified genes associated with SRNS is increasing along with our understanding of their impact on treatment response and risk of recurrence. A systematic approach to genetic testing in patients with SRNS might aid the physician in selecting appropriate treatment.
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Affiliation(s)
- S Joshi
- Department of Clinical Medicine - The Department of Pediatrics; Research Laboratory-A; Aarhus University Hospital; Aarhus N Denmark
| | - R Andersen
- Department of Clinical Medicine - The Department of Pediatrics; Research Laboratory-A; Aarhus University Hospital; Aarhus N Denmark
| | - B Jespersen
- Department of Clinical Medicine - The Department of Medicine and Nephrology C; Aarhus University Hospital; Aarhus N Denmark
| | - S Rittig
- Department of Clinical Medicine - The Department of Pediatrics; Research Laboratory-A; Aarhus University Hospital; Aarhus N Denmark
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Abstract
Renal biopsy was introduced in the 1950s. By 1980 the pathologic diagnostic criteria for the majority of medical kidney diseases known today, including pediatric diseases, were established using light, electron microscopy and immunohistochemistry. However, it has become clear that there are limitations in the morphologic evaluation, mainly because a given pattern of injury can be caused by different aetiologies and, conversely, a single aetiology may present with more than one histological pattern. An explosion in kidney disease research in the last 20-30 years has brought new knowledge from bench to bedside rapidly and resulted in new molecular and genetic tools that enhance the diagnostic and prognostic power of the renal biopsy. Genomic technologies such as polymerase chain reaction (PCR), in situ hybridization and oligonucleotide microarrays, collectively known as genomics, detect single or multiple genes underscoring the pathologic changes and revealing specific causes of injury that may require different treatment. The aims of this review are to (1) summarize current recommendations for diagnostic renal biopsies encompassing light microscopy, immunofluorescence or immunohistochemistry and electron microscopy; (2) address the limitations of morphology; (3) show current contributions of genomic technologies adjunct to the renal biopsy, and provide examples of how these may transform pathologic interpretation into molecular disease phenotypes.
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Fervenza FC. A patient with nephrotic-range proteinuria and focal global glomerulosclerosis. Clin J Am Soc Nephrol 2013; 8:1979-87. [PMID: 23886564 DOI: 10.2215/cjn.03400313] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
A young male is evaluated for nephrotic-range proteinuria, hypercalciuria, and an elevated serum creatinine. A renal biopsy is performed and shows focal global glomerulosclerosis. The absence of nephrotic syndrome suggest that glomerulosclerosis was a secondary process. Further analysis of the proteinuria showed it to be due mainly to low-molecular weight proteins. The case illustrates the crucial role of electron microscopy as well as evaluation of the identity of the proteinuria that accompanies a biopsy finding of focal and global or focal and segmental glomerulosclerosis.
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Affiliation(s)
- Fernando C Fervenza
- Division of Nephrology and Hypertension, Mayo Clinic College of Medicine, Rochester, Minnesota
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56
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Lipska BS, Iatropoulos P, Maranta R, Caridi G, Ozaltin F, Anarat A, Balat A, Gellermann J, Trautmann A, Erdogan O, Saeed B, Emre S, Bogdanovic R, Azocar M, Balasz-Chmielewska I, Benetti E, Caliskan S, Mir S, Melk A, Ertan P, Baskin E, Jardim H, Davitaia T, Wasilewska A, Drozdz D, Szczepanska M, Jankauskiene A, Higuita LMS, Ardissino G, Ozkaya O, Kuzma-Mroczkowska E, Soylemezoglu O, Ranchin B, Medynska A, Tkaczyk M, Peco-Antic A, Akil I, Jarmolinski T, Firszt-Adamczyk A, Dusek J, Simonetti GD, Gok F, Gheissari A, Emma F, Krmar RT, Fischbach M, Printza N, Simkova E, Mele C, Ghiggeri GM, Schaefer F. Genetic screening in adolescents with steroid-resistant nephrotic syndrome. Kidney Int 2013; 84:206-13. [PMID: 23515051 DOI: 10.1038/ki.2013.93] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2012] [Revised: 12/31/2012] [Accepted: 01/10/2013] [Indexed: 02/08/2023]
Abstract
Genetic screening paradigms for congenital and infantile nephrotic syndrome are well established; however, screening in adolescents has received only minor attention. To help rectify this, we analyzed an unselected adolescent cohort of the international PodoNet registry to develop a rational screening approach based on 227 patients with nonsyndromic steroid-resistant nephrotic syndrome aged 10-20 years. Of these, 21% had a positive family history. Autosomal dominant cases were screened for WT1, TRPC6, ACTN4, and INF2 mutations. All other patients had the NPHS2 gene screened, and WT1 was tested in sporadic cases. In addition, 40 sporadic cases had the entire coding region of INF2 tested. Of the autosomal recessive and the sporadic cases, 13 and 6%, respectively, were found to have podocin-associated nephrotic syndrome, and 56% of them were compound heterozygous for the nonneutral p.R229Q polymorphism. Four percent of the sporadic and 10% of the autosomal dominant cases had a mutation in WT1. Pathogenic INF2 mutations were found in 20% of the dominant but none of the sporadic cases. In a large cohort of adolescents including both familial and sporadic disease, NPHS2 mutations explained about 7% and WT1 4% of cases, whereas INF2 proved relevant only in autosomal dominant familial disease. Thus, screening of the entire coding sequence of NPHS2 and exons 8-9 of WT1 appears to be the most rational and cost-effective screening approach in sporadic juvenile steroid-resistant nephrotic syndrome.
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Affiliation(s)
- Beata S Lipska
- Division of Pediatric Nephrology, Center for Pediatric and Adolescent Medicine, University of Heidelberg, Heidelberg, Germany.
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Mottl AK, Lu M, Fine CA, Weck KE. A novel TRPC6 mutation in a family with podocytopathy and clinical variability. BMC Nephrol 2013; 14:104. [PMID: 23663351 PMCID: PMC3662586 DOI: 10.1186/1471-2369-14-104] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Accepted: 04/05/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Mutation in several podocyte-specific genes have been noted to result in phenotypic heterogeneity. Herein, we report a novel, autosomal dominant TRPC6 mutation in a family with disease ranging from asymptomatic minimal change disease to end-stage kidney disease. CASE PRESENTATION A 35 year old woman developed asymptomatic, nephrotic range proteinuria during pregnancy that did not resolve after delivery. Her mother had end-stage kidney disease of unknown etiology and her brother had asymptomatic proteinuria. Kidney biopsy revealed minimal change disease in both the proband and her brother. Genetic testing was performed in the proband and mother, revealing a novel frameshift mutation in TRPC6, D873fsX878. The proband continues to have subnephrotic range proteinuria and normal creatinine but her brother has since developed progressive chronic kidney disease. CONCLUSIONS The current case report underscores the heterogeneity of disease in podocytopathies and related genes. Genetic testing of podocyte genes is useful in order to understand the pathophysiologic processes underlying these overlapping diseases.
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Affiliation(s)
- Amy K Mottl
- University of North Carolina Kidney Center, UNC School of Medicine, Chapel Hill, NC, USA.
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Saleem MA. New developments in steroid-resistant nephrotic syndrome. Pediatr Nephrol 2013; 28:699-709. [PMID: 22782578 DOI: 10.1007/s00467-012-2239-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2012] [Revised: 05/04/2012] [Accepted: 05/04/2012] [Indexed: 12/20/2022]
Abstract
Nephrotic syndrome is a disorder of the glomerular filtration barrier, a highly specialised tri-layer structure with unique functional properties. Recent advances emanating from the field of molecular genetics have revealed the podocyte as probably the central player in the control of glomerular filtration. More specifically, the cell-cell junction between adjacent podocyte foot processes, namely, the slit diaphragm, has been revealed to be made up of a sophisticated multi-protein complex which dynamically controls foot process architecture via signalling to the actin cytoskeleton. Key genes that have been identified from the study of inherited nephrotic syndromes include those encoding nephrin, podocin, TRPC6 (transient receptor potential canonical channel-6) and α-actinin-4, and more remain to be found. It is now possible to identify genetic causes underlying a proportion of nephrotic syndromes presenting at any age. The next big challenge for clinicians and researchers is to translate the molecular information learnt into the understanding of acquired, non-inherited forms of the disease and to guide therapeutic options. In this regard several exciting advances have been made, both in understanding the molecular mechanisms of current therapies and in revealing circulating plasma factors and the molecular pathways they trigger in the podocyte, that could be targeted by novel therapies.
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Affiliation(s)
- Moin A Saleem
- Academic Renal Unit, Learning and Research Building, Southmead Hospital, Bristol, UK.
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NPHS2 p.V290M mutation in late-onset steroid-resistant nephrotic syndrome. Pediatr Nephrol 2013; 28:751-7. [PMID: 23242530 DOI: 10.1007/s00467-012-2379-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Revised: 10/19/2012] [Accepted: 11/01/2012] [Indexed: 10/27/2022]
Abstract
BACKGROUND The most frequently mutated gene of steroid-resistant nephrotic syndrome (SRNS) is NPHS2. Current guidelines propose the sequencing of all NPHS2 exons only in childhood-onset SRNS. METHODS A cohort of 38 Hungarian patients with childhood-onset nephrotic-range proteinuria was screened for NPHS2 mutations. The frequency of the p.V290M mutation in late-onset SRNS was examined in the French and PodoNet cohorts. RESULTS Of the 38 Hungarian patients screened, seven carried NPHS2 mutations on both alleles, of whom two-diagnosed with proteinuria through school screening programs at the age of 9.7 and 14 years, respectively-did not develop nephrotic syndrome in childhood. The first, an 18-year-old boy, homozygous for p.V290M, has never developed edema. The second, a 31-year-old woman-compound heterozygous for p.V290M and p.R138Q-was first detected with hypoalbuminemia (<30 g/l) and edema at the age of 24.3 and 27.5 years, respectively. Both patients currently have a normal glomerular filtration rate. The mutation p.V290M was carried by three of the 38 patients in the Hungarian cohort, by two of the 95 patients with late-onset SRNS in the PodoNet cohort and by none of the 83 patients in the French cohort. CONCLUSIONS We propose that not only the p.R229Q variant, but also the p.V290M mutation should be screened in Central and Eastern European patients with late-onset SRNS.
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Abstract
Observations of hereditary glomerular disease support the contention that podocyte intercellular junction proteins are essential for junction formation and maintenance. Genetic deletion of most of these podocyte intercellular junction proteins results in foot process effacement and proteinuria. This review focuses on the current understanding of molecular mechanisms by which podocyte intercellular junction proteins such as the nephrin-neph1-podocin-receptor complex coordinate cytoskeletal dynamics and thus intercellular junction formation, maintenance, and injury-dependent remodeling.
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Gupta IR, Baldwin C, Auguste D, Ha KCH, El Andalousi J, Fahiminiya S, Bitzan M, Bernard C, Akbari MR, Narod SA, Rosenblatt DS, Majewski J, Takano T. ARHGDIA: a novel gene implicated in nephrotic syndrome. J Med Genet 2013; 50:330-8. [PMID: 23434736 PMCID: PMC3625828 DOI: 10.1136/jmedgenet-2012-101442] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Background Congenital nephrotic syndrome arises from a defect in the glomerular filtration barrier that permits the unrestricted passage of protein across the barrier, resulting in proteinuria, hypoalbuminaemia, and severe oedema. While most cases are due to mutations in one of five genes, in up to 15% of cases, a genetic cause is not identified. We investigated two sisters with a presumed recessive form of congenital nephrotic syndrome. Methods and results Whole exome sequencing identified five genes with diallelic mutations that were shared by the sisters, and Sanger sequencing revealed that ARHGDIA that encodes Rho GDP (guanosine diphosphate) dissociation inhibitor α (RhoGDIα, OMIM 601925) was the most likely candidate. Mice with targeted inactivation of ARHGDIA are known to develop severe proteinuria and nephrotic syndrome, therefore this gene was pursued in functional studies. The sisters harbour a homozygous in-frame deletion that is predicted to remove a highly conserved aspartic acid residue within the interface where the protein, RhoGDIα, interacts with the Rho family of small GTPases (c.553_555del(p.Asp185del)). Rho-GTPases are critical regulators of the actin cytoskeleton and when bound to RhoGDIα, they are sequestered in an inactive, cytosolic pool. In the mouse kidney, RhoGDIα was highly expressed in podocytes, a critical cell within the glomerular filtration barrier. When transfected in HEK293T cells, the mutant RhoGDIα was unable to bind to the Rho-GTPases, RhoA, Rac1, and Cdc42, unlike the wild-type construct. When RhoGDIα was knocked down in podocytes, RhoA, Rac1, and Cdc42 were hyperactivated and podocyte motility was impaired. The proband's fibroblasts demonstrated mislocalisation of RhoGDIα to the nucleus, hyperactivation of the three Rho-GTPases, and impaired cell motility, suggesting that the in-frame deletion leads to a loss of function. Conclusions Mutations in ARHGDIA need to be considered in the aetiology of heritable forms of nephrotic syndrome.
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Affiliation(s)
- Indra Rani Gupta
- Department of Pediatrics, Division of Nephrology, Montreal Children's Hospital and McGill University, 2300, rue Tupper-E222, Montreal, Quebec, Canada H3H 1P3.
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Littman MP, Wiley CA, Raducha MG, Henthorn PS. Glomerulopathy and mutations in NPHS1 and KIRREL2 in soft-coated Wheaten Terrier dogs. Mamm Genome 2013; 24:119-26. [PMID: 23325127 DOI: 10.1007/s00335-012-9445-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Accepted: 12/10/2012] [Indexed: 02/08/2023]
Abstract
Dogs of the soft-coated wheaten terrier breed (SCWT) are predisposed to adult-onset, genetically complex, protein-losing nephropathy (average onset age = 6.3 ± 2.0 years). A genome-wide association study using 62 dogs revealed a chromosomal region containing three statistically significant SNPs (p(raw) ≤ 4.13 × 10(-8); p(genome) ≤ 0.005) when comparing DNA samples from affected and geriatric (≥14 years) unaffected SCWTs. Sequencing of candidate genes in the region revealed single nucleotide changes in each of two closely linked genes, NPHS1 and KIRREL2, which encode the slit diaphragm proteins nephrin and Neph3/filtrin, respectively. In humans, mutations in nephrin and decreased expression of Neph3 are associated with podocytopathy and protein-losing nephropathy. The base substitutions change a glycine to arginine in the fibronectin type 3 domain of nephrin and a proline to arginine in a conserved proline-rich region in Neph3. These novel mutations are not described in other species, nor were they found in 550 dogs of 105 other breeds, except in 3 dogs, including an affected Airedale terrier, homozygous for both substitutions. Risk for nephropathy is highest in dogs homozygous for the mutations (OR = 9.06; 95 % CI = 4.24-19.35). This is the first molecular characterization of an inherited podocytopathy in dogs and may serve as a model for continued studies of complex genetic and environmental interactions in glomerular disease.
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Affiliation(s)
- Meryl P Littman
- Department of Clinical Studies, University of Pennsylvania School of Veterinary Medicine-Philadelphia, Philadelphia, PA 19104-6010, USA.
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Che R, Zhang A. Mechanisms of Glucocorticoid Resistance in Idiopathic Nephrotic Syndrome. ACTA ACUST UNITED AC 2013; 37:360-78. [DOI: 10.1159/000350163] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/19/2013] [Indexed: 11/19/2022]
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Abstract
PURPOSE OF REVIEW Focal segmental glomerulosclerosis (FSGS) is a major cause of nephrotic syndrome and renal failure. All forms of FSGS share podocyte injury and depletion as central mediators. This review focuses on new insights into pathogenesis from study of extrinsic toxins in experimental models, permeability factors in human disease, and novel genetic causes. RECENT FINDINGS Experimental toxin models have advanced our understanding of the threshold and dynamics of podocyte injury. Following initial podocyte depletion, spreading fields of podocyte injury through secondary mediators appear to be important in generating the segmental pathologic lesions. Proliferating glomerular epithelial cells are common in FSGS, although there are conflicting views about their identity. Evidence suggests potential contributions by mature parietal epithelial cells, facultative stem cells and podocytes. A number of novel candidate permeability factors that affect podocyte function and motility have been discovered in human FSGS and related podocytopathy minimal change disease. Exome capture has identified new monogenic causes of familial FSGS. Apolipoprotein L-1 (APOL1) is expressed in podocytes, and the prevalence of APOL1 risk alleles in patients of African descent with primary FSGS and HIV-associated nephropathy is high, implicating potential podocyte effects. SUMMARY FSGS is caused by a complex interplay of inherent genetic susceptibilities and external injurious factors acting on podocytes. Critical levels of podocyte stress eventuate in podocyte depletion, segmental glomerular scarring, and glomerular epithelial cell hyperplasia.
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Büscher AK, Weber S. Educational paper: the podocytopathies. Eur J Pediatr 2012; 171:1151-60. [PMID: 22237399 DOI: 10.1007/s00431-011-1668-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Accepted: 12/20/2011] [Indexed: 02/07/2023]
Abstract
In the recent past, hereditary podocytopathies have increasingly been recognized to be involved in the development of steroid-resistant nephrotic syndrome (SRNS). Mutations in podocyte genes substantially alter the development and structural architecture of the podocyte including its interdigitating foot processes. These constitute the basis of the slit diaphragm which is an essential part of the glomerular filtration barrier. Depending on the affected protein, the clinical course is variable with respect to onset and severity of the disease as well as treatment options. In general, hereditary podocytopathies are associated with a poorer renal outcome than the non-genetic variants. In addition, they require a different approach with respect to the applied therapeutic strategies as most patients do not respond to immunosuppressive agents. Therefore, genetic testing of podocyte genes should be considered as a routine diagnostic tool for patients with SRNS because the identification of a genetic origin has a direct implication on clinical course, renal outcome, and genetic counseling. In this educational paper, we will give an overview over the podocyte genes identified so far to be involved into the pathophysiology of hereditary podocytopathies.
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Affiliation(s)
- Anja K Büscher
- Pediatric Nephrology, Pediatrics II, University-Children's Hospital Essen, Hufelandstraße 55, 45122 Essen, Germany.
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Schell C, Huber TB. New players in the pathogenesis of focal segmental glomerulosclerosis. Nephrol Dial Transplant 2012; 27:3406-12. [PMID: 22767631 DOI: 10.1093/ndt/gfs273] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Focal segmental glomerulosclerosis (FSGS) is the most common primary glomerular disorder causing end-stage renal disease. Since the first description of this clinicopathological entity in the early 1930s, various studies have identified numerous underlying pathogenetic mechanisms. Nevertheless, FSGS is still a complex, only partially understood and in its classification sometimes confusing disease. A unifying pathophysiological concept has not been identified and might not even exist. However, research efforts of past decades identified FSGS as a podocytopathy with several podocyte molecules being key players in the development and the course of FSGS. Podocytes are crucially involved in the formation of the glomerular barrier and any assault on their delicate physiological balance and architecture can result in the development of proteinuria. The following review article will introduce most recent examples identifying novel players in the complex pathogenesis of FSGS.
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Understanding the mechanisms of proteinuria: therapeutic implications. Int J Nephrol 2012; 2012:546039. [PMID: 22844592 PMCID: PMC3398673 DOI: 10.1155/2012/546039] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Accepted: 04/30/2012] [Indexed: 12/18/2022] Open
Abstract
A large body of evidence indicates that proteinuria is a strong predictor of morbidity, a cause of inflammation, oxidative stress and progression of chronic kidney disease, and development of cardiovascular disease. The processes that lead to proteinuria are complex and involve factors such as glomerular hemodynamic, tubular absorption, and diffusion gradients. Alterations in various different molecular pathways and interactions may lead to the identical clinical end points of proteinuria and chronic kidney disease. Glomerular diseases include a wide range of immune and nonimmune insults that may target and thus damage some components of the glomerular filtration barrier. In many of these conditions, the renal visceral epithelial cell (podocyte) responds to injury along defined pathways, which may explain the resultant clinical and histological changes. The recent discovery of the molecular components of the slit diaphragm, specialized structure of podocyte-podocyte interaction, has been a major breakthrough in understanding the crucial role of the epithelial layer of the glomerular barrier and the pathogenesis of proteinuria. This paper provides an overview and update on the structure and function of the glomerular filtration barrier and the pathogenesis of proteinuria, highlighting the role of the podocyte in this setting. In addition, current antiproteinuric therapeutic approaches are briefly commented.
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Chapter 6: Idiopathic focal segmental glomerulosclerosis in adults. Kidney Int Suppl (2011) 2012; 2:181-185. [PMID: 25018931 PMCID: PMC4089762 DOI: 10.1038/kisup.2012.19] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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Sethi S, Fervenza FC, Zhang Y, Smith RJH. Secondary focal and segmental glomerulosclerosis associated with single-nucleotide polymorphisms in the genes encoding complement factor H and C3. Am J Kidney Dis 2012; 60:316-21. [PMID: 22594991 DOI: 10.1053/j.ajkd.2012.04.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Accepted: 04/12/2012] [Indexed: 01/25/2023]
Abstract
Genetic causes of focal and segmental glomerulosclerosis (FSGS) typically involve mutations and allele variants of genes expressed in podocytes or, more rarely, glomerular basement membranes. In this report, we describe a 60-year-old woman with chronic kidney disease whose kidney biopsy showed FSGS. Immunoglobulins and C3 were undetectable in immunofluorescence studies. Electron microscopy showed subendothelial fluffy granular material with occasional double-contour formation suggestive of capillary wall injury and prompting work-up for a prothrombotic state. Evaluation of the alternative pathway of complement showed a novel polymorphism in short consensus repeat (SCR) 12 of complement factor H (CFH; c.2195C>T, p.Thr732Met) and a previously reported but largely uncharacterized polymorphism in complement factor C3 (c.463A>C, p.Lys155Gln). Dysregulation of the alternative pathway is associated with atypical hemolytic syndrome and dense deposit disease, but heretofore has not been associated with FSGS. This case highlights the expanding spectrum of complement-mediated glomerular disease and shows that FSGS with features of capillary wall injury should prompt evaluation for abnormalities in the alternative pathway. This case also expands the list of genetic polymorphisms that can be associated with an FSGS phenotype.
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Affiliation(s)
- Sanjeev Sethi
- Division of Anatomic Pathology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55905, USA.
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71
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Rood IM, Deegens JKJ, Wetzels JFM. Genetic causes of focal segmental glomerulosclerosis: implications for clinical practice. Nephrol Dial Transplant 2012; 27:882-90. [PMID: 22334613 DOI: 10.1093/ndt/gfr771] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Focal segmental glomerulosclerosis (FSGS) is a common cause of steroid-resistant nephrotic syndrome in children and adults. Although FSGS is considered a podocyte disease, the aetiology is diverse. In recent years, many inheritable genetic forms of FSGS have been described, caused by mutations in proteins that are important for podocyte function. In the present commentary, we review these genetic causes of FSGS and describe their prevalence in familial and sporadic FSGS. In routine clinical practice, the decision to perform the costly DNA analysis should be based on the assessment if the results affect the care of the individual patient with respect to the evaluation of extra-renal manifestations, treatment decisions, transplantation and genetic counselling.
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Affiliation(s)
- Ilse M Rood
- Department of Nephrology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
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Affiliation(s)
- Vivette D D'Agati
- Department of Pathology, Columbia University College of Physicians and Surgeons, New York, NY, USA.
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Abstract
Focal segmental glomerulosclerosis (FSGS) is not a disease but a clinicopathologic entity. The term FSGS itself is a misnomer because its lesions are not always focal, segmental, or sclerotic. Its clinical expression also widely varies and is nonspecific. Confronted with such diversity, one cannot but translate the title of this contribution into a unifying version focusing on the podocyte, initial culprit, or victim of multiple processes leading to FSGS. Some have been identified in human glomerulopathies and/or in animal or cell culture models, and are classified as secondary. Genetic forms, nonsyndromic or syndromic, have adduced a wealth of knowledge on the slit diaphragm architecture and explain the reason for their steroid resistance. Others, mostly expressed by a nephrotic syndrome, will be considered as idiopathic until the offending factor(s) that affect the molecular array of the slit diaphragm filtration barrier are identified and counteracted. Recent research has lead to suggesting that FSGS is not a T-cell-driven autoimmune glomerulopathy. Thus, treatments considered as etiologic, including glucocorticoids and calcineurin inhibitors, are in fact endowed with a mode of action on podocytes that suggests that drugs used such as immunosuppressors also might be considered as antiproteinuric agents.
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Piscione TD, Licht C. Genetics of proteinuria: an overview of gene mutations associated with nonsyndromic proteinuric glomerulopathies. Adv Chronic Kidney Dis 2011; 18:273-89. [PMID: 21782134 DOI: 10.1053/j.ackd.2011.06.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2011] [Revised: 06/02/2011] [Accepted: 06/16/2011] [Indexed: 02/08/2023]
Abstract
Heritable causes of proteinuria are rare and account for a relatively small proportion of all cases of proteinuria affecting children and adults. Yet, significant contributions to understanding the mechanistic basis for proteinuria have been made through genetic and molecular analyses of a small group of syndromic and nonsyndromic proteinuric disorders which are caused by mutations encoding structural components of the glomerular filtration barrier. Technological advances in genomic analyses and improved accessibility to mutational screening at clinically approved laboratories have facilitated diagnosis of proteinuria in the clinical setting. From a clinical standpoint, it may be argued that a genetic diagnosis mitigates exposure to potentially ineffective and harmful treatments in instances where a clear genotype-phenotype correlation exists between a specific gene mutation and treatment nonresponsiveness. However, cautious interpretation of risk may be necessitated in cases with phenotypic heterogeneity (eg, variability in clinical or histological presentation). This review summarizes gene mutations which are known to be associated with proteinuric glomerulopathies in children and adults.
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Gbadegesin R, Lavin P, Foreman J, Winn M. Pathogenesis and therapy of focal segmental glomerulosclerosis: an update. Pediatr Nephrol 2011; 26:1001-15. [PMID: 21110043 PMCID: PMC3624015 DOI: 10.1007/s00467-010-1692-x] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2010] [Revised: 09/28/2010] [Accepted: 10/04/2010] [Indexed: 02/07/2023]
Abstract
Focal and segmental glomerulosclerosis (FSGS) is an important cause of steroid-resistant nephrotic syndrome in adults and children. It is responsible for 5-20% of all cases of end-stage kidney disease (ESKD) in the United States. The pathogenesis of FSGS has not been fully elucidated; however, data from molecular studies of familial cases in the last two decades suggest that FSGS is a defect of the podocyte. The therapeutic agents available for treatment of FSGS are not very effective and only a small percentage of affected individuals will achieve complete remission. Recent data from molecular biology and molecular genetics has provided insight into the mechanisms of action of old agents and also identification of other novel therapeutic targets. This review focuses on recent advances in the molecular pathogenesis of FSGS and currently available therapeutic agents as well as potential novel therapies.
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Affiliation(s)
- Rasheed Gbadegesin
- Department of Pediatrics, Duke University Medical Center, Durham, NC 27710, USA.
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Santín S, Bullich G, Tazón-Vega B, García-Maset R, Giménez I, Silva I, Ruíz P, Ballarín J, Torra R, Ars E. Clinical utility of genetic testing in children and adults with steroid-resistant nephrotic syndrome. Clin J Am Soc Nephrol 2011; 6:1139-48. [PMID: 21415313 DOI: 10.2215/cjn.05260610] [Citation(s) in RCA: 149] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND AND OBJECTIVES The increasing number of podocyte-expressed genes implicated in steroid-resistant nephrotic syndrome (SRNS), the phenotypic variability, and the uncharacterized relative frequency of mutations in these genes in pediatric and adult patients with SRNS complicate their routine genetic analysis. Our aim was to compile the clinical and genetic data of eight podocyte genes analyzed in 110 cases (125 patients) with SRNS (ranging from congenital to adult onset) to provide a genetic testing approach. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Mutation analysis was performed by sequencing the NPHS1, NPHS2, TRPC6, CD2AP, PLCE1, INF2, WT1 (exons 8 and 9), and ACTN4 (exons 1 to 10) genes. RESULTS We identified causing mutations in 34% (37/110) of SRNS patients, representing 67% (16/24) familial and 25% (21/86) sporadic cases. Mutations were detected in 100% of congenital-onset, 57% of infantile-onset, 24 and 36% of early and late childhood-onset, 25% of adolescent-onset, and 14% of adult-onset patients. The most frequently mutated gene was NPHS1 in congenital onset and NPHS2 in the other groups. A partial remission was observed in 7 of 26 mutation carriers treated with immunosuppressive agents and/or angiotensin-converting enzyme inhibitors. Patients with NPHS1 mutations showed a faster progression to ESRD than patients with NPHS2 mutations. None of these mutation carriers relapsed after kidney transplantation. CONCLUSIONS We propose a genetic testing algorithm for SRNS based on the age at onset and the familial/sporadic status. Mutation analysis of specific podocyte-genes has a clinical value in all age groups, especially in children.
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Affiliation(s)
- Sheila Santín
- Molecular Biology Laboratory, Fundació Puigvert, Universitat Autònoma de Barcelona, REDinREN, Instituto de Investigación Carlos III, Barcelona, Spain
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Pozzi A. Diseased renal glomeruli are getting soft. Focus on "Biophysical properties of normal and diseased renal glomeruli". Am J Physiol Cell Physiol 2010; 300:C394-6. [PMID: 21178112 DOI: 10.1152/ajpcell.00511.2010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Benoit G, Machuca E, Heidet L, Antignac C. Hereditary kidney diseases: highlighting the importance of classical Mendelian phenotypes. Ann N Y Acad Sci 2010; 1214:83-98. [PMID: 20969579 DOI: 10.1111/j.1749-6632.2010.05817.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
A Mendelian inheritance underlies a nonnegligible proportion of hereditary kidney diseases, suggesting that the encoded proteins are essential for maintenance of the renal function. The identification of genes involved in congenital anomalies of the kidney and in familial forms of nephrotic syndrome significantly increased our understanding of the renal development and kidney filtration barrier physiology. This review will focus on the classical phenotype and clinical heterogeneity observed in the monogenic forms of these disorders. In addition, the role of susceptibility genes in kidney diseases with a complex inheritance will also be discussed.
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Santín S, Tazón-Vega B, Silva I, Cobo MÁ, Giménez I, Ruíz P, García-Maset R, Ballarín J, Torra R, Ars E. Clinical value of NPHS2 analysis in early- and adult-onset steroid-resistant nephrotic syndrome. Clin J Am Soc Nephrol 2010; 6:344-54. [PMID: 20947785 DOI: 10.2215/cjn.03770410] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
BACKGROUND AND OBJECTIVES To date, very few cases with adult-onset focal segmental glomerulosclerosis (FSGS) carrying NPHS2 variants have been described, all of them being compound heterozygous for the p.R229Q variant and one pathogenic mutation. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Mutation analysis was performed in 148 unrelated Spanish patients, of whom 50 presented with FSGS after 18 years of age. Pathogenicity of amino acid substitutions was evaluated through an in silico scoring system. Haplotype analysis was carried out using NPHS2 single nucleotide polymorphism and microsatellite markers. RESULTS Compound heterozygous or homozygous NPHS2 pathogenic mutations were identified in seven childhood-onset steroid-resistant nephrotic syndrome (SRNS) cases. Six additional cases with late childhood- and adult-onset SRNS were compound heterozygotes for p.R229Q and one pathogenic mutation, mostly p.A284V. p.R229Q was more frequent among SRNS cases relative to controls (odds ratio=2.65; P=0.02). Significantly higher age at onset of the disease and slower progression to ESRD were found in patients with one pathogenic mutation plus the p.R229Q variant in respect to patients with two NPHS2 pathogenic mutations. CONCLUSIONS NPHS2 analysis has a clinical value in both childhood- and adult-onset SRNS patients. For adult-onset patients, the first step should be screening for p.R229Q and, if positive, for p.A284V. These alleles are present in conserved haplotypes, suggesting a common origin for these substitutions. Patients carrying this specific NPHS2 allele combination did not respond to corticoids or immunosuppressors and showed FSGS, average 8-year progression to ESRD, and low risk for recurrence of FSGS after kidney transplant.
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Affiliation(s)
- Sheila Santín
- Fundació Puigvert, Cartagena 340-350, 08025 Barcelona, Spain
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Benoit G, Machuca E, Antignac C. Hereditary nephrotic syndrome: a systematic approach for genetic testing and a review of associated podocyte gene mutations. Pediatr Nephrol 2010; 25:1621-32. [PMID: 20333530 PMCID: PMC2908444 DOI: 10.1007/s00467-010-1495-0] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Revised: 02/04/2010] [Accepted: 02/08/2010] [Indexed: 11/30/2022]
Abstract
Several genes have been implicated in genetic forms of nephrotic syndrome occurring in children. It is now known that the phenotypes associated with mutations in these genes display significant variability, rendering genetic testing and counselling a more complex task. This review will focus on the recent clinical findings associated with those genes known to be involved in isolated steroid-resistant nephrotic syndrome in children and, thereby, propose an approach for appropriate mutational screening. The recurrence of proteinuria after transplantation in patients with hereditary forms of nephrotic syndrome will also be discussed.
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Affiliation(s)
- Geneviève Benoit
- Inserm, U983, Hôpital Necker-Enfants Malades, Paris, France ,CHU Sainte-Justine, Université de Montréal, Montréal, Canada
| | - Eduardo Machuca
- Inserm, U983, Hôpital Necker-Enfants Malades, Paris, France ,Pontificia Universidad Católica de Chile, Escuela de Medicina, Santiago, Chile
| | - Corinne Antignac
- Inserm, U983, Hôpital Necker-Enfants Malades, Paris, France ,Faculté de Médecine Paris Descartes, Université Paris Descartes, Paris, France ,Département de Génétique, Hôpital Necker-Enfants Malades, Assistance Publique-Hôpitaux de Paris (AP-HP), Paris, France ,Inserm, U983, 6e étage, Tour Lavoisier, Hôpital Necker-Enfants Malades, 149 rue de Sèvres, 75015 Paris, France
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Machuca E, Benoit G, Nevo F, Tête MJ, Gribouval O, Pawtowski A, Brandström P, Loirat C, Niaudet P, Gubler MC, Antignac C. Genotype-phenotype correlations in non-Finnish congenital nephrotic syndrome. J Am Soc Nephrol 2010; 21:1209-17. [PMID: 20507940 DOI: 10.1681/asn.2009121309] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Mutations in NPHS1, which encodes nephrin, are the main causes of congenital nephrotic syndrome (CNS) in Finnish patients, whereas mutations in NPHS2, which encodes podocin, are typically responsible for childhood-onset steroid-resistant nephrotic syndrome in European populations. Genotype-phenotype correlations are not well understood in non-Finnish patients. We evaluated the clinical presentation, kidney histology, and disease progression in non-Finnish CNS cases by mutational screening in 107 families (117 cases) by sequencing the entire coding regions of NPHS1, NPHS2, PLCE1, WT1, LAMB2, PDSS2, COQ2, and NEPH1. We found that CNS describes a heterogeneous group of disorders in non-Finnish populations. We identified nephrin and podocin mutations in most families and only rarely found mutations in genes implicated in other hereditary forms of NS. In approximately 20% of cases, we could not identify the underlying genetic cause. Consistent with the major role of nephrin at the slit diaphragm, NPHS1 mutations associated with an earlier onset of disease and worse renal outcomes than NPHS2 mutations. Milder cases resulting from mutant NPHS1 had either two mutations in the cytoplasmic tail or two missense mutations in the extracellular domain, including at least one that preserved structure and function. In addition, we extend the spectrum of known NPHS1 mutations by describing long NPHS1 deletions. In summary, these data demonstrate that CNS is not a distinct clinical entity in non-Finnish populations but rather a clinically and genetically heterogeneous group of disorders.
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Grünfeld JP, Hwu WL, Van Keimpema L, Alamovitch S, Zivna M, Brown EJ, Chien YH, Lee NC, Chiang SC, Dobrovolny R, Huang AC, Yeh HY, Chao MC, Lin SJ, Kitagawa T, Desnick RJ, Hsu LW, Nevens F, Vanslembrouck R, Van Oijen GH, Hoffmann AL, Dekker HM, De Man RA, Drenth JPH, Plaisier E, Favrole P, Prost C, Chen Z, Van Agrmael T, Marro B, Ronco P, Hulkova H, Matignon M, Hodanova K, Vylet'al P, Kalbacova M, Baresova V, Sikora J, Blazkova H, Zivny J, Ivanek R, Stranecky V, Sovova J, Claes K, Lerut E, Fryns JP, Hart PS, Hart TC, Adams JN, Pawtowski A, Clemessy M, Gasc JM, Gubler MC, Antignac C, Elleder M, Kapp K, Grimbert P, Bleyer AJ, Kmoch S, Schlöndorff JS, Becker DJ, Tsukaguchi H, Uschinski AL, Higgs HN, Henderson JM, Pollak MR. More on Clinical Renal GeneticsNewborn screening for Fabry disease in Taiwan reveals a high incidence of the later-onset mutation c.936+919G>A (IVS4+919G>A). Hum Mutat 30: 1397–1405, 2009Lanreotide reduces the volume of polycystic liver: A randomized, double-blind, placebo-controlled trial. Gastroenterology 137: 1661–1668, 2009Cerebrovascular disease related to COL4A1 mutations in HANAC syndrome. Neurology 73: 1873–1882, 2009Dominant renin gene mutations associated with early-onset hyperuricemia, anemia, and chronic renal failure. Am J Hum Genet 85: 204–213, 2009Mutations in the formin gene INF2 cause focal segmental glomerulosclerosis. Nat Genet 42: 72–76, 2009. Clin J Am Soc Nephrol 2010; 5:563-7. [DOI: 10.2215/cjn.01720210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Brown EJ, Schlöndorff JS, Becker DJ, Tsukaguchi H, Uschinski AL, Higgs HN, Henderson JM, Pollak MR. More on Clinical Renal Genetics. Clin J Am Soc Nephrol 2010. [DOI: 10.2215/01.cjn.0000927112.36833.90] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023]
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Abstract
The nephrin gene NPHS1 was cloned in 1998. Studies in families with congenital nephrotic syndrome led to the identification of this critical component of the glomerular slit diaphragm. Studies such as the new one by Santín et al. are expanding our understanding of the spectrum of disease associated with NPHS1 mutations.
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