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Bonilla M, Efe O, Selvaskandan H, Lerma EV, Wiegley N. A Review of Focal Segmental Glomerulosclerosis Classification With a Focus on Genetic Associations. Kidney Med 2024; 6:100826. [PMID: 38765809 PMCID: PMC11099322 DOI: 10.1016/j.xkme.2024.100826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2024] Open
Abstract
Focal segmental glomerulosclerosis (FSGS) defines a distinct histologic pattern observed in kidney tissue that is linked to several distinct underlying causes, all converging on the common factor of podocyte injury. It presents a considerable challenge in terms of classification because of its varied underlying causes and the limited correlation between histopathology and clinical outcomes. Critically, precise nomenclature is key to describe and delineate the pathogenesis, subsequently guiding the selection of suitable and precision therapies. A proposed pathomechanism-based approach has been suggested for FSGS classification. This approach differentiates among primary, secondary, genetic, and undetermined causes, aiming to provide clarity. Genetic FSGS from monogenic mutations can emerge during childhood or adulthood, and it is advisable to conduct genetic testing in cases in which there is a family history of chronic kidney disease, nephrotic syndrome, or resistance to treatment. Genome-wide association studies have identified several genetic risk variants, such as those in apolipoprotein L1 (APOL1), that play a role in the development of FSGS. Currently, no specific treatments have been approved to treat genetic FSGS; however, interventions targeting underlying cofactor deficiencies have shown potential in some cases. Furthermore, encouraging results have emerged from a phase 2 trial investigating inaxaplin, a novel small molecule APOL1 channel inhibitor, in APOL1-associated FSGS.
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Affiliation(s)
- Marco Bonilla
- Section of Nephrology, Department of Medicine, University of Chicago, Chicago, IL
| | - Orhan Efe
- Division of Nephrology, Massachusetts General Hospital, Boston, MA
- Harvard Medical School, Boston, MA
| | - Haresh Selvaskandan
- IgA Mayer Nephropathy Laboratories, Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
- John Walls Renal Unit, University Hospitals of Leicester NHS Trust, Leicester, United Kingdom
| | - Edgar V. Lerma
- Section of Nephrology, University of Illinois at Chicago/Advocate Christ Medical Center, Oak Lawn, IL
| | - Nasim Wiegley
- University of California Davis School of Medicine, Division of Nephrology, Sacramento, CA
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2
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Levy M, Bazak L, Lev-El N, Greenberg R, Kropach N, Basel-Salmon L, Maya I. Potential Founder Variants in COL4A4 Identified in Bukharian Jews Linked to Autosomal Dominant and Autosomal Recessive Alport Syndrome. Genes (Basel) 2023; 14:1854. [PMID: 37895203 PMCID: PMC10606019 DOI: 10.3390/genes14101854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Revised: 09/12/2023] [Accepted: 09/22/2023] [Indexed: 10/29/2023] Open
Abstract
BACKGROUND Alport syndrome is a hereditary disorder caused by pathogenic variants in the COL4A gene, which can be inherited in an autosomal recessive, dominant, or X-linked pattern. In the Bukharian Jewish population, no founder pathogenic variant has been reported in COL4A4. METHODS The cohort included 38 patients from 22 Bukharian Jewish families with suspected Alport syndrome who were referred the nephrogenetics clinic between 2012 and 2022. The study collected demographic, clinical, and genetic data from electronic medical records, which were used to evaluate the molecular basis of the disease using Sanger sequencing, and next-generation sequencing. RESULTS Molecular diagnosis was confirmed in 20/38 patients, with each patient having at least one of the three disease-causing COL4A4 variants detected: c.338G A (p.Gly1008Arg), and c.871-6T>C. In addition, two patients were obligate carriers. Overall, there were 17 heterozygotes, 2 compound heterozygotes, and 3 homozygotes. Each variant was detected in more than one unrelated family. All patients had hematuria with/without proteinuria at referral, and the youngest patient with proteinuria (age 5 years) was homozygous for the c.338G>A variant. End-stage renal disease was diagnosed in two patients at the age of 38 years, a compound heterozygote for c.338G>A and c.871-6T>C. Hearing deterioration was detected in three patients, the youngest aged 40 years, all of whom were heterozygous for c.338G>A. CONCLUSION This study unveils three novel disease-causing variants, c.3022G>A, c.871-6T>C, and c.338G>A, in the COL4A4 gene that are recurrent among Jews of Bukharian ancestry, and cause Alport syndrome in both dominant and recessive autosomal inheritance patterns.
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Affiliation(s)
- Michal Levy
- The Raphael Recanati Genetic Institute, Rabin Medical Center, Petah Tikva 49100, Israel (N.L.-E.); (L.B.-S.); (I.M.)
- School of Medicine, Tel Aviv University, Tel Aviv P.O.B 39040, Israel
| | - Lily Bazak
- The Raphael Recanati Genetic Institute, Rabin Medical Center, Petah Tikva 49100, Israel (N.L.-E.); (L.B.-S.); (I.M.)
| | - Noa Lev-El
- The Raphael Recanati Genetic Institute, Rabin Medical Center, Petah Tikva 49100, Israel (N.L.-E.); (L.B.-S.); (I.M.)
| | - Rotem Greenberg
- The Raphael Recanati Genetic Institute, Rabin Medical Center, Petah Tikva 49100, Israel (N.L.-E.); (L.B.-S.); (I.M.)
| | - Nesia Kropach
- School of Medicine, Tel Aviv University, Tel Aviv P.O.B 39040, Israel
- Pediatric Genetics Unit, Schneider Children’s Medical Center, Petah Tikva 4920235, Israel
| | - Lina Basel-Salmon
- The Raphael Recanati Genetic Institute, Rabin Medical Center, Petah Tikva 49100, Israel (N.L.-E.); (L.B.-S.); (I.M.)
- School of Medicine, Tel Aviv University, Tel Aviv P.O.B 39040, Israel
- Felsenstein Medical Research Center, Petach Tikva 4920235, Israel
| | - Idit Maya
- The Raphael Recanati Genetic Institute, Rabin Medical Center, Petah Tikva 49100, Israel (N.L.-E.); (L.B.-S.); (I.M.)
- School of Medicine, Tel Aviv University, Tel Aviv P.O.B 39040, Israel
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3
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Lim SW, Na D, Lee H, Fang X, Cui S, Shin YJ, Lee KI, Lee JY, Yang CW, Chung BH. Modeling of FAN1-Deficient Kidney Disease Using a Human Induced Pluripotent Stem Cell-Derived Kidney Organoid System. Cells 2023; 12:2319. [PMID: 37759541 PMCID: PMC10529520 DOI: 10.3390/cells12182319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 08/27/2023] [Accepted: 09/18/2023] [Indexed: 09/29/2023] Open
Abstract
Karyomegalic interstitial nephritis (KIN) is a genetic kidney disease caused by mutations in the FANCD2/FANCI-Associated Nuclease 1 (FAN1) gene on 15q13.3, which results in karyomegaly and fibrosis of kidney cells through the incomplete repair of DNA damage. The aim of this study was to explore the possibility of using a human induced pluripotent stem cell (hiPSC)-derived kidney organoid system for modeling FAN1-deficient kidney disease, also known as KIN. We generated kidney organoids using WTC-11 (wild-type) hiPSCs and FAN1-mutant hiPSCs which include KIN patient-derived hiPSCs and FAN1-edited hiPSCs (WTC-11 FAN1+/-), created using the CRISPR/Cas9 system in WTC-11-hiPSCs. Kidney organoids from each group were treated with 20 nM of mitomycin C (MMC) for 24 or 48 h, and the expression levels of Ki67 and H2A histone family member X (H2A.X) were analyzed to detect DNA damage and assess the viability of cells within the kidney organoids. Both WTC-11-hiPSCs and FAN1-mutant hiPSCs were successfully differentiated into kidney organoids without structural deformities. MMC treatment for 48 h significantly increased the expression of DNA damage markers, while cell viability in both FAN1-mutant kidney organoids was decreased. However, these findings were observed in WTC-11-kidney organoids. These results suggest that FAN1-mutant kidney organoids can recapitulate the phenotype of FAN1-deficient kidney disease.
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Affiliation(s)
- Sun Woo Lim
- Transplantation Research Center, College of Medicine, The Catholic University of Korea, Seoul 06591, Republic of Korea
| | - Dohyun Na
- Transplantation Research Center, College of Medicine, The Catholic University of Korea, Seoul 06591, Republic of Korea
- Division of Nephrology, Department of Internal Medicine, Seoul St. Mary’s Hospital, The College of Medicine, The Catholic University of Korea, Seoul 06591, Republic of Korea
| | - Hanbi Lee
- Transplantation Research Center, College of Medicine, The Catholic University of Korea, Seoul 06591, Republic of Korea
- Division of Nephrology, Department of Internal Medicine, Seoul St. Mary’s Hospital, The College of Medicine, The Catholic University of Korea, Seoul 06591, Republic of Korea
| | - Xianying Fang
- Transplantation Research Center, College of Medicine, The Catholic University of Korea, Seoul 06591, Republic of Korea
| | - Sheng Cui
- Transplantation Research Center, College of Medicine, The Catholic University of Korea, Seoul 06591, Republic of Korea
| | - Yoo Jin Shin
- Transplantation Research Center, College of Medicine, The Catholic University of Korea, Seoul 06591, Republic of Korea
| | - Kang In Lee
- ToolGen, Inc., Seoul 06591, Republic of Korea
| | | | - Chul Woo Yang
- Transplantation Research Center, College of Medicine, The Catholic University of Korea, Seoul 06591, Republic of Korea
- Division of Nephrology, Department of Internal Medicine, Seoul St. Mary’s Hospital, The College of Medicine, The Catholic University of Korea, Seoul 06591, Republic of Korea
| | - Byung Ha Chung
- Transplantation Research Center, College of Medicine, The Catholic University of Korea, Seoul 06591, Republic of Korea
- Division of Nephrology, Department of Internal Medicine, Seoul St. Mary’s Hospital, The College of Medicine, The Catholic University of Korea, Seoul 06591, Republic of Korea
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Deltas C, Papagregoriou G, Louka SF, Malatras A, Flinter F, Gale DP, Gear S, Gross O, Hoefele J, Lennon R, Miner JH, Renieri A, Savige J, Turner AN. Genetic Modifiers of Mendelian Monogenic Collagen IV Nephropathies in Humans and Mice. Genes (Basel) 2023; 14:1686. [PMID: 37761826 PMCID: PMC10530214 DOI: 10.3390/genes14091686] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Revised: 08/09/2023] [Accepted: 08/17/2023] [Indexed: 09/29/2023] Open
Abstract
Familial hematuria is a clinical sign of a genetically heterogeneous group of conditions, accompanied by broad inter- and intrafamilial variable expressivity. The most frequent condition is caused by pathogenic (or likely pathogenic) variants in the collagen-IV genes, COL4A3/A4/A5. Pathogenic variants in COL4A5 are responsible for the severe X-linked glomerulopathy, Alport syndrome (AS), while homozygous or compound heterozygous variants in the COL4A3 or the COL4A4 gene cause autosomal recessive AS. AS usually leads to progressive kidney failure before the age of 40-years when left untreated. People who inherit heterozygous COL4A3/A4 variants are at-risk of a slowly progressive form of the disease, starting with microscopic hematuria in early childhood, developing Alport spectrum nephropathy. Sometimes, they are diagnosed with benign familial hematuria, and sometimes with autosomal dominant AS. At diagnosis, they often show thin basement membrane nephropathy, reflecting the uniform thin glomerular basement membrane lesion, inherited as an autosomal dominant condition. On a long follow-up, most patients will retain normal or mildly affected kidney function, while a substantial proportion will develop chronic kidney disease (CKD), even kidney failure at an average age of 55-years. A question that remains unanswered is how to distinguish those patients with AS or with heterozygous COL4A3/A4 variants who will manifest a more aggressive kidney function decline, requiring prompt medical intervention. The hypothesis that a subgroup of patients coinherit additional genetic modifiers that exacerbate their clinical course has been investigated by several researchers. Here, we review all publications that describe the potential role of candidate genetic modifiers in patients and include a summary of studies in AS mouse models.
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Affiliation(s)
- Constantinos Deltas
- School of Medicine, University of Cyprus, Nicosia 2109, Cyprus
- biobank.cy Center of Excellence in Biobanking and Biomedical Research, University of Cyprus, Nicosia 2109, Cyprus
| | - Gregory Papagregoriou
- biobank.cy Center of Excellence in Biobanking and Biomedical Research, University of Cyprus, Nicosia 2109, Cyprus
| | - Stavroula F. Louka
- biobank.cy Center of Excellence in Biobanking and Biomedical Research, University of Cyprus, Nicosia 2109, Cyprus
| | - Apostolos Malatras
- biobank.cy Center of Excellence in Biobanking and Biomedical Research, University of Cyprus, Nicosia 2109, Cyprus
| | - Frances Flinter
- Clinical Genetics Department, Guy’s & St Thomas’ NHS Foundation Trust, London SE1 9RT, UK
| | - Daniel P. Gale
- Department of Renal Medicine, University College London, London NW3 2PF, UK
| | | | - Oliver Gross
- Clinic for Nephrology and Rheumatology, University Medicine Goettingen, 37075 Goettingen, Germany
| | - Julia Hoefele
- Institute of Human Genetics, Klinikum Rechts der Isar, School of Medicine & Health, Technical University Munich, 81675 Munich, Germany
| | - Rachel Lennon
- Wellcome Centre for Cell-Matrix Research, University of Manchester, Manchester M13 9WU, UK
| | - Jeffrey H. Miner
- Division of Nephrology, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Alessandra Renieri
- Medical Genetics, University of Siena, 53100 Siena, Italy
- Med Biotech Hub and Competence Center, Department of Medical Biotechnologies, University of Siena, 53100 Siena, Italy
- Genetica Medica, Azienda Ospedaliero-Universitaria Senese, 53100 Siena, Italy
| | - Judy Savige
- Department of Medicine (Melbourne Health and Northern Health), The University of Melbourne, Parkville, VIC 3052, Australia
| | - A. Neil Turner
- Renal Medicine, Royal Infirmary, University of Edinburgh, Edinburgh EH16 4UX, UK
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5
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Zhu F, Li Y, Wang Y, Yao Y, Zeng R. The same heterozygous Col4A4 mutation triggered different renal pathological changes in Chinese family members. Front Genet 2023; 14:1180149. [PMID: 37323683 PMCID: PMC10265269 DOI: 10.3389/fgene.2023.1180149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Accepted: 05/18/2023] [Indexed: 06/17/2023] Open
Abstract
Background: Mutations in the collagen components of the glomerular basement membrane (GBM) often lead to hereditary glomerulonephritis. Previous studies have identified that autosomal dominant mutations of Col4A3, Col4A4 or Col4A5 are associated with thin basement membrane nephropathy (TBMN), Alport syndrome and other hereditary kidney diseases. However, the genetic mutations underlying other glomerulonephritis types have not been elucidated. Methods: In this study, we investigated a Chinese family with hereditary nephritis using the methods of genetic sequencing and renal biopsy. Genomic DNA was extracted from peripheral blood of the proband and her sister, and subsequently was performed genetic sequencing. They were found to have the similar mutation sites. Other family members were then validated using Sanger sequencing. The proband and her sister underwent renal puncture biopsies, and experienced pathologists performed PAS, Masson, immunofluorescence, and immunoelectron microscopic staining of the kidney tissue sections. Results: Through genetic sequencing analysis, we detected a novel heterozygous frameshift mutation c.1826delC in the COL4A4 (NM_000092.4) gene coding region, and 1 hybrid missense variation c.86G>A (p. R29Q) was also detected in the TNXB (NM_019105.6) gene coding region in several members of this Chinese family. Interestingly, we found that the same mutations caused different clinical features and distinct pathological changes in individual family members, which confirmed that pathological and genetic testing are crucial for the diagnosis and treatment of hereditary kidney diseases. Conclusion: In this study, we found a novel heterozygous mutation in Col4A4 and co-mutations of the TNXB gene in this Chinese family. Our study indicated that the same Col4A4 mutated variants produced different pathological and clinical changes in different family members. This discovery may provide novel insights into the study of hereditary kidney disease. In addition, new genetic biology techniques and renal biopsy of individual family members are essential.
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Affiliation(s)
- Fengming Zhu
- Department of Nephrology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yueqiang Li
- Department of Nephrology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yuxi Wang
- Department of Nephrology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Ying Yao
- Department of Nephrology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Department of Nutrition, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Rui Zeng
- Department of Nephrology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Key Laboratory of Organ Transplantation, Ministry of Education, NHC Key Laboratory of Organ Transplantation, Key Laboratory of Organ Transplantation, Chinese Academy of Medical Sciences, Wuhan, China
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6
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Groen In 't Woud S, Rood IM, Steenbergen E, Willemsen B, Dijkman HB, van Geel M, Schoots J, Wetzels JFM, Lugtenberg D, Deegens JKJ, Bongers EMHF. Kidney Disease Associated With Mono-allelic COL4A3 and COL4A4 Variants: A Case Series of 17 Families. Kidney Med 2023; 5:100607. [PMID: 36925663 PMCID: PMC10011433 DOI: 10.1016/j.xkme.2023.100607] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Rationale & Objective Mono-allelic variants in COL4A3 and COL4A4 (COL4A3/COL4A4) have been identified in a spectrum of glomerular basement membrane nephropathies, including thin basement membrane nephropathy and autosomal dominant Alport syndrome. With the increasing use of next generation sequencing, mono-allelic COL4A3/COL4A4 variants are detected more frequently, but phenotypic heterogeneity impedes counseling. We aimed to investigate the phenotypic spectrum, kidney biopsy results, and segregation patterns of patients with mono-allelic COL4A3/COL4A4 variants identified by whole exome sequencing. Study Design Case series. Setting & Participants We evaluated clinical and pathologic characteristics of 17 Dutch index patients with mono-allelic variants in COL4A3/COL4A4 detected by diagnostic whole exome sequencing and 25 affected family members with variants confirmed by Sanger sequencing. Results Eight different mono-allelic COL4A3/COL4A4 variants were identified across members of 11 families, comprising 7 glycine substituted missense variants and 1 frameshift variant. All index patients had microscopic hematuria at clinical presentation (median age 43 years) and 14 had (micro)albuminuria/proteinuria. All family members showed co-segregation of the variant with at least hematuria. At end of follow-up of all 42 individuals (median age 54 years), 16/42 patients had kidney function impairment, of whom 6 had kidney failure. Reports of kidney biopsies of 14 patients described thin basement membrane nephropathy, focal segmental glomerulosclerosis, minimal change lesions, and Alport syndrome. Electron microscopy images of 7 patients showed a significantly thinner glomerular basement membrane compared with images of patients with idiopathic focal segmental glomerulosclerosis and other hereditary glomerular diseases. No genotype-phenotype correlations could be established. Limitations Retrospective design, ascertainment bias toward severe kidney phenotypes, and familial hematuria. Conclusions This study confirms the wide phenotypic spectrum associated with mono-allelic COL4A3/COL4A4 variants, extending from isolated microscopic hematuria to kidney failure with high intra- and interfamilial variability.
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Affiliation(s)
- Sander Groen In 't Woud
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.,Department for Health Evidence, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Ilse M Rood
- Department of Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Eric Steenbergen
- Department of Pathology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Brigith Willemsen
- Department of Pathology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Henry B Dijkman
- Department of Pathology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Michel van Geel
- Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Jeroen Schoots
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jack F M Wetzels
- Department of Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Dorien Lugtenberg
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jeroen K J Deegens
- Department of Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Ernie M H F Bongers
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
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Alge JL, Bekheirnia N, Willcockson AR, Qin X, Scherer SE, Braun MC, Bekheirnia MR. Variants in genes coding for collagen type IV α-chains are frequent causes of persistent, isolated hematuria during childhood. Pediatr Nephrol 2023; 38:687-695. [PMID: 35759000 DOI: 10.1007/s00467-022-05627-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 05/04/2022] [Accepted: 05/06/2022] [Indexed: 01/19/2023]
Abstract
BACKGROUND Children with persistent, isolated microscopic hematuria typically undergo a limited diagnostic workup and are monitored for signs of kidney disease in long-term longitudinal follow-up, which can delay diagnosis and allow disease progression in some cases. METHODS To determine the clinical utility of genetic screening in this population, we performed targeted genetic testing using a custom, 32-gene next-generation sequencing panel for progressive kidney disease on children referred to the Texas Children's Hospital Pediatric Nephrology clinic for persistent, microscopic hematuria (n = 30; cohort 1). Patients with microscopic hematuria identified by urinalysis on at least two separate occasions were eligible for enrollment, but those with other evidence of kidney disease were excluded. Results were analyzed for sequence variants using the American College of Medical Genetics and Genomics (ACMG) guideline for data interpretation and were validated using a secondary analysis of a dataset of children with hematuria and normal kidney function who had undergone genetic testing as part of an industry-sponsored program (cohort 2; n = 67). RESULTS In cohort 1 33% of subjects (10/30) had pathogenic or likely pathogenic (P/LP) variants in the type IV collagen genes (COL4A3/A4/A5), and 10% (3/30) had variants of uncertain significance in these genes. The high diagnostic rate in type IV collagen genes was confirmed in cohort 2, where 27% (18/67) of subjects had P/LP variants in COL4A3/A4/A5 genes. CONCLUSIONS Children with persistent, isolated microscopic hematuria have a high likelihood of having pathogenic variants in type IV collagen genes and genetic screening should be considered. A higher resolution version of the Graphical abstract is available as Supplementary information.
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Affiliation(s)
- Joseph L Alge
- Department of Pediatrics, Division of Pediatric Nephrology, Baylor College Medicine, Houston, TX, 77030, USA
| | - Nasim Bekheirnia
- Department of Pediatrics, Division of Pediatric Nephrology, Baylor College Medicine, Houston, TX, 77030, USA
| | | | - Xiang Qin
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Steven E Scherer
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, 77030, USA.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Michael C Braun
- Department of Pediatrics, Division of Pediatric Nephrology, Baylor College Medicine, Houston, TX, 77030, USA
| | - Mir Reza Bekheirnia
- Department of Pediatrics, Division of Pediatric Nephrology, Baylor College Medicine, Houston, TX, 77030, USA. .,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA.
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8
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Gao Y, Yuan L, Yuan J, Yang Y, Wang J, Chen Y, Zhang H, Ai Y, Deng H. Identification of COL4A4 variants in Chinese patients with familial hematuria. Front Genet 2023; 13:1064491. [PMID: 36699462 PMCID: PMC9868811 DOI: 10.3389/fgene.2022.1064491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Accepted: 12/15/2022] [Indexed: 01/11/2023] Open
Abstract
Background: Benign familial hematuria and Alport syndrome are common causes of familial hematuria among children and young adults, which are attributable to variants in the collagen type IV alpha chain genes, COL4A3, COL4A4, or COL4A5. The study was conducted to identify the underlying genetic causes in patients with familial hematuria. Methods: Two unrelated Han-Chinese pedigrees with familial hematuria were recruited for this study. Whole exome sequencing was combined with in silico analysis to identify potential genetic variants, followed by variant confirmation by Sanger sequencing. Reverse transcription, PCR, and Sanger sequencing were performed to evaluate the effect of the detected splicing variant on mRNA splicing. Results: A novel heterozygous splicing c.595-1G>A variant and a known heterozygous c.1715G>C variant in the collagen type IV alpha 4 chain gene (COL4A4) were identified and confirmed in patients of pedigree 1 and pedigree 2, respectively. Complementary DNA analysis indicated this splicing variant could abolish the canonical splice acceptor site and cause a single nucleotide deletion of exon 10, which was predicted to produce a truncated protein. Conclusions: The two COL4A4 variants, c.595-1G>A variant and c.1715G>C (p.Gly572Ala) variant, were identified as the genetic etiologies of two families with familial hematuria, respectively. Our study broadened the variant spectrum of the COL4A4 gene and explained the possible pathogenesis, which will benefit clinical management and genetic counseling.
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Affiliation(s)
- Yanan Gao
- Health Management Center, The Third Xiangya Hospital, Central South University, Changsha, China,Center for Experimental Medicine, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Lamei Yuan
- Health Management Center, The Third Xiangya Hospital, Central South University, Changsha, China,Center for Experimental Medicine, The Third Xiangya Hospital, Central South University, Changsha, China,Disease Genome Research Center, Central South University, Changsha, China
| | - Jinzhong Yuan
- Department of Nephrology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Yan Yang
- Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Jiangang Wang
- Health Management Center, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Yong Chen
- National Health Committee Key Laboratory of Birth Defects for Research and Prevention, Hunan Provincial Maternal and Child Health Care Hospital, Changsha, China
| | - Hao Zhang
- Department of Nephrology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Yinze Ai
- Center for Experimental Medicine, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Hao Deng
- Health Management Center, The Third Xiangya Hospital, Central South University, Changsha, China,Center for Experimental Medicine, The Third Xiangya Hospital, Central South University, Changsha, China,Disease Genome Research Center, Central South University, Changsha, China,*Correspondence: Hao Deng,
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Novel and Founder Pathogenic Variants in X-Linked Alport Syndrome Families in Greece. Genes (Basel) 2022; 13:genes13122203. [PMID: 36553470 PMCID: PMC9778032 DOI: 10.3390/genes13122203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 11/08/2022] [Accepted: 11/18/2022] [Indexed: 11/27/2022] Open
Abstract
Alport syndrome (AS) is the most frequent monogenic inherited glomerulopathy and is also genetically and clinically heterogeneous. It is caused by semi-dominant pathogenic variants in the X-linked COL4A5 (NM_000495.5) gene or recessive variants in the COL4A3/COL4A4 (NM_000091.4/NM_000092.4) genes. The disease manifests in early childhood with persistent microhematuria and can progress to proteinuria and kidney failure in adolescence or early adulthood if left untreated. On biopsy, pathognomonic features include alternate thinning, thickening and lamellation of the glomerular basement membrane (GBM), in the presence of podocyte foot process effacement. Although previous studies indicate a prevalence of AS of about 1/50,000, a recent publication reported a predicted rate of pathogenic COL4A5 variants of 1/2320. We herewith present 98 patients (40 M/58 F) from 26 Greek families. We are selectively presenting the families segregating the X-linked form of AS with pathogenic variants in the COL4A5 gene. We found 21 different pathogenic variants, 12 novel: eight glycine and one proline substitutions in the collagenous domain, one cysteine substitution in the NC1 domain, two premature termination of translation codons, three splicing variants, one 5-bp insertion/frameshift variant, one indel-frameshift variant and four gross deletions. Notably, patients in six families we describe here and three families we reported previously, carried the COL4A5-p.G624D substitution, a founder defect encountered all over Europe which is hypomorphic with mostly milder symptomatology. Importantly, on several occasions, the correct genetic diagnosis reclassified patients as patients with AS, leading to termination of previous immunosuppressive/cyclosporine A therapy and a switch to angiotensin converting enzyme inhibitors (ACEi). With the understanding that all 98 patients span a wide range of ages from infancy to late adulthood, 15 patients (11 M/4 F) reached kidney failure and 11 (10 M/1 F) received a transplant. The prospects of avoiding lengthy diagnostic investigations and erroneous medications, and the advantage of delaying kidney failure with very early administration of renin-angiotensin-aldosterone system (RAAS) blockade, highlights the importance of timely documentation of AS by genetic diagnosis.
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Chen X, Ye N, Zhang L, Zheng W, Cheng J, Gong M. Functional assessment of a novel COL4A5 splicing site variant in a Chinese X-linked Alport syndrome family. ANNALS OF TRANSLATIONAL MEDICINE 2021; 9:1420. [PMID: 34733972 PMCID: PMC8506736 DOI: 10.21037/atm-21-3523] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 09/03/2021] [Indexed: 02/05/2023]
Abstract
Background Chronic kidney disease caused by X-linked Alport syndrome (XLAS) is relatively rare. However, due to the nonspecific pathologic and clinical manifestations of this disease, it is easily misdiagnosed. Genetic testing is crucial in identifying suspected cases. In addition, the results of genetic testing are an important indicator of patient prognosis. This study demonstrated a novel pathogenic COL4A5 splicing site variant in a Chinese family with XLAS. Methods Targeted next generation sequencing (NGS) was performed to identify the gene variant in the family members, and the gene mutation site was confirmed by Sanger sequencing. We then further analyzed the consequences of this gene mutation on the translated protein of this variant using in silico and in vitro approaches. Results A novel splice region variant, c.1033-2(IVS 18) A>G, in COL4A5 intron 18 was identified in the affected family members. Sanger sequencing confirmed that this variant is segregated with disease. In silico analysis, this variant led to frame-shift and premature termination on the translation of the nucleic acid, and this result was verified by RNA splicing analysis in a cell model. Unexpectedly, we still observed positive immunohistology staining of collagen IV α5 in the glomerular basement membrane (GBM) of the index patient, which implied that another potential transcription or translation mechanism skipping the mutated site might exist. Conclusions Our present finding expands the mutational spectrum for the COL4A5 gene associated with XLAS and highlights the genotype-phenotype correlations in this disease.
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Affiliation(s)
- Xiaolei Chen
- Department of Nephrology, West China Hospital, Sichuan University, Chengdu, China
| | - Nan Ye
- Laboratory of Proteomics and Metabolomics for Diseases, Institutes for Systems Genetics, Frontiers Science Center for Disease-Related Molecular Network, West China Hospital, Sichuan University, Chengdu, China
| | - Lu Zhang
- Laboratory of Proteomics and Metabolomics for Diseases, Institutes for Systems Genetics, Frontiers Science Center for Disease-Related Molecular Network, West China Hospital, Sichuan University, Chengdu, China
| | - Wen Zheng
- Laboratory of Proteomics and Metabolomics for Diseases, Institutes for Systems Genetics, Frontiers Science Center for Disease-Related Molecular Network, West China Hospital, Sichuan University, Chengdu, China
| | - Jingqiu Cheng
- Laboratory of Proteomics and Metabolomics for Diseases, Institutes for Systems Genetics, Frontiers Science Center for Disease-Related Molecular Network, West China Hospital, Sichuan University, Chengdu, China
| | - Meng Gong
- Laboratory of Proteomics and Metabolomics for Diseases, Institutes for Systems Genetics, Frontiers Science Center for Disease-Related Molecular Network, West China Hospital, Sichuan University, Chengdu, China
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Furlano M, Martínez V, Pybus M, Arce Y, Crespí J, Venegas MDP, Bullich G, Domingo A, Ayasreh N, Benito S, Lorente L, Ruíz P, Gonzalez VL, Arlandis R, Cabello E, Torres F, Guirado L, Ars E, Torra R. Clinical and Genetic Features of Autosomal Dominant Alport Syndrome: A Cohort Study. Am J Kidney Dis 2021; 78:560-570.e1. [PMID: 33838161 DOI: 10.1053/j.ajkd.2021.02.326] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Accepted: 02/14/2021] [Indexed: 12/15/2022]
Abstract
RATIONALE & OBJECTIVE Alport syndrome is a common genetic kidney disease accounting for approximately 2% of patients receiving kidney replacement therapy (KRT). It is caused by pathogenic variants in the gene COL4A3, COL4A4, or COL4A5. The aim of this study was to evaluate the clinical and genetic spectrum of patients with autosomal dominant Alport syndrome (ADAS). STUDY DESIGN Retrospective cohort study. SETTING & PARTICIPANTS 82 families (252 patients) with ADAS were studied. Clinical, genetic, laboratory, and pathology data were collected. OBSERVATIONS A pathogenic DNA variant in COL4A3 was identified in 107 patients (35 families), whereas 133 harbored a pathogenic variant in COL4A4 (43 families). Digenic/complex inheritance was observed in 12 patients. Overall, the median kidney survival was 67 (95% CI, 58-73) years, without significant differences across sex (P=0.8), causative genes (P=0.6), or type of variant (P=0.9). Microhematuria was the most common kidney manifestation (92.1%), and extrarenal features were rare. Findings on kidney biopsies ranged from normal to focal segmental glomerulosclerosis. The slope of estimated glomerular filtration rate change was-1.46 (-1.66 to-1.26) mL/min/1.73m2 per year for the overall group, with no significant differences between ADAS genes (P=0.2). LIMITATIONS The relatively small size of this series from a single country, potentially limiting generalizability. CONCLUSIONS Patients with ADAS have a wide spectrum of clinical presentations, ranging from asymptomatic to kidney failure, a pattern not clearly related to the causative gene or type of variant. The diversity of ADAS phenotypes contributes to its underdiagnosis in clinical practice.
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Affiliation(s)
- Mónica Furlano
- Inherited Kidney Diseases, Nephrology Department, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau, Medicine Department-Universitat Autónoma de Barcelona, Red de Investigación Renal, Instituto de Investigación Carlos III, Barcelona, Spain
| | - Victor Martínez
- Nephrology Department, Hospital Clínico Universitario Virgen de la Arrixaca, Murcia, Spain
| | - Marc Pybus
- Molecular Biology Laboratory, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau, Universitat Autónoma de Barcelona, Red de Investigación Renal, Instituto de Investigación Carlos III, Barcelona, Spain
| | - Yolanda Arce
- Department of Pathology, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau, Universitat Autónoma de Barcelona, Red de Investigación Renal, Instituto de Investigación Carlos III, Barcelona, Spain
| | - Jaume Crespí
- Departments of Ophthalmology, Hospital de Sant Pau i la Santa Creu, Instituto de Investigaciones Biomédicas Sant Pau, Universitat Autónoma de Barcelona, Barcelona, Spain
| | - María Del Prado Venegas
- Otolaryngology-Head and Neck Surgery, Hospital de Sant Pau i la Santa Creu, Instituto de Investigaciones Biomédicas Sant Pau, Universitat Autónoma de Barcelona, Barcelona, Spain
| | - Gemma Bullich
- Centre Nacional d'Anàlisi Genómica, Centre for Genomic Regulation, Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Andrea Domingo
- Molecular Biology Laboratory, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau, Universitat Autónoma de Barcelona, Red de Investigación Renal, Instituto de Investigación Carlos III, Barcelona, Spain
| | - Nadia Ayasreh
- Nephrology Department, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau, Medicine Department-Universitat Autónoma de Barcelona, Red de Investigación Renal, Instituto de Investigación Carlos III, Barcelona, Spain
| | - Silvia Benito
- Nephrology Department, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau, Medicine Department-Universitat Autónoma de Barcelona, Red de Investigación Renal, Instituto de Investigación Carlos III, Barcelona, Spain
| | - Laura Lorente
- Molecular Biology Laboratory, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau, Universitat Autónoma de Barcelona, Red de Investigación Renal, Instituto de Investigación Carlos III, Barcelona, Spain
| | - Patricia Ruíz
- Molecular Biology Laboratory, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau, Universitat Autónoma de Barcelona, Red de Investigación Renal, Instituto de Investigación Carlos III, Barcelona, Spain
| | - Vanesa López Gonzalez
- Genetics Laboratory, Hospital Clínico Universitario Virgen de la Arrixaca, Murcia, Spain
| | - Rosa Arlandis
- Nephrology Department, Hospital General de la Palma, Islas Canarias, Spain
| | - Elisa Cabello
- Nephrology Department, Hospital General Universitario de Castellón, Castellón de la Plana, Spain
| | - Ferran Torres
- Biostatistics Unit, Faculty of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain; Medical Statistics Core Facility, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Hospital Clinic de Barcelona, Barcelona, Spain
| | - Lluis Guirado
- Nephrology Department, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau, Medicine Department-Universitat Autónoma de Barcelona, Red de Investigación Renal, Instituto de Investigación Carlos III, Barcelona, Spain
| | - Elisabet Ars
- Molecular Biology Laboratory, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau, Universitat Autónoma de Barcelona, Red de Investigación Renal, Instituto de Investigación Carlos III, Barcelona, Spain.
| | - Roser Torra
- Inherited Kidney Diseases, Nephrology Department, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau, Medicine Department-Universitat Autónoma de Barcelona, Red de Investigación Renal, Instituto de Investigación Carlos III, Barcelona, Spain.
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Wang T, Bw H. Fibronectin glomerulopathy: A case report and literature review. Nefrologia 2021; 41:74-76. [PMID: 36165367 DOI: 10.1016/j.nefroe.2021.02.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2019] [Accepted: 01/19/2020] [Indexed: 06/16/2023] Open
Affiliation(s)
- Ting Wang
- Department of Nephrology, The Third Hospital of Mian Yang (Sichuan Mental Health Center), Mian Yang, Si Chuan, PR, China.
| | - Hong Bw
- Department of Nephrology, The Third Hospital of Mian Yang (Sichuan Mental Health Center), Mian Yang, Si Chuan, PR, China
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Odiatis C, Savva I, Pieri M, Ioannou P, Petrou P, Papagregoriou G, Antoniadou K, Makrides N, Stefanou C, Ljubanović DG, Nikolaou G, Borza DB, Stylianou K, Gross O, Deltas C. A glycine substitution in the collagenous domain of Col4a3 in mice recapitulates late onset Alport syndrome. Matrix Biol Plus 2020; 9:100053. [PMID: 33718859 PMCID: PMC7930875 DOI: 10.1016/j.mbplus.2020.100053] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 11/18/2020] [Accepted: 11/20/2020] [Indexed: 12/13/2022] Open
Abstract
Alport syndrome (AS) is a severe inherited glomerulopathy caused by mutations in the genes encoding the α-chains of type-IV collagen, the most abundant component of the extracellular glomerular basement membrane (GBM). Currently most AS mouse models are knockout models for one of the collagen-IV genes. In contrast, about half of AS patients have missense mutations, with single aminoacid substitutions of glycine being the most common. The only mouse model for AS with a homozygous knockin missense mutation, Col4a3-p.Gly1332Glu, was partly described before by our group. Here, a detailed in-depth description of the same mouse is presented, along with another compound heterozygous mouse that carries the glycine substitution in trans with a knockout allele. Both mice recapitulate essential features of AS, including shorten lifespan by 30–35%, increased proteinuria, increased serum urea and creatinine, pathognomonic alternate GBM thinning and thickening, and podocyte foot process effacement. Notably, glomeruli and tubuli respond differently to mutant collagen-IV protomers, with reduced expression in tubules but apparently normal in glomeruli. However, equally important is the fact that in the glomeruli the mutant α3-chain as well as the normal α4/α5 chains seem to undergo a cleavage at, or near the point of the mutation, possibly by the metalloproteinase MMP-9, producing a 35 kDa C-terminal fragment. These mouse models represent a good tool for better understanding the spectrum of molecular mechanisms governing collagen-IV nephropathies and could be used for pre-clinical studies aimed at better treatments for AS. Two mouse models were generated that recapitulate essential features of AS patients. Glomeruli and tubuli respond differently to mutant collagen IV protomers. The mutant colIV protomers in glomeruli probably undergo a cleavage process by MMP9. The two AS mouse models represent a good tool for studying collagen-IV nephropathies. These models could be used for pre-clinical studies aimed at better treatments.
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Key Words
- ARAS, autosomal recessive alport syndrome
- AS, alport syndrome
- Alport syndrome
- BSA, bovine serum albumin
- Collagen-IV
- EM, electron microscopy
- ESRD, end stage renal disease
- GBM, glomerular basement membrane
- Glomerular basement membrane
- Glycine missense mutation
- Kidney disease
- Mouse model
- PAS, periodic acid schiff
- TBM, tubular basement membrane
- TGF-b1, transforming growth factor beta1
- UPR, unfolded protein response
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Affiliation(s)
- Christoforos Odiatis
- Center of Excellence in Biobanking and Biomedical Research, Molecular Medicine Research Center, University of Cyprus Medical School, Cyprus
| | - Isavella Savva
- Center of Excellence in Biobanking and Biomedical Research, Molecular Medicine Research Center, University of Cyprus Medical School, Cyprus
| | - Myrtani Pieri
- Department of Life and Health Sciences, School of Sciences and Engineering, University of Nicosia, Cyprus
| | - Pavlos Ioannou
- Center of Excellence in Biobanking and Biomedical Research, Molecular Medicine Research Center, University of Cyprus Medical School, Cyprus
| | - Petros Petrou
- Department of Biochemistry, The Cyprus Institute of Neurology and Genetics, Cyprus
| | - Gregory Papagregoriou
- Center of Excellence in Biobanking and Biomedical Research, Molecular Medicine Research Center, University of Cyprus Medical School, Cyprus
| | - Kyriaki Antoniadou
- Center of Excellence in Biobanking and Biomedical Research, Molecular Medicine Research Center, University of Cyprus Medical School, Cyprus
| | - Neoklis Makrides
- Department of Developmental Functional Genetics, The Cyprus Institute of Neurology and Genetics, Cyprus
| | - Charalambos Stefanou
- Center of Excellence in Biobanking and Biomedical Research, Molecular Medicine Research Center, University of Cyprus Medical School, Cyprus
| | | | - Georgios Nikolaou
- Veterinary diagnostic laboratory, Vet ex Machina LTD, Nicosia, Cyprus
| | - Dorin-Bogdan Borza
- Dept. of Microbiology, Immunology and Physiology, Meharry Medical College, Nashville, TN, United States of America
| | - Kostas Stylianou
- Department of Nephrology, University of Crete Medical School, Greece
| | - Oliver Gross
- Clinic for Nephrology and Rheumatology, University Medical Center Göttingen, Göttingen, Germany
| | - Constantinos Deltas
- Center of Excellence in Biobanking and Biomedical Research, Molecular Medicine Research Center, University of Cyprus Medical School, Cyprus
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Matthaiou A, Poulli T, Deltas C. Prevalence of clinical, pathological and molecular features of glomerular basement membrane nephropathy caused by COL4A3 or COL4A4 mutations: a systematic review. Clin Kidney J 2020; 13:1025-1036. [PMID: 33391746 PMCID: PMC7769542 DOI: 10.1093/ckj/sfz176] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Accepted: 11/06/2019] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Patients heterozygous for COL4A3 or COL4A4 mutations show a wide spectrum of disease, extending from familial isolated microscopic haematuria, as a result of thin basement membranes (TBMs), to autosomal dominant Alport syndrome (ADAS) and end-stage renal disease (ESRD). Many patients are mentioned in the literature under the descriptive diagnosis of TBM nephropathy (TBMN), in which case it actually describes a histological finding that represents the carriers of autosomal recessive Alport syndrome (ARAS), a severe glomerulopathy, as most patients reach ESRD at a mean age of 25 years. METHODS We performed a systematic literature review for patients with heterozygous COL4A3/A4 mutations with the aim of recording the spectrum and frequency of pathological features. We searched three databases (PubMed, Embase and Scopus) using the keywords 'Autosomal Dominant Alport Syndrome' OR 'Thin Basement Membrane Disease' OR 'Thin Basement Membrane Nephropathy'. We identified 48 publications reporting on 777 patients from 258 families. RESULTS In total, 29% of the patients developed chronic kidney disease (CKD) and 15.1% reached ESRD at a mean age of 52.8 years. Extrarenal features and typical Alport syndrome (AS) findings had a low prevalence in patients as follows: hearing loss, 16%; ocular lesions, 3%; basement membrane thickening, 18.4%; and podocyte foot process effacement, 6.9%. Data for 76 patients from 54 families emphasize extensive inter- and intrafamilial heterogeneity, with age at onset of ESRD ranging between 21 and 84 years (mean 52.8). CONCLUSIONS The analysis enabled a comparison of the clinical course of patients with typical ARAS or X-linked AS with those with heterozygous COL4A mutations diagnosed with TBMN or ADAS. Despite the consequence of a potential ascertainment bias, an important outcome is that TBM poses a global high risk of developing severe CKD, over a long follow-up, with a variable spectrum of other findings. The results are useful to practicing nephrologists for better evaluation of patients.
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Affiliation(s)
| | | | - Constantinos Deltas
- Molecular Medicine Research Center and Laboratory of Molecular and Medical Genetics, Department of Biological Sciences, University of Cyprus, Nicosia, Cyprus
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15
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Fibronectin glomerulopathy: A case report and literature review. Nefrologia 2020; 41:74-76. [PMID: 32402469 DOI: 10.1016/j.nefro.2020.01.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2019] [Revised: 12/01/2019] [Accepted: 01/19/2020] [Indexed: 11/21/2022] Open
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Lanktree MB, Iliuta IA, Haghighi A, Song X, Pei Y. Evolving role of genetic testing for the clinical management of autosomal dominant polycystic kidney disease. Nephrol Dial Transplant 2020; 34:1453-1460. [PMID: 30165646 DOI: 10.1093/ndt/gfy261] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2018] [Indexed: 01/01/2023] Open
Abstract
Autosomal dominant polycystic kidney disease (ADPKD) is caused primarily by mutations of two genes, PKD1 and PKD2. In the presence of a positive family history of ADPKD, genetic testing is currently seldom indicated as the diagnosis is mostly based on imaging studies using well-established criteria. Moreover, PKD1 mutation screening is technically challenging due to its large size, complexity (i.e. presence of six pseudogenes with high levels of DNA sequence similarity) and extensive allelic heterogeneity. Despite these limitations, recent studies have delineated a strong genotype-phenotype correlation in ADPKD and begun to unravel the role of genetics underlying cases with atypical phenotypes. Furthermore, adaptation of next-generation sequencing (NGS) to clinical PKD genetic testing will provide a high-throughput, accurate and comprehensive screen of multiple cystic disease and modifier genes at a reduced cost. In this review, we discuss the evolving indications of genetic testing in ADPKD and how NGS-based screening promises to yield clinically important prognostic information for both typical as well as unusual genetic (e.g. allelic or genic interactions, somatic mosaicism, cystic kidney disease modifiers) cases to advance personalized medicine in the era of novel therapeutics for ADPKD.
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Affiliation(s)
- Matthew B Lanktree
- Division of Nephrology, University Health Network and University of Toronto, Toronto, ON, Canada
| | - Ioan-Andrei Iliuta
- Division of Nephrology, University Health Network and University of Toronto, Toronto, ON, Canada
| | - Amirreza Haghighi
- Division of Nephrology, University Health Network and University of Toronto, Toronto, ON, Canada
| | - Xuewen Song
- Division of Nephrology, University Health Network and University of Toronto, Toronto, ON, Canada
| | - York Pei
- Division of Nephrology, University Health Network and University of Toronto, Toronto, ON, Canada
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Neuburg S, Dussold C, Gerber C, Wang X, Francis C, Qi L, David V, Wolf M, Martin A. Genetic background influences cardiac phenotype in murine chronic kidney disease. Nephrol Dial Transplant 2019; 33:1129-1137. [PMID: 29309658 DOI: 10.1093/ndt/gfx332] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 11/03/2017] [Indexed: 01/01/2023] Open
Abstract
Background Levels of fibroblast growth factor 23 (FGF23) increase early in chronic kidney disease (CKD) and are independently associated with left ventricular hypertrophy (LVH), heart failure and death. Experimental models of CKD with elevated FGF23 and LVH are needed. We hypothesized that slow rates of CKD progression in the Col4a3 knockout (Col4a3KO) mouse model of CKD would promote development of LVH by prolonging exposure to elevated FGF23. Methods We studied congenic Col4a3KO and wild-type (WT) mice with either 75% 129X1/SvJ (129Sv) or 94% C57Bl6/J (B6) genomes. Results B6-Col4a3KO lived longer than 129Sv-Col4a3KO mice (21.4 ± 0.6 versus 11.4 ± 0.4 weeks; P < 0.05). 10-week-old 129Sv-Col4a3KO mice showed impaired renal function (blood urea nitrogen 191 ± 39 versus 34 ± 4 mg/dL), hyperphosphatemia (14.1 ± 1.4 versus 6.8 ± 0.3 mg/dL) and 33-fold higher serum FGF23 levels (P < 0.05 versus WT for each). Consistent with their slower CKD progression, 10 week-old B6-Col4a3KO mice showed milder impairment of renal function than 129Sv-Col4a3KO mice and modest FGF23 elevation without other alterations of mineral metabolism. At 20 weeks, further declines in renal function in B6-Col4a3KO mice was accompanied by hyperphosphatemia and 8-fold higher FGF23 levels (P < 0.05 versus WT for each). Only the 20-week-old B6-Col4a3KO mice developed LVH (LV mass 125 ± 3 versus 98 ± 6 mg; P < 0.05 versus WT) in association with significantly increased cardiac expression of FGF receptor 4 (FGFR4) messenger RNA and protein and markers of LVH (Atrial natriuretic peptide (ANP), B-type natriuretic peptide (BNP), beta-myosin heavy chain (β-MHC); P < 0.05 versus WT for each). Conclusions In conclusion, B6-Col4a3KO mice manifest slower CKD progression and longer survival than 129Sv-Col4a3KO mice and can serve as a novel model of cardiorenal disease.
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Affiliation(s)
- Samantha Neuburg
- Division of Nephrology and Hypertension, Department of Medicine, Center for Translational Metabolism and Health, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Corey Dussold
- Division of Nephrology and Hypertension, Department of Medicine, Center for Translational Metabolism and Health, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Claire Gerber
- Division of Nephrology and Hypertension, Department of Medicine, Center for Translational Metabolism and Health, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Xueyan Wang
- Division of Nephrology and Hypertension, Department of Medicine, Center for Translational Metabolism and Health, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Connor Francis
- Division of Nephrology and Hypertension, Department of Medicine, Center for Translational Metabolism and Health, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Lixin Qi
- Division of Nephrology and Hypertension, Department of Medicine, Center for Translational Metabolism and Health, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Valentin David
- Division of Nephrology and Hypertension, Department of Medicine, Center for Translational Metabolism and Health, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Myles Wolf
- Division of Nephrology, Department of Medicine, Duke Clinical Research Institute, Duke University, Durham, NC, USA
| | - Aline Martin
- Division of Nephrology and Hypertension, Department of Medicine, Center for Translational Metabolism and Health, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
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Yang C, Song Y, Chen Z, Yuan X, Chen X, Ding G, Guan Y, McGrath M, Song C, Tong Y, Wang H. A Nonsense Mutation in COL4A4 Gene Causing Isolated Hematuria in Either Heterozygous or Homozygous State. Front Genet 2019; 10:628. [PMID: 31312213 PMCID: PMC6614519 DOI: 10.3389/fgene.2019.00628] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 06/17/2019] [Indexed: 01/15/2023] Open
Abstract
Alport syndrome (AS) is a hereditary nephropathy characterized by glomerular basement membrane lesions. AS shows a relatively rare entity with autosomal dominant gene mutation (accounts for less than 5% of AS cases) and is widely believed to be a consequence of heterozygous variants in the COL4A3 and COL4A4 genes. Until now, there have been no reports of homozygous variants in genes in AS patients, and it is scarce to detect both homozygous and heterozygous variants in a single AS pedigree. We performed genetic analysis by exome sequencing (exome-seq) in a Chinese family with AS and found four individuals harboring the COL4A4 c.4599T > G variant, a novel COL4A4 nonsense mutation that gains stop codon and results in a truncated protein. The proband and her two siblings were determined to be heterozygous, whereas their mother was homozygous. The proband satisfied the criteria for the diagnosis of AS, which included clinical manifestations of microscopic hematuria and proteinuria, and pathological features of the glomerular basement membrane (GBM), including irregular thickening and splitting. However, the other three individuals who were homozygous or heterozygous for the variant exhibited mild clinical features with isolated microscopic hematuria. In summary, we identified a novel pathogenic variant in either the heterozygous or homozygous state of the COL4A4 gene in a Chinese family with AS. Our results also suggest that the severity of clinical manifestations may not be entirely attributed to by the COL4A4 genetic variant itself in patients.
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Affiliation(s)
- Cheng Yang
- Renal Department, Renmin Hospital of Wuhan University, Wuhan, China
| | - Yuan Song
- Renal Department, Renmin Hospital of Wuhan University, Wuhan, China
| | - Zhaowei Chen
- Renal Department, Renmin Hospital of Wuhan University, Wuhan, China
| | - Xiaohan Yuan
- Renal Department, Renmin Hospital of Wuhan University, Wuhan, China
| | - Xinhua Chen
- Renal Department, Renmin Hospital of Wuhan University, Wuhan, China
| | - Guohua Ding
- Renal Department, Renmin Hospital of Wuhan University, Wuhan, China
| | - Yang Guan
- Ultrastructure Center, Renmin Hospital of Wuhan University, Wuhan, China
| | - Mary McGrath
- Department of Pediatrics, Pennsylvania State University College of Medicine, Hershey, PA, United States
| | - Chunhua Song
- Department of Pediatrics, Pennsylvania State University College of Medicine, Hershey, PA, United States
| | - Yongqing Tong
- Department of Laboratory Science, Renmin Hospital of Wuhan University, Wuhan, China
| | - Huiming Wang
- Renal Department, Renmin Hospital of Wuhan University, Wuhan, China
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19
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Savige J, Ariani F, Mari F, Bruttini M, Renieri A, Gross O, Deltas C, Flinter F, Ding J, Gale DP, Nagel M, Yau M, Shagam L, Torra R, Ars E, Hoefele J, Garosi G, Storey H. Expert consensus guidelines for the genetic diagnosis of Alport syndrome. Pediatr Nephrol 2019; 34:1175-1189. [PMID: 29987460 DOI: 10.1007/s00467-018-3985-4] [Citation(s) in RCA: 76] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 02/22/2018] [Accepted: 05/10/2018] [Indexed: 12/16/2022]
Abstract
Recent expert guidelines recommend genetic testing for the diagnosis of Alport syndrome. Here, we describe current best practice and likely future developments. In individuals with suspected Alport syndrome, all three COL4A5, COL4A3 and COL4A4 genes should be examined for pathogenic variants, probably by high throughput-targeted next generation sequencing (NGS) technologies, with a customised panel for simultaneous testing of the three Alport genes. These techniques identify up to 95% of pathogenic COL4A variants. Where causative pathogenic variants cannot be demonstrated, the DNA should be examined for deletions or insertions by re-examining the NGS sequencing data or with multiplex ligation-dependent probe amplification (MLPA). These techniques identify a further 5% of variants, and the remaining few changes include deep intronic splicing variants or cases of somatic mosaicism. Where no pathogenic variants are found, the basis for the clinical diagnosis should be reviewed. Genes in which mutations produce similar clinical features to Alport syndrome (resulting in focal and segmental glomerulosclerosis, complement pathway disorders, MYH9-related disorders, etc.) should be examined. NGS approaches have identified novel combinations of pathogenic variants in Alport syndrome. Two variants, with one in COL4A3 and another in COL4A4, produce a more severe phenotype than an uncomplicated heterozygous change. NGS may also identify further coincidental pathogenic variants in genes for podocyte-expressed proteins that also modify the phenotype. Our understanding of the genetics of Alport syndrome is evolving rapidly, and both genetic and non-genetic factors are likely to contribute to the observed phenotypic variability.
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Affiliation(s)
- Judy Savige
- Department of Medicine, Melbourne and Northern Health, The University of Melbourne, Parkville, VIC, 3050, Australia.
| | | | | | | | | | - Oliver Gross
- Clinic of Nephrology and Rheumatology, University of Gottingen, Gottingen, Germany
| | | | - Frances Flinter
- Department of Clinical Genetics, Guys' and St Thomas' NHS Foundation Trust, London, UK
| | - Jie Ding
- Peking University First Hospital, Beijing, China
| | - Daniel P Gale
- Centre for Nephrology, Royal Free Hospital, University College London, London, UK
| | - Mato Nagel
- Centre for Nephrology and Metabolic Disorders, Weisswasser, Germany
| | - Michael Yau
- Genetics, Guy's Hospital, Viapath, London, UK
| | - Lev Shagam
- Institute of Pediatrics, Pirogov Russian Medical University, Moscow, Russia
| | - Roser Torra
- Inherited Kidney Disorders, Nephrology Department, Fundacio Puigvert, Instituto de Investigacion Carlos III, Universitat Autonoma de Barcelona, Barcelona, Spain
| | - Elisabet Ars
- Molecular Biology Laboratory, Fundacio Puigvert, Instituto de Investigacion Carlos III, Universitat Autonoma de Barcelona, Barcelona, Spain
| | - Julia Hoefele
- Institute of Human Genetics, Technical University Munich, Munich, Germany
| | - Guido Garosi
- Nephrology, Dialysis and Transplantation, Azienda Ospedaliera Universitaria Senese, Siena, Italy
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20
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Glomerular Hematuria: Cause or Consequence of Renal Inflammation? Int J Mol Sci 2019; 20:ijms20092205. [PMID: 31060307 PMCID: PMC6539976 DOI: 10.3390/ijms20092205] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 04/21/2019] [Accepted: 04/28/2019] [Indexed: 12/12/2022] Open
Abstract
Glomerular hematuria is a cardinal symptom of renal disease. Glomerular hematuria may be classified as microhematuria or macrohematuria according to the number of red blood cells in urine. Recent evidence suggests a pathological role of persistent glomerular microhematuria in the progression of renal disease. Moreover, gross hematuria, or macrohematuria, promotes acute kidney injury (AKI), with subsequent impairment of renal function in a high proportion of patients. In this pathological context, hemoglobin, heme, or iron released from red blood cells in the urinary space may cause direct tubular cell injury, oxidative stress, pro-inflammatory cytokine production, and further monocyte/macrophage recruitment. The aim of this manuscript is to review the role of glomerular hematuria in kidney injury, the role of inflammation as cause and consequence of glomerular hematuria, and to discuss novel therapies to combat hematuria.
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21
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Imafuku A, Nozu K, Sawa N, Hasegawa E, Hiramatsu R, Kawada M, Hoshino J, Tanaka K, Ishii Y, Takaichi K, Fujii T, Ohashi K, Iijima K, Ubara Y. Autosomal dominant form of type IV collagen nephropathy exists among patients with hereditary nephritis difficult to diagnose clinicopathologically. Nephrology (Carlton) 2019; 23:940-947. [PMID: 28704582 PMCID: PMC6767408 DOI: 10.1111/nep.13115] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/10/2017] [Indexed: 01/01/2023]
Abstract
The study revealed that 69% of families with hereditary nephritis that was difficult to diagnose clinicopathologically had heterozygous mutations of COL4A3/A4 (TBMN/ADAS). The finding suggests the importance of genetic testing in appropriate patients. Aim Type IV collagen nephropathies include Alport Syndrome and thin basement membrane nephropathy (TBMN), which are caused by mutations in COL4A3/A4/A5 genes. Recently, reports of patients with heterozygous mutations in COL4A3/A4 have been increasing. The clinical course of these patients has a wide variety, and they are diagnosed as TBMN, autosomal dominant Alport syndrome (ADAS), or familial focal segmental glomerular sclerosis. However, diagnosis, frequency and clinicopathological manifestation of them remains unclear. We tested COL4A3/A4/A5 genes in patients with hereditary nephritis that was difficult to diagnose clinicopathologically, and investigated who should undergo such testing. Methods We performed immunostaining for α5 chain of type IV collagen [α5 (IV)] in 27 patients from 21 families who fitted the following criteria: (i) haematuria and proteinuria (± renal dysfunction); (ii) family history of haematuria, proteinuria, and/or renal dysfunction (autosomal dominant inheritance); (iii) no specific glomerulonephritis; and (iv) thinning, splitting, or lamellation of the glomerular basement membrane (GBM) on electron microscopy. Then we performed genetic testing in 19 patients from 16 families who showed normal α5 (IV) patterns. We conducted a retrospective analysis of their clinicopathological findings. Results Among 16 families, 69% were detected heterozygous mutations in COL4A3/A4, suggesting the diagnosis of TBMN/ADAS. Twenty‐one percent of patients developed end stage renal disease. All patients showed thinning of GBM, which was accompanied by splitting or lamellation in seven patients. Conclusion A considerable fraction of patients with hereditary nephritis that is difficult to diagnose clinicopathologically have TBMN/ADAS. It is important to recognize TBMN/ADAS and perform genetic testing in appropriate patients.
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Affiliation(s)
- Aya Imafuku
- Nephrology Center, Toranomon Hospital, Minato-ku, Japan
| | - Kandai Nozu
- Department of Pediatrics, Kobe University, Kobe, Japan
| | - Naoki Sawa
- Nephrology Center, Toranomon Hospital, Minato-ku, Japan
| | - Eiko Hasegawa
- Nephrology Center, Toranomon Hospital, Minato-ku, Japan
| | | | | | | | - Kiho Tanaka
- Nephrology Center, Toranomon Hospital, Minato-ku, Japan
| | - Yasuo Ishii
- Nephrology Center, Toranomon Hospital, Minato-ku, Japan
| | - Kenmei Takaichi
- Nephrology Center, Toranomon Hospital, Minato-ku, Japan.,Okinaka Memorial Institute for Medical Research, Toranomon Hospital, Minato-ku, Japan
| | - Takeshi Fujii
- Department of Pathology, Toranomon Hospital, Minato-ku, Japan
| | - Kenichi Ohashi
- Department of Pathology, Toranomon Hospital, Minato-ku, Japan.,Department of Pathology, Yokohama City University, Graduate School of Medicine, Yokohama-shi, Japan
| | | | - Yoshifumi Ubara
- Nephrology Center, Toranomon Hospital, Minato-ku, Japan.,Okinaka Memorial Institute for Medical Research, Toranomon Hospital, Minato-ku, Japan
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22
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Hirakawa Y, Miura R, Sasaki Y, Yoshida Y, Mimura I, Katsura M, Shintani-Domoto Y, Ogawa M, Hayashi A, Nangaku M. Nutcracker Syndrome with the Superimposition of Thin Basement Membrane Syndrome. Intern Med 2019; 58:411-414. [PMID: 30210125 PMCID: PMC6395115 DOI: 10.2169/internalmedicine.1433-18] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
A 21-year-old woman was referred to our hospital because of proteinuria and hematuria. She had occasional flank pain. A renal biopsy was performed and revealed a thin basement membrane. Therefore, she was diagnosed with thin basement membrane disease. However, the frequency of her flank pain increased. Since her left kidney was slightly larger than the right, nutcracker syndrome (NCS) was suspected. Renal vein ultrasonography and venography were performed, and NCS was confirmed. Her hematuria was multifactorial, and NCS can go unnoticed if there is a comorbidity that also causes hematuria.
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Affiliation(s)
- Yosuke Hirakawa
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, Japan
| | - Rika Miura
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, Japan
| | - Yuji Sasaki
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, Japan
| | - Yui Yoshida
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, Japan
| | - Imari Mimura
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, Japan
| | - Masaki Katsura
- Department of Radiology, The University of Tokyo Hospital, Japan
| | | | - Makiko Ogawa
- Department of Pathology, Graduate School of Medicine, The University of Tokyo, Japan
| | - Akimasa Hayashi
- Department of Pathology, Graduate School of Medicine, The University of Tokyo, Japan
| | - Masaomi Nangaku
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, Japan
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23
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Zhu F, Li W, Li Z, Zhu H, Xiong J. Identification of a Novel COL4A4 Variant in Compound-Heterozygous State in a Patient With Alport Syndrome and Histological Findings Similar to Focal Segmental Glomerulosclerosis (FSGS). Front Genet 2019; 9:748. [PMID: 30745910 PMCID: PMC6360158 DOI: 10.3389/fgene.2018.00748] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 12/31/2018] [Indexed: 01/15/2023] Open
Abstract
Alport syndrome (AS) is a rare and inherited renal disorder with an autosomal recessive mode of inheritance. AS patients usually manifest with hematuria and progressive renal disorder also occasionally accompanied by hearing loss and ophthalmic disease. Germline variants in collagen type IV α-4 (COL4A4) gene lead to autosomal recessive Alport syndrome. In the present study, we investigated a Chinese family with Alport syndrome. The index patient is a 24-year-old Chinese woman who has been suffering from proteinuria. Renal biopsy and renal pathology were performed and found focal segmental glomerulosclerosis (FSGS) like lesion in the index patient. The index patient also presented with binocular edema and blurred vision. However, binocular edema dissipated gradually without any further treatment. Unlikely, the index patient was not diagnosed with hearing impairment. Index patient's parents are phenotypically normal. Targeted next generation sequencing and Sanger sequencing was performed. A novel heterozygous single nucleotide insertion, c.4760_4761insC and a previously reported likely pathogenic variant, c.1323_1340delTGGCTTGCCTGGAGCACC in the COL4A4 gene were identified in the index patient. The novel heterozygous single nucleotide insertion (c.4760_4761insC) leads to a frameshift which eventually results in the formations of a truncated COL4A4 protein. In addition, the other heterozygous likely pathogenic variant, c.1323_1340delTGGCTTGCCTGGAGCACC, has been already identified with causing AS an autosomal recessive mode of inheritance. Sanger sequencing confirmed that these two variants were inherited in the index patient from her father and mother, respectively. These two variants were not found in 100 normal control individuals. In conclusion, our present finding emphasizes the significance of high throughput targeted next generation sequencing technology for rapid and cost-effective genetic screening which allows us easy and accurate clinical diagnosis of AS patients.
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Affiliation(s)
- Feng Zhu
- Department of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Wencheng Li
- Department of Urology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zhenqiong Li
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Hongyan Zhu
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jing Xiong
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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24
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Kashtan CE. Renal transplantation in patients with Alport syndrome: patient selection, outcomes, and donor evaluation. Int J Nephrol Renovasc Dis 2018; 11:267-270. [PMID: 30410383 PMCID: PMC6198874 DOI: 10.2147/ijnrd.s150539] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Alport syndrome is an inherited disorder of basement membrane collagen IV that frequently results in end-stage renal disease. Patients with Alport syndrome who undergo renal transplantation have generally excellent outcomes. Posttransplant antiglomerular basement membrane nephritis is a rare complication of renal transplantation for Alport syndrome. Because Alport syndrome is a genetic disorder, potential related donors must be carefully evaluated in order to minimize harm.
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Affiliation(s)
- Clifford E Kashtan
- Division of Nephrology, Department of Pediatrics, University of Minnesota Medical School, Minneapolis, MN 55454, USA,
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25
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Voskarides K, Papagregoriou G, Hadjipanagi D, Petrou I, Savva I, Elia A, Athanasiou Y, Pastelli A, Kkolou M, Hadjigavriel M, Stavrou C, Pierides A, Deltas C. COL4A5 and LAMA5 variants co-inherited in familial hematuria: digenic inheritance or genetic modifier effect? BMC Nephrol 2018; 19:114. [PMID: 29764427 PMCID: PMC5954460 DOI: 10.1186/s12882-018-0906-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 10/25/2017] [Accepted: 01/21/2018] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND About 40-50% of patients with familial microscopic hematuria (FMH) caused by thin basement membrane nephropathy (TBMN) inherit heterozygous mutations in collagen IV genes (COL4A3, COL4A4). On long follow-up, the full phenotypic spectrum of these patients varies a lot, ranging from isolated MH or MH plus low-grade proteinuria to chronic renal failure of variable degree, including end-stage renal disease (ESRD). METHODS Here, we performed Whole Exome Sequencing (WES) in patients of six families, presenting with autosomal dominant FMH, with or without progression to proteinuria and loss of renal function, all previously found negative for severe collagen IV mutations. Hierarchical filtering of the WES data was performed, followed by mutation prediction analysis, Sanger sequencing and genetic segregation analysis. RESULTS In one family with four patients, we found evidence for the contribution of two co-inherited variants in two crucial genes expressed in the glomerular basement membrane (GBM); LAMA5-p.Pro1243Leu and COL4A5-p.Asp654Tyr. Mutations in COL4A5 cause classical X-linked Alport Syndrome, while rare mutations in the LAMA5 have been reported in patients with focal segmental glomerulosclerosis. The phenotypic spectrum of the patients includes hematuria, proteinuria, focal segmental glomerulosclerosis, loss of kidney function and renal cortical cysts. CONCLUSIONS A modifier role of LAMA5 on the background of a hypomorphic Alport syndrome causing mutation is a possible explanation of our findings. Digenic inheritance is another scenario, following the concept that mutations at both loci more accurately explain the spectrum of symptoms, but further investigation is needed under this concept. This is the third report linking a LAMA5 variant with human renal disease and expanding the spectrum of genes involved in glomerular pathologies accompanied by familial hematurias. The cystic phenotype overlaps with that of a mouse model, which carried a Lama5 hypomorphic mutation that caused severely reduced Lama5 protein levels and produced kidney cysts.
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Affiliation(s)
- Konstantinos Voskarides
- Molecular Medicine Research Center, Department of Biological Sciences, University of Cyprus, 1, University Avenue, 2109, Nicosia, Cyprus. .,Medical School, University of Cyprus, Nicosia, Cyprus.
| | - Gregory Papagregoriou
- Molecular Medicine Research Center, Department of Biological Sciences, University of Cyprus, 1, University Avenue, 2109, Nicosia, Cyprus
| | - Despina Hadjipanagi
- Molecular Medicine Research Center, Department of Biological Sciences, University of Cyprus, 1, University Avenue, 2109, Nicosia, Cyprus
| | - Ioanelli Petrou
- Molecular Medicine Research Center, Department of Biological Sciences, University of Cyprus, 1, University Avenue, 2109, Nicosia, Cyprus
| | - Isavella Savva
- Molecular Medicine Research Center, Department of Biological Sciences, University of Cyprus, 1, University Avenue, 2109, Nicosia, Cyprus
| | - Avraam Elia
- Department of Pediatric Nephrology, Archbishop Makarios III Hospital, Nicosia, Cyprus
| | | | | | - Maria Kkolou
- Department of Nephrology, Larnaca General Hospital, Larnaca, Cyprus
| | | | | | - Alkis Pierides
- Molecular Medicine Research Center, Department of Biological Sciences, University of Cyprus, 1, University Avenue, 2109, Nicosia, Cyprus.,Hippocrateon Hospital, Nicosia, Cyprus
| | - Constantinos Deltas
- Molecular Medicine Research Center, Department of Biological Sciences, University of Cyprus, 1, University Avenue, 2109, Nicosia, Cyprus. .,College of Medicine, Qatar University, Doha, Qatar.
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26
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de Brot S, Adamany J, Baiker K, Dhumeaux M, Allegrucci C, Polledo L, Grau-Roma L. Pathology in Practice. Hereditary nephropathy (familial nephropathy) in an English Cocker Spaniel. J Am Vet Med Assoc 2017; 251:661-664. [PMID: 28857708 DOI: 10.2460/javma.251.6.661] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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27
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Santos S, Marques S, Golper T, Langone A, Fogo AB. Thin Glomerular Basement Membrane in a Kidney Transplant of an Alport's Syndrome Patient: A Case Report. Transplant Proc 2017; 49:2384-2387. [PMID: 29198685 DOI: 10.1016/j.transproceed.2017.07.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 07/30/2017] [Indexed: 10/18/2022]
Abstract
Alport syndrome (AS) and thin basement membrane lesions are caused by various mutations in type IV collagen genes. Although AS is considered a rare disease, thin basement membrane is a frequent pattern, especially in families with a history of persistent hematuria. We report a patient with a diagnosis of AS who developed end-stage kidney disease (ESKD) and received a kidney transplant from a living unrelated donor. The graft biopsy specimen surprisingly showed a pattern of thin basement membranes.
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Affiliation(s)
- S Santos
- Department of Nephrology, Centro Hospitalar do Porto, Porto, Portugal; Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
| | - S Marques
- Department of Nephrology, Hospital São João, Porto, Portugal; Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - T Golper
- Department of Medicine, Division of Nephrology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - A Langone
- Department of Medicine, Division of Nephrology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - A B Fogo
- Department of Medicine, Division of Nephrology, Vanderbilt University Medical Center, Nashville, Tennessee, USA; Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
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28
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Li Y, Wang Y, He Q, Dang X, Cao Y, Wu X, Mo S, He X, Yi Z. Genetic mutational testing of Chinese children with familial hematuria with biopsy‑proven FSGS. Mol Med Rep 2017; 17:1513-1526. [PMID: 29138824 PMCID: PMC5780091 DOI: 10.3892/mmr.2017.8023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 08/31/2017] [Indexed: 12/27/2022] Open
Abstract
Focal segmental glomerulosclerosis (FSGS) is a pathological lesion rather than a disease, with a diverse etiology. FSGS may result from genetic and non‑genetic factors. FSGS is considered a podocyte disease due to the fact that in the majority of patients with proven‑FSGS, the lesion results from defects in the podocyte structure or function. However, FSGS does not result exclusively from podocyte‑associated genes, however also from other genes including collagen IV‑associated genes. Patients who carry the collagen type IVA3 chain (COL4A3) or COL4A4 mutations usually exhibit Alport Syndrome (AS), thin basement membrane neuropathy or familial hematuria (FH). Previous studies revealed that long‑time persistent microscopic hematuria may lead to FSGS. A case of a family is presented here where affected individuals exhibited FH with FSGS‑proven, or chronic kidney disease. Renal biopsies were unhelpful and failed to demonstrate glomerular or basement membrane defects consistent with an inherited glomerulopathy, and therefore a possible underlying genetic cause for a unifying diagnosis was pursued. Genomic DNA of the siblings affected by FH with biopsy‑proven FSGS was analyzed, and their father was screened for 18 gene mutations associated with FSGS [nephrin, podocin, CD2 associated protein, phospholipase C ε, actinin α 4, transient receptor potential cation channel subfamily C member 6, inverted formin, FH2 and WH2 domain containing, Wilms tumor 1, LIM homeobox transcription factor 1 β, laminin subunit β 2, laminin subunit β 3, galactosida α, integrin subunit β 4, scavenger receptor class B member 2, coenzyme Q2, decaprenyl diphosphate synthase subunit 2, mitochondrially encoded tRNA leucine 1 (UUA/G; TRNL1) and SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily a like 1] using matrix‑assisted laser desorption/ionization time‑of‑flight mass spectrometry technology. Then whole exome sequencing (WES) was performed in the two probands to ascertain whether there were other known or unknown gene mutations that segregated with the disease. Using mass array technology, a TRNL1 missense homozygous mutation (m. 3290T>C) was identified in the probands diagnosed with FH and manifested as FSGS on biopsy. In addition, a COL4A4 missense mutation c. 4195A>T (p. M1399L) in heterozygous pattern was identified using WES. None of these variants were detected in their father. In the present study, a mutation in TRNL1 (m. 3290T>C) was identified, which was the first reported variant associated with FSGS. The COL4A4 (c. 4195A>T) may co‑segregate with FSGS. Screening for COL4A mutations in familial FSGS patients is suggested in the present study. Genetic investigations of families with similar clinical phenotypes should be a priority for nephrologists. The combination of mass array technology and WES may improve the detection rate of genetic mutation with a high level of accuracy.
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Affiliation(s)
- Yongzhen Li
- Division of Pediatric Nephrology, Children's Medical Center of The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, P.R. China
| | - Ying Wang
- Division of Pediatric Nephrology, Children's Medical Center of The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, P.R. China
| | - Qingnan He
- Division of Pediatric Nephrology, Children's Medical Center of The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, P.R. China
| | - Xiqiang Dang
- Division of Pediatric Nephrology, Children's Medical Center of The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, P.R. China
| | - Yan Cao
- Division of Pediatric Nephrology, Children's Medical Center of The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, P.R. China
| | - Xiaochuan Wu
- Division of Pediatric Nephrology, Children's Medical Center of The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, P.R. China
| | - Shuanghong Mo
- Division of Pediatric Nephrology, Children's Medical Center of The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, P.R. China
| | - Xiaoxie He
- Division of Pediatric Nephrology, Children's Medical Center of The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, P.R. China
| | - Zhuwen Yi
- Division of Pediatric Nephrology, Children's Medical Center of The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, P.R. China
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29
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Papazachariou L, Papagregoriou G, Hadjipanagi D, Demosthenous P, Voskarides K, Koutsofti C, Stylianou K, Ioannou P, Xydakis D, Tzanakis I, Papadaki A, Kallivretakis N, Nikolakakis N, Perysinaki G, Gale DP, Diamantopoulos A, Goudas P, Goumenos D, Soloukides A, Boletis I, Melexopoulou C, Georgaki E, Frysira E, Komianou F, Grekas D, Paliouras C, Alivanis P, Vergoulas G, Pierides A, Daphnis E, Deltas C. Frequent COL4 mutations in familial microhematuria accompanied by later-onset Alport nephropathy due to focal segmental glomerulosclerosis. Clin Genet 2017. [PMID: 28632965 DOI: 10.1111/cge.13077] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Familial microscopic hematuria (FMH) is associated with a genetically heterogeneous group of conditions including the collagen-IV nephropathies, the heritable C3/CFHR5 nephropathy and the glomerulopathy with fibronectin deposits. The clinical course varies widely, ranging from isolated benign familial hematuria to end-stage renal disease (ESRD) later in life. We investigated 24 families using next generation sequencing (NGS) for 5 genes: COL4A3, COL4A4, COL4A5, CFHR5 and FN1. In 17 families (71%), we found 15 pathogenic mutations in COL4A3/A4/A5, 9 of them novel. In 5 families patients inherited classical AS with hemizygous X-linked COL4A5 mutations. Even more patients developed later-onset Alport-related nephropathy having inherited heterozygous COL4A3/A4 mutations that cause thin basement membranes. Amongst 62 heterozygous or hemizygous patients, 8 (13%) reached ESRD, while 25% of patients with heterozygous COL4A3/A4 mutations, aged >50-years, reached ESRD. In conclusion, COL4A mutations comprise a frequent cause of FMH. Heterozygous COL4A3/A4 mutations predispose to renal function impairment, supporting that thin basement membrane nephropathy is not always benign. The molecular diagnosis is essential for differentiating the X-linked from the autosomal recessive and dominant inheritance. Finally, NGS technology is established as the gold standard for the diagnosis of FMH and associated collagen-IV glomerulopathies, frequently averting the need for invasive renal biopsies.
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Affiliation(s)
- L Papazachariou
- Molecular Medicine Research Center & Laboratory of Molecular and Medical Genetics, Department of Biological Sciences, University of Cyprus, Nicosia, Cyprus
| | - G Papagregoriou
- Molecular Medicine Research Center & Laboratory of Molecular and Medical Genetics, Department of Biological Sciences, University of Cyprus, Nicosia, Cyprus
| | - D Hadjipanagi
- Molecular Medicine Research Center & Laboratory of Molecular and Medical Genetics, Department of Biological Sciences, University of Cyprus, Nicosia, Cyprus
| | - P Demosthenous
- Molecular Medicine Research Center & Laboratory of Molecular and Medical Genetics, Department of Biological Sciences, University of Cyprus, Nicosia, Cyprus
| | - K Voskarides
- Molecular Medicine Research Center & Laboratory of Molecular and Medical Genetics, Department of Biological Sciences, University of Cyprus, Nicosia, Cyprus
| | - C Koutsofti
- Molecular Medicine Research Center & Laboratory of Molecular and Medical Genetics, Department of Biological Sciences, University of Cyprus, Nicosia, Cyprus
| | - K Stylianou
- Department of Nephrology, University of Crete-Greece, Heraklion, Greece
| | - P Ioannou
- Department of Nephrology, University of Crete-Greece, Heraklion, Greece
| | - D Xydakis
- Department of Nephrology, University of Crete-Greece, Heraklion, Greece
| | - I Tzanakis
- Department of Nephrology, General Hospital of Chania, Crete, Greece
| | - A Papadaki
- Department of Nephrology, General Hospital of Chania, Crete, Greece
| | - N Kallivretakis
- Department of Nephrology, General Hospital of Chania, Crete, Greece
| | - N Nikolakakis
- Division of Nephrology, General Hospital of Rethymno, Crete, Greece
| | - G Perysinaki
- Division of Nephrology, General Hospital of Rethymno, Crete, Greece
| | - D P Gale
- UCL Division of Medicine and Centre for Nephrology, University College London, London, UK
| | | | - P Goudas
- IATOS Dialysis Unit, Patra, Greece
| | - D Goumenos
- Department of Nephrology, Medical School, University of Patras, Patra, Greece
| | - A Soloukides
- Protypo Nefrologiko Athinon Dialysis Center, Athens, Greece
| | - I Boletis
- Department of Nephrology, Laikon Hospital, Athens, Greece
| | - C Melexopoulou
- Department of Nephrology, Laikon Hospital, Athens, Greece
| | - E Georgaki
- Pediatric Nephrology Unit, "IASO" Children's Hospital, Athens, Greece
| | - E Frysira
- Department of Pediatrics, Athens University Medical School, Agia Sophia Children's Hospital, Athens, Greece
| | - F Komianou
- Department of Medical Genetics, Athens University Medical School, Agia Sophia Children's Hospital, Athens, Greece
| | - D Grekas
- University Hospital AXEPA, Thessaloniki, Greece
| | - C Paliouras
- Department of Nephrology, General Hospital of Rhodes, Rhodes, Greece
| | - P Alivanis
- Department of Nephrology, General Hospital of Rhodes, Rhodes, Greece
| | - G Vergoulas
- Organ Transplant Unit, Hippokratio General Hospital, Thessaloniki, Greece
| | - A Pierides
- Molecular Medicine Research Center & Laboratory of Molecular and Medical Genetics, Department of Biological Sciences, University of Cyprus, Nicosia, Cyprus.,Department of Nephrology, Hippocrateon Hospital, Nicosia, Cyprus
| | - E Daphnis
- Department of Nephrology, University of Crete-Greece, Heraklion, Greece
| | - C Deltas
- Molecular Medicine Research Center & Laboratory of Molecular and Medical Genetics, Department of Biological Sciences, University of Cyprus, Nicosia, Cyprus
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30
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Abstract
Most genetic disorders are clinically and genetically heterogeneous. Next-generation sequencing (NGS) has revolutionized the field and is providing rapidly growing insights into the pathomechanism of hereditary nephropathies. Current best-practice guidelines for most hereditary nephropathies include genetic diagnostics. The increasing number of genes that have to be considered in patients with hereditary nephropathies is often challenging when addressed by conventional techniques and largely benefits from NGS-based approaches that allow the parallel analysis of all disease genes in a single test at relatively low cost, e.g., by the use of multi-gene panels. Knowledge of the underlying genotype is of advantage in discussions with regard to transplantation and therapeutic options. Further, genetics may aid the early detection and treatment of renal and extrarenal complications and the reduction of invasive procedures. An accurate genetic diagnosis is crucial for genetic counselling, provides information about the recurrence risk and may help to improve the clinical management of patients and their families. The bottleneck in genetics is no longer the primary wet lab process but the interpretation of the obtained genetic data, which is by far the most challenging and work-intensive part of the analysis. This can only be managed in a multidisciplinary setting that brings together expert knowledge in genetics and the respective medical field. In the future, bench and bedside benefits can be expected from this kind of digitized medicine.
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Protein Array-Based Detection of Proteins in Kidney Tissues from Patients with Membranous Nephropathy. BIOMED RESEARCH INTERNATIONAL 2017; 2017:7843584. [PMID: 28337458 PMCID: PMC5350302 DOI: 10.1155/2017/7843584] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/19/2016] [Revised: 01/25/2017] [Accepted: 01/29/2017] [Indexed: 11/26/2022]
Abstract
Membranous nephropathy (MN) is an autoimmune inflammatory disease in which proteins related with plenty of biological processes play an important role. However, the role of these proteins in the pathogenesis of MN is still unclear. This study aimed to screen differential proteins in kidney tissue samples from MN patients by using protein arrays and determine the pathways involved in the pathogenesis of MN. This study first tested a quantitative protein array (QAH-INF-3) and two semiquantitative protein arrays (L-493 and L-507) with normal renal tissue and identified L-493 as the most appropriate assay to compare protein levels between MN tissues and normal control tissues. The L-493 array identified 66 differentially expressed proteins (DEPs) that may be associated with MN. The gene oncology (GO) and protein-protein interaction (PPI) analyses revealed several processes potentially involved in MN, including extracellular matrix disassembly and organization, cell adhesion, cell-cell signaling, cellular protein metabolic process, and immune response (P < 0.05). We suggest that these different pathways work together via protein signaling and result in the pathogenesis and progression of MN.
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A functional variant in NEPH3 gene confers high risk of renal failure in primary hematuric glomerulopathies. Evidence for predisposition to microalbuminuria in the general population. PLoS One 2017; 12:e0174274. [PMID: 28334007 PMCID: PMC5363870 DOI: 10.1371/journal.pone.0174274] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Accepted: 03/06/2017] [Indexed: 01/06/2023] Open
Abstract
Background Recent data emphasize that thin basement membrane nephropathy (TBMN) should not be viewed as a form of benign familial hematuria since chronic renal failure (CRF) and even end-stage renal disease (ESRD), is a possible development for a subset of patients on long-term follow-up, through the onset of focal and segmental glomerulosclerosis (FSGS). We hypothesize that genetic modifiers may explain this variability of symptoms. Methods We looked in silico for potentially deleterious functional SNPs, using very strict criteria, in all the genes significantly expressed in the slit diaphragm (SD). Two variants were genotyped in a cohort of well-studied adult TBMN patients from 19 Greek-Cypriot families, with a homogeneous genetic background. Patients were categorized as “Severe” or “Mild”, based on the presence or not of proteinuria, CRF and ESRD. A larger pooled cohort (HEMATURIA) of 524 patients, including IgA nephropathy patients, was used for verification. Additionally, three large general population cohorts [Framingham Heart Study (FHS), KORAF4 and SAPHIR] were used to investigate if the NEPH3-V353M variant has any renal effect in the general population. Results and conclusions Genotyping for two high-scored variants in 103 TBMN adult patients with founder mutations who were classified as mildly or severely affected, pointed to an association with variant NEPH3-V353M (filtrin). This promising result prompted testing in the larger pooled cohort (HEMATURIA), indicating an association of the 353M variant with disease severity under the dominant model (p = 3.0x10-3, OR = 6.64 adjusting for gender/age; allelic association: p = 4.2x10-3 adjusting for patients’ kinships). Subsequently, genotyping 6,531 subjects of the Framingham Heart Study (FHS) revealed an association of the homozygous 353M/M genotype with microalbuminuria (p = 1.0x10-3). Two further general population cohorts, KORAF4 and SAPHIR confirmed the association, and a meta-analysis of all three cohorts (11,258 individuals) was highly significant (p = 1.3x10-5, OR = 7.46). Functional studies showed that Neph3 homodimerization and Neph3-Nephrin heterodimerization are disturbed by variant 353M. Additionally, 353M was associated with differential activation of the unfolded protein response pathway, when overexpressed in stressed cultured undifferentiated podocyte cells, thus attesting to its functional significance. Genetics and functional studies support a “rare variant-strong effect” role for NEPH3-V353M, by exerting a negative modifier effect on primary glomerular hematuria. Additionally, genetics studies provide evidence for a role in predisposing homozygous subjects of the general population to micro-albuminuria.
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33
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Familial hematuria: A review. Medicina (B Aires) 2017; 53:1-10. [DOI: 10.1016/j.medici.2017.01.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 12/23/2016] [Accepted: 01/16/2017] [Indexed: 12/17/2022] Open
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Nakagawa N, Barron L, Gomez IG, Johnson BG, Roach AM, Kameoka S, Jack RM, Lupher ML, Gharib SA, Duffield JS. Pentraxin-2 suppresses c-Jun/AP-1 signaling to inhibit progressive fibrotic disease. JCI Insight 2016; 1:e87446. [PMID: 27942582 DOI: 10.1172/jci.insight.87446] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Pentraxin-2 (PTX-2), also known as serum amyloid P component (SAP/APCS), is a constitutive, antiinflammatory, innate immune plasma protein whose circulating level is decreased in chronic human fibrotic diseases. Here we show that recombinant human PTX-2 (rhPTX-2) retards progression of chronic kidney disease in Col4a3 mutant mice with Alport syndrome, reducing blood markers of kidney failure, enhancing lifespan by 20%, and improving histological signs of disease. Exogenously delivered rhPTX-2 was detected in macrophages but also in tubular epithelial cells, where it counteracted macrophage activation and was cytoprotective for the epithelium. Computational analysis of genes regulated by rhPTX-2 identified the transcriptional regulator c-Jun along with its activator protein-1 (AP-1) binding partners as a central target for the function of rhPTX-2. Accordingly, PTX-2 attenuates c-Jun and AP-1 activity, and reduces expression of AP-1-dependent inflammatory genes in both monocytes and epithelium. Our studies therefore identify rhPTX-2 as a potential therapy for chronic fibrotic disease of the kidney and an important inhibitor of pathological c-Jun signaling in this setting.
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Affiliation(s)
- Naoki Nakagawa
- Division of Nephrology, Departments of Medicine and Pathology, and.,Institute of Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington, USA.,Department of Internal Medicine, Asahikawa Medical University, Asahikawa, Japan
| | - Luke Barron
- Research and Development, Biogen, Cambridge, Massachusetts, USA
| | - Ivan G Gomez
- Division of Nephrology, Departments of Medicine and Pathology, and.,Institute of Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington, USA.,Research and Development, Biogen, Cambridge, Massachusetts, USA
| | - Bryce G Johnson
- Division of Nephrology, Departments of Medicine and Pathology, and.,Institute of Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington, USA.,Research and Development, Biogen, Cambridge, Massachusetts, USA
| | - Allie M Roach
- Division of Nephrology, Departments of Medicine and Pathology, and.,Institute of Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington, USA.,Research and Development, Biogen, Cambridge, Massachusetts, USA
| | - Sei Kameoka
- Research and Development, Biogen, Cambridge, Massachusetts, USA
| | | | | | - Sina A Gharib
- Institute of Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington, USA.,Computational Medicine Core.,Divsion of Pulmonary and Critical Care Medicine, University of Washington, Seattle, Washington, USA
| | - Jeremy S Duffield
- Division of Nephrology, Departments of Medicine and Pathology, and.,Institute of Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington, USA.,Research and Development, Biogen, Cambridge, Massachusetts, USA
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35
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Wickman L, Hodgin JB, Wang SQ, Afshinnia F, Kershaw D, Wiggins RC. Podocyte Depletion in Thin GBM and Alport Syndrome. PLoS One 2016; 11:e0155255. [PMID: 27192434 PMCID: PMC4871445 DOI: 10.1371/journal.pone.0155255] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 04/26/2016] [Indexed: 01/15/2023] Open
Abstract
The proximate genetic cause of both Thin GBM and Alport Syndrome (AS) is abnormal α3, 4 and 5 collagen IV chains resulting in abnormal glomerular basement membrane (GBM) structure/function. We previously reported that podocyte detachment rate measured in urine is increased in AS, suggesting that podocyte depletion could play a role in causing progressive loss of kidney function. To test this hypothesis podometric parameters were measured in 26 kidney biopsies from 21 patients aged 2–17 years with a clinic-pathologic diagnosis including both classic Alport Syndrome with thin and thick GBM segments and lamellated lamina densa [n = 15] and Thin GBM cases [n = 6]. Protocol biopsies from deceased donor kidneys were used as age-matched controls. Podocyte depletion was present in AS biopsies prior to detectable histologic abnormalities. No abnormality was detected by light microscopy at <30% podocyte depletion, minor pathologic changes (mesangial expansion and adhesions to Bowman’s capsule) were present at 30–50% podocyte depletion, and FSGS was progressively present above 50% podocyte depletion. eGFR did not change measurably until >70% podocyte depletion. Low level proteinuria was an early event at about 25% podocyte depletion and increased in proportion to podocyte depletion. These quantitative data parallel those from model systems where podocyte depletion is the causative event. This result supports a hypothesis that in AS podocyte adherence to the GBM is defective resulting in accelerated podocyte detachment causing progressive podocyte depletion leading to FSGS-like pathologic changes and eventual End Stage Kidney Disease. Early intervention to reduce podocyte depletion is projected to prolong kidney survival in AS.
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Affiliation(s)
- Larysa Wickman
- Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Jeffrey B. Hodgin
- Department of Pathology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Su Q. Wang
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Farsad Afshinnia
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, United States of America
| | - David Kershaw
- Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Roger C. Wiggins
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail:
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36
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Moreno JA, Yuste C, Gutiérrez E, Sevillano ÁM, Rubio-Navarro A, Amaro-Villalobos JM, Praga M, Egido J. Haematuria as a risk factor for chronic kidney disease progression in glomerular diseases: A review. Pediatr Nephrol 2016; 31:523-33. [PMID: 25980470 DOI: 10.1007/s00467-015-3119-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Revised: 04/15/2015] [Accepted: 04/20/2015] [Indexed: 12/18/2022]
Abstract
Haematuria has long been considered to be a benign condition associated with glomerular diseases. However, new evidences suggest that haematuria has a pathogenic role in promoting kidney disease progression. An increased risk for end-stage renal disease has been reported in adolescents and young adults with persistent microscopic haematuria. A persistent impairment of renal function has been also reported following macroscopic haematuria-associated acute kidney injury in immunoglobulin A nephropathy. Haematuria-induced renal damage has been related to oxidant, cytotoxic and inflammatory effects induced by haemoglobin or haem released from red blood cells. The pathophysiological origin of haematuria may be due to a more fragile and easily ruptured glomerular filtration barrier, as reported in several glomerular diseases. In this review we describe a number of the key issues associated with the epidemiology and pathogenesis of haematuria-associated diseases, provide an update of recent knowledge on the role of haematuria on renal function outcome and discuss specific therapeutic approaches in this setting. KEY SUMMARY POINTS: 1. Glomerular haematuria is a common observation in a number of renal diseases that may lead to persistent renal injury. 2. Haematuria in children differs from that in adults in specific aspects, particularly in the frequency of glomerular diseases and renal disease outcome. 3. Regular follow-up of renal function in children with isolated microhaematuria may be recommended.
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Affiliation(s)
- Juan Antonio Moreno
- Renal, Vascular and Diabetes Research Laboratory, IIS-Fundación Jiménez Díaz, Autonoma University, Av. Reyes Católicos 2, 28040, Madrid, Spain.
| | - Claudia Yuste
- Department of Nephrology, Gregorio Marañon Hospital, 28007, Madrid, Spain
| | - Eduardo Gutiérrez
- Department of Nephrology, 12 de Octubre Hospital, 28041, Madrid, Spain
| | - Ángel M Sevillano
- Department of Nephrology, 12 de Octubre Hospital, 28041, Madrid, Spain
| | - Alfonso Rubio-Navarro
- Renal, Vascular and Diabetes Research Laboratory, IIS-Fundación Jiménez Díaz, Autonoma University, Av. Reyes Católicos 2, 28040, Madrid, Spain
| | - Juan Manuel Amaro-Villalobos
- Renal, Vascular and Diabetes Research Laboratory, IIS-Fundación Jiménez Díaz, Autonoma University, Av. Reyes Católicos 2, 28040, Madrid, Spain
| | - Manuel Praga
- Department of Nephrology, 12 de Octubre Hospital, 28041, Madrid, Spain
| | - Jesús Egido
- Renal, Vascular and Diabetes Research Laboratory, IIS-Fundación Jiménez Díaz, Autonoma University, Av. Reyes Católicos 2, 28040, Madrid, Spain.,Spanish Biomedical Research Network in Diabetes and Associated Metabolic Disorders (CIBERDEM), Madrid, Spain
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Yuan L, Xu H, Yuan J, Deng X, Xiong W, Yang Z, Huang Y, Deng H. A novel FN1 variant associated with familial hematuria: TBMN? Clin Biochem 2016; 49:816-20. [PMID: 26968105 DOI: 10.1016/j.clinbiochem.2016.01.026] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2015] [Revised: 12/17/2015] [Accepted: 01/05/2016] [Indexed: 12/19/2022]
Abstract
OBJECTIVE Thin basement membrane nephropathy (TBMN), an autosomal dominant inherited condition in general, is characterized clinically by persistent hematuria and pathologically by thinning of glomerular basement membrane. TBMN is occasionally accompanied with proteinuria, hypertension and renal impairment in some cases. The aim of this study is to explore the genetic defect in a Chinese pedigree with familial hematuria. DESIGN AND METHODS A four-generation Chinese Han pedigree with familial hematuria was recruited. Exome sequencing was conducted in the proband diagnosed as TBMN, followed by verification in the proband and other family members with Sanger sequencing. RESULTS A novel missense variant, c.4616C>G (p.S1539C), in the fibronectin 1 gene (FN1), was identified, and it co-segregated with the disease condition in the family. It was not observed in 100 normal controls. CONCLUSIONS A missense variant in the FN1 gene is possibly responsible for familial hematuria or TBMN in this family, which may broaden the phenotype and mutation spectrums of the FN1 gene. A male patient in this family progressed to end-stage renal disease requiring kidney transplantation, supporting that familial hematuria or TBMN may not always be as benign as generally thought. The findings may have new implications for clinical monitoring and genetic counseling of the family, and may also help understand the pathogenesis.
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Affiliation(s)
- Lamei Yuan
- Center for Experimental Medicine and Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Hongbo Xu
- Center for Experimental Medicine and Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Jinzhong Yuan
- Department of Nephrology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Xiong Deng
- Center for Experimental Medicine and Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Wei Xiong
- Cancer Research Institute, Xiangya School of Medicine, Central South University, Changsha, China
| | - Zhijian Yang
- Center for Experimental Medicine and Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Yuzhou Huang
- Center for Experimental Medicine and Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Hao Deng
- Center for Experimental Medicine and Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, China.
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38
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A Novel COL4A4 Mutation Identified in a Chinese Family with Thin Basement Membrane Nephropathy. Sci Rep 2016; 6:20244. [PMID: 26833262 PMCID: PMC4735746 DOI: 10.1038/srep20244] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 12/29/2015] [Indexed: 11/08/2022] Open
Abstract
Thin basement membrane nephropathy (TBMN) is often attributable to mutations in the COL4A3 or COL4A4 genes that encode the α3 and α4 chains of type IV collagen, respectively, a major structural protein in the glomerular basement membrane. The aim of this study was to explore a new disease-related genetic mutation associated with the clinical phenotype observed in a Chinese Han family with autosomal dominant TBMN. We conducted a clinical and genetic study comprising seven members of this TBMN family. Mutation screening for COL4A3 and COL4A4 was carried out by direct sequencing. The RNA sequences associated with both proteins were also analyzed with reverse transcription PCR and TA cloning. The result showed that every affected patient had a novel heterozygous splicing mutation in COL4A4 (c.1459 + 1G > A), which led to the elimination of the entire exon 21 from the COL4A4 cDNA and resulted in the direct splicing of exons 20 and 22. This in turn caused a frameshift mutation after exon 20 in the open reading frame of COL4A4. In conclusion, we describe a novel splicing mutation in COL4A4 that results in TBMN. This analysis increases our understanding of TBMN phenotype-genotype correlations, which should facilitate more accurate diagnosis and prenatal diagnosis of TBMN.
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39
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Vivante A, Hildebrandt F. Exploring the genetic basis of early-onset chronic kidney disease. Nat Rev Nephrol 2016; 12:133-46. [PMID: 26750453 DOI: 10.1038/nrneph.2015.205] [Citation(s) in RCA: 215] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The primary causes of chronic kidney disease (CKD) in children differ from those of CKD in adults. In the USA the most common diagnostic groups of renal disease that manifest before the age of 25 years are congenital anomalies of the kidneys and urinary tract, steroid-resistant nephrotic syndrome, chronic glomerulonephritis and renal cystic ciliopathies, which together encompass >70% of early-onset CKD diagnoses. Findings from the past decade suggest that early-onset CKD is caused by mutations in any one of over 200 different monogenic genes. Developments in high-throughput sequencing in the past few years has rendered identification of causative mutations in this high number of genes feasible. Use of genetic analyses in patients with early onset-CKD will provide patients and their families with a molecular genetic diagnosis, generate new insights into disease mechanisms, facilitate aetiology-based classifications of patient cohorts for clinical studies, and might have consequences for personalized approaches to the prevention and treatment of CKD. In this Review, we discuss the implications of next-generation sequencing in clinical genetic diagnostics and the discovery of novel genes in early-onset CKD. We also delineate the resulting opportunities for deciphering disease mechanisms and the therapeutic implications of these findings.
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Affiliation(s)
- Asaf Vivante
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, Massachusetts 02115, USA.,Talpiot Medical Leadership Program, Sheba Medical Center, Tel-Hashomer 52621, Israel
| | - Friedhelm Hildebrandt
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, Massachusetts 02115, USA
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40
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COL4A3/COL4A4 heterozygous mutations with TBMN presenting as focal segmental glomerulosclerosis. Kidney Int 2015; 87:859. [PMID: 25826548 DOI: 10.1038/ki.2015.38] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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41
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Athanasiou Y, Voskarides K, Chatzikyriakidou A, Ignatiou A, Demosthenous P, Elia A, Zavros M, Georgiou I, Pierides A, Deltas C. Molecular and Clinical Investigation of Cystinuria in the Greek-Cypriot Population. Genet Test Mol Biomarkers 2015; 19:641-5. [PMID: 26540609 DOI: 10.1089/gtmb.2015.0144] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND AND AIMS Cystinuria represents 3% of nephrolithiasis in humans. Two genes have been identified as the main genetic causes of cystinuria, SLC3A1 and SLC7A9, with an autosomal recessive mode of inheritance. In the present study, we studied for the first time, genetically and clinically, all the cystinuric families identified so far in the Greek-Cypriot population. METHODS Discovery of mutations was performed through polymerase chain reaction (PCR)-single analysis and DNA resequencing. New families were investigated through PCR-RFLPs. Clinical data were collected through the hospital patients' records and analytical follow-up of the families. RESULTS AND DISCUSSION We found a total of five mutations in 28 Greek-Cypriot cystinuric patients belonging in 12 families. The most frequent mutation among the 28 Greek-Cypriot patients is the SLC3A1-p.T216M, which is also the second most frequent mutation in Europe, representing a genetic founder effect. Sixteen of the 28 patients are homozygous for this mutation. Even though a consanguinity loop was obvious in only one family, other patients were from families in small villages where endogamy was practiced for many centuries. Timely clinical and genetic diagnosis, accompanied by early treatment, is significant for the good health of most of our patients. Only ∼14% of them developed chronic renal failure, and only one reached end-stage renal disease (ESRD). CONCLUSION Five SLC3A1 and SLC7A9 mutations appear to be responsible for the genetic basis of cystinuria in the Greek-Cypriot patients; having such a limited number of causative mutations will simplify diagnostics for this population.
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Affiliation(s)
| | - Konstantinos Voskarides
- 2 Department of Biological Sciences and Molecular Medicine Research Center, University of Cyprus , Nicosia, Cyprus
| | - Anthi Chatzikyriakidou
- 3 Laboratory of General Biology and Genetics, Medical School, Aristotle University of Thessaloniki , Greece
| | - Anastasia Ignatiou
- 2 Department of Biological Sciences and Molecular Medicine Research Center, University of Cyprus , Nicosia, Cyprus
| | - Panayiota Demosthenous
- 2 Department of Biological Sciences and Molecular Medicine Research Center, University of Cyprus , Nicosia, Cyprus
| | - Avraam Elia
- 4 Department of Pediatric/Pediatric Nephrology, Archbishop Makarios III Hospital , Nicosia, Cyprus
| | - Michalis Zavros
- 1 Department of Nephrology, Nicosia General Hospital , Nicosia, Cyprus
| | - Ioannis Georgiou
- 5 Laboratory of Medical Genetics, Medical School, Ioannina University , Greece
| | - Alkis Pierides
- 6 Department of Nephrology, Hippocrateon Hospital , Nicosia, Cyprus
| | - Constantinos Deltas
- 2 Department of Biological Sciences and Molecular Medicine Research Center, University of Cyprus , Nicosia, Cyprus
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42
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Deltas C, Savva I, Voskarides K, Papazachariou L, Pierides A. Carriers of Autosomal Recessive Alport Syndrome with Thin Basement Membrane Nephropathy Presenting as Focal Segmental Glomerulosclerosis in Later Life. Nephron Clin Pract 2015. [PMID: 26201269 DOI: 10.1159/000435789] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Collagen IV nephropathies (COL4Ns) comprise benign familial microscopic hematuria, thin basement membrane nephropathy (TBMN), X-linked Alport syndrome (AS) and also autosomal recessive and dominant AS. Apart from the X-linked form of AS, which is caused by hemizygous mutations in the COL4A5 gene, the other entities are caused by mutations in the COL4A3 or COL4A4 genes. The diagnosis of these conditions used to be based on clinical and/or histological findings of renal biopsies, but it is the new molecular genetics approach that revolutionised their investigation and proved particularly instrumental, especially, in many not so clear-cut cases. More recently, the spectrum of COL4N has expanded to include late onset focal segmental glomerulosclerosis (FSGS) that develops on top of TBMN in later life. Also, other reports showed that some patients with a primary diagnosis of familial FSGS proved to have variants in COL4 genes. In the presence of a renal biopsy picture of FSGS and in the absence of either electron microscopy studies or molecular genetic studies that point to TBMN and COL4N, the patient and his family may be mistakenly diagnosed with hereditary FSGS leading to unnecessary further investigations, erroneous family counselling and improper corticosteroid treatment. TBMN is a frequent finding in the general population, and according to several recent reports, it may be the underlying cause and the explanation for many familial and sporadic cases of late-onset FSGS with non-nephrotic proteinuria. This is an important new finding that needs widespread recognition. It is anticipated that the molecular genetic analysis with next generation sequencing will certainly offer timely correct diagnosis.
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Affiliation(s)
- Constantinos Deltas
- Molecular Medicine Research Center and Laboratory of Molecular and Medical Genetics, Department of Biological Sciences, University of Cyprus, Nicosia, Cyprus
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43
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Stefanou C, Pieri M, Savva I, Georgiou G, Pierides A, Voskarides K, Deltas C. Co-Inheritance of Functional Podocin Variants with Heterozygous Collagen IV Mutations Predisposes to Renal Failure. Nephron Clin Pract 2015; 130:200-12. [PMID: 26138234 DOI: 10.1159/000432406] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 05/16/2015] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS A subset of patients who present with proteinuria and are diagnosed with focal segmental glomerulosclerosis (FSGS) have inherited heterozygous COL4A3/A4 mutations and are also diagnosed with thin basement membrane nephropathy (TBMN-OMIM: 141200). Two studies showed that co-inheritance of NPHS2-p.Arg229Gln, a podocin variant, may increase the risk for proteinuria and renal function decline. METHODS We hypothesized that additional podocin variants may exert a similar effect. We studied genetically a well-characterized Cypriot TBMN patient cohort by re-sequencing the NPHS2 coding region. We also performed functional studies in cell culture experiments, investigating the interaction of podocin variants with itself and with nephrin. RESULTS Potentially disease-modifying podocin variants were searched for by analyzing NPHS2 in 35 'severe' TBMN patients. One non-synonymous variant, p.Glu237Gln, was detected. Both variants, p.Arg229Gln and p.Glu237Gln, were tested in a larger cohort of 122 TBMN patients, who were categorized as 'mild' or 'severe' based on the presence of microscopic hematuria alone or combined with chronic renal failure and/or proteinuria. Seven 'severe' patients carried either of the 2 variants; none was present in the 'mild' patients (p = 0.05, Pearson χ(2)). The 7 carriers belong in 2 families segregating mutation COL4A3-p.Gly1334Glu. Inheritance of the wild-type (WT) and mutant alleles correlated with the phenotype (combined concordance probability 0.003). Immunofluorescence (IF) experiments after dual co-transfection of WT and mutant podocin suggested altered co-localization of mutant homodimers. IF experiments after co-transfection of WT podocin and nephrin showed normal membrane localization, while both podocin variants interfered with normal trafficking, demonstrating perinuclear staining. Immunoprecipitation experiments showed stronger binding of mutant podocin to WT podocin or nephrin. CONCLUSION The results support the hypothesis that certain hypomorphic podocin variants may act as adverse genetic modifiers when co-inherited with COL4A3/A4 mutations, thus predisposing to FSGS and severe kidney function decline.
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Affiliation(s)
- Charalambos Stefanou
- Molecular Medicine Research Center and Laboratory of Molecular and Medical Genetics, Department of Biological Sciences, University of Cyprus, Nicosia, Cyprus
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44
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Yuste C, Gutierrez E, Sevillano AM, Rubio-Navarro A, Amaro-Villalobos JM, Ortiz A, Egido J, Praga M, Moreno JA. Pathogenesis of glomerular haematuria. World J Nephrol 2015; 4:185-95. [PMID: 25949932 PMCID: PMC4419128 DOI: 10.5527/wjn.v4.i2.185] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Revised: 12/19/2014] [Accepted: 12/29/2014] [Indexed: 02/06/2023] Open
Abstract
Haematuria was known as a benign hallmark of some glomerular diseases, but over the last decade, new evidences pointed its negative implications on kidney disease progression. Cytotoxic effects of oxidative stress induced by hemoglobin, heme, or iron released from red blood cells may account for the tubular injury observed in human biopsy specimens. However, the precise mechanisms responsible for haematuria remain unclear. The presence of red blood cells (RBCs) with irregular contours and shape in the urine indicates RBCs egression from the glomerular capillary into the urinary space. Therefore glomerular haematuria may be a marker of glomerular filtration barrier dysfunction or damage. In this review we describe some key issues regarding epidemiology and pathogenesis of haematuric diseases as well as their renal morphological findings.
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45
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Feehally J, Barratt J. The Genetics of IgA Nephropathy: An Overview from Western Countries. KIDNEY DISEASES 2015; 1:33-41. [PMID: 27536663 DOI: 10.1159/000381738] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2015] [Revised: 03/16/2015] [Indexed: 12/27/2022]
Abstract
BACKGROUND IgA nephropathy (IgAN) is the commonest primary glomerulonephritis worldwide and a significant cause of chronic kidney disease and end-stage renal disease. It is widely accepted that genetic factors play a role in the pathogenesis of IgAN. However, the identity of these genetic factors remains uncertain. SUMMARY Critical to all genetic studies is a precise phenotypic definition of the disease. It is well recognised that IgAN displays striking phenotypic variation, raising the possibility that it may not be a single disease and it may not be the same disease in different parts of the world. In this review, we discuss the challenges that this phenotypic variation poses to interpreting genetic data and the current evidence for specific gene involvement in IgAN, focusing particularly on data from European IgAN cohorts. KEY MESSAGE With advances in genetic techniques, in particular next-generation sequencing, and an increased understanding of the importance of copy number variations, epigenetics and transcriptomics, it is likely that we will gain a greater understanding of the genetic basis for IgAN. However, due to the lack of consistency in epidemiological clinicopathological studies both within and between continents, this will only be achieved if we are able to more precisely phenotype IgAN populations. FACTS FROM EAST AND WEST The reported prevalence of IgAN is higher in Asia than in Europe and North America. However, differences in use of biopsy for the diagnosis of IgAN should be taken into account in analysing data from both East and West. In Europe, IgAN affects men more frequently than women; this is not the case in Asia. Familial IgAN has been more frequently reported in Europe than in Asia. Within Europe, familial IgAN is more evident in southern than in northern populations. Changes in the pattern of serum IgA1 O-glycosylation is a common finding in IgAN patients in the East and West. SNPs within the gene coding for the enzyme C1GALT1 have been reported in Chinese and European patients. However, there is no evidence for a role of gene polymorphism of the C1GALT1 chaperone cosmc in Europeans. Genetic variants in the HLA gene family have been observed in populations from the East and West. Associations between IgAN and variants of the TAP1/PSMB and DEFA genes were observed in Asian but not in Western patients. Association with the angiotensin-converting enzyme gene was seen only in Asian patients.
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Affiliation(s)
- John Feehally
- The John Walls Renal Unit, University Hospitals of Leicester, and Department of Infection, Immunity and Inflammation, University of Leicester, Leicester, UK
| | - Jonathan Barratt
- The John Walls Renal Unit, University Hospitals of Leicester, and Department of Infection, Immunity and Inflammation, University of Leicester, Leicester, UK
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Papazachariou L, Demosthenous P, Pieri M, Papagregoriou G, Savva I, Stavrou C, Zavros M, Athanasiou Y, Ioannou K, Patsias C, Panagides A, Potamitis C, Demetriou K, Prikis M, Hadjigavriel M, Kkolou M, Loukaidou P, Pastelli A, Michael A, Lazarou A, Arsali M, Damianou L, Goutziamani I, Soloukides A, Yioukas L, Elia A, Zouvani I, Polycarpou P, Pierides A, Voskarides K, Deltas C. Frequency of COL4A3/COL4A4 mutations amongst families segregating glomerular microscopic hematuria and evidence for activation of the unfolded protein response. Focal and segmental glomerulosclerosis is a frequent development during ageing. PLoS One 2014; 9:e115015. [PMID: 25514610 PMCID: PMC4267773 DOI: 10.1371/journal.pone.0115015] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Accepted: 11/17/2014] [Indexed: 12/29/2022] Open
Abstract
Familial glomerular hematuria(s) comprise a genetically heterogeneous group of conditions which include Alport Syndrome (AS) and thin basement membrane nephropathy (TBMN). Here we investigated 57 Greek-Cypriot families presenting glomerular microscopic hematuria (GMH), with or without proteinuria or chronic kidney function decline, but excluded classical AS. We specifically searched the COL4A3/A4 genes and identified 8 heterozygous mutations in 16 families (28,1%). Eight non-related families featured the founder mutation COL4A3-p.(G1334E). Renal biopsies from 8 patients showed TBMN and focal segmental glomerulosclerosis (FSGS). Ten patients (11.5%) reached end-stage kidney disease (ESKD) at ages ranging from 37-69-yo (mean 50,1-yo). Next generation sequencing of the patients who progressed to ESKD failed to reveal a second mutation in any of the COL4A3/A4/A5 genes, supporting that true heterozygosity for COL4A3/A4 mutations predisposes to CRF/ESKD. Although this could be viewed as a milder and late-onset form of autosomal dominant AS, we had no evidence of ultrastructural features or extrarenal manifestations that would justify this diagnosis. Functional studies in cultured podocytes transfected with wild type or mutant COL4A3 chains showed retention of mutant collagens and differential activation of the unfolded protein response (UPR) cascade. This signifies the potential role of the UPR cascade in modulating the final phenotype in patients with collagen IV nephropathies.
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Affiliation(s)
- Louiza Papazachariou
- Molecular Medicine Research Center and Laboratory of Molecular and Medical Genetics, University of Cyprus, Nicosia, Cyprus
| | - Panayiota Demosthenous
- Molecular Medicine Research Center and Laboratory of Molecular and Medical Genetics, University of Cyprus, Nicosia, Cyprus
| | - Myrtani Pieri
- Molecular Medicine Research Center and Laboratory of Molecular and Medical Genetics, University of Cyprus, Nicosia, Cyprus
| | - Gregory Papagregoriou
- Molecular Medicine Research Center and Laboratory of Molecular and Medical Genetics, University of Cyprus, Nicosia, Cyprus
| | - Isavella Savva
- Molecular Medicine Research Center and Laboratory of Molecular and Medical Genetics, University of Cyprus, Nicosia, Cyprus
| | | | - Michael Zavros
- Department of Nephrology, Nicosia General Hospital, Nicosia, Cyprus
| | | | - Kyriakos Ioannou
- Department of Nephrology, Nicosia General Hospital, Nicosia, Cyprus
| | | | - Alexia Panagides
- Department of Nephrology, Nicosia General Hospital, Nicosia, Cyprus
| | - Costas Potamitis
- Department of Nephrology, Nicosia General Hospital, Nicosia, Cyprus
| | | | - Marios Prikis
- Department of Nephrology, Nicosia General Hospital, Nicosia, Cyprus
| | | | - Maria Kkolou
- Department of Nephrology, Larnaca General Hospital, Larnaca, Cyprus
| | | | | | - Aristos Michael
- Department of Nephrology, Limassol General Hospital, Limassol, Cyprus
| | - Akis Lazarou
- Department of Nephrology, Limassol General Hospital, Limassol, Cyprus
| | - Maria Arsali
- Department of Nephrology, Limassol General Hospital, Limassol, Cyprus
| | - Loukas Damianou
- Department of Nephrology, Limassol General Hospital, Limassol, Cyprus
| | | | | | - Lakis Yioukas
- Department of Nephrology, Paphos General Hospital, Paphos, Cyprus
| | - Avraam Elia
- Department of Pediatrics, Archbishop Makarios III Hospital, Nicosia, Cyprus
| | - Ioanna Zouvani
- Department of Histopathology, Nicosia General Hospital, Nicosia, Cyprus
| | | | - Alkis Pierides
- Department of Nephrology, Hippocrateon Hospital, Nicosia, Cyprus
- * E-mail: (CD); (A. Pierides)
| | - Konstantinos Voskarides
- Molecular Medicine Research Center and Laboratory of Molecular and Medical Genetics, University of Cyprus, Nicosia, Cyprus
| | - Constantinos Deltas
- Molecular Medicine Research Center and Laboratory of Molecular and Medical Genetics, University of Cyprus, Nicosia, Cyprus
- * E-mail: (CD); (A. Pierides)
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Gomez IG, MacKenna DA, Johnson BG, Kaimal V, Roach AM, Ren S, Nakagawa N, Xin C, Newitt R, Pandya S, Xia TH, Liu X, Borza DB, Grafals M, Shankland SJ, Himmelfarb J, Portilla D, Liu S, Chau BN, Duffield JS. Anti-microRNA-21 oligonucleotides prevent Alport nephropathy progression by stimulating metabolic pathways. J Clin Invest 2014; 125:141-56. [PMID: 25415439 DOI: 10.1172/jci75852] [Citation(s) in RCA: 298] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Accepted: 10/23/2014] [Indexed: 02/06/2023] Open
Abstract
MicroRNA-21 (miR-21) contributes to the pathogenesis of fibrogenic diseases in multiple organs, including the kidneys, potentially by silencing metabolic pathways that are critical for cellular ATP generation, ROS production, and inflammatory signaling. Here, we developed highly specific oligonucleotides that distribute to the kidney and inhibit miR-21 function when administered subcutaneously and evaluated the therapeutic potential of these anti-miR-21 oligonucleotides in chronic kidney disease. In a murine model of Alport nephropathy, miR-21 silencing did not produce any adverse effects and resulted in substantially milder kidney disease, with minimal albuminuria and dysfunction, compared with vehicle-treated mice. miR-21 silencing dramatically improved survival of Alport mice and reduced histological end points, including glomerulosclerosis, interstitial fibrosis, tubular injury, and inflammation. Anti-miR-21 enhanced PPARα/retinoid X receptor (PPARα/RXR) activity and downstream signaling pathways in glomerular, tubular, and interstitial cells. Moreover, miR-21 silencing enhanced mitochondrial function, which reduced mitochondrial ROS production and thus preserved tubular functions. Inhibition of miR-21 was protective against TGF-β-induced fibrogenesis and inflammation in glomerular and interstitial cells, likely as the result of enhanced PPARα/RXR activity and improved mitochondrial function. Together, these results demonstrate that inhibition of miR-21 represents a potential therapeutic strategy for chronic kidney diseases including Alport nephropathy.
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48
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Ozdemir O, Kayatas M, Cetinkaya S, Yildirim ME, Silan F, Kurtulgan HK, Koksal B, Urfali M, Candan F. Bcıı--RFLP profiles for serum amiloid A1 and mutated MEFV gene prevalence in chronic renal failure patients requiring long-term hemodialysis. Ren Fail 2014; 37:292-6. [PMID: 25394530 DOI: 10.3109/0886022x.2014.982954] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND AND AIM There is an increased mortality risk in long-term hemodialysis patients of renal failure due to the chronic inflammation. The relationship between the chronic renal failure (CRF) and the role of familial genetic markers remains incompletely understood. In the current study, it was aimed to find out the prevalence of common MEFV gene mutations and BcII polymorphism in serum amyloid A1 (SAA1) gene in chronic renal patients (CRF) who require long-term hemodialysis. METHOD Current cohort includes 242 CRF patients and 245 healthy individuals from the same population. Total genomic DNA was isolated from peripheral blood-EDTA samples and genotyping of target MEFV gene was carried out by reverse hybridization Strip Assay and real-time techniques. The SAA1 gene was genotyped by the BclI-RFLP method. RESULTS Increased mutated MEFV genotypes were found in current CRF patients when compared with the control group from the same ethnicity and the difference was statistically significant (Table 2) (OR: 4.9401, 95% CI: 3.0694-7.9509), p<0.0001. The most frequent point mutations were M694V and E148Q. The mutated T allel frequency in the SAA1 gene was also different when compared with the healthy controls and the difference was found to be statistically significant (χ2: 13.18; p=0.000). CONCLUSIONS The current results indicate the germ-line mutations in both genetic biomarkers (MEFV and SAA1 genes) that are related to inflammation and amyloidosis processes may play a crucial role in CRF pathogenesis due to the long-term chronic inflammation.
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Affiliation(s)
- Ozturk Ozdemir
- Department of Medical Genetics, Faculty of Medicine, Cumhuriyet University , Sivas , Turkey
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49
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Nabais Sá MJ, Storey H, Flinter F, Nagel M, Sampaio S, Castro R, Araújo JA, Gaspar MA, Soares C, Oliveira A, Henriques AC, da Costa AG, Abreu CP, Ponce P, Alves R, Pinho L, Silva SE, de Moura CP, Mendonça L, Carvalho F, Pestana M, Alves S, Carvalho F, Oliveira JP. Collagen type IV-related nephropathies in Portugal: pathogenic COL4A3 and COL4A4 mutations and clinical characterization of 25 families. Clin Genet 2014; 88:456-61. [PMID: 25307543 DOI: 10.1111/cge.12521] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2014] [Revised: 10/04/2014] [Accepted: 10/06/2014] [Indexed: 12/22/2022]
Abstract
Pathogenic mutations in genes COL4A3/COL4A4 are responsible for autosomal Alport syndrome (AS) and thin basement membrane nephropathy (TBMN). We used Sanger sequencing to analyze all exons and splice site regions of COL4A3/COL4A4, in 40 unrelated Portuguese probands with clinical suspicion of AS/TBMN. To assess genotype-phenotype correlations, we compared clinically relevant phenotypes/outcomes between homozygous/compound heterozygous and apparently heterozygous patients. Seventeen novel and four reportedly pathogenic COL4A3/COL4A4 mutations were identified in 62.5% (25/40) of the probands. Regardless of the mutated gene, all patients with ARAS manifested chronic renal failure (CRF) and hearing loss, whereas a minority of the apparently heterozygous patients had CRF or extrarenal symptoms. CRF was diagnosed at a significantly younger age in patients with ARAS. In our families, the occurrence of COL4A3/COL4A4 mutations was higher, while the prevalence of XLAS was lower than expected. Overall, a pathogenic COL4A3/COL4A4/COL4A5 mutation was identified in >50% of patients with fewer than three of the standard diagnostic criteria of AS. With such a population background, simultaneous next-generation sequencing of all three genes may be recommended as the most expedite approach to diagnose collagen IV-related glomerular basement membrane nephropathies.
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Affiliation(s)
- M J Nabais Sá
- Department of Genetics, Faculty of Medicine, Porto, Portugal.,Unit of Research and Development of Nephrology (FCT-725), Faculty of Medicine, University of Porto, Porto, Portugal
| | - H Storey
- Molecular Genetics Laboratory, Viapath, UK
| | - F Flinter
- Genetics Centre, Guy's and St. Thomas' Hospital National Health Service Foundation Trust, London, UK
| | - M Nagel
- Center for Nephrology and Metabolic Diseases, Weisswasser, Germany
| | - S Sampaio
- Unit of Research and Development of Nephrology (FCT-725), Faculty of Medicine, University of Porto, Porto, Portugal.,Department of Nephrology, Hospital de São João, Porto, Portugal
| | - R Castro
- Department of Nephrology, Centro Hospitalar de Trás-os-Montes e Alto Douro, Vila Real, Portugal
| | - J A Araújo
- Department of Nephrology, Hospital dos Marmeleiros, Funchal, Portugal
| | - M A Gaspar
- Dialysis Clinic, NephroCare Restelo, Fresenius Medical Care, Lisboa, Portugal
| | - C Soares
- Department of Nephrology, Hospital de Braga, Braga, Portugal
| | - A Oliveira
- Dialysis Clinic Paredes, Diaverum, Paredes, Portugal
| | - A C Henriques
- Dialysis Clinic, NephroCare Braga, Fresenius Medical Care, Braga, Portugal
| | - A G da Costa
- Department of Nephrology, Hospital de Santa Maria, Lisboa, Portugal
| | - C P Abreu
- Dialysis Clinic Lumiar, Diaverum, Lisboa, Portugal
| | - P Ponce
- Dialysis Clinic, NephroCare Lumiar, Fresenius Medical Care, Lisboa, Portugal
| | - R Alves
- Dialysis Clinic, NephroCare Viseu, Fresenius Medical Care, Viseu, Portugal
| | - L Pinho
- Dialysis Clinic Paredes, Diaverum, Paredes, Portugal
| | - S E Silva
- Department of Ophthalmology, Porto, Portugal
| | - C P de Moura
- Department of Otolaryngology, Porto, Portugal.,Medical Genetics Outpatient Clinic, Hospital de São João, Porto, Portugal
| | - L Mendonça
- Department of Ophthalmology, Hospital de Braga, Braga, Portugal
| | - F Carvalho
- Unit of Renal Morphology, Department of Nephrology, Hospital Curry Cabral, Lisboa, Portugal
| | - M Pestana
- Unit of Research and Development of Nephrology (FCT-725), Faculty of Medicine, University of Porto, Porto, Portugal.,Department of Nephrology, Hospital de São João, Porto, Portugal
| | - S Alves
- Department of Genetics, Faculty of Medicine, Porto, Portugal
| | - F Carvalho
- Department of Genetics, Faculty of Medicine, Porto, Portugal
| | - J P Oliveira
- Department of Genetics, Faculty of Medicine, Porto, Portugal.,Unit of Research and Development of Nephrology (FCT-725), Faculty of Medicine, University of Porto, Porto, Portugal.,Medical Genetics Outpatient Clinic, Hospital de São João, Porto, Portugal
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50
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Nabais Sá MJ, Sampaio S, Oliveira A, Alves S, Moura CP, Silva SE, Castro R, Araújo JA, Rodrigues M, Neves F, Seabra J, Soares C, Gaspar MA, Tavares I, Freitas L, Sousa TC, Henriques AC, Costa FT, Morgado E, Sousa FT, Sousa JP, da Costa AG, Filipe R, Garrido J, Montalban J, Ponce P, Alves R, Faria B, Carvalho MF, Pestana M, Carvalho F, Oliveira JP. Collagen type IV-related nephropathies in Portugal: pathogenic COL4A5 mutations and clinical characterization of 22 families. Clin Genet 2014; 88:462-7. [PMID: 25307721 DOI: 10.1111/cge.12522] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Revised: 10/08/2014] [Accepted: 10/08/2014] [Indexed: 11/28/2022]
Abstract
Alport syndrome (AS) is caused by pathogenic mutations in the genes encoding α3, α4 or α5 chains of collagen IV (COL4A3/COL4A4/COL4A5), resulting in hematuria, chronic renal failure (CRF), sensorineural hearing loss (SNHL) and ocular abnormalities. Mutations in the X-linked COL4A5 gene have been identified in 85% of the families (XLAS). In this study, 22 of 60 probands (37%) of unrelated Portuguese families, with clinical diagnosis of AS and no evidence of autosomal inheritance, had pathogenic COL4A5 mutations detected by Sanger sequencing and/or multiplex-ligation probe amplification, of which 12 (57%) are novel. Males had more severe and earlier renal and extrarenal complications, but microscopic hematuria was a constant finding irrespective of gender. Nonsense and splice site mutations, as well as small and large deletions, were associated with younger age of onset of SNHL in males, and with higher risk of CRF and SNHL in females. Pathogenic COL4A3 or COL4A4 mutations were subsequently identified in more than half of the families without a pathogenic mutation in COL4A5. The lower than expected prevalence of XLAS in Portuguese families warrants the use of next-generation sequencing for simultaneous COL4A3/COL4A4/COL4A5 analysis, as first-tier approach to the genetic diagnosis of collagen type IV-related nephropathies.
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Affiliation(s)
- M J Nabais Sá
- Department of Genetics, Faculty of Medicine, Porto, Portugal.,Unit of Research and Development of Nephrology (FCT-725), Faculty of Medicine, University of Porto, Porto, Portugal
| | - S Sampaio
- Unit of Research and Development of Nephrology (FCT-725), Faculty of Medicine, University of Porto, Porto, Portugal.,Department of Nephrology, Porto, Portugal
| | - A Oliveira
- Department of Nephrology, Porto, Portugal
| | - S Alves
- Department of Genetics, Faculty of Medicine, Porto, Portugal
| | - C P Moura
- Department of Otolaryngology, Porto, Portugal.,Medical Genetics Outpatient Clinic, Porto, Portugal
| | - S E Silva
- Department of Ophthalmology, Hospital de São João, Porto, Portugal
| | - R Castro
- Department of Nephrology, Centro Hospitalar de Trás-os-Montes e Alto Douro, Vila Real, Portugal
| | - J A Araújo
- Department of Nephrology, Hospital dos Marmeleiros, Funchal, Portugal
| | - M Rodrigues
- Department of Medical Genetics, Hospital Dona Estefânia, Lisboa, Portugal
| | - F Neves
- Dialysis Clinic of Santarém, NephroCare-Portugal, Santarém, Portugal
| | - J Seabra
- Department of Nephrology, Centro Hospitalar Vila Nova de Gaia/Espinho, Vila Nova de Gaia, Portugal
| | - C Soares
- Department of Nephrology, Hospital de Braga, Braga, Portugal
| | - M A Gaspar
- Dialysis Clinic of Restelo, NephroCare-Portugal, Lisboa, Portugal
| | - I Tavares
- Unit of Research and Development of Nephrology (FCT-725), Faculty of Medicine, University of Porto, Porto, Portugal.,Dialysis Clinic of Santo Tirso, Uninefro, Santo Tirso, Portugal
| | - L Freitas
- Department of Nephrology, Centro Hospitalar e Universitário de Coimbra, Coimbra, Portugal
| | - T C Sousa
- Department of Nephrology, Hospital de São Teotónio, Viseu, Portugal.,Dialysis Clinic of Guarda, NephroCare-Portugal, Guarda, Portugal
| | - A C Henriques
- Dialysis Clinic of Braga, NephroCare-Portugal, Braga, Portugal
| | - F T Costa
- Department of Nephrology, Hospital Garcia de Orta, Almada, Portugal
| | - E Morgado
- Department of Nephrology, Hospital de Faro, Faro, Portugal
| | - F T Sousa
- Dialysis Clinic of Montijo, NephroCare-Portugal, Montijo, Portugal
| | - J P Sousa
- Department of Nephrology, Centro Hospitalar e Universitário de Coimbra, Coimbra, Portugal.,Dialysis Clinic of Coimbra, NephroCare-Portugal, Coimbra, Portugal
| | - A G da Costa
- Department of Nephrology, Hospital de Santa Maria, Lisboa, Portugal
| | - R Filipe
- Department of Nephrology, Hospital Amato Lusitano, Castelo Branco, Portugal
| | - J Garrido
- Department of Nephrology, Hospital de São Teotónio, Viseu, Portugal
| | - J Montalban
- Dialysis Clinic of Covilhã, NephroCare-Portugal, Covilhã, Portugal
| | - P Ponce
- Dialysis Clinic of Lumiar, NephroCare-Portugal, Lisboa, Portugal
| | - R Alves
- Dialysis Clinic of Viseu, NephroCare-Portugal, Viseu, Portugal
| | - B Faria
- Dialysis Clinic of Guarda, NephroCare-Portugal, Guarda, Portugal
| | - M F Carvalho
- Unit of Renal Morphology, Department of Nephrology, Hospital Curry Cabral, Lisboa, Portugal
| | - M Pestana
- Unit of Research and Development of Nephrology (FCT-725), Faculty of Medicine, University of Porto, Porto, Portugal.,Department of Nephrology, Porto, Portugal
| | - F Carvalho
- Department of Genetics, Faculty of Medicine, Porto, Portugal
| | - J P Oliveira
- Department of Genetics, Faculty of Medicine, Porto, Portugal.,Unit of Research and Development of Nephrology (FCT-725), Faculty of Medicine, University of Porto, Porto, Portugal.,Medical Genetics Outpatient Clinic, Porto, Portugal
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