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Abstract
Since its first description more than 40 years ago, IgA nephropathy has become the most common pattern of primary glomerulonephritis identified in all areas of the world where renal biopsy is routinely performed. This review discusses advances in our understanding of the pathogenesis of IgA nephropathy, principally focusing on work published in the past 5 years. It has been recognized for some time that one of the most consistent features of IgA nephropathy is an alteration in the complement of serum IgA1 O-glycoforms, with an overrepresentation of poorly galactosylated IgA1 O-glycoforms both in the serum and mesangial deposits of patients with IgA nephropathy. New data suggest that poorly galactosylated IgA1 O-glycoforms might act either as autoantigens driving the formation of glycan-specific antibodies, or antigens for cross-reactive antimicrobial antibodies. Formation of these circulating and mesangial IgA-containing immune complexes appears pivotal to the pathogenesis of IgA nephropathy and there is strong in vitro data to support their role in activation of mesangial cells, induction of podocyte injury, and activation of proximal tubular epithelial cells. Genetic factors are likely to influence many facets of pathogenesis both in primary and familial IgA nephropathy, however, to date work in this area has failed to identify consistent candidate genes.
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Affiliation(s)
- Jonathan Barratt
- The John Walls Renal Unit, Leicester General Hospital and Department of Infection, Immunity & Inflammation, University of Leicester, Leicester, United Kingdom
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Floege J. The Pathogenesis of IgA Nephropathy: What Is New and How Does It Change Therapeutic Approaches? Am J Kidney Dis 2011; 58:992-1004. [DOI: 10.1053/j.ajkd.2011.05.033] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2011] [Accepted: 05/26/2011] [Indexed: 02/07/2023]
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Bertinetto FE, Calafell F, Roggero S, Chidichimo R, Garino E, Marcuccio C, Coppo R, Scolari F, Frascá GM, Savoldi S, Schena FP, Amoroso A. Search for genetic association between IgA nephropathy and candidate genes selected by function or by gene mapping at loci IGAN2 and IGAN3. Nephrol Dial Transplant 2011; 27:2328-37. [PMID: 22131235 DOI: 10.1093/ndt/gfr633] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND IgA nephropathy (IgAN) is not generally considered a hereditary disease, even though extensive evidence suggests an undefined genetic influence. Linkage analysis identified a number of genome regions that could contain variations linked to IgAN. METHODS In this case-control association study, genes possibly involved in the development of IgAN were investigated. DNA samples from 460 North Italian patients with IgAN and 444 controls were collected. Candidate genes were selected based on their possible functional involvement (6 genes) or because of their location within linkage-identified genomic regions IGAN2 and IGAN3 (5 and 13 genes within chromosome 4q26-31 and 17q12-22, respectively). One hundred and ninety-two tag and functional single-nucleotide polymorphisms (SNPs) were typed with Veracode GoldenGate technology (Illumina). RESULTS C1GALT1 showed an association with IgAN (rs1008898: P = 0.0019 and rs7790522: P = 0.0049). Associations were found when the population was stratified by gender (C1GALT1, CD300LG, GRN, ITGA2B, ITGB3 in males and C1GALT1, TRPC3, B4GALNT2 in females) and by age (TLR4, ITGB3 in patients aged <27 years). Furthermore, rs7873784 in TLR4 showed an association with proteinuria (G allele: P = 0.0091; GG genotype: P = 0.0077). CONCLUSIONS Age and gender are likely to evidence distinct immunological and inflammatory reactions leading to individual susceptibility to IgAN. Overall, a genetic predisposition to sporadic IgAN was found. We might hypothesize that C1GALT1 and TLR4 polymorphisms influence the risk to develop IgAN and proteinuria, respectively.
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Friedman DJ, Pollak MR. Genetics of kidney failure and the evolving story of APOL1. J Clin Invest 2011; 121:3367-74. [PMID: 21881214 DOI: 10.1172/jci46263] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Chronic kidney disease (CKD) results from a wide array of processes that impair the kidney's ability to perform its major functions. As many as 20 million Americans suffer from CKD and nearly a half million from end-stage renal disease, but there are also examples of centenarians with adequate renal function. Family-based and genome-wide studies suggest that genetic differences substantially influence an individual's lifetime risk for kidney disease. One emerging theme is that evolution of genes related to host defense against pathogens may limit kidney longevity. The identification of these genetic factors will be critical for expanding our understanding of renal development and function as well as for the design of novel therapeutics for kidney disease.
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Affiliation(s)
- David J Friedman
- Nephrology Division, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02115, USA.
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Yamamoto R, Nagasawa Y, Shoji T, Katakami N, Ohtoshi K, Hayaishi-Okano R, Yamasaki Y, Yamauchi A, Tsubakihara Y, Imai E, Rakugi H, Isaka Y. A candidate gene approach to genetic contributors to the development of IgA nephropathy. Nephrol Dial Transplant 2011; 27:1020-30. [PMID: 21737517 DOI: 10.1093/ndt/gfr369] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Genetic factors contributing to the development of IgA nephropathy remain to be elucidated. METHODS The present multicenter cross-sectional case-control study measured genotype frequencies of 65 atherosclerotic disease-related gene polymorphisms in 230 Japanese patients with IgA nephropathy and 262 apparently healthy volunteers with estimated glomerular filtration rate (eGFR) ≥60 mL/min/1.73 m(2) and negative or trace proteinuria and hematuria by dipstick test [non-chronic kidney disease (CKD) participants]. Clinical characteristics at kidney biopsy of patients with IgA nephropathy and those at the study recruitment of non-CKD participants were included as covariates in multivariate logistic regression models. RESULTS Among 31 gene polymorphisms with ≥5% of minor genotype in non-CKD participants, methionine synthase MTR A2756G (D919G) was significantly associated with IgA nephropathy using χ(2) test even after controlling for family-wise error rate by the method of Bonferroni (P = 0.044). A multivariate nonconditional logistic regression model identified MTR A2756G as a significant contributor of IgA nephropathy [2756AG and GG versus AA, odds ratio 0.42 (95% confidence interval 0.25-0.69) and 0.21 (95% confidence interval 0.06-0.68), P(trend) < 0.001]. After each patient with IgA nephropathy was randomly matched to a non-CKD participant on age (±5 years), gender, mean arterial pressure (±5 mmHg) and eGFR (±5 mL/min/1.73 m(2)), a multivariate conditional logistic regression model also verified their significant association [odds ratio 0.42 (95% confidence interval 0.18-1.00) and odds ratio 0.09 (95% confidence interval 0.01-0.73), P(trend) = 0.004]. MTR A2756G was not associated with slope of eGFR (mL/min/1.73 m(2)/year) in 230 patients with IgA nephropathy. CONCLUSION MTR A2756G was associated with the development, but not progression, of IgA nephropathy.
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Affiliation(s)
- Ryohei Yamamoto
- Department of Geriatric Medicine and Nephrology, Osaka University Graduate School of Medicine, Suita, Japan
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Gharavi AG, Kiryluk K, Choi M, Li Y, Hou P, Xie J, Sanna-Cherchi S, Men CJ, Julian BA, Wyatt RJ, Novak J, He JC, Wang H, Lv J, Zhu L, Wang W, Wang Z, Yasuno K, Gunel M, Mane S, Umlauf S, Tikhonova I, Beerman I, Savoldi S, Magistroni R, Ghiggeri GM, Bodria M, Lugani F, Ravani P, Ponticelli C, Allegri L, Boscutti G, Frasca G, Amore A, Peruzzi L, Coppo R, Izzi C, Viola BF, Prati E, Salvadori M, Mignani R, Gesualdo L, Bertinetto F, Mesiano P, Amoroso A, Scolari F, Chen N, Zhang H, Lifton RP. Genome-wide association study identifies susceptibility loci for IgA nephropathy. Nat Genet 2011; 43:321-7. [PMID: 21399633 DOI: 10.1038/ng.787] [Citation(s) in RCA: 473] [Impact Index Per Article: 36.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Accepted: 02/15/2011] [Indexed: 12/15/2022]
Abstract
We carried out a genome-wide association study of IgA nephropathy, a major cause of kidney failure worldwide. We studied 1,194 cases and 902 controls of Chinese Han ancestry, with targeted follow up in Chinese and European cohorts comprising 1,950 cases and 1,920 controls. We identified three independent loci in the major histocompatibility complex, as well as a common deletion of CFHR1 and CFHR3 at chromosome 1q32 and a locus at chromosome 22q12 that each surpassed genome-wide significance (P values for association between 1.59 × 10⁻²⁶ and 4.84 × 10⁻⁹ and minor allele odds ratios of 0.63-0.80). These five loci explain 4-7% of the disease variance and up to a tenfold variation in interindividual risk. Many of the alleles that protect against IgA nephropathy impart increased risk for other autoimmune or infectious diseases, and IgA nephropathy risk allele frequencies closely parallel the variation in disease prevalence among Asian, European and African populations, suggesting complex selective pressures.
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Affiliation(s)
- Ali G Gharavi
- Department of Medicine, Columbia University College of Physicians and Surgeons, New York, New York, USA
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Ju T, Otto VI, Cummings RD. The Tn antigen-structural simplicity and biological complexity. Angew Chem Int Ed Engl 2011; 50:1770-91. [PMID: 21259410 PMCID: PMC7159538 DOI: 10.1002/anie.201002313] [Citation(s) in RCA: 266] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2010] [Indexed: 01/01/2023]
Abstract
Glycoproteins in animal cells contain a variety of glycan structures that are added co- and/or posttranslationally to proteins. Of over 20 different types of sugar-amino acid linkages known, the two major types are N-glycans (Asn-linked) and O-glycans (Ser/Thr-linked). An abnormal mucin-type O-glycan whose expression is associated with cancer and several human disorders is the Tn antigen. It has a relatively simple structure composed of N-acetyl-D-galactosamine with a glycosidic α linkage to serine/threonine residues in glycoproteins (GalNAcα1-O-Ser/Thr), and was one of the first glycoconjugates to be chemically synthesized. The Tn antigen is normally modified by a specific galactosyltransferase (T-synthase) in the Golgi apparatus of cells. Expression of active T-synthase is uniquely dependent on the molecular chaperone Cosmc, which is encoded by a gene on the X chromosome. Expression of the Tn antigen can arise as a consequence of mutations in the genes for T-synthase or Cosmc, or genes affecting other steps of O-glycosylation pathways. Because of the association of the Tn antigen with disease, there is much interest in the development of Tn-based vaccines and other therapeutic approaches based on Tn expression.
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Affiliation(s)
- Tongzhong Ju
- Department of Biochemistry, Emory University School of Medicine, O. Wayne Rollins Research Center, 1510 Clifton Road, Suite 4001, Atlanta, GA 30322 (USA), Fax: (+1) 404‐727‐2738
| | - Vivianne I. Otto
- Institute of Pharmaceutical Sciences, ETH Zurich, 8093 Zurich (Switzerland)
| | - Richard D. Cummings
- Department of Biochemistry, Emory University School of Medicine, O. Wayne Rollins Research Center, 1510 Clifton Road, Suite 4001, Atlanta, GA 30322 (USA), Fax: (+1) 404‐727‐2738
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Ju T, Otto VI, Cummings RD. Das Tn-Antigen - strukturell einfach und biologisch komplex. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201002313] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Cheng W, Zhou X, Zhu L, Shi S, Lv J, Liu L, Zhang H. Polymorphisms in the nonmuscle myosin heavy chain 9 gene (MYH9) are associated with the progression of IgA nephropathy in Chinese. Nephrol Dial Transplant 2011; 26:2544-9. [PMID: 21245129 DOI: 10.1093/ndt/gfq768] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND IgA nephropathy (IgAN) is the leading cause of end-stage renal disease (ESRD) in China considering different compositions of ESRD causes in different ethnicities. A recent genome-wide association study (GWAS) indicated that the MYH9 gene was significantly associated with non-diabetic ESRD in African-Americans and also influenced kidney function in Europeans. Thus, in the present study, we aim to clarify whether MYH9 confers a shared mechanism among different causes of ESRD and to seek possible further insight into our understanding of IgAN by applying GWAS data from ESRD to IgAN. METHODS One thousand one hundred and sixteen Chinese, including 527 patients with renal biopsy-proven IgAN and 589 healthy controls, were enrolled in the present study. Four single neucleotide polymorphisms (SNPs) (rs3752462, rs4821480, rs11089788 and rs2413396) reported to be associated with ESRD with the most significance were genotyped by TaqMan assay or a restriction fragment length polymorphism assay for a further case-control study. RESULTS None of the four SNPs was associated with the susceptibility to IgAN or clinical and pathological characters at the time of renal biopsy. However, estimated glomerular filtration rate decline rate was associated with rs11089788 in the dominant model (P = 0.021). Cox regression showed that rs11089788 (hazard ratio, 3.95; 95% confidence interval, 1.23-12.63; P = 2.1 × 10(-2)) was an independent predictive factor for renal survival. CONCLUSIONS Based on a large Chinese IgAN cohort, we found an association between rs11089788 and prognosis of IgAN, adding to the mounting evidence of MYH9 as an important gene in IgAN to ESRD.
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Affiliation(s)
- Wenrong Cheng
- Renal Division, Peking University First Hospital, Peking University Institute of Nephrology, and Key Laboratory of Renal Disease, Ministry of Health of China, Beijing 100034, People's Republic of China
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61
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Kiryluk K, Julian BA, Wyatt RJ, Scolari F, Zhang H, Novak J, Gharavi AG. Genetic studies of IgA nephropathy: past, present, and future. Pediatr Nephrol 2010; 25:2257-68. [PMID: 20386929 PMCID: PMC2937145 DOI: 10.1007/s00467-010-1500-7] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Revised: 01/08/2010] [Accepted: 01/30/2010] [Indexed: 11/24/2022]
Abstract
Immunoglobulin A nephropathy (IgAN) is the most common form of primary glomerulonephritis worldwide and an important cause of kidney disease in young adults. Highly variable clinical presentation and outcome of IgAN suggest that this diagnosis may encompass multiple subsets of disease that are not distinguishable by currently available clinical tools. Marked differences in disease prevalence between individuals of European, Asian, and African ancestry suggest the existence of susceptibility genes that are present at variable frequencies in these populations. Familial forms of IgAN have also been reported throughout the world but are probably underrecognized because associated urinary abnormalities are often intermittent in affected family members. Of the many pathogenic mechanisms reported, defects in IgA1 glycosylation that lead to formation of immune complexes have been consistently demonstrated. Recent data indicates that these IgA1 glycosylation defects are inherited and constitute a heritable risk factor for IgAN. Because of the complex genetic architecture of IgAN, the efforts to map disease susceptibility genes have been difficult, and no causative mutations have yet been identified. Linkage-based approaches have been hindered by disease heterogeneity and lack of a reliable noninvasive diagnostic test for screening family members at risk of IgAN. Many candidate-gene association studies have been published, but most suffer from small sample size and methodological problems, and none of the results have been convincingly validated. New genomic approaches, including genome-wide association studies currently under way, offer promising tools for elucidating the genetic basis of IgAN.
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Affiliation(s)
- Krzysztof Kiryluk
- Department of Medicine, Division of Nephrology, College of Physicians and Surgeons, Columbia University, 1150 St. Nicholas Avenue, Russ Berrie Pavilion #413, New York, NY 10032 USA
| | - Bruce A. Julian
- Departments of Microbiology and Medicine, University of Alabama at Birmingham, Birmingham, AL USA
| | - Robert J. Wyatt
- Division of Pediatric Nephrology, Department of Pediatrics, Children’s Foundation Research Center at the Le Bonheur Children’s Medical Center, University of Tennessee Health Sciences Center, Memphis, TN USA
| | | | - Hong Zhang
- Renal Division of First Hospital, Institute of Nephrology, Peking University, Beijing, China
| | - Jan Novak
- Departments of Microbiology and Medicine, University of Alabama at Birmingham, Birmingham, AL USA
| | - Ali G. Gharavi
- Department of Medicine, Division of Nephrology, College of Physicians and Surgeons, Columbia University, 1150 St. Nicholas Avenue, Russ Berrie Pavilion #413, New York, NY 10032 USA
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Vuong MT, Hahn-Zoric M, Lundberg S, Gunnarsson I, van Kooten C, Wramner L, Seddighzadeh M, Fernström A, Hanson LÅ, Do LT, Jacobson SH, Padyukov L. Association of soluble CD89 levels with disease progression but not susceptibility in IgA nephropathy. Kidney Int 2010; 78:1281-7. [PMID: 20811333 DOI: 10.1038/ki.2010.314] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The Fc-α receptor (FcαR/CD89) is involved in IgA complex formation and may affect the development of IgA nephropathy (IgAN). In this study, we tested the genetic variations of the CD89 gene in relation to disease susceptibility in IgAN and the expression of soluble CD89 (sCD89) in sera of patients with IgAN and in controls. There was a significant difference between the levels of sCD89-IgA complexes, measured by sandwich enzyme-linked immunosorbent assay (ELISA), in 177 patients with IgAN with and without disease progression at the time of first diagnosis. No such difference was found in 42 patients with other renal diseases. The patients with IgAN without disease progression had stable but high levels of sCD89 over 5-15 years of follow-up in contrast to stable but low levels of sCD89 in the disease progression group. Moreover, levels of sCD89 complexes were correlated with one of the five CD89 genetic variants in 212 patients with IgAN and 477 healthy Caucasians; the single-nucleotide polymorphism (SNP) rs11084377 was significantly associated with a lower expression of sCD89. However, no association between CD89 gene polymorphisms and susceptibility to IgAN was detected. Thus, we found an association between the levels of sCD89-IgA complexes in serum and the severity of IgAN, and a possible genetic component in regulating the production or expression of sCD89.
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Affiliation(s)
- Mai T Vuong
- Rheumatology Unit, Department of Medicine, Karolinska Institutet, Karolinska University Hospital at Solna, Stockholm, Sweden
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63
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Altered modulation of WNT–β-catenin and PI3K/Akt pathways in IgA nephropathy. Kidney Int 2010; 78:396-407. [DOI: 10.1038/ki.2010.138] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Feehally J, Farrall M, Boland A, Gale DP, Gut I, Heath S, Kumar A, Peden JF, Maxwell PH, Morris DL, Padmanabhan S, Vyse TJ, Zawadzka A, Rees AJ, Lathrop M, Ratcliffe PJ. HLA has strongest association with IgA nephropathy in genome-wide analysis. J Am Soc Nephrol 2010; 21:1791-7. [PMID: 20595679 DOI: 10.1681/asn.2010010076] [Citation(s) in RCA: 195] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Demographic and family studies support the existence of a genetic contribution to the pathogenesis of IgA nephropathy, but results from genetic association studies of candidate genes are inconsistent. To systematically survey common genetic variation in this disease, we performed a genome-wide analysis in a cohort of patients with IgA nephropathy selected from the UK Glomerulonephritis DNA Bank. We used two groups of controls: parents of affected individuals and previously genotyped, unaffected, ancestry-matched individuals from the 1958 British Birth Cohort and the UK Blood Service. We genotyped 914 affected or family controls for 318,127 single nucleotide polymorphisms (SNPs). Filtering for low genotype call rates and inferred non-European ancestry left 533 genotyped individuals (187 affected children) for the family-based association analysis and 244 cases and 4980 controls for the case-control analysis. A total of 286,200 SNPs with call rates >95% were available for analysis. Genome-wide analysis showed a strong signal of association on chromosome 6p in the region of the MHC (P = 1 × 10(-9)). The two most strongly associated SNPs showed consistent association in both family-based and case-control analyses. HLA imputation analysis showed that the strongest association signal arose from a combination of DQ loci with some support for an independent HLA-B signal. These results suggest that the HLA region contains the strongest common susceptibility alleles that predispose to IgA nephropathy in the European population.
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Affiliation(s)
- John Feehally
- The John Walls Renal Unit, Leicester General Hospital and Department of Infection, Immunity, and Inflammation, University of Leicester, Leicester, United Kingdom.
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Abstract
BACKGROUND Two decades ago, pedigrees of patients with IgA nephropathy (IgAN) from Pike County, KY, USA, provided evidence for a role of genetic factors in the pathogenesis of this disorder. Subsequently additional pedigrees were described for several communities from northern Italy. Recently, we found another cluster of patients in the Clay County, KY area, about 100 miles southwest of Pike County. AIM The purpose of this study was to evaluate and expand the pedigrees of patients with IgAN from Clay County, KY to provide additional insight into the mechanisms of inheritance of IgAN and assess the possible influence of a founder effect on the prevalence of IgAN in the region. METHOD Since 1980, most patients with IgAN and their relatives in eastern KY have provided personal genealogic data. These data were used to construct pedigrees that included the patients born in Clay County. Nine of 11 patients with IgAN born in Clay County, KY, USA were members of 1 or more of 5 pedigrees, each with 3 - 11 patients with IgAN. CONCLUSION Our findings suggest the possibility of a low-penetrance ancestral mutation in the IgAN kindreds from Clay County.
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McKnight AJ, Currie D, Maxwell AP. Unravelling the genetic basis of renal diseases; from single gene to multifactorial disorders. J Pathol 2010; 220:198-216. [PMID: 19882676 DOI: 10.1002/path.2639] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Chronic kidney disease is common with up to 5% of the adult population reported to have an estimated glomerular filtration rate of < 60 ml/min/1.73 m(2). A large number of pathogenic mutations have been identified that are responsible for 'single gene' renal disorders, such as autosomal dominant polycystic kidney disease and X-linked Alport syndrome. These single gene disorders account for < 15% of the burden of end-stage renal disease that requires dialysis or kidney transplantation. It has proved more difficult to identify the genetic susceptibility underlying common, complex, multifactorial kidney conditions, such as diabetic nephropathy and hypertensive nephrosclerosis. This review describes success to date and explores strategies currently employed in defining the genetic basis for a number of renal disorders. The complementary use of linkage studies, candidate gene and genome-wide association analyses are described and a collation of renal genetic resources highlighted.
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Affiliation(s)
- Amy J McKnight
- Nephrology Research Group, Queen's University of Belfast, Belfast BT9 7AB, Northern Ireland, UK
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Lou T, Zhang J, Gale DP, Rees AJ, Rhodes B, Feehally J, Li C, Li Y, Li R, Huang W, Hu B, Leung JC, Lam MF, Lai KN, Wang Y, Maxwell PH. Variation in IGHMBP2 is not associated with IgA nephropathy in independent studies of UK Caucasian and Chinese Han patients. Nephrol Dial Transplant 2009; 25:1547-54. [DOI: 10.1093/ndt/gfp661] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Kiryluk K, Gharavi AG, Izzi C, Scolari F. IgA nephropathy--the case for a genetic basis becomes stronger. Nephrol Dial Transplant 2009; 25:336-8. [PMID: 19914997 DOI: 10.1093/ndt/gfp593] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Coppo R, Feehally J. Is progression of IgA nephropathy conditioned by genes regulating atherosclerotic damage? Nephrol Dial Transplant 2009; 24:3573-5. [DOI: 10.1093/ndt/gfp524] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Barua M, Pei Y. Identifying susceptibility genes of IgA nephropathy: research in progress. Nephrol Dial Transplant 2009; 24:2957-9. [DOI: 10.1093/ndt/gfp376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Zhu L, Tang W, Li G, Lv J, Ding J, Yu L, Zhao M, Li Y, Zhang X, Shen Y, Zhang H, Wang H. Interaction between variants of two glycosyltransferase genes in IgA nephropathy. Kidney Int 2009; 76:190-8. [DOI: 10.1038/ki.2009.99] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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McKnight AJ, O'Donoghue D, Peter Maxwell A. Annotated chromosome maps for renal disease. Hum Mutat 2009; 30:314-20. [PMID: 19085929 DOI: 10.1002/humu.20885] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A combination of linkage analyses and association studies are currently employed to promote the identification of genetic factors contributing to inherited renal disease. We have standardized and merged complex genetic data from disparate sources, creating unique chromosomal maps to enhance genetic epidemiological investigations. This database and novel renal maps effectively summarize genomic regions of suggested linkage, association, or chromosomal abnormalities implicated in renal disease. Chromosomal regions associated with potential intermediate clinical phenotypes have been integrated, adding support for particular genomic intervals. More than 500 reports from medical databases, published scientific literature, and the World Wide Web were interrogated for relevant renal-related information. Chromosomal regions highlighted for prioritized investigation of renal complications include 3q13-26, 6q22-27, 10p11-15, 16p11-13, and 18q22. Combined genetic and physical maps are effective tools to organize genetic data for complex diseases. These renal chromosome maps provide insights into renal phenotype-genotype relationships and act as a template for future genetic investigations into complex renal diseases. New data from individual researchers and/or future publications can be readily incorporated to this resource via a user-friendly web-form accessed from the website: www.qub.ac.uk/neph-res/CORGI/index.php.
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Affiliation(s)
- Amy Jayne McKnight
- Nephrology Research Group, Queen's University of Belfast, United Kingdom.
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Li R, Xue C, Li C, Lou T, Tao Y, Li Y, Huang W, Zhang J, Leung JCK, Lam MF, Vyse TJ, Lai KN, Wu C, Wang Y. TRAC variants associate with IgA nephropathy. J Am Soc Nephrol 2009; 20:1359-67. [PMID: 19470682 DOI: 10.1681/asn.2008080842] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
The T cell receptor alpha constant gene (TRAC) encodes the constant region of the alpha chain for the T cell receptor, and the association of its gene variants with IgA nephropathy remains controversial. The authors resequenced the gene in 100 patients with IgA nephropathy and 100 controls, tested its linkage disequilibrium pattern, constructed haplotypes, and performed association and functional studies. First, the association between TRAC variants and IgA nephropathy was tested in 704 patients and 704 controls. Next, these 704 patients were divided into two independent datasets--310 with family member(s) and 394 single patients--to test the association separately. Results showed that the gene is located in a recombination hot spot, with nine linkage disequilibrium blocks within a 6.9-kb region. There is a hypervariable region with six single-nucleotide polymorphisms (SNPs) in an 85-bp stretch in intron 1. We identified multiple SNPs and two haplotypes that associate with IgA nephropathy (P = 0.0000013-0.0096 by logistic regression for SNPs; P = 0.0003 and P = 0.0398 for haplotype associations). The family-based study replicated both haplotype findings, and the 394 single-patient case-control study replicated the association with haplotype 1 (P = 0.0033). The overtransmitted/observed haplotypes demonstrated reduced transcription activity compared with the undertransmitted/observed haplotypes. In conclusion, this study suggests an association between TRAC variants and susceptibility to IgA nephropathy.
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Affiliation(s)
- Ru Li
- Department of Medical Genetics and Center for Genome Research, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
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75
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Vuong MT, Lundberg S, Gunnarsson I, Wramner L, Seddighzadeh M, Hahn-Zoric M, Fernström A, Hanson LA, Do LT, Jacobson SH, Padyukov L. Genetic variation in the transforming growth factor-beta1 gene is associated with susceptibility to IgA nephropathy. Nephrol Dial Transplant 2009; 24:3061-7. [PMID: 19258388 PMCID: PMC2747497 DOI: 10.1093/ndt/gfp079] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Background. There is growing evidence of genetic risk for susceptibility to IgA nephropathy. Among several candidate genes related to immunological regulation in renal tissue, TGFB1 is known to be a contributor to proliferation and the development of fibrosis. Methods. We analysed several SNPs in a region of this gene using 212 DNA samples from biopsy-proven IgA nephropathy patients, 146 men and 66 women and 477 healthy age-matched controls (321 men and 156 women) from the same population in Sweden. Results. Frequencies of four out of five selected SNPs (rs6957, rs2241715, rs1800471, rs1982073 and rs1800469) were found to significantly differ between male patients and male controls in a co-dominant model (corrected P ≤ 0.05) and of two SNPs (rs1982073 and rs1800469) in the allelic model (P ≤ 0.05 in 100 000 permutation test). Haplotype analysis for five selected SNPs revealed a significant association of TGGCG with protective effect (P = 0.0012, empirical P = 0.006, 100 000 permutations) and of CTGTA with susceptibility effect (P = 0.0018, empirical P = 0.008, 100 000 permutations). In our study, no association with TGFB1 variations was found when comparing female patients and female controls. No association was found for TGFB1 markers with disease progression for selected individuals from the patient's group. In addition, meta-analysis performed for SNP rs1982073 for combined patients and controls from our study together with published data from two independent studies showed a significant association. Conclusions. Our experimental data together with the meta-analysis suggest TGFB1 as an important candidate gene for further biological studies of IgA nephropathy and as a possible target for therapy. Our data also indicate a possibility of a gender effect in the genetic background of IgA nephropathy.
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Affiliation(s)
- Mai Tuyet Vuong
- Department of Medicine, Danderyd Hospital, Karolinska Institutet, Stockholm, Sweden
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76
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Edey M, Strain L, Ward R, Ahmed S, Thomas T, Goodship THJ. Is complement factor H a susceptibility factor for IgA nephropathy? Mol Immunol 2009; 46:1405-8. [PMID: 19162324 DOI: 10.1016/j.molimm.2008.12.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2008] [Accepted: 12/08/2008] [Indexed: 11/18/2022]
Abstract
There is substantial evidence to suggest that complement activation plays a pivotal role in the pathogenesis of IgA nephropathy. Mesangial C3 deposition is seen in approximately 90% of patients and polymeric IgA has been shown to activate the alternative and lectin pathways. In addition there have been reports of deficiency and mutations in the serum complement regulator factor H (CFH) in association with IgA nephropathy. In this study we have examined the hypothesis that CFH is a susceptibility factor for IgA nephropathy. In 46 IgA nephropathy patients we undertook genotyping of three CFH SNPS (rs3753394, rs3753396 and rs1065489). There was no significant difference in the allele frequency of these 3 SNPs between the patients and normal controls. In the same group of patients we undertook mutation screening of CFH exons 18-23 using direct sequencing and found no abnormalities. All the patients had a normal serum factor H concentration. In this small cohort of IgA nephropathy patients we have not found evidence to support the hypothesis that factor H is a major susceptibility factor for the disease.
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Affiliation(s)
- Matthew Edey
- Institute of Human Genetics, Newcastle University, Newcastle upon Tyne, UK
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77
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Ijpelaar DHT, Schulz A, Aben J, van der Wal A, Bruijn JA, Kreutz R, de Heer E. Genetic predisposition for glomerulonephritis-induced glomerulosclerosis in rats is linked to chromosome 1. Physiol Genomics 2008; 35:173-81. [PMID: 18682577 DOI: 10.1152/physiolgenomics.00268.2007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Genetic factors influence renal disease progression, and several loci have been linked to the spontaneous development of proteinuria and glomerulosclerosis in animal models. However, the role of genetic susceptibility in glomerulonephritis-induced progressive glomerulosclerosis is unknown. In a rat model of mesangial proliferative glomerulonephritis, anti-Thy-1 glomerulonephritis (antiThy1GN), Lewis/Maastricht (Lew/Maa) rats exhibit progression to glomerulosclerosis, whereas in genetically related Lewis/Møllegard (Lew/Moll) rats, glomerular lesions are repaired within 3 wk. The genetic factors underlying this strain-related difference are not known. To identify novel quantitative trait loci (QTL) involved in progression or repair in Lewis rats, 145 female backcross rats [F1(Lew/Maa x Lew/Moll) x Lew/Maa] were studied. After induction of antiThy1GN proteinuria, we determined mesangial activation, the percentage of microaneurysms, and the glomerular damage score for each animal; a genome scan using 187 microsatellite markers was performed. QTL mapping revealed a significant QTL for glomerular damage score on chromosome 1 with a logarithm of odds (LOD) score of 3.9. Homozygosity for Lew/Maa DNA in this region was associated with a higher percentage of damaged glomeruli on day 21. Furthermore, suggestive linkage was found for the percentage of glomeruli with microaneurysms on day 3 on chromosome 1, 6, and 11; for mesangial activation on day 7 on chromosome 18, while proteinuria was suggestively linked to chromosome 5 (day 0), 4 (day 3), and 6 (day 7). This study identifies a QTL on rat chromosome 1 that is significantly linked to progressive glomerulosclerosis after acute glomerulonephritis.
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78
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Buraczynska M. Genetic predictors of renal failure. EXPERT OPINION ON MEDICAL DIAGNOSTICS 2008; 2:651-664. [PMID: 23495776 DOI: 10.1517/17530059.2.6.651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
BACKGROUND Both environmental and genetic factors contribute to the development and progression of chronic kidney disease. The completion of the human genome sequence and advances in genomic technology make possible identification of gene variants associated with renal failure. OBJECTIVE This review discusses the relevant genetic studies in chronic kidney disease, with particular emphasis on the most common causes of end stage renal failure, diabetic nephropathy and glomerulonephritis. METHODS Most of the studies presented were performed in recent years and employed association studies, both population-based and with candidate genes, as well as the genome-wide association and genome-wide scan approaches. RESULTS/CONCLUSION Increasing evidence supports an important role of genetic susceptibility in the development and progression of renal failure. Identification of disease genes will allow the identification of patients at high risk and the development of new strategies to prevent or delay the renal disease process.
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Affiliation(s)
- Monika Buraczynska
- Professor of Medical Sciences Medical University of Lublin, Laboratory for DNA Analysis and Molecular Diagnostics, Department of Nephrology, Dr K Jaczewskiego 8, 20-954 Lublin, Poland +48 81 7244 716 ; +48 81 7244 716 ;
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79
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Primer: strategies for identifying genes involved in renal disease. ACTA ACUST UNITED AC 2008; 4:265-76. [PMID: 18364721 DOI: 10.1038/ncpneph0785] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2007] [Accepted: 01/31/2008] [Indexed: 12/22/2022]
Abstract
The globally increasing number of patients with end-stage renal disease urges the identification of molecular pathways involved in renal pathophysiology, to serve as targets for intervention. Moreover, the identification of genetic risk factors or protective genes can aid tailored therapy. Tools that can be used to identify genes involved in renal disease include gene expression arrays, linkage analysis and association studies. Arrays are a powerful and widely used approach to the analysis of gene transcription and protein expression, whereas linkage analysis and association studies link disease susceptibility to particular genetic regions. Animal models are available to pinpoint the disease-associated genes. Candidate genes so far identified in renal disease include those encoding the podocyte proteins nephrin and podocin, the transcription factor WT1, the calcium channel TRPC6 and the enzyme phospholipase C-epsilon-1 (in congenital nephrotic syndrome and focal segmental glomerulosclerosis), and carnosinase (in diabetic nephropathy). In addition, linkage studies have identified chromosomal regions implicated in systemic lupus erythematosus, diabetic nephropathy and familial IgA nephropathy. Future studies will elucidate the emerging role of epigenetic regulation of gene expression in renal disease.
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80
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Gharavi AG, Moldoveanu Z, Wyatt RJ, Barker CV, Woodford SY, Lifton RP, Mestecky J, Novak J, Julian BA. Aberrant IgA1 glycosylation is inherited in familial and sporadic IgA nephropathy. J Am Soc Nephrol 2008; 19:1008-14. [PMID: 18272841 DOI: 10.1681/asn.2007091052] [Citation(s) in RCA: 191] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
IgA nephropathy (IgAN) is a complex trait determined by genetic and environmental factors. Most IgAN patients exhibit a characteristic undergalactosylation of the O-glycans of the IgA1 hinge region, which promotes formation and glomerular deposition of immune complexes. It is not known whether this aberrant glycosylation is the result of an acquired or inherited defect, or whether the presence of aberrant IgA1 glycoforms alone can produce IgAN. A newly validated lectin enzyme-linked immunosorbent assay (ELISA) was used to determine the serum level of galactose-deficient IgA1 (Gd-IgA1) in a cohort of 89 IgAN patients and 266 of their relatives. High Gd-IgA1 levels (> or =95th percentile for controls) were observed in all 5 available patients with familial IgAN, in 21 of 45 (47%) of their at-risk relatives (assuming autosomal dominant inheritance), and in only 1 of 19 (5%) of unrelated individuals who married into the family. This provides evidence that abnormal IgA1 glycosylation is an inherited rather than acquired trait. Similarly, Gd-IgA1 levels were high in 65 of 84 (78%) patients with sporadic IgAN and in 50 of 202 (25%) blood relatives. Heritability of Gd-IgA1 was estimated at 0.54 (P = 0.0001), and segregation analysis suggested the presence of a major dominant gene on a polygenic background. Because most relatives with abnormal IgA1 glycoforms were asymptomatic, additional cofactors must be required for IgAN to develop. The fact that abnormal IgA1 glycosylation clusters in most but not all families suggests that measuring Gd-IgA1 may help distinguish patients with different pathogenic mechanisms of disease.
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Affiliation(s)
- Ali G Gharavi
- Department of Medicine, Columbia University College of Physicians and Surgeons, 630 W 168th Street, P&S 10-445 New York, New York 10032, USA.
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81
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Liu XQ, Paterson AD, He N, St George-Hyslop P, Rauta V, Gronhagen-Riska C, Laakso M, Thibaudin L, Berthoux F, Cattran D, Pei Y. IL5RA and TNFRSF6B gene variants are associated with sporadic IgA nephropathy. J Am Soc Nephrol 2008; 19:1025-33. [PMID: 18256354 DOI: 10.1681/asn.2007091013] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Familial clustering and genome-wide linkage scans strongly support a genetic susceptibility to familial IgA nephropathy (IgAN), but genetic factors that predispose to sporadic IgAN are unknown. A high-throughput single nucleotide polymorphism (SNP) association study was conducted using a customized Illumina BeadChip in 732 white patients with biopsy-proven IgAN and 503 control subjects from Canada, France, and Finland. Approximately 93% of 1536 SNPs on the array were tag SNPs from Phase I+II of the HapMap with a minor allele frequency > or =5%, designed to capture the common variants of genes within the critical interval of IGAN1 on chromosome 6q22 and 69 biologic candidate genes for IgAN. SNPs of suggestive or significant association were identified by using logistic regression to adjust for age, gender, study site, and population stratification. Despite using a dense marker set that covered an average interval of 6.5 kb between SNPs, there was no strong and consistent association signal within the IGAN1 critical interval. Among the biologic candidate genes examined, two significant association signals were found at IL5RA and TNFRSF6B, the latter being particularly interesting because this gene encodes a decoy receptor for a TNF family ligand that causes IgAN in mice when overexpressed. Pending replication, these data suggest that variants of IL5RA and TNFRSF6B may predispose to sporadic IgAN.
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Affiliation(s)
- Xiao-Qing Liu
- Program in Genetics and Genome Biology, Hospital for Sick Children, University Health, Network and University of Toronto, Toronto, Ontario, Canada
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82
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83
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Barratt J, Smith AC, Molyneux K, Feehally J. Immunopathogenesis of IgAN. Semin Immunopathol 2007; 29:427-43. [PMID: 17851660 DOI: 10.1007/s00281-007-0089-9] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2007] [Accepted: 08/17/2007] [Indexed: 01/29/2023]
Abstract
The defining hallmark of IgA nephropathy (IgAN) is deposition of polymeric IgA1 in the glomerular mesangium accompanied by a mesangial proliferative glomerulonephritis. The mechanisms involved in mesangial polymeric IgA1 deposition and the initiation of inflammatory glomerular injury remain unclear. This lack of a complete understanding of the pathogenesis of IgAN has meant that there is still no treatment known to modify mesangial deposition of IgA. Increasing evidence, however, supports the importance of IgA-containing immune complex formation as a pivotal factor driving mesangial IgA deposition and triggering of glomerular injury. A number of potentially important changes to the IgA1 molecule have been identified in IgAN, which may contribute to immune complex formation. These changes suggest that the polymeric IgA1 that deposits in IgA nephropathy is derived from mucosally primed plasma cells. The presence of this IgA in the circulation reflects displacement of mucosal B lineage cells to systemic sites and may be the result of mishoming of lymphocytes trafficking along the mucosa-bone marrow axis.
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Affiliation(s)
- Jonathan Barratt
- John Walls Renal Unit, Leicester General Hospital, Leicester, LE4 5PW, UK.
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84
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Beerman I, Novak J, Wyatt RJ, Julian BA, Gharavi AG. The genetics of IgA nephropathy. ACTA ACUST UNITED AC 2007; 3:325-38. [PMID: 17525715 DOI: 10.1038/ncpneph0492] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2006] [Accepted: 02/21/2007] [Indexed: 11/09/2022]
Abstract
IgA nephropathy is the most common form of primary glomerulonephritis. Variations in clinical manifestations indicate that a diagnosis of IgA nephropathy encompasses multiple disease subsets that cannot be distinguished on the basis of renal pathology or clinical variables alone. Familial forms of the disease have been reported throughout the world, but are probably under-recognized because associated urinary abnormalities are often intermittent in affected family members. IgA nephropathy has complex determination, with different genes probably causing disease in different patient subgroups. Of the many pathogenic mechanisms reported, defects in IgA1 glycosylation that lead to formation of immune complexes have been consistently implicated. Here, we present the evidence for genetic contributions to the disease, review clinical patterns of familial disease, and summarize some of the most promising genetic studies conducted to date. Linkage-based approaches to the study of familial forms of the disease have identified significant or suggestive loci on chromosomes 6q22-23, 2q36, 4q26-31, 17q12-22 and 3p24-23, but no causal gene has yet been identified. Many interesting, but poorly replicated, genetic association studies have also been reported. We discuss recent developments in analytic tools that should enable genetic studies of sporadic forms of disease by the genome-wide association approach.
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Affiliation(s)
- Isabel Beerman
- Department of Genetics, Yale University, New Haven, CT, USA
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85
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Paterson AD, Liu XQ, Wang K, Magistroni R, Song X, Kappel J, Klassen J, Cattran D, St George-Hyslop P, Pei Y. Genome-wide linkage scan of a large family with IgA nephropathy localizes a novel susceptibility locus to chromosome 2q36. J Am Soc Nephrol 2007; 18:2408-15. [PMID: 17634434 DOI: 10.1681/asn.2007020241] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
IgA nephropathy (IgAN) is the most common glomerulonephritis worldwide and an important cause of ESRD. Familial clustering of cases suggests genetic predisposition to this disease. Two recent genome-wide studies in IgAN have identified a major susceptibility locus on chromosome 6q22 (IGAN1) and two additional loci with suggestive linkage signals on chromosomes 4q26-31 and 17q12-22. A large four-generation family with 14 affected individuals has been clinically ascertained and excluded from linkage to these loci. A genome-wide linkage scan was performed on this family with GeneChip Mapping 10K 2.0 Arrays using an "affected-only" strategy. By nonparametric analysis, two regions of suggestive linkage (multipoint logarithm of odds [LOD] scores >2) were identified on chromosomes 2q36 and 13p12.3. By parametric analysis (assuming an autosomal dominant inheritance, a disease allele frequency of 0.001, phenocopy rate of 0.01, and penetrance of 75%), a significant linkage to chromosome 2q36 (maximum multipoint LOD score 3.47) was found. Nine simple sequence repeat markers then were genotyped in 21 members (included all of the affected individuals), and significant linkage to chromosome 2q36 over a region of 12.2 cM (maximum multipoint LOD score 3.46) was confirmed. Recombination events in two affected individuals, as detected by haplotype analysis, delineated a critical interval of approximately 9 cM (equivalent to approximately 7 Mb) between D2S1323 and D2S362. Taken together, these data provide strong evidence for a novel disease susceptibility locus for familial IgAN.
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Affiliation(s)
- Andrew D Paterson
- Hospital for Sick Children, University of Toronto, Ontario, Canada M5G 2N2
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86
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Woo KT, Lau YK, Wong KS, Zhao Y, Chan CM. Parallel Genotyping of 10,204 Single Nucleotide Polymorphisms to Screen for Susceptible Genes for IgA Nephropathy. ANNALS OF THE ACADEMY OF MEDICINE, SINGAPORE 2000. [DOI: 10.47102/annals-acadmedsg.v38n10p894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Introduction: IgA nephritis (IgAN) is the most common glomerulonephritis worldwide. We aim to genotype SNPs (single nucleotide polymorphisms) genomewide in patients with IgAN to search for genetic clues to its aetiology.
Materials and Methods: Genotyping for 10,204 SNPs genomewide was done with the Gene Chip Human Mapping 10K Microarray (Affymetrix). Twenty-eight patients with IgAN and 30 normal subjects were screened and analysed for differences in genotype frequency, allele frequency and heterozygosity reduction.
Results: Among the most significantly associated SNPs, 48 SNPs were found mapping directly to the intron of 42 genes that localised in 13 somatic chromosomes and chromosome X. Genotype distribution of these SNPs did not deviate from the Hardy-Weinberg equilibrium in normal subjects. The most significantly associated gene, glial cells missing homolog 1 (GCM, 2 =13.05, P = 0.000) is a transcription factor mapped to 6p12.2. GCM1 reported decreased in placenta of patients with pre-eclampsia. The second gene, Tenascin-R (TNR, 2 = 9.85, P = 0.002) is a glycoprotein and extra-cellular matrix component mapped to 1q25.1. Tenascin-R was associated with motor coordination impairment and enhanced anxiety profile in deficient mice. Interestingly, Triadin (TRDN, 2 = 9.16, P = 0.01) is an integral membrane protein mapped to 6q22.31 within the IgAN1 locus. Triadin was shown to participate in cardiac myocyte arrhythemia. However, there is no published study of these genes in IgAN.
Conclusion: Forty-two associated genes (particularly GCM1, TNR and TRDN) are identified as possible susceptibility or marker genes for IgAN. Knowledge of their mesangial expression and binding capacity for IgA-containing complexes may help elucidate the pathogenesis of IgAN.
Key words: Glomerulonephritis, IgA nephritis
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Affiliation(s)
| | | | | | - Yi Zhao
- Singapore General Hospital, Singapore
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