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Savige J. Tips for Testing Adults With Suspected Genetic Kidney Disease. Am J Kidney Dis 2024; 83:816-824. [PMID: 38147894 DOI: 10.1053/j.ajkd.2023.10.011] [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: 04/10/2023] [Revised: 10/08/2023] [Accepted: 10/14/2023] [Indexed: 12/28/2023]
Abstract
Genetic kidney disease is common but often unrecognized. It accounts for most cystic kidney diseases and tubulopathies, many forms of congenital abnormalities of the kidney and urinary tract (CAKUT), and some glomerulopathies. Genetic kidney disease is typically suspected where the disease usually has a genetic basis or there is another affected family member, a young age at onset, or extrarenal involvement, but there are also many exceptions to these "rules". Genetic testing requires the patient's written informed consent. When a patient declines testing, another later conversation may be worthwhile. Genetic testing not only indicates the diagnosis but also the inheritance pattern, likely at-risk family members, disease in other organs, clinical course, and possibly effective treatments. Sometimes genetic testing does not identify a pathogenic variant even where other evidence is strong. A variant of uncertain significance (VUS) may be reported but should not be used for clinical decision making. It may be reclassified after more information becomes available without necessarily retesting the patient. Patients should be provided with a copy of their genetic test report, the results explained, and at-risk family members offered "cascade" testing. A referral to a clinical geneticist or genetic counselor helps identify affected family members and in providing advice to assist with reproductive decisions.
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Affiliation(s)
- Judy Savige
- University of Melbourne Department of Medicine (Melbourne Health and Northern health), Royal Melbourne Hospital, Parkville, Australia.
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Puapatanakul P, Miner JH. Alport syndrome and Alport kidney diseases - elucidating the disease spectrum. Curr Opin Nephrol Hypertens 2024; 33:283-290. [PMID: 38477333 PMCID: PMC10990029 DOI: 10.1097/mnh.0000000000000983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2024]
Abstract
PURPOSE OF REVIEW With the latest classification, variants in three collagen IV genes, COL4A3 , COL4A4 , and COL4A5 , represent the most prevalent genetic kidney disease in humans, exhibiting diverse, complex, and inconsistent clinical manifestations. This review breaks down the disease spectrum and genotype-phenotype correlations of kidney diseases linked to genetic variants in these genes and distinguishes "classic" Alport syndrome (AS) from the less severe nonsyndromic genetically related nephropathies that we suggest be called "Alport kidney diseases". RECENT FINDINGS Several research studies have focused on the genotype-phenotype correlation under the latest classification scheme of AS. The historic diagnoses of "benign familial hematuria" and "thin basement membrane nephropathy" linked to heterozygous variants in COL4A3 or COL4A4 are suggested to be obsolete, but instead classified as autosomal AS by recent expert consensus due to a significant risk of disease progression. SUMMARY The concept of Alport kidney disease extends beyond classic AS. Patients carrying pathogenic variants in any one of the COL4A3/A4/A5 genes can have variable phenotypes ranging from completely normal/clinically unrecognizable, hematuria without or with proteinuria, or progression to chronic kidney disease and kidney failure, depending on sex, genotype, and interplays of other genetic as well as environmental factors.
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Affiliation(s)
- Pongpratch Puapatanakul
- Division of Nephrology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
- Division of Nephrology, Department of Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Jeffrey H. Miner
- Division of Nephrology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
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Bergeron NAD, Garneau AP, Rousseau-Gagnon M, Riopel J, Isenring P. X-linked Alport syndrome presenting in mother and son with the same unique histopathological features. J Nephrol 2024; 37:769-772. [PMID: 38668984 DOI: 10.1007/s40620-024-01942-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Accepted: 03/24/2024] [Indexed: 06/05/2024]
Abstract
Alport syndrome has been linked to three different genes, that is, COL4A3, COL4A4 and COL4A5. It is characterized by progressive and non-specific glomerulosclerosis with irregular thickening of the glomerular basement membrane (GBM). At times, the histopathologic picture is dominated by lesions that are consistent with focal and segmental glomerulosclerosis or IgA nephropathy. Here, we report the cases of two related individuals (mother and son) who were diagnosed with COL4A5-related Alport syndrome due to a missense variant (p.Gly1170Ser) in a G-X-Y repeat and found to present the same highly unusual histopathological abnormalities on their kidney biopsies. One of the abnormalities shared, which does not appear to have been reported, was reduced COL4A5 immunolabeling that was limited to Bowman's capsule even though the ultrastructure of the GBM was distorted. The other abnormality was superimposed segmental IgA deposition in both individuals, accompanied by mesangial changes in the mother. We feel that these findings provide novel insight into the mechanisms of disease manifestation in Alport syndrome. They suggest, in particular, that collagen expression and/or assemblies in Bowman's capsule is more vulnerable to missense mutations in COL4A5 than elsewhere in the kidney. Our findings also suggest that certain coinherited gene polymorphisms act as unexpectedly important phenotypic determinants in COL4A-related disorders.
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Affiliation(s)
- Nicolas A D Bergeron
- Service of Nephrology, L'Hôtel-Dieu de Québec Research Center, CHU de Québec-Université Laval, 10 McMahon Street (Room 3852), Québec, QC, G1R 2J6, Canada
| | - Alexandre P Garneau
- Service de Néphrologie-Transplantation Rénale Adultes, Hôpital Necker-Enfants Malades, AP-HP, Inserm U1151, Université Paris Cité, Rue de Sèvres, Paris, France
| | - Mathieu Rousseau-Gagnon
- Service of Nephrology, L'Hôtel-Dieu de Québec Research Center, CHU de Québec-Université Laval, 10 McMahon Street (Room 3852), Québec, QC, G1R 2J6, Canada
| | - Julie Riopel
- Service of Pathology, CHU de Québec-Université Laval, Québec, QC, G1R 2J6, Canada
| | - Paul Isenring
- Service of Nephrology, L'Hôtel-Dieu de Québec Research Center, CHU de Québec-Université Laval, 10 McMahon Street (Room 3852), Québec, QC, G1R 2J6, Canada.
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Zheng Q, Gu X, He JC, Xie J. Progress in therapeutic targets on podocyte for Alport syndrome. J Transl Int Med 2024; 12:129-133. [PMID: 38812923 PMCID: PMC11135632 DOI: 10.2478/jtim-2024-0005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2024] Open
Affiliation(s)
- Qimin Zheng
- Department of Nephrology, Shanghai Ruijin Hospital, Shanghai Jiao Tong University, School of Medicine, Shanghai, China
- Institute of Nephrology, Shanghai Jiao Tong University, School of Medicine, Shanghai, China
| | - Xiangchen Gu
- Department of Nephrology, Shanghai Ruijin Hospital, Shanghai Jiao Tong University, School of Medicine, Shanghai, China
- Institute of Nephrology, Shanghai Jiao Tong University, School of Medicine, Shanghai, China
| | - John Cijiang He
- Department of Medicine, Barbara T. Murphy Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, USA
| | - Jingyuan Xie
- Department of Nephrology, Shanghai Ruijin Hospital, Shanghai Jiao Tong University, School of Medicine, Shanghai, China
- Institute of Nephrology, Shanghai Jiao Tong University, School of Medicine, Shanghai, China
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Zeni L, Mescia F, Toso D, Dordoni C, Mazza C, Savoldi G, Econimo L, Cortinovis R, Fisogni S, Alberici F, Scolari F, Izzi C. Clinical Significance of the Cystic Phenotype in Alport Syndrome. Am J Kidney Dis 2024:S0272-6386(24)00681-4. [PMID: 38514012 DOI: 10.1053/j.ajkd.2024.02.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 01/16/2024] [Accepted: 02/02/2024] [Indexed: 03/23/2024]
Abstract
RATIONALE & OBJECTIVE Alport syndrome (AS) is the most common genetic glomerular disease caused by mutations that affect type IV collagen. However, the clinical characteristics and significance of AS with kidney cysts are not well defined. This study investigated the prevalence and clinical significance of cystic kidney phenotype in AS. STUDY DESIGN Retrospective cohort study. SETTING & PARTICIPANTS One hundred-eight patients with AS and a comparison cohort of 79 patients with IgA nephropathy (IgAN). Clinical, genetic, and imaging data were collected from medical records. EXPOSURE Cystic kidney phenotype evaluated by ultrasonography and defined as the presence of≥3 cysts in each kidney; demographic characteristics and estimated glomerular filtration rate (eGFR) at disease onset. OUTCOME Cystic kidney phenotype in the AS and IgAN cohorts; time to chronic kidney disease (CKD) stage 3b and longitudinal changes in eGFR in the AS cohort. ANALYTICAL APPROACH Logistic regression analysis to test independent strengths of associations of clinical/demographic features with the binary outcome of cystic phenotype. Survival analysis for the outcome of reaching CKD stage 3b and linear mixed models for changes in eGFR over time in the AS cohort. RESULTS We studied 108 patients with AS; 76 (70%) had a genetic diagnosis. Autosomal dominant AS was prevalent, accounting for 68% of patients with a genetic diagnosis. Cystic kidney phenotype was observed in 38% of patients with AS and was associated with normal-sized kidneys in all but 3 patients, who showed increased total kidney volume, mimicking autosomal dominant polycystic kidney disease. The prevalence of cystic kidney phenotype was significantly higher in patients with AS when compared with the group of patients with IgAN (42% vs 19%; P=0.002). Patients with the cystic kidney phenotype were older and had more marked reduction in eGFR than patients without cystic changes. Among patients with AS, the cystic phenotype was associated with older age and a faster decline eGFR. LIMITATIONS Retrospective, single-center study. CONCLUSIONS Cystic kidney phenotype is a common finding in AS. The cystic kidney phenotype is a common finding in AS, suggesting a possible role in cystogenesis for the genetic variants that cause this disease. PLAIN-LANGUAGE SUMMARY Hematuria is the classic renal presentation of Alport syndrome (AS), a hereditary glomerulopathy caused by pathogenic variants of the COL4A3-5 genes. An atypical kidney cystic phenotype has been rarely reported in individuals with these variants. To determine the prevalence of kidney cysts, we performed abdominal ultrasonography in a large group of patients with AS and a comparison group of patients with another glomerular kidney disease, IgA nephropathy (IgAN). Multiple kidney cysts, usually with normal kidney volume, were found in 38% of patients with AS. A few patients' kidney volumes were large enough to mimic a different hereditary cystic kidney disease, autosomal dominant polycystic kidney disease. The overall prevalence of kidney cysts in AS was more than double that observed in the well-matched comparison group with IgAN. These findings emphasize the high prevalence of cystic kidney phenotype in AS, suggesting a likely association between the genetic variants that cause this disease and the development of kidney cysts.
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Affiliation(s)
- Letizia Zeni
- Division of Nephrology and Dialysis, Azienda Socio Sanitaria Territoriale (ASST) Spedali Civili
| | - Federica Mescia
- Division of Nephrology and Dialysis, Azienda Socio Sanitaria Territoriale (ASST) Spedali Civili; Department of Medical and Surgical Specialties, Radiological Sciences and Public Health, University of Brescia, Brescia, Italy
| | - Diego Toso
- Division of Nephrology and Dialysis, Azienda Socio Sanitaria Territoriale (ASST) Spedali Civili; Department of Medical and Surgical Specialties, Radiological Sciences and Public Health, University of Brescia, Brescia, Italy
| | - Chiara Dordoni
- Clinical Genetics Unit, Department of Obstetrics and Gynaecology, Azienda Socio Sanitaria Territoriale (ASST) Spedali Civili
| | - Cinzia Mazza
- Medical Genetics Laboratory, Azienda Socio Sanitaria Territoriale (ASST) Spedali Civili
| | - Gianfranco Savoldi
- Medical Genetics Laboratory, Azienda Socio Sanitaria Territoriale (ASST) Spedali Civili
| | - Laura Econimo
- Division of Nephrology and Dialysis, Azienda Socio Sanitaria Territoriale (ASST) Spedali Civili
| | - Roberta Cortinovis
- Division of Nephrology and Dialysis, Azienda Socio Sanitaria Territoriale (ASST) Spedali Civili
| | - Simona Fisogni
- Section of Pathology, Department of Molecular and Translational Medicine, ASST-Spedali Civili, University of Brescia, Brescia, Italy
| | - Federico Alberici
- Division of Nephrology and Dialysis, Azienda Socio Sanitaria Territoriale (ASST) Spedali Civili; Department of Medical and Surgical Specialties, Radiological Sciences and Public Health, University of Brescia, Brescia, Italy
| | - Francesco Scolari
- Division of Nephrology and Dialysis, Azienda Socio Sanitaria Territoriale (ASST) Spedali Civili; Department of Medical and Surgical Specialties, Radiological Sciences and Public Health, University of Brescia, Brescia, Italy
| | - Claudia Izzi
- Clinical Genetics Unit, Department of Obstetrics and Gynaecology, Azienda Socio Sanitaria Territoriale (ASST) Spedali Civili; Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy.
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Dissanayake LV, Kravtsova O, Lowe M, McCrorey MK, Van Beusecum JP, Palygin O, Staruschenko A. The presence of xanthine dehydrogenase is crucial for the maturation of the rat kidneys. Clin Sci (Lond) 2024; 138:269-288. [PMID: 38358003 DOI: 10.1042/cs20231144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 01/24/2024] [Accepted: 02/14/2024] [Indexed: 02/16/2024]
Abstract
The development of the kidney involves essential cellular processes, such as cell proliferation and differentiation, which are led by interactions between multiple signaling pathways. Xanthine dehydrogenase (XDH) catalyzes the reaction producing uric acid in the purine catabolism, which plays a multifaceted role in cellular metabolism. Our previous study revealed that the genetic ablation of the Xdh gene in rats leads to smaller kidneys, kidney damage, decline of renal functions, and failure to thrive. Rats, unlike humans, continue their kidney development postnatally. Therefore, we explored whether XDH plays a critical role in kidney development using SS-/- rats during postnatal development phase. XDH expression was significantly increased from postnatal day 5 to 15 in wild-type but not homozygote rat kidneys. The transcriptomic profile of renal tissue revealed several dysregulated pathways due to the lack of Xdh expression with the remodeling in inflammasome, purinergic signaling, and redox homeostasis. Further analysis suggested that lack of Xdh affects kidney development, likely via dysregulation of epidermal growth factor and its downstream STAT3 signaling. The present study showed that Xdh is essential for kidney maturation. Our data, alongside the previous research, suggests that loss of Xdh function leads to developmental issues, rendering them vulnerable to kidney diseases in adulthood.
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Affiliation(s)
- Lashodya V Dissanayake
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida; Tampa, FL 33602, U.S.A
| | - Olha Kravtsova
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida; Tampa, FL 33602, U.S.A
| | - Melissa Lowe
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida; Tampa, FL 33602, U.S.A
| | - Marice K McCrorey
- Department of Medicine, Division of Nephrology, Medical University of South Carolina, Charleston, SC 29425, U.S.A
| | - Justin P Van Beusecum
- Department of Medicine, Division of Nephrology, Medical University of South Carolina, Charleston, SC 29425, U.S.A
- Ralph H. Johnson Veterans Affairs Healthcare System, Charleston, SC 29403, U.S.A
| | - Oleg Palygin
- Department of Medicine, Division of Nephrology, Medical University of South Carolina, Charleston, SC 29425, U.S.A
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, SC 29425, U.S.A
| | - Alexander Staruschenko
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida; Tampa, FL 33602, U.S.A
- Hypertension and Kidney Research Center, University of South Florida, Tampa, FL 33602, U.S.A
- James A. Haley Veterans' Hospital, Tampa, FL 33612, U.S.A
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Xu LL, Zhou XJ, Zhang H. An Update on the Genetics of IgA Nephropathy. J Clin Med 2023; 13:123. [PMID: 38202130 PMCID: PMC10780034 DOI: 10.3390/jcm13010123] [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: 11/09/2023] [Revised: 12/15/2023] [Accepted: 12/22/2023] [Indexed: 01/12/2024] Open
Abstract
Immunoglobulin A (IgA) nephropathy (IgAN), the most common form of glomerulonephritis, is one of the leading causes of end-stage kidney disease (ESKD). It is widely believed that genetic factors play a significant role in the development of IgAN. Previous studies of IgAN have provided important insights to unravel the genetic architecture of IgAN and its potential pathogenic mechanisms. The genome-wide association studies (GWASs) together have identified over 30 risk loci for IgAN, which emphasizes the importance of IgA production and regulation in the pathogenesis of IgAN. Follow-up fine-mapping studies help to elucidate the candidate causal variant and the potential pathogenic molecular pathway and provide new potential therapeutic targets. With the rapid development of next-generation sequencing technologies, linkage studies based on whole-genome sequencing (WGS)/whole-exome sequencing (WES) also identify rare variants associated with IgAN, accounting for some of the missing heritability. The complexity of pathogenesis and phenotypic variability may be better understood by integrating genetics, epigenetics, and environment. We have compiled a review summarizing the latest advancements in genetic studies on IgAN. We similarly summarized relevant studies examining the involvement of epigenetics in the pathogenesis of IgAN. Future directions and challenges in this field are also proposed.
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Affiliation(s)
- Lin-Lin Xu
- Renal Division, Peking University First Hospital, Beijing 100034, China; (L.-L.X.); (H.Z.)
- Kidney Genetics Center, Peking University Institute of Nephrology, Beijing 100034, China
- Key Laboratory of Renal Disease, Ministry of Health of China, Beijing 100034, China
- Key Laboratory of Chronic Kidney Disease Prevention and Treatment, Peking University, Ministry of Education, Beijing 100034, China
- Research Units of Diagnosis and Treatment of Immune-Mediated Kidney Diseases, Chinese Academy of Medical Sciences, Beijing 100034, China
- State Key Laboratory of Vascular Homeostasis and Remodeling, Peking University, Beijing 100034, China
| | - Xu-Jie Zhou
- Renal Division, Peking University First Hospital, Beijing 100034, China; (L.-L.X.); (H.Z.)
- Kidney Genetics Center, Peking University Institute of Nephrology, Beijing 100034, China
- Key Laboratory of Renal Disease, Ministry of Health of China, Beijing 100034, China
- Key Laboratory of Chronic Kidney Disease Prevention and Treatment, Peking University, Ministry of Education, Beijing 100034, China
- Research Units of Diagnosis and Treatment of Immune-Mediated Kidney Diseases, Chinese Academy of Medical Sciences, Beijing 100034, China
- State Key Laboratory of Vascular Homeostasis and Remodeling, Peking University, Beijing 100034, China
| | - Hong Zhang
- Renal Division, Peking University First Hospital, Beijing 100034, China; (L.-L.X.); (H.Z.)
- Kidney Genetics Center, Peking University Institute of Nephrology, Beijing 100034, China
- Key Laboratory of Renal Disease, Ministry of Health of China, Beijing 100034, China
- Key Laboratory of Chronic Kidney Disease Prevention and Treatment, Peking University, Ministry of Education, Beijing 100034, China
- Research Units of Diagnosis and Treatment of Immune-Mediated Kidney Diseases, Chinese Academy of Medical Sciences, Beijing 100034, China
- State Key Laboratory of Vascular Homeostasis and Remodeling, Peking University, Beijing 100034, China
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Chen YT, Jiang WZ, Lu KD. Novel COL4A3 synonymous mutation causes Alport syndrome coexistent with immunoglobulin A nephropathy in a woman: A case report. World J Clin Cases 2023; 11:5947-5953. [PMID: 37727481 PMCID: PMC10506036 DOI: 10.12998/wjcc.v11.i25.5947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 07/31/2023] [Accepted: 08/08/2023] [Indexed: 09/01/2023] Open
Abstract
BACKGROUND Alport syndrome (AS) is an inherited disease of the glomerular basement membrane caused by mutations in genes encoding α3, α4, or α5 chains of type IV collagen. It manifests with hematuria or proteinuria, which is often accompanied by hearing impairments and ocular abnormalities. Histopathologically, AS shows mesangial proliferation and sometimes incidental immunoglobulin A (IgA) deposition. Hematuria or proteinuria is also a common presentation in patients with IgA nephropathy that makes it difficult to differentially diagnose AS and IgA nephropathy solely based on these clinical and pathological features. CASE SUMMARY Herein, we present the case of a 59-year-old female patient who was admitted to our hospital with persistent microscopic hematuria and occasional proteinuria that had lasted for > 2 years. This patient had a familial history of renal disease and was diagnosed with autosomal dominant AS (ADAS) and IgA nephropathy based on the findings of renal biopsy as well as genetic testing performed using whole-exome sequencing, which suggested that the patient carried a novel heterozygous variation (c.888G>A:p.Gln296Gln) in the COL4A3 gene that enriches the mutation spectrum of ADAS. The proband received an angiotensin receptor blocker therapy after a definitive diagnosis was established. After one year of therapy, a significant reduction in proteinuria was observed. The number of microscopic red blood cells per high-power field decreased to one-quarter of the baseline levels. Renal function also maintained well during the follow-up. CONCLUSION Our case highlights the significance of performing kidney biopsy and genetic testing in the diagnosis of AS and familial IgA nephropathy.
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Affiliation(s)
- Yu-Ting Chen
- The First Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou 310053, Zhejiang Province, China
| | - Wen-Ze Jiang
- The First Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou 310053, Zhejiang Province, China
| | - Ke-Da Lu
- Department of Nephrology, The Third Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou 310005, Zhejiang Province, China
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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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Yuan X, Su Q, Wang H, Shi S, Liu L, Lv J, Wang S, Zhu L, Zhang H. Genetic Variants of the COL4A3 , COL4A4 , and COL4A5 Genes Contribute to Thinned Glomerular Basement Membrane Lesions in Sporadic IgA Nephropathy Patients. J Am Soc Nephrol 2023; 34:132-144. [PMID: 36130833 PMCID: PMC10101589 DOI: 10.1681/asn.2021111447] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 08/22/2022] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Thinned glomerular basement membrane (tGBM) lesions are not uncommon in IgA nephropathy (IgAN). Type IV collagen-built of α 3, α 4, and α 5 chains, encoded by COL4A3 / COL4A4 / COL4A5 genes-is the major component of glomerular basement membrane (GBM). In recent years, mutations in type IV collagen-encoding genes were also reported in patients with a histologic diagnosis of FSGS. Pathogenic COL4A3 / COL4A4 / COL4A5 variants were recently identified in familial cases of IgAN, but the contribution of these variants to sporadic IgAN is still unclear. METHODS We compared 161 patients with sporadic IgAN with tGBM lesions (IgAN-tGBM) to matched patients with IgAN without tGBM lesions and matched patients with thin basement membrane nephropathy (TBMN). Variants of COL4A3 / COL4A4 / COL4A5 genes were screened and evaluated after whole-exome sequencing. GBM thickness was measured, and levels of circulating galactose-deficient IgA1 (Gd-IgA1) were assessed by ELISA. RESULTS The patients with IgAN-tGBM manifested milder disease than did patients with IgAN without tGBM but had more severe features than the patients with TBMN. Exome sequence analysis of the 122 patients with IgAN-tGBM identified 37 diagnostic variants of the COL4A3 / COL4A4 / COL4A5 genes among 38 patients (31.1%). Furthermore, patients with IgAN-tGBM who had diagnostic variants had higher proportions of GBM thickness <250 nm and milder glomerular injury, whereas patients with IgAN-tGBM who did not have diagnostic variants showed more characteristic features of IgAN, including higher intensity of glomerular IgA deposits and elevated Gd-IgA1 levels. These findings suggest different mechanisms in patients with versus without diagnostic variants of these collagen genes. CONCLUSIONS COL4A3 / COL4A4 / COL4A5 variant detection is essential in evaluating patients with sporadic IgAN with tGBM lesions.
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Affiliation(s)
- Xiaohan Yuan
- Renal Division, Department of Medicine, Peking University First Hospital, Beijing, China
- Key Laboratory of Renal Disease (Peking University), National Health Commission, Beijing, China
- Key Laboratory of Chronic Kidney Disease Prevention and Treatment, Ministry of Education, Beijing, China
- Research Units of Diagnosis and Treatment of Immuno-Mediated Kidney Diseases, Chinese Academy of Medical Sciences, Beijing, China
| | - Qing Su
- Renal Division, Department of Medicine, Peking University First Hospital, Beijing, China
- Key Laboratory of Renal Disease (Peking University), National Health Commission, Beijing, China
- Key Laboratory of Chronic Kidney Disease Prevention and Treatment, Ministry of Education, Beijing, China
- Research Units of Diagnosis and Treatment of Immuno-Mediated Kidney Diseases, Chinese Academy of Medical Sciences, Beijing, China
| | - Hui Wang
- Laboratory of Electron Microscopy, Ultrastructural Pathology Center, Peking University First Hospital, Beijing, China
| | - Sufang Shi
- Renal Division, Department of Medicine, Peking University First Hospital, Beijing, China
- Key Laboratory of Renal Disease (Peking University), National Health Commission, Beijing, China
- Key Laboratory of Chronic Kidney Disease Prevention and Treatment, Ministry of Education, Beijing, China
- Research Units of Diagnosis and Treatment of Immuno-Mediated Kidney Diseases, Chinese Academy of Medical Sciences, Beijing, China
| | - Lijun Liu
- Renal Division, Department of Medicine, Peking University First Hospital, Beijing, China
- Key Laboratory of Renal Disease (Peking University), National Health Commission, Beijing, China
- Key Laboratory of Chronic Kidney Disease Prevention and Treatment, Ministry of Education, Beijing, China
- Research Units of Diagnosis and Treatment of Immuno-Mediated Kidney Diseases, Chinese Academy of Medical Sciences, Beijing, China
| | - Jicheng Lv
- Renal Division, Department of Medicine, Peking University First Hospital, Beijing, China
- Key Laboratory of Renal Disease (Peking University), National Health Commission, Beijing, China
- Key Laboratory of Chronic Kidney Disease Prevention and Treatment, Ministry of Education, Beijing, China
- Research Units of Diagnosis and Treatment of Immuno-Mediated Kidney Diseases, Chinese Academy of Medical Sciences, Beijing, China
| | - Suxia Wang
- Laboratory of Electron Microscopy, Ultrastructural Pathology Center, Peking University First Hospital, Beijing, China
| | - Li Zhu
- Renal Division, Department of Medicine, Peking University First Hospital, Beijing, China
- Key Laboratory of Renal Disease (Peking University), National Health Commission, Beijing, China
- Key Laboratory of Chronic Kidney Disease Prevention and Treatment, Ministry of Education, Beijing, China
- Research Units of Diagnosis and Treatment of Immuno-Mediated Kidney Diseases, Chinese Academy of Medical Sciences, Beijing, China
| | - Hong Zhang
- Renal Division, Department of Medicine, Peking University First Hospital, Beijing, China
- Key Laboratory of Renal Disease (Peking University), National Health Commission, Beijing, China
- Key Laboratory of Chronic Kidney Disease Prevention and Treatment, Ministry of Education, Beijing, China
- Research Units of Diagnosis and Treatment of Immuno-Mediated Kidney Diseases, Chinese Academy of Medical Sciences, Beijing, China
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11
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Prevalence of hereditary tubulointerstitial kidney diseases in the German Chronic Kidney Disease study. Eur J Hum Genet 2022; 30:1413-1422. [PMID: 36100708 PMCID: PMC9712573 DOI: 10.1038/s41431-022-01177-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 07/14/2022] [Accepted: 08/15/2022] [Indexed: 11/09/2022] Open
Abstract
Hereditary chronic kidney disease (CKD) appears to be more frequent than the clinical perception. Exome sequencing (ES) studies in CKD cohorts could identify pathogenic variants in ~10% of individuals. Tubulointerstitial kidney diseases, showing no typical clinical/histologic finding but tubulointerstitial fibrosis, are particularly difficult to diagnose. We used a targeted panel (29 genes) and MUC1-SNaPshot to sequence 271 DNAs, selected in defined disease entities and age cutoffs from 5217 individuals in the German Chronic Kidney Disease cohort. We identified 33 pathogenic variants. Of these 27 (81.8%) were in COL4A3/4/5, the largest group being 15 COL4A5 variants with nine unrelated individuals carrying c.1871G>A, p.(Gly624Asp). We found three cysteine variants in UMOD, a novel missense and a novel splice variant in HNF1B and the homoplastic MTTF variant m.616T>C. Copy-number analysis identified a heterozygous COL4A5 deletion, and a HNF1B duplication/deletion, respectively. Overall, pathogenic variants were present in 12.5% (34/271) and variants of unknown significance in 9.6% (26/271) of selected individuals. Bioinformatic predictions paired with gold standard diagnostics for MUC1 (SNaPshot) could not identify the typical cytosine duplication ("c.428dupC") in any individual, implying that ADTKD-MUC1 is rare. Our study shows that >10% of selected individuals carry disease-causing variants in genes partly associated with tubulointerstitial kidney diseases. COL4A3/4/5 genes constitute the largest fraction, implying they are regularly overlooked using clinical Alport syndrome criteria and displaying the existence of phenocopies. We identified variants easily missed by some ES pipelines. The clinical filtering criteria applied enriched for an underlying genetic disorder.
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12
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Xu H, Yu X, Li Y, Huang Z, Zhang L, Min Q, Bi J, Li Z, Liu L, Liang Y, Xu Z, Sun H, Yang S, Shao M. Collagen IV and Podocyte-Related Gene Variants in Patients with Concurrent IgA Nephropathy and Thin Basement Membrane Nephropathy. Nephron Clin Pract 2022; 147:301-310. [PMID: 36349777 PMCID: PMC10906470 DOI: 10.1159/000526971] [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: 01/14/2022] [Accepted: 08/30/2022] [Indexed: 03/03/2024] Open
Abstract
INTRODUCTION IgA nephropathy is the most common primary glomerulonephritis among adults in clinic. Thin basement membrane nephropathy is often underestimated or even omitted if it coincides with IgA nephropathy. Therefore, it is necessary to study the epidemiological, clinical, and molecular characteristics of the concurrence of this entity. METHODS Eight patients with concurrent IgA nephropathy and thin basement membrane nephropathy (IgA-T) were retrospectively analyzed based on their clinicopathological characteristics. Genetic analysis was performed using whole-exome sequencing and Sanger's sequencing. Data of the patients with IgA nephropathy and normal basement membrane (IgA-N) and variants in the local in-house database were used as controls. All candidate variants were assessed in silico. RESULTS The clinical manifestations of patients with IgA-T were hematuria, proteinuria, and renal insufficiency. Histopathological analysis showed mild mesangial hyperplasia, focal segmental glomerulosclerosis, podocyte activation, and foot process fusion. Crescent was rarely seen. COL4A and/or podocyte cytoskeleton and mitochondria-related gene variants were detected in seven IgA-T patients. Three patients exhibited pathogenic variants of COL4A, including a new variant. All IgA-T and one IgA-N patient possessed ITGB4 and/or PLEC variants, but there was no corresponding genotype-phenotype relationship. Six patients possessed other podocyte cytoskeleton and mitochondria-related gene variants such as NPHS2, SRGAP1, MYO1E, MYO1C, WT1, and COQ9, which were first reported in patients with IgA-T and were not in controls. Altogether, there were no significant differences in the degrees of proteinuria, serum creatinine, and eGFR during the follow-up period of 5-10 years, but there was a significant difference in the degree of proteinuria between IgA-T patients with podocyte-related gene variants and IgA-N patients. In the IgA-T group, patients with podocyte-related gene variants seemed predisposed to progress than patients without those variants, with higher proteinuria and serum creatinine and reduced eGFR. CONCLUSION Concurrent thin basement membrane nephropathy and/or heterozygous COL4A gene pathogenic variants do not necessarily predict the short-term progress of sporadic IgA nephropathy in adults. Predisposition factors for this disease progression should be considered for detecting the variants of COL4A and podocyte cytoskeleton and mitochondria-related genes simultaneously, which also manifests the complexity and heterogeneity of IgA nephropathy with concurrent thin basement membrane nephropathy.
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Affiliation(s)
- Hua Xu
- Department of Pathology, The Fourth Clinical Medical College of Guangzhou University of Chinese Medicine, Shenzhen Traditional Chinese Medicine Hospital, Shenzhen, China
| | - XueWen Yu
- Department of Pathology, The Fourth Clinical Medical College of Guangzhou University of Chinese Medicine, Shenzhen Traditional Chinese Medicine Hospital, Shenzhen, China
| | - Yun Li
- Department of Nephrology, The Fourth Clinical Medical College of Guangzhou University of Chinese Medicine, Shenzhen Traditional Chinese Medicine Hospital, Shenzhen, China
| | - ZhongHua Huang
- Department of Pathology, The Fourth Clinical Medical College of Guangzhou University of Chinese Medicine, Shenzhen Traditional Chinese Medicine Hospital, Shenzhen, China
| | - Lu Zhang
- Department of Pathology, The Fourth Clinical Medical College of Guangzhou University of Chinese Medicine, Shenzhen Traditional Chinese Medicine Hospital, Shenzhen, China
| | - QinQin Min
- Department of Pathology, The Fourth Clinical Medical College of Guangzhou University of Chinese Medicine, Shenzhen Traditional Chinese Medicine Hospital, Shenzhen, China
| | - JiaXin Bi
- Department of Pathology, The Fourth Clinical Medical College of Guangzhou University of Chinese Medicine, Shenzhen Traditional Chinese Medicine Hospital, Shenzhen, China
| | - ZhenGuo Li
- Department of Pathology, The Fourth Clinical Medical College of Guangzhou University of Chinese Medicine, Shenzhen Traditional Chinese Medicine Hospital, Shenzhen, China
| | - LingYun Liu
- Department of Pathology, The Fourth Clinical Medical College of Guangzhou University of Chinese Medicine, Shenzhen Traditional Chinese Medicine Hospital, Shenzhen, China
| | - YingYing Liang
- Department of Pathology, The Fourth Clinical Medical College of Guangzhou University of Chinese Medicine, Shenzhen Traditional Chinese Medicine Hospital, Shenzhen, China
| | - ZhouWen Xu
- Department of Pathology, The Fourth Clinical Medical College of Guangzhou University of Chinese Medicine, Shenzhen Traditional Chinese Medicine Hospital, Shenzhen, China
| | - HuiLi Sun
- Department of Nephrology, The Fourth Clinical Medical College of Guangzhou University of Chinese Medicine, Shenzhen Traditional Chinese Medicine Hospital, Shenzhen, China
| | - ShuDong Yang
- Department of Nephrology, The Fourth Clinical Medical College of Guangzhou University of Chinese Medicine, Shenzhen Traditional Chinese Medicine Hospital, Shenzhen, China
| | - MuMin Shao
- Department of Pathology, The Fourth Clinical Medical College of Guangzhou University of Chinese Medicine, Shenzhen Traditional Chinese Medicine Hospital, Shenzhen, China
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13
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Caliskan Y, Lentine KL. Approach to genetic testing to optimize the safety of living donor transplantation in Alport syndrome spectrum. Pediatr Nephrol 2022; 37:1981-1994. [PMID: 35088158 DOI: 10.1007/s00467-022-05430-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 11/26/2021] [Accepted: 12/06/2021] [Indexed: 10/19/2022]
Abstract
Alport syndrome spectrum can be considered as a group of genetic diseases affecting the major basement membrane collagen type IV network in various organs including the ear, eye, and kidney. The living donor candidate evaluation is an ever-changing landscape. Recently, next-generation sequence (NGS) panels have become readily available and provide opportunities to genetically screen recipient and donor candidates for collagen network gene variants. In this review, our aim is to provide a comprehensive update on the role of genetic testing for the evaluation of potential living kidney donors to kidney candidates with Alport syndrome spectrum. We examine the utility of genetic testing in the evaluation of potential donors for recipients with Alport syndrome spectrum, and discuss risks and unresolved challenges. Suggested algorithms in the context of related and unrelated donation are offered. In contemporary practice, an approach to the evaluation of living donor candidates for transplant candidates with Alport syndrome spectrum can incorporate genetic testing in algorithms tailored for donor-recipient relationship status. Ongoing research is needed to inform optimal practice.
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Affiliation(s)
- Yasar Caliskan
- Saint Louis University Center for Abdominal Transplantation, 1201 S. Grand Blvd, St. Louis, MO, 63110, USA.
| | - Krista L Lentine
- Saint Louis University Center for Abdominal Transplantation, 1201 S. Grand Blvd, St. Louis, MO, 63110, USA
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14
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Gomes AM, Lopes D, Almeida C, Santos S, Malheiro J, Lousa I, Caldas Afonso A, Beirão I. Potential Renal Damage Biomarkers in Alport Syndrome—A Review of the Literature. Int J Mol Sci 2022; 23:ijms23137276. [PMID: 35806283 PMCID: PMC9266446 DOI: 10.3390/ijms23137276] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 06/24/2022] [Accepted: 06/28/2022] [Indexed: 02/01/2023] Open
Abstract
Alport syndrome (AS) is the second most common cause of inherited chronic kidney disease. This disorder is caused by genetic variants on COL4A3, COL4A4 and COL4A5 genes. These genes encode the proteins that constitute collagen type IV of the glomerular basement membrane (GBM). The heterodimer COL4A3A4A5 constitutes the majority of the GBM, and it is essential for the normal function of the glomerular filtration barrier (GFB). Alterations in any of collagen type IV constituents cause disruption of the GMB structure, allowing leakage of red blood cells and albumin into the urine, and compromise the architecture of the GFB, inducing inflammation and fibrosis, thus resulting in kidney damage and loss of renal function. The advances in DNA sequencing technologies, such as next-generation sequencing, allow an accurate diagnose of AS. Due to the important risk of the development of progressive kidney disease in AS patients, which can be delayed or possibly prevented by timely initiation of therapy, an early diagnosis of this condition is mandatory. Conventional biomarkers such as albuminuria and serum creatinine increase relatively late in AS. A panel of biomarkers that might detect early renal damage, monitor therapy, and reflect the prognosis would have special interest in clinical practice. The aim of this systematic review is to summarize the biomarkers of renal damage in AS as described in the literature. We found that urinary Podocin and Vascular Endothelial Growth Factor A are important markers of podocyte injury. Urinary Epidermal Growth Factor has been related to tubular damage, interstitial fibrosis and rapid progression of the disease. Inflammatory markers such as Transforming Growth Factor Beta 1, High Motility Group Box 1 and Urinary Monocyte Chemoattractant Protein- 1 are also increased in AS and indicate a higher risk of kidney disease progression. Studies suggest that miRNA-21 is elevated when renal damage occurs. Novel techniques, such as proteomics and microRNAs, are promising.
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Affiliation(s)
- Ana Marta Gomes
- Nephrology Department, Hospital Centre Vila Nova de Gaia/Espinho, 4434-502 Vila Nova de Gaia, Portugal; (A.M.G.); (D.L.); (C.A.)
- UMIB—Unit for Multidiscisciplinary Research on Biomedicine, Department of Nephrology, Dialysis and Transplantation, ICBAS—School of Medicine and Biomedical Sciences, University of Porto, Rua de Jorge Viterbo Ferreira n.º 228, 4050-313 Porto, Portugal; (S.S.); (J.M.)
| | - Daniela Lopes
- Nephrology Department, Hospital Centre Vila Nova de Gaia/Espinho, 4434-502 Vila Nova de Gaia, Portugal; (A.M.G.); (D.L.); (C.A.)
| | - Clara Almeida
- Nephrology Department, Hospital Centre Vila Nova de Gaia/Espinho, 4434-502 Vila Nova de Gaia, Portugal; (A.M.G.); (D.L.); (C.A.)
| | - Sofia Santos
- UMIB—Unit for Multidiscisciplinary Research on Biomedicine, Department of Nephrology, Dialysis and Transplantation, ICBAS—School of Medicine and Biomedical Sciences, University of Porto, Rua de Jorge Viterbo Ferreira n.º 228, 4050-313 Porto, Portugal; (S.S.); (J.M.)
- ITR, Laboratory for Integrative and Translational Research in Population Health, 4050-313 Porto, Portugal
- Nephrology Department, University Hospital Centre of Porto (CHUP), 4099-001 Porto, Portugal
| | - Jorge Malheiro
- UMIB—Unit for Multidiscisciplinary Research on Biomedicine, Department of Nephrology, Dialysis and Transplantation, ICBAS—School of Medicine and Biomedical Sciences, University of Porto, Rua de Jorge Viterbo Ferreira n.º 228, 4050-313 Porto, Portugal; (S.S.); (J.M.)
- ITR, Laboratory for Integrative and Translational Research in Population Health, 4050-313 Porto, Portugal
- Nephrology Department, University Hospital Centre of Porto (CHUP), 4099-001 Porto, Portugal
| | - Irina Lousa
- UCIBIO/REQUIMTE, Laboratory of Biochemistry, Department of Biological Sciences, Faculty Pharmacy, University of Porto, 4050-313 Porto, Portugal;
| | - Alberto Caldas Afonso
- Paediatrics Department, University Hospital Centre of Porto (CHUP), 4099-001 Porto, Portugal;
- European Rare Kidney Disease Centre (ERKNET)—Universitary Hospital Centre of Porto (CHUP), 4099-001 Porto, Portugal
| | - Idalina Beirão
- UMIB—Unit for Multidiscisciplinary Research on Biomedicine, Department of Nephrology, Dialysis and Transplantation, ICBAS—School of Medicine and Biomedical Sciences, University of Porto, Rua de Jorge Viterbo Ferreira n.º 228, 4050-313 Porto, Portugal; (S.S.); (J.M.)
- ITR, Laboratory for Integrative and Translational Research in Population Health, 4050-313 Porto, Portugal
- Nephrology Department, University Hospital Centre of Porto (CHUP), 4099-001 Porto, Portugal
- European Rare Kidney Disease Centre (ERKNET)—Universitary Hospital Centre of Porto (CHUP), 4099-001 Porto, Portugal
- Correspondence: or ; Tel.: +351-222077500
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15
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Savige J. Heterozygous pathogenic COL4A3 or COL4A4 variants (AD Alport syndrome) is common, and not typically associated with end-stage kidney failure, hearing loss or ocular abnormalities. Kidney Int Rep 2022; 7:1933-1938. [PMID: 36090501 PMCID: PMC9458992 DOI: 10.1016/j.ekir.2022.06.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 05/03/2022] [Accepted: 06/01/2022] [Indexed: 12/03/2022] Open
Abstract
The term “autosomal dominant (AD) Alport syndrome” is often used to describe the condition associated with heterozygous pathogenic COL4A3 or COL4A4 variants and has largely replaced “thin basement membrane nephropathy (TBMN).” AD Alport syndrome implies that affected individuals develop end-stage kidney failure (ESKF) as well as the typical Alport hearing loss and ocular abnormalities, but these features have been considered rare with TBMN. Recent studies suggest that ESKF occurs in 14% to 30% of those with heterozygous pathogenic COL4A3 or COL4A4 variants but confirm that the hearing loss and ocular defects occur uncommonly if at all. Uncertainty over the risk of ESKF has persisted. However all the cited studies of heterozygous pathogenic COL4A3 or COL4A4 variants and kidney failure are from hospital-based patients and thus biased toward more severe disease. Multiple unselected cohorts with ESKF have found heterozygous pathogenic variants in COL4A3 and COL4A4 occur about as often as COL4A5 variants, which suggests that AD Alport syndrome causes ESKF as often as X-linked (XL) disease. In the normal population, heterozygous pathogenic COL4A3 and COL4A4 variants are present 20 times more often than COL4A5 variants. Therefore, AD Alport syndrome is complicated by ESKF 20 times less often than XL disease and occurs in fewer than 3% of those with pathogenic COL4A3 or COL4A4 variants by the age of 60. Nevertheless, individuals with heterozygous pathogenic COL4A3 or COL4A4 variants referred to a hospital are still more likely to develop impaired kidney function than those who remain at home undiagnosed.
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16
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The 2019 and 2021 International Workshops on Alport Syndrome. Eur J Hum Genet 2022; 30:507-516. [PMID: 35260866 PMCID: PMC8904161 DOI: 10.1038/s41431-022-01075-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Revised: 02/04/2022] [Accepted: 02/14/2022] [Indexed: 01/27/2023] Open
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17
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Savige J, Lipska-Zietkiewicz BS, Watson E, Hertz JM, Deltas C, Mari F, Hilbert P, Plevova P, Byers P, Cerkauskaite A, Gregory M, Cerkauskiene R, Ljubanovic DG, Becherucci F, Errichiello C, Massella L, Aiello V, Lennon R, Hopkinson L, Koziell A, Lungu A, Rothe HM, Hoefele J, Zacchia M, Martic TN, Gupta A, van Eerde A, Gear S, Landini S, Palazzo V, al-Rabadi L, Claes K, Corveleyn A, Van Hoof E, van Geel M, Williams M, Ashton E, Belge H, Ars E, Bierzynska A, Gangemi C, Renieri A, Storey H, Flinter F. Guidelines for Genetic Testing and Management of Alport Syndrome. Clin J Am Soc Nephrol 2022; 17:143-154. [PMID: 34930753 PMCID: PMC8763160 DOI: 10.2215/cjn.04230321] [Citation(s) in RCA: 38] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Genetic testing for pathogenic COL4A3-5 variants is usually undertaken to investigate the cause of persistent hematuria, especially with a family history of hematuria or kidney function impairment. Alport syndrome experts now advocate genetic testing for persistent hematuria, even when a heterozygous pathogenic COL4A3 or COL4A4 is suspected, and cascade testing of their first-degree family members because of their risk of impaired kidney function. The experts recommend too that COL4A3 or COL4A4 heterozygotes do not act as kidney donors. Testing for variants in the COL4A3-COL4A5 genes should also be performed for persistent proteinuria and steroid-resistant nephrotic syndrome due to suspected inherited FSGS and for familial IgA glomerulonephritis and kidney failure of unknown cause.
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Affiliation(s)
- Judy Savige
- Department of Medicine (Melbourne Health and Northern Health), The University of Melbourne, Parkville, Victoria, Australia
| | | | - Elizabeth Watson
- South West Genetic Laboratory Hub, North Bristol Trust, Bristol, United Kingdom
| | - Jens Michael Hertz
- Department of Clinical Genetics, Odense University Hospital, Odense, Denmark
| | - Constantinos Deltas
- Center of Excellence in Biobanking and Biomedical Research, University of Cyprus Medical School, Nicosia, Cyprus
| | - Francesca Mari
- Department of Medical Biotechnology, Medical Genetics, University of Siena, Siena, Italy
| | - Pascale Hilbert
- Departement de Biologie Moleculaire, Institute de Pathologie et de Genetique, Gosselies, Belgium
| | - Pavlina Plevova
- Department of Medical Genetics, University Hospital of Ostrava, Ostrava, Czech Republic
- Department of Biomedical Sciences, University Hospital of Ostrava, Ostrava, Czech Republic
| | - Peter Byers
- Department of Pathology, University of Washington, Seattle, Washington
- Department of Medicine (Medical Genetics), University of Washington, Seattle, Washington
| | - Agne Cerkauskaite
- Institute of Biomedical Sciences, Faculty of Medicine, Vilnius University, Vilnius, Lithuania
| | - Martin Gregory
- Division of Nephrology, Department of Medicine, University of Utah Health, Salt Lake City, Utah
| | - Rimante Cerkauskiene
- Clinic of Pediatrics, Institute of Clinical Medicine, Faculty of Medicine, Vilnius University, Vilnius, Lithuania
| | - Danica Galesic Ljubanovic
- Department of Pathology, University of Zagreb, School of Medicine, Dubrava University Hospital, Zagreb, Croatia
| | | | | | - Laura Massella
- Division of Nephrology and Dialysis, Bambino Gesù Children's Hospital, Rome, Italy
| | - Valeria Aiello
- Department of Experimental Diagnostic and Specialty Medicine, Nephrology, Dialysis and Renal Transplant Unit, S. Orsola Hospital, University of Bologna, Bologna, Italy
| | - Rachel Lennon
- Wellcome Centre for Cell-Matrix Research, Division of Cell-Matrix Biology and Regenerative Medicine, School of Biological Sciences, Faculty of Biology Medicine and Health, The University of Manchester, Manchester, United Kingdom
| | - Louise Hopkinson
- Wellcome Centre for Cell-Matrix Research, Division of Cell-Matrix Biology and Regenerative Medicine, School of Biological Sciences, Faculty of Biology Medicine and Health, The University of Manchester, Manchester, United Kingdom
| | - Ania Koziell
- School of Immunology and Microbial Sciences, Faculty of Life Sciences, King's College London, London, United Kingdom
| | - Adrian Lungu
- Pediatric Nephrology Department, Fundeni Clinical Institute, Bucharest, Romania
| | | | - Julia Hoefele
- Institute of Human Genetics, Technical University of Munich, Munich, Germany
| | | | | | - Asheeta Gupta
- Birmingham Children’s Hospital, Birmingham, United Kingdom
| | | | | | - Samuela Landini
- Medical Genetics Unit, Department of Clinical and Experimental Biomedical Sciences “Mario Serio,” University of Florence, Florence, Italy
| | - Viviana Palazzo
- Medical Genetics Unit, Meyer Children's University Hospital, Florence, Italy
| | - Laith al-Rabadi
- Health Sciences Centre, University of Utah, Salt Lake City, Utah
| | - Kathleen Claes
- Department of Nephrology and Renal Transplantation, University Hospitals Leuven, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Anniek Corveleyn
- Center for Human Genetics, University Hospitals and Katholieke Universiteit Leuven, Leuven, Belgium
| | - Evelien Van Hoof
- Center for Human Genetics, University Hospitals and Katholieke Universiteit Leuven, Leuven, Belgium
| | - Micheel van Geel
- Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Maggie Williams
- Bristol Genetics Laboratory Pathology Sciences, Southmead Hospital, Southmead, United Kingdom
| | - Emma Ashton
- North East Thames Regional Genetics Laboratory, Great Ormond Street Hospital, London, United Kingdom
| | - Hendica Belge
- Institut de Pathologie et de Génétique, Center for Human Genetics, Gosselies, Belgium
| | - Elisabet Ars
- Molecular Biology Laboratory, Fundacio Puigvert, Instituto de Investigaciones Biomédicas Sant Pau, Universitat Autonoma de Barcelona, Instituto de Investigación Carlos III, Barcelona, Spain
| | - Agnieszka Bierzynska
- Bristol Renal Unit, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Concetta Gangemi
- Division of Nephrology and Dialysis, University Hospital of Verona, Verona, Italy
| | - Alessandra Renieri
- Department of Medical Biotechnology, Medical Genetics, University of Siena, Siena, Italy
| | - Helen Storey
- Molecular Genetics, Viapath Laboratories, Guy’s Hospital, London, United Kingdom
| | - Frances Flinter
- Department of Clinical Genetics, Guy’s and St. Thomas’ National Health Service Foundation Trust, London, United Kingdom
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18
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Kumar R, Keskinyan V, Stangl MC, Lane BM, Buckley AF, Barisoni L, Howell DN, Gbadegesin RA. Case Report: Unusual Aggregation of Different Glomerulopathies in a Family Resolved by Genetic Testing and Reverse Phenotyping. Front Pediatr 2022; 10:826330. [PMID: 35295700 PMCID: PMC8918647 DOI: 10.3389/fped.2022.826330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 01/20/2022] [Indexed: 11/24/2022] Open
Abstract
Glomerular diseases (GDs) are a major cause of chronic kidney disease in children. The conventional approach to diagnosis of GDs includes clinical evaluation and, in most cases, kidney biopsy to make a definitive diagnosis. However, in many cases, clinical presentations of different GDs can overlap, leading to uncertainty in diagnosis and management even after renal biopsy. In this report, we identify a family with clinical diagnoses of postinfectious glomerulonephritis and IgA nephropathy in a parent and two children. Renal biopsies were initially inconclusive; however, genetic testing showed that the two individuals diagnosed at different points with IgA nephropathy carried novel segregating pathogenic variants in COL4A5 gene. We were only able to make the final diagnoses in each of the family members after genetic testing and reverse phenotyping. This case highlights the utility of genetic testing and reverse phenotyping in resolving clinical diagnosis in families with unusual constellations of different glomerulopathies. We propose that clustering of different glomerular disease phenotypes in a family should be an indication for genetic testing followed by reverse phenotyping.
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Affiliation(s)
- Reeti Kumar
- Division of Nephrology, Department of Pediatrics, Duke University Medical Center, Durham, NC, United States
| | - Vahakn Keskinyan
- Division of Nephrology, Department of Pediatrics, Duke University Medical Center, Durham, NC, United States
| | - Megan Chryst Stangl
- Division of Nephrology, Department of Pediatrics, Duke University Medical Center, Durham, NC, United States
| | - Brandon M Lane
- Division of Nephrology, Department of Pediatrics, Duke University Medical Center, Durham, NC, United States
| | - Anne F Buckley
- Division of Renal Pathology, Department of Pathology, Duke University Medical Center, Durham, NC, United States
| | - Laura Barisoni
- Division of Renal Pathology, Department of Pathology, Duke University Medical Center, Durham, NC, United States
| | - David N Howell
- Division of Renal Pathology, Department of Pathology, Duke University Medical Center, Durham, NC, United States
| | - Rasheed A Gbadegesin
- Division of Nephrology, Department of Pediatrics, Duke University Medical Center, Durham, NC, United States
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19
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Savige J, Storey H, Watson E, Hertz JM, Deltas C, Renieri A, Mari F, Hilbert P, Plevova P, Byers P, Cerkauskaite A, Gregory M, Cerkauskiene R, Ljubanovic DG, Becherucci F, Errichiello C, Massella L, Aiello V, Lennon R, Hopkinson L, Koziell A, Lungu A, Rothe HM, Hoefele J, Zacchia M, Martic TN, Gupta A, van Eerde A, Gear S, Landini S, Palazzo V, al-Rabadi L, Claes K, Corveleyn A, Van Hoof E, van Geel M, Williams M, Ashton E, Belge H, Ars E, Bierzynska A, Gangemi C, Lipska-Ziętkiewicz BS. Consensus statement on standards and guidelines for the molecular diagnostics of Alport syndrome: refining the ACMG criteria. Eur J Hum Genet 2021; 29:1186-1197. [PMID: 33854215 PMCID: PMC8384871 DOI: 10.1038/s41431-021-00858-1] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 02/13/2021] [Accepted: 03/02/2021] [Indexed: 02/06/2023] Open
Abstract
The recent Chandos House meeting of the Alport Variant Collaborative extended the indications for screening for pathogenic variants in the COL4A5, COL4A3 and COL4A4 genes beyond the classical Alport phenotype (haematuria, renal failure; family history of haematuria or renal failure) to include persistent proteinuria, steroid-resistant nephrotic syndrome, focal and segmental glomerulosclerosis (FSGS), familial IgA glomerulonephritis and end-stage kidney failure without an obvious cause. The meeting refined the ACMG criteria for variant assessment for the Alport genes (COL4A3-5). It identified 'mutational hotspots' (PM1) in the collagen IV α5, α3 and α4 chains including position 1 Glycine residues in the Gly-X-Y repeats in the intermediate collagenous domains; and Cysteine residues in the carboxy non-collagenous domain (PP3). It considered that 'well-established' functional assays (PS3, BS3) were still mainly research tools but sequencing and minigene assays were commonly used to confirm splicing variants. It was not possible to define the Minor Allele Frequency (MAF) threshold above which variants were considered Benign (BA1, BS1), because of the different modes of inheritances of Alport syndrome, and the occurrence of hypomorphic variants (often Glycine adjacent to a non-collagenous interruption) and local founder effects. Heterozygous COL4A3 and COL4A4 variants were common 'incidental' findings also present in normal reference databases. The recognition and interpretation of hypomorphic variants in the COL4A3-COL4A5 genes remains a challenge.
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Affiliation(s)
- Judy Savige
- grid.1008.90000 0001 2179 088XDepartment of Medicine (MH and NH), The University of Melbourne, Parkville, VIC Australia
| | - Helen Storey
- grid.239826.40000 0004 0391 895XMolecular Genetics, Viapath Laboratories, Guy’s Hospital, London, UK
| | - Elizabeth Watson
- Elizabeth Watson, South West Genomic Laboratory Hub, North Bristol Trust, Bristol, UK
| | - Jens Michael Hertz
- grid.7143.10000 0004 0512 5013Jens Michael Hertz, Department of Clinical Genetics, Odense University Hospital, Odense, Denmark
| | - Constantinos Deltas
- grid.6603.30000000121167908Center of Excellence in Biobanking and Biomedical Research and Molecule Medicine Center, University of Cyprus, Nicosia, Cyprus
| | - Alessandra Renieri
- grid.9024.f0000 0004 1757 4641Medical Genetics, University of Siena, Siena, Italy
| | - Francesca Mari
- Institute de Pathologie et de Genetique ASBL, Departement de Biologie Moleculaire, Gosselies, Belgium
| | - Pascale Hilbert
- Institute de Pathologie et de Genetique ASBL, Departement de Biologie Moleculaire, Gosselies, Belgium
| | - Pavlina Plevova
- grid.412727.50000 0004 0609 0692Department of Medical Genetics, and Department of Biomedical Sciences, University Hospital of Ostrava, Ostrava, Czech Republic
| | - Peter Byers
- grid.34477.330000000122986657Departments of Pathology and Medicine (Medical Genetics), University of Washington, Seattle, WA USA
| | - Agne Cerkauskaite
- grid.6441.70000 0001 2243 2806Institute of Biomedical Sciences, Faculty of Medicine, Vilnius University, Vilnius, Lithuania
| | - Martin Gregory
- grid.223827.e0000 0001 2193 0096Division of Nephrology, Department of Medicine, University of Utah Health, Salt Lake City, UT USA
| | - Rimante Cerkauskiene
- grid.6441.70000 0001 2243 2806Clinic of Pediatrics, Institute of Clinical Medicine, Faculty of Medicine, Vilnius University, Vilnius, Lithuania
| | - Danica Galesic Ljubanovic
- grid.412095.b0000 0004 0631 385XDepartment of Pathology, University of Zagreb, School of Medicine, Dubrava University Hospital, Zagreb, Croatia
| | - Francesca Becherucci
- grid.411477.00000 0004 1759 0844Nephrology Unit and Meyer Children’s University Hospital, Firenze, Italy
| | - Carmela Errichiello
- grid.411477.00000 0004 1759 0844Nephrology Unit and Meyer Children’s University Hospital, Firenze, Italy
| | - Laura Massella
- grid.414125.70000 0001 0727 6809Division of Nephrology and Dialysis, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Valeria Aiello
- grid.6292.f0000 0004 1757 1758Department of Experimental Diagnostic and Specialty Medicine (DIMES), Nephrology, Dialysis and Renal Transplant Unit, S. Orsola Hospital, University of Bologna, Bologna, Italy
| | - Rachel Lennon
- grid.5379.80000000121662407Wellcome Centre for Cell-Matrix Research, Division of Cell-Matrix Biology and Regenerative Medicine, School of Biological Sciences, Faculty of Biology Medicine and Health, The University of Manchester, Manchester, UK
| | - Louise Hopkinson
- grid.5379.80000000121662407Wellcome Centre for Cell-Matrix Research, Division of Cell-Matrix Biology and Regenerative Medicine, School of Biological Sciences, Faculty of Biology Medicine and Health, The University of Manchester, Manchester, UK
| | - Ania Koziell
- grid.13097.3c0000 0001 2322 6764School of Immunology and Microbial Sciences, Faculty of Life Sciences, King’s College London, London, UK
| | - Adrian Lungu
- grid.415180.90000 0004 0540 9980Fundeni Clinical Institute, Pediatric Nephrology Department, Bucharest, Romania
| | | | - Julia Hoefele
- grid.6936.a0000000123222966Institute of Human Genetics, Technical University of Munich, München, Germany
| | | | - Tamara Nikuseva Martic
- grid.4808.40000 0001 0657 4636Department of Biology, School of Medicine University of Zagreb, Zagreb, Croatia
| | - Asheeta Gupta
- grid.415246.00000 0004 0399 7272Birmingham Children’s Hospital, Birmingham, UK
| | - Albertien van Eerde
- grid.5477.10000000120346234Departments of Genetics and Center for Molecular Medicine, University Medical Center, Utrecht University, Utrecht, The Netherlands
| | | | - Samuela Landini
- grid.8404.80000 0004 1757 2304Medical Genetics Unit, Department of Clinical and Experimental Biomedical Sciences “Mario Serio”, University of Florence, Florence, Italy
| | - Viviana Palazzo
- grid.411477.00000 0004 1759 0844Medical Genetics Unit, Meyer Children’s University Hospital, Florence, Italy
| | - Laith al-Rabadi
- grid.223827.e0000 0001 2193 0096Health Sciences Centre, University of UTAH, Salt Lake City, UT USA
| | - Kathleen Claes
- grid.410569.f0000 0004 0626 3338Department of Nephrology and Renal Transplantation, University Hospitals Leuven, Leuven, Belgium
| | - Anniek Corveleyn
- grid.410569.f0000 0004 0626 3338Center for Human Genetics, University Hospitals and KU Leuven, Leuven, Belgium
| | - Evelien Van Hoof
- grid.410569.f0000 0004 0626 3338Center for Human Genetics, University Hospitals and KU Leuven, Leuven, Belgium
| | - Micheel van Geel
- grid.412966.e0000 0004 0480 1382Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Maggie Williams
- grid.416201.00000 0004 0417 1173Bristol Genetics Laboratory Pathology Sciences, Southmead Hospital, Bristol, UK
| | - Emma Ashton
- grid.420468.cNorth East Thames Regional Genetics Laboratory, Great Ormond Street Hospital, London, UK
| | - Hendica Belge
- grid.10417.330000 0004 0444 9382Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Elisabeth Ars
- grid.7080.f0000 0001 2296 0625Inherited Kidney Disorders, Fundacio Puigvert, Universitat Autonoma de Barcelona, Barcelona, Spain
| | - Agnieszka Bierzynska
- grid.5337.20000 0004 1936 7603Bristol Renal Unit, Bristol Medical School, University of Bristol, Bristol, UK
| | - Concetta Gangemi
- grid.411475.20000 0004 1756 948XDivision of Nephrology and Dialysis, University Hospital of Verona, Verona, Italy
| | - Beata S. Lipska-Ziętkiewicz
- grid.11451.300000 0001 0531 3426Centre for Rare Diseases, and Clinical Genetics Unit, Medical University of Gdansk, Gdansk, Poland
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20
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Quinlan C, Rheault MN. Genetic Basis of Type IV Collagen Disorders of the Kidney. Clin J Am Soc Nephrol 2021; 16:1101-1109. [PMID: 33849932 PMCID: PMC8425620 DOI: 10.2215/cjn.19171220] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The glomerular basement membrane is a vital component of the filtration barrier of the kidney and is primarily composed of a highly structured matrix of type IV collagen. Specific isoforms of type IV collagen, the α3(IV), α4(IV), and α5(IV) isoforms, assemble into trimers that are required for normal glomerular basement membrane function. Disruption or alteration in these isoforms leads to breakdown of the glomerular basement membrane structure and function and can lead to progressive CKD known as Alport syndrome. However, there is wide variability in phenotype among patients with mutations affecting type IV collagen that depends on a complex interplay of sex, genotype, and X-chromosome inactivation. This article reviews the genetic basis of collagen disorders of the kidney as well as potential treatments for these conditions, including direct alteration of the DNA, RNA therapies, and manipulation of collagen proteins.
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Affiliation(s)
- Catherine Quinlan
- Department of Nephrology, Royal Children’s Hospital, Melbourne, Victoria, Australia,Department of Kidney Regeneration, Murdoch Children’s Research Institute, Melbourne, Victoria, Australia,Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
| | - Michelle N. Rheault
- Division of Pediatric Nephrology, Department of Pediatrics, University of Minnesota Masonic Children’s Hospital, Minneapolis, Minnesota
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21
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Sato Y, Tsukaguchi H, Higasa K, Kawata N, Inui K, Linh TNT, Quynh TTH, Yoshihiko I, Koiwa F, Yoshimura A. Positive renal familial history in IgA nephropathy is associated with worse renal outcomes: a single-center longitudinal study. BMC Nephrol 2021; 22:230. [PMID: 34147067 PMCID: PMC8214250 DOI: 10.1186/s12882-021-02425-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Accepted: 05/31/2021] [Indexed: 12/01/2022] Open
Abstract
Background IgA nephropathy (IgAN) is the most common primary glomerulonephritis worldwide. Although most IgAN cases are sporadic, few show a familial aggregation. However, the prevalence and prognosis of IgAN individuals with positive familial history (FH) of renal disorders remains uncertain. To address these issues, we conducted a longitudinal observational study on a single-institution cohort of patients with biopsy-proven IgAN. Methods A total of 467 IgAN patients who underwent renal biopsy during 1994 to 2019 were ascertained to have positive- or negative-FH by history taking and were followed for an average of 8.9 years. We compared the clinical and pathological features of the two subgroups. The primary outcome, a composite of a hard endpoint (end-stage renal disease [ESRD]) and surrogate endpoint (a 50% or more reduction in the estimated glomerular filtration rate [eGFR] from baseline), was evaluated. To estimate the risk for progression to ESRD, a Cox proportional hazards analysis was performed for a subset of patients who underwent follow-up for > 2 years and had an eGFR > 30 mL/min/1.73 m2 at baseline (n = 389; observation, 8.7 years). Results Positive-FH subtype accounted for 11.6% (n = 54) of all IgAN patients. At baseline, there were no significant differences between the positive- and negative-FH subgroups regarding age, sex, comorbid disease, MEST-C score, observation period, and therapeutic interventions. However, the eGFR value at baselines was significantly lower in the positive-FH subgroup than in the negative-FH subgroup (P < 0.01). On multivariate analysis, positive-FH emerged an independent determinant of poorer renal outcomes (odds ratio, 2.31; 95% confidence interval, 1.10–4.85; P = 0.03), after adjusting for confounding factors. eGFR at follow-up was significantly lower in the positive-FH subgroup than in the negative-FH subgroup after adjustment for age and observation period. Conclusions Positive-FH was found in 11.6% of all IgAN patients, consistent with the incidence seen in previous literature. A significantly lower eGFR at baseline and last follow-up and unfavorable renal outcomes in the positive-FH subgroup suggest that certain genetic risk factors predisposing to renal failure may exist in a fraction of our IgAN cohort. (331 words). Supplementary Information The online version contains supplementary material available at 10.1186/s12882-021-02425-8.
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Affiliation(s)
- Yoshinori Sato
- Department of Internal Medicine, Division of Nephrology, Showa University School of Medicine, Fujigaoka Hospital, 1-30 Fujigaoka, Aobaku, Yokohama, Kanagawa, 227-8501, Japan.
| | - Hiroyasu Tsukaguchi
- 2nd Department of Internal Medicine, Kansai Medical University, Hirakata, Osaka 573-1010, Japan
| | - Koichiro Higasa
- Department of Genome Analysis, Institute of Biomedical Science, Kansai Medical University, Hirakata, Osaka 573-1010, Japan
| | - Naoto Kawata
- Department of Internal Medicine, Division of Nephrology, Showa University School of Medicine, Fujigaoka Hospital, 1-30 Fujigaoka, Aobaku, Yokohama, Kanagawa, 227-8501, Japan
| | - Kiyoko Inui
- Department of Internal Medicine, Division of Nephrology, Showa University School of Medicine, Fujigaoka Hospital, 1-30 Fujigaoka, Aobaku, Yokohama, Kanagawa, 227-8501, Japan
| | - Tran Nguyen Truc Linh
- 2nd Department of Internal Medicine, Kansai Medical University, Hirakata, Osaka 573-1010, Japan
| | - Tran Thuy Huong Quynh
- 2nd Department of Internal Medicine, Kansai Medical University, Hirakata, Osaka 573-1010, Japan
| | - Inoue Yoshihiko
- Department of Internal Medicine, Division of Nephrology, Showa University School of Medicine, Fujigaoka Hospital, 1-30 Fujigaoka, Aobaku, Yokohama, Kanagawa, 227-8501, Japan
| | - Fumihiko Koiwa
- Department of Internal Medicine, Division of Nephrology, Showa University School of Medicine, Fujigaoka Hospital, 1-30 Fujigaoka, Aobaku, Yokohama, Kanagawa, 227-8501, Japan
| | - Ashio Yoshimura
- Department of Internal Medicine, Division of Nephrology, Showa University School of Medicine, Fujigaoka Hospital, 1-30 Fujigaoka, Aobaku, Yokohama, Kanagawa, 227-8501, Japan.,Shinyokohama-Daiichi Clinic, Yokohama, Kanagawa, Japan
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22
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Cambier A, Robert T, Hogan J, Rabant M, Peuchmaur M, Boyer O, Ulinski T, Monteiro RC, Mesnard L. Rare Collagenous Heterozygote Variants in Children With IgA Nephropathy. Kidney Int Rep 2021; 6:1326-1335. [PMID: 34013111 PMCID: PMC8116726 DOI: 10.1016/j.ekir.2021.02.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 02/05/2021] [Accepted: 02/08/2021] [Indexed: 01/15/2023] Open
Abstract
Introduction Childhood IgA nephropathy (cIgAN) is a primary glomerulonephritis clinically characterized by microscopic hematuria and proteinuria, the presence of which may potentially overlap with Alport syndrome. Interestingly, earlier studies suggested that familial IgAN could be linked to the chromosome 2q36 region, also the coding region for collagen type 4 alpha 3/4 (COL4A3/A4). Methods To investigate a possible relationship or phenocopy between Alport syndrome and cIgAN, COL4A3, COL4A4, and COL4A5 exons were sequenced in 36 cIgAN patients. Clinical data and treatment were collected retrospectively. COL4A3/A4/A5 variants were classified according to American College of Medical Genetics and the Association for Molecular Pathology (ACMG/AMP) guidelines. Results Four of 36 cIgAN patients were affected by ACMG class 4/5 COL4A3 heterozygous variants (COL4A3-cIgAN). We found no COL4A4 or COL4A5 variant. Despite having rare and deleterious COL4A3 variants, 3 of 4 COL4A3-cIgAN children developed clinical and biologic features of active IgAN rather than Alport syndrome. Response to intensive immunosuppressive treatment was favorable, leading to a reduction of endocapillary and extracapillary proliferation lesions. High levels of immune immunoglobulin G and A (IgG/IgA) complexes, reduction of proteinuria, and gradual stabilization of estimated glomerular filtration rate (eGFR) argued against Alport syndrome. Nevertheless, COL4A3-cIgAN patients seemed predisposed to a more serious IgAN presentation compared with the non‒COL4A3-cIgAN group, with more glomerulosclerosis and a lower eGFR over time. One of the 4 patients underwent kidney transplant with subsequent IgAN recurrence. Conclusions Predisposition factors for developing serious cIgAN flare-up should be considered for cIgAN with COL4A3 pathologic heterozygous variants. COL4A3 variants, usually responsible for Alport syndrome in adults, should not automatically exclude an immunosuppressive regimen in cIgAN. Moreover, evidence of an ACMG class 4/5 COL4A3 variant in early-stage cIgAN could be a helpful tool for stratifying severity of cIgAN beyond the Oxford classification.
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Affiliation(s)
- Alexandra Cambier
- Service de néphrologie pédiatrique, APHP, Hôpital Universitaire Robert-Debré, Paris, France.,Université de Paris, Paris, France; INSERM U1149; CNRS ERL8252; Centre de recherche sur l'inflammation; Inflamex Laboratory of Excellence, Paris, France.,Inserm UMR_S1155, Paris, France.,Sorbonne Université, Paris, France.,Néphrologie pédiatrique, Centre Hospitalier Universitaire Sainte-Justine, Montréal, Québec, Canada
| | - Thomas Robert
- Centre de néphrologie et transplantation rénale, APHM, Hôpital Universitaire de la Conception, Marseille, France.,Aix Marseille Université, Inserm, MMG, Bioinformatic et genetics.UMRS_1251, Paris, France
| | - Julien Hogan
- Service de néphrologie pédiatrique, APHP, Hôpital Universitaire Robert-Debré, Paris, France
| | - Marion Rabant
- Service de Pathologie, Hôpital Universitaire Hôpital Necker, APHP, Paris, France
| | - Michel Peuchmaur
- Service de Pathologie, Hôpital Universitaire Robert Debré APHP, Paris et Université Diderot, Paris, France
| | - Olivia Boyer
- Service de néphrologie pédiatrique, APHP, Hôpital Universitaire Necker, Paris, France
| | - Tim Ulinski
- Service de néphrologie pédiatrique, APHP, Hôpital Trousseau, Paris, France
| | - Renato C Monteiro
- Université de Paris, Paris, France; INSERM U1149; CNRS ERL8252; Centre de recherche sur l'inflammation; Inflamex Laboratory of Excellence, Paris, France
| | - Laurent Mesnard
- Inserm UMR_S1155, Paris, France.,Sorbonne Université, Paris, France.,Service des urgences néphrologiques et transplantation rénales, APHP, Hôpital Tenon, Paris, France.,Institut des Sciences du Calcul et des Données, Sorbonne Université, Paris, France
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