1
|
Jyoti SS, Islam F, Shrabonee II, Sultana TN, Chaity NI, Nahid NA, Islam MR, Islam MS, Apu MNH. Prevalence of NPHS2 gene R229Q polymorphism in Bangladeshi children with nephrotic syndrome. Heliyon 2020; 6:e05317. [PMID: 33102883 PMCID: PMC7578689 DOI: 10.1016/j.heliyon.2020.e05317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 09/12/2020] [Accepted: 10/16/2020] [Indexed: 01/10/2023] Open
Abstract
Background Limited and contradictory pharmacogenetic studies of NPHS2 gene R229Q polymorphism in nephrotic syndrome (NS) children of different ethnicities steered us to investigate the genotype frequency and associated risk of this polymorphism in Bangladeshi NS children. Methods A prospective case-control study was conducted which comprised a total of 142 children having nephrotic syndrome (NS), divided into 2 groups: case group consisted of 40 children with steroid-resistant nephrotic syndrome (SRNS), and control group involved 102 children with steroid-sensitive nephrotic syndrome (SSNS). Both were genotyped by using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method for R229Q polymorphism. Results The results indicate the presence of R229Q polymorphism in 27.50% of SRNS and 12.75% of SSNS children. SRNS children possess 2.94-fold greater risk (p = 0.025) of carrying Arg/Gln genotype compared to SSNS children. Moreover, R229Q variant in SRNS children was observed as in a compound heterozygous form with p.Ala297Val located in exon 8. Age of onset (4–6 years) presents as a significant contributing factor (adjusted OR = 1.06; 95% CI = 1.023–1.094; p = 0.001) for SRNS susceptibility in Bangladeshi children. Contrarily, though the incidence of SRNS was higher in male children than female (80% vs 20%), gender remains to be a neutral factor (p = 0.257) in relation to SRNS susceptibility. Conclusion Compound heterozygosity of NPHS2 p.R229Q gene variant with p.Ala297Val may cause pathogenic SRNS in Bangladeshi children. Large scale studies are warranted to establish the genotype-phenotype correlation. It is recommended to screen for p.R229Q first and, if positive, for p.Ala297Val in Bangladeshi SRNS children.
Collapse
Affiliation(s)
- Sharmin Sultana Jyoti
- Department of Clinical Pharmacy and Pharmacology, Faculty of Pharmacy, University of Dhaka, Dhaka, 1000, Bangladesh
| | - Farhana Islam
- Department of Clinical Pharmacy and Pharmacology, Faculty of Pharmacy, University of Dhaka, Dhaka, 1000, Bangladesh
| | - Ishrat Islam Shrabonee
- Department of Pediatric, Mymensingh Medical College Hospital, Mymensingh, 2200, Bangladesh
| | - Taposhi Nahid Sultana
- Department of Clinical Pharmacy and Pharmacology, Faculty of Pharmacy, University of Dhaka, Dhaka, 1000, Bangladesh
| | - Nusrat Islam Chaity
- Department of Clinical Pharmacy and Pharmacology, Faculty of Pharmacy, University of Dhaka, Dhaka, 1000, Bangladesh
| | - Noor Ahmed Nahid
- Department of Clinical Pharmacy and Pharmacology, Faculty of Pharmacy, University of Dhaka, Dhaka, 1000, Bangladesh
| | - Md Reazul Islam
- Department of Clinical Pharmacy and Pharmacology, Faculty of Pharmacy, University of Dhaka, Dhaka, 1000, Bangladesh
| | - Md Saiful Islam
- Department of Clinical Pharmacy and Pharmacology, Faculty of Pharmacy, University of Dhaka, Dhaka, 1000, Bangladesh
| | - Mohd Nazmul Hasan Apu
- Department of Clinical Pharmacy and Pharmacology, Faculty of Pharmacy, University of Dhaka, Dhaka, 1000, Bangladesh
- Corresponding author.
| |
Collapse
|
2
|
Abstract
PURPOSE OF REVIEW In this review, we take a combined membrane biologist's and geneticist's view of the podocyte, to examine how genetics have informed our understanding of membrane receptors, channels, and other signaling molecules affecting podocyte health and disease. RECENT FINDINGS An integral part of the kidney, the glomerulus, is responsible for the kidney's filter function. Within the glomerulus, the podocyte is a unique cell serving a critically important role: it is exposed to signals from the urinary space in Bowman's capsule, it receives and transmits signals to/from the basement membrane upon which it elaborates, and it receives signals from the vascular space with which it also communicates, thus exposed to toxins, viruses, chemicals, proteins, and cellular components or debris that flow in the blood stream. Our understanding of how podocytes perform their important role has been largely informed by human genetics, and the recent revolution afforded by exome sequencing has brought a tremendous wealth of new genetic data to light. SUMMARY Genetically defined, rare/orphan podocytopathies, as reviewed here, are critically important to study as they may reveal the next generation targets for precision medicine in nephrology.
Collapse
|
3
|
|
4
|
|
5
|
Wahl P, Wolf M. FGF23 in Chronic Kidney Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 728:107-25. [DOI: 10.1007/978-1-4614-0887-1_8] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
6
|
Gigante M, Piemontese M, Gesualdo L, Iolascon A, Aucella F. Molecular and genetic basis of inherited nephrotic syndrome. Int J Nephrol 2011; 2011:792195. [PMID: 21904677 PMCID: PMC3167185 DOI: 10.4061/2011/792195] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Revised: 06/16/2011] [Accepted: 06/16/2011] [Indexed: 12/26/2022] Open
Abstract
Nephrotic syndrome is an heterogeneous disease characterized by increased permeability of the glomerular filtration barrier for macromolecules. Podocytes, the visceral epithelial cells of glomerulus, play critical role in ultrafiltration of plasma and are involved in a wide number of inherited and acquired glomerular diseases. The identification of mutations in nephrin and other podocyte genes as causes of genetic forms of nephrotic syndrome has revealed new important aspects of the pathogenesis of proteinuric kidney diseases and expanded our knowledge of the glomerular biology. Moreover, a novel concept of a highly dynamic slit diaphragm proteins is emerging. The most significant discoveries in our understanding of the structure and function of the glomerular filtration barrier are reviewed in this paper.
Collapse
Affiliation(s)
- Maddalena Gigante
- Division of Nephrology, Department of Biomedical Science, University of Foggia, 71121 Foggia, Italy
| | | | | | | | | |
Collapse
|
7
|
Clinical trials treating focal segmental glomerulosclerosis should measure patient quality of life. Kidney Int 2010; 79:678-685. [PMID: 21178977 DOI: 10.1038/ki.2010.485] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Optimal therapy of patients with steroid-resistant primary focal segmental glomerulosclerosis (FSGS) remains controversial. This report describes the initial study design, baseline characteristics, and quality of life of patients enrolled in the FSGS Clinical Trial, a large multicenter randomized study of this glomerulopathy comparing a 12-month regimen of cyclosporine to the combination of mycophenolate mofetil and oral dexamethasone. Patients with age ranging 2-40 years, with an estimated glomerular filtration rate > 40 ml/min per 1.73 m², a first morning urine protein-to-creatinine ratio over one, and resistant to corticosteroids were eligible. The primary outcome was complete or partial remission of proteinuria over 52 weeks after randomization. In all, 192 patients were screened, of whom 138 were randomized for treatment. Ethnic distributions were 53 black, 78 white, and 7 other. By self- or parent-proxy reporting, 26 of the 138 patients were identified as Hispanic. The baseline glomerular filtration rate was 112.4 (76.5, 180.0) ml/min per 1.73 m², and urine protein was 4.0 (2.1, 5.3) g/g. Overall, the quality of life of the patients with FSGS was lower than healthy controls and similar to that of patients with end-stage renal disease. Thus, the impact of FSGS on quality of life is significant and this measurement should be included in all trials.
Collapse
|
8
|
Gattineni J, Baum M. Regulation of phosphate transport by fibroblast growth factor 23 (FGF23): implications for disorders of phosphate metabolism. Pediatr Nephrol 2010; 25:591-601. [PMID: 19669798 PMCID: PMC3151467 DOI: 10.1007/s00467-009-1273-z] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Revised: 06/16/2009] [Accepted: 06/17/2009] [Indexed: 01/08/2023]
Abstract
There are a number of hypophosphatemic disorders due to renal phosphate wasting that cannot be explained by elevated levels of parathyroid hormone. The circulating factors responsible for the phosphaturia have been designated as phosphatonins. Studies of patients with tumor-induced osteomalacia and other genetic diseases of phosphate metabolism have resulted in the identification of a number of hormones that regulate phosphate homeostasis, including matrix extracellular phosphoglycoprotein (MEPE), secreted frizzled-related protein 4 (sFRP-4), dentin matrix protein 1 (DMP1), fibroblast growth factor 7 (FGF7), fibroblast growth factor 23 (FGF23), and Klotho. Our understanding of the actions of these hypophosphatemic peptides has been enhanced by studies in mice either overexpressing or not expressing these hormones. This review focuses on FGF23 since its regulation is disordered in diseases that affect children, such as X-linked hypophosphatemia, autosomal dominant and recessive hypophosphatemic rickets as well as chronic kidney disease. Recent studies have shown that FGF23 is unique among the FGFs in its requirement for Klotho for receptor activation. Here, we also discuss new potentially clinically important data pointing to the receptor(s) that mediate the binding and action of FGF23 and Klotho.
Collapse
Affiliation(s)
- Jyothsna Gattineni
- Department of Pediatrics, University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Blvd, Dallas 75390-9063 TX, USA
| | - Michel Baum
- Department of Pediatrics, University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Blvd, Dallas 75390-9063 TX, USA. Department of Internal Medicine, University of Texas Southwestern Medical Center at Dallas, Dallas 75235-9063 TX, USA
| |
Collapse
|
9
|
Hinkes B, Vlangos C, Heeringa S, Mucha B, Gbadegesin R, Liu J, Hasselbacher K, Ozaltin F, Hildebrandt F. Specific podocin mutations correlate with age of onset in steroid-resistant nephrotic syndrome. J Am Soc Nephrol 2008; 19:365-71. [PMID: 18216321 DOI: 10.1681/asn.2007040452] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Mutations in the gene encoding podocin (NPHS2) cause autosomal recessive steroid-resistant nephrotic syndrome (SRNS). For addressing the possibility of a genotype-phenotype correlation between podocin mutations and age of onset, a worldwide cohort of 430 patients from 404 different families with SRNS were screened by direct sequencing. Recessive podocin mutations were present in 18.1% (73 of 404) of families with SRNS, and 69.9% of these mutations were nonsense, frameshift, or homozygous R138Q. Patients with these mutations manifested symptoms at a significantly earlier age (mean onset <1.75 years) than any other patient group, with or without podocin mutations, in this study (mean onset >4.17 yr). All but one patient affected by truncating or homozygous R138Q mutations developed SRNS before 6 yr of age. Patient groups with other recessive podocin mutations, with single heterozygous podocin mutations, with sequence variants, and with no podocin changes could not be distinguished from each other on the basis of age of onset. In conclusion, nephrotic syndrome in children with truncating or homozygous R138Q mutations manifests predominantly before 6 yr of life, and the onset of disease is significantly earlier than for any other podocin mutations. Because the age of onset can vary by several years among those with identical mutations, additional factors may modify the phenotype.
Collapse
Affiliation(s)
- Bernward Hinkes
- Department of Pediatrics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Zhang Y, Xudong X, Du L, Gu W, Dai Y, Liu A, Xia Y, Mao J. Lack of association between NPHS2 gene polymorphisms and Henoch-Schönlein purpura nephritis. Arch Dermatol Res 2007; 299:151-5. [PMID: 17393177 DOI: 10.1007/s00403-007-0752-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2006] [Revised: 03/05/2007] [Accepted: 03/06/2007] [Indexed: 10/23/2022]
Abstract
Henoch-Schönlein purpura (HSP) is one of the most common forms of small-vessel vasculitis in childhood, and renal involvement (HSP nephritis, HSPN) is the main determinant of morbidity after acute phase. Considering the racial diversity and clinical heterogeneity in the prevalence, genetic factors might play a role in pathogenesis of HSP and HSPN. Direct sequencing was performed after PCR amplification of all 8 exons of the NPHS2 gene in 20 Chinese children with HSPN and 30 controls in present study. The genetic analyses revealed 3 polymorphisms (954T > C heterozygous, 1038A > G heterozygous and homozygous, all in exon 8) in 7 out of 20 patients studied, but there was no significant difference in the genotypic and allelic frequencies of these polymorphisms between the patients and controls. The result did not support the possible role of the NPHS2 gene in susceptibility to HSPN in the population studied. Studies in a larger sample population with different genetic backgrounds will be necessary in the future.
Collapse
Affiliation(s)
- Yang Zhang
- Department of Epidemiology, Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, PR China
| | | | | | | | | | | | | | | |
Collapse
|
11
|
Mao J, Zhang Y, Du L, Dai Y, Gu W, Liu A, Shang S, Liang L. NPHS1 and NPHS2 gene mutations in Chinese children with sporadic nephrotic syndrome. Pediatr Res 2007; 61:117-22. [PMID: 17211152 DOI: 10.1203/01.pdr.0000250041.19306.3d] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Recent discoveries indicate that the molecules in glomerular podocytes and slit diaphragms may play an important role in the development of proteinuria and nephrotic syndrome. Mutational analyses of NPHS1 and NPHS2 were performed to verify this hypothesis in sporadic nephrotic syndrome (NS) patients. Clinical characteristics and DNA samples were collected from 38 Chinese children with sporadic steroid-sensitive NS, 22 with steroid-resistant NS and 30 controls. Direct sequencing was performed after PCR amplification of all 29 and 8 exons of the NPHS1 and NPHS2 genes, respectively. In NPHS1, 4 patients had heterozygous missense mutations leading to amino acid substitutions (R800C, Q453R). Furthermore, 3 known single nucleotide polymorphism (SNP) were found (T741T, V763V, S1105S). In NPHS2, 3 patients had novel heterozygous allelic variants leading to amino acid substitutions (S206I, E188D), while 1 patient was found to carry a novel nonsense mutation leading to a truncated protein product (Glu237STOP). Two known polymorphisms were also found (A318A, L346L). The results demonstrate that NPHS1 and NPHS2 mutations are also present in Chinese sporadic NS patients, suggesting that genetic changes of nephrin and podocin may play pathogenetic roles in some patients with sporadic steroid resistant NS.
Collapse
Affiliation(s)
- Jianhua Mao
- Department of Nephrology, Zhejiang University School of Medicine, Children's Hospital, Hangzhou 310006, Zhejiang Province, PR China
| | | | | | | | | | | | | | | |
Collapse
|
12
|
Abstract
Fibroblast growth factor (FGF) 23 shares a fundamentally common structure with the members of the FGF family and has a unique sequence extension at the C-terminus. The molecular behavior of FGF23 as a systemic factor can be justified by the altered conformation of the beta-trefoil structure similar to that suspected in FGF19. On the other hand, the biological activity of FGF23 is quite distinct from those of other FGFs and requires the C-terminal unique extended structure. Two types of enzyme-linked immunosorbent assays (ELISA) have been developed to detect the intact mature form of FGF23 and its C-terminal portion. The former ELISA method enables the detection of rodent FGF23 and human FGF23. Studies on experimental animal models and laboratory examinations of physiologic and disordered conditions using these assays are contributing toward elucidating the physiology and pathophysiology of FGF23.
Collapse
Affiliation(s)
- Takeyoshi Yamashita
- Pharmaceutical Research Laboratories, Pharmaceutical Division, Kirin Brewery Co., Ltd, Takasaki, Gunma, Japan.
| |
Collapse
|
13
|
Lahdenkari AT, Suvanto M, Kajantie E, Koskimies O, Kestilä M, Jalanko H. Clinical features and outcome of childhood minimal change nephrotic syndrome: is genetics involved? Pediatr Nephrol 2005; 20:1073-80. [PMID: 15968559 DOI: 10.1007/s00467-005-1965-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2005] [Revised: 04/29/2005] [Accepted: 05/02/2005] [Indexed: 11/29/2022]
Abstract
The pathogenesis of minimal change nephrotic syndrome (MCNS) is still unknown. We performed a clinical and genetic evaluation of 104 adults (mean age 35 years) who presented with MCNS in childhood (mean follow-up 30 years). Clinical data and the present health status were evaluated. Also, the genes encoding the four major slit diaphragm proteins, nephrin, podocin, Neph1 and CD2-associated protein were sequenced in 38 patients with MCNS of varying severity. MCNS presented at the mean age of 5 years, and 80% of the patients relapsed 1-28 (median 3) times during childhood. The 14 subjects (14%) who had proteinuric episodes still in adulthood had a refractory disease already as children. The participants did not show a strong tendency for allergy or immune diseases, and no familial clustering of MCNS was observed. The genetic analyses revealed heterozygous amino acid changes in nephrin and podocin in 10 of the 38 patients studied. On the other hand, the genes coding for Neph1 and CD2AP were highly conserved and no amino acid substitutions were detected. In conclusion, MCNS is a multifactorial disease, in which genetics play a minor role. Allelic variants of the podocyte proteins may, however, modify the phenotype in occasional individuals.
Collapse
Affiliation(s)
- Anne-Tiina Lahdenkari
- Hospital for Children and Adolescents and Biomedicum Helsinki, University of Helsinki, Finland.
| | | | | | | | | | | |
Collapse
|
14
|
Jonsson KB. The role of fibroblast growth factor 23 in renal disease. Nephrol Dial Transplant 2005; 20:479-82. [PMID: 15735238 DOI: 10.1093/ndt/gfh701] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
15
|
Aucella F, De Bonis P, Gatta G, Muscarella LA, Vigilante M, di Giorgio G, D'Errico M, Zelante L, Stallone C, Bisceglia L. Molecular analysis of NPHS2 and ACTN4 genes in a series of 33 Italian patients affected by adult-onset nonfamilial focal segmental glomerulosclerosis. Nephron Clin Pract 2004; 99:c31-6. [PMID: 15627790 DOI: 10.1159/000082864] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2004] [Accepted: 05/12/2004] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Mutations in the NPHS2 gene, encoding podocin, and in the ACTN4 gene, encoding alpha-actinin-4, have been identified in familial childhood-onset forms of focal and segmental glomerulosclerosis (FSGS). NPHS2 may be also responsible for some sporadic cases. The role of NPHS2 and ACTN4 in the adult sporadic form of the disease is being clarifying. METHODS Thirty-three adult subjects affected by sporadic FSGS were studied at molecular level. At biopsy, 12 patients had nephrotic syndrome, 5 patients had isolated proteinuria and 16 patients showed proteinuria and hematuria. Glomerular filtration rate (GFR) was in the normal range in 19 subjects and 14 patients had a variable degree of renal failure. Multiplex families presenting with a clear familial inheritance for proteinuria or other congenital nephrotic syndrome were excluded. The whole coding region, all intron/exon boundaries and flanking intronic regions of NPHS2 gene and the exon 8, i.e. hot-spot mutations of the ACTN4 gene, were analyzed in all patients by denaturing high-performance liquid chromatography (DHPLC) to search disease-causing defects. RESULTS The analysis identified four already described and two new polymorphisms, IVS3-21C>T and IVS3-46C>T, on the NPHS2 gene. Moreover, the R229Q allele was identified in 3/33 patients and in 7/124 controls, accounting for an allelic frequency of 0.045 and 0.028, respectively. The new intronic polymorphism IVS7-54C>T was also found in the exon 8 of the ACTN4 gene. CONCLUSIONS In this study, we exhaustively analyzed the NPHS2 and the exon 8 of the ACTN4 genes in a series of sporadic 'adult-onset' FSGS patients. No causative mutations were found while the R229Q allele was identified in 3 patients confirming its possible role as a 'disease-associated NPHS2 allele' although its pathogenetic involvement needs to be further clarified. Moreover, the description of new intronic polymorphisms in both genes is reported.
Collapse
Affiliation(s)
- Filippo Aucella
- Department of Nephrology and Dialysis, Casa Sollievo della Sofferenza Hospital, IRCCS, San Giovanni Rotondo, Italy
| | | | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Schmid H, Henger A, Cohen CD, Frach K, Gröne HJ, Schlöndorff D, Kretzler M. Gene expression profiles of podocyte-associated molecules as diagnostic markers in acquired proteinuric diseases. J Am Soc Nephrol 2004; 14:2958-66. [PMID: 14569107 DOI: 10.1097/01.asn.0000090745.85482.06] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
For identifying potential diagnostic markers of proteinuric glomerulopathies, glomerular mRNA levels of molecules relevant for podocyte function (alpha-actinin-4, glomerular epithelial protein 1, Wilms tumor antigen 1, synaptopodin, dystroglycan, nephrin, podoplanin, and podocin) were determined by quantitative real-time RT-PCR from microdissected glomeruli. Biopsies from 83 patients with acquired proteinuric diseases were analyzed (minimal change disease [MCD; n = 13], benign nephrosclerosis [n = 16], membranous glomerulopathy [n = 31], focal and segmental glomerulosclerosis [FSGS; n = 9], and controls [n = 14]). Gene expression levels normalized to two different housekeeping transcripts (glyceraldehyde-3-phosphate-dehydrogenase and 18 S rRNA) did not allow a separation between proteinuric disease categories. However, a significant positive correlation between alpha-actinin-4, glomerular epithelial protein 1, synaptopodin, dystroglycan, Wilms tumor antigen 1, and nephrin was found in all analyzed glomeruli, whereas podocin mRNA expression did not correlate. Because varying amounts of housekeeper cDNA per glomerulus can confound expression ratios relevant for a subpopulation of cells, an "in silico" microdissection was performed using a podocyte-specific cDNA as a reference gene. Expression ratio of podocin to synaptopodin, the two genes with the most disparate expression, allowed a robust separation of FSGS from MCD and nephrosclerosis. Segregation of FSGS from MCD via this ratio was confirmed in an independent population of formaldehyde-fixed archival biopsies (MCD, n = 5; FSGS, n = 4) after glomerular laser capture microdissection. In addition, the expression marker was able to predict steroid responsiveness in diagnostically challenging cases of MCD versus FSGS (n = 6). As the above approach can be performed as an add-on diagnostic tool, these molecular diagnostic parameters could give novel information for the management of proteinuric diseases.
Collapse
Affiliation(s)
- Holger Schmid
- Medizinische Poliklinik, Ludwig-Maximilians-University of Munich, Munich, Germany
| | | | | | | | | | | | | |
Collapse
|
17
|
Abstract
Childhood nephrotic syndromes are most commonly caused by one of two idiopathic diseases: minimal-change nephrotic syndrome (MCNS) and focal segmental glomerulosclerosis (FSGS). A third distinct type, membranous nephropathy, is rare in children. Other causes of isolated nephrotic syndrome can be subdivided into two major categories: rare genetic disorders, and secondary diseases associated with drugs, infections, or neoplasia. The cause of idiopathic nephrotic syndrome remains unknown, but evidence suggests it may be a primary T-cell disorder that leads to glomerular podocyte dysfunction. Genetic studies in children with familial nephrotic syndrome have identified mutations in genes that encode important podocyte proteins. Patients with idiopathic nephrotic syndrome are initially treated with corticosteroids. Steroid-responsiveness is of greater prognostic use than renal histology. Several second-line drugs, including alkylating agents, ciclosporin, and levamisole, may be effective for complicated and steroid-unresponsive MCNS and FSGS patients. Nephrotic syndrome is associated with several medical complications, the most severe and potentially fatal being bacterial infections and thromboembolism. Idiopathic nephrotic syndrome is a chronic relapsing disease for most steroid-responsive patients, whereas most children with refractory FSGS ultimately develop end-stage renal disease. Research is being done to further elucidate the disorder's molecular pathogenesis, identify new prognostic indicators, and to develop better approaches to treatment.
Collapse
Affiliation(s)
- Allison A Eddy
- Department of Pediatrics, University of Washington, Children's Hospital and Regional Medical Center, Seattle, WA 98105, USA.
| | | |
Collapse
|
18
|
Chung KW, Ferrell RE, Ellis D, Barmada M, Moritz M, Finegold DN, Jaffe R, Vats A. African American hypertensive nephropathy maps to a new locus on chromosome 9q31-q32. Am J Hum Genet 2003; 73:420-9. [PMID: 12840782 PMCID: PMC1180380 DOI: 10.1086/377184] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2003] [Accepted: 05/28/2003] [Indexed: 12/17/2022] Open
Abstract
Hypertensive nephropathy (HN) and focal segmental glomerulosclerosis (FSGS) are significant causes of end-stage renal disease (ESRD), but no genes or loci have been associated with this phenotype among African Americans, a group at high risk. We performed a genomewide linkage scan with approximately 400 microsatellite markers on 23 individuals of a large four-generation African American family with 18 affected individuals (7 with ESRD), in which the 13-year-old proband (also with ESRD) presented with hypertension and proteinuria (2-4 g/day) and underwent a kidney biopsy that revealed FSGS-like lesions with arteriolar thickening. A genomewide scan revealed LOD scores of >2.5 for markers on chromosomes 3 and 9, and fine mapping was performed on 5 additional members (total 28 members) that showed a maximum multipoint LOD score of 5.4 in the 9q31-q32 region, under an autosomal dominant model with 99% penetrance. This 8-cM (6-Mb) region is flanked by markers D9S172 and D9S105, and further candidate gene sequencing studies excluded the coding regions of three genes (ACTL7A, ACTL7B, and CTNNAL1). To our knowledge, this is the first report of a locus, denoted as "HNP1," for the HN/FSGS phenotype in a large African American family with dominantly inherited nephropathy characterized by ESRD, hypertension, and some features of FSGS.
Collapse
Affiliation(s)
- Ki Wha Chung
- Departments of Pediatrics and Pathology, Children’s Hospital of Pittsburgh, University of Pittsburgh School of Medicine, and Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh
| | - Robert E. Ferrell
- Departments of Pediatrics and Pathology, Children’s Hospital of Pittsburgh, University of Pittsburgh School of Medicine, and Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh
| | - Demetrius Ellis
- Departments of Pediatrics and Pathology, Children’s Hospital of Pittsburgh, University of Pittsburgh School of Medicine, and Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh
| | - Michael Barmada
- Departments of Pediatrics and Pathology, Children’s Hospital of Pittsburgh, University of Pittsburgh School of Medicine, and Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh
| | - Michael Moritz
- Departments of Pediatrics and Pathology, Children’s Hospital of Pittsburgh, University of Pittsburgh School of Medicine, and Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh
| | - David N. Finegold
- Departments of Pediatrics and Pathology, Children’s Hospital of Pittsburgh, University of Pittsburgh School of Medicine, and Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh
| | - Ronald Jaffe
- Departments of Pediatrics and Pathology, Children’s Hospital of Pittsburgh, University of Pittsburgh School of Medicine, and Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh
| | - Abhay Vats
- Departments of Pediatrics and Pathology, Children’s Hospital of Pittsburgh, University of Pittsburgh School of Medicine, and Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh
| |
Collapse
|
19
|
Abstract
Nephrotic syndrome is a clinical and laboratory syndrome caused by the increased permeability of the glomerular capillary wall for macromolecules. Nephrotic syndrome is a potentially life-threatening state and persistent nephrotic syndrome has a poor prognosis with a high risk of progression to end-stage renal failure and a high risk of cardiovascular complications due to severe hyperlipidemia. Pathogenesis of increased glomerular permeability in different glomerular diseases has not been fully elucidated. Recently, identification of the mutated genes for some podocyte proteins (nephrin, podocin, alpha-actinin-4) in rare familial forms of nephrotic syndrome shed has new light on the molecular mechanisms of glomerular permselectivity. Gradually it becomes apparent that sporadic mutations of podocyte proteins (e.g., podocin) may be present even in some patients with acquired nephrotic syndrome. Expression of other podocyte proteins may change during the course of experimental nephrotic syndrome, possibly as a response to podocyte damage resulting either in apoptosis or stimulation of proliferation and some form of repair, including glomerular sclerosis. Better understanding of these mechanisms could clearly also have therapeutic implications. Glomerular permeability factors are believed to play a role in some noninflammatory glomerular diseases, mainly minimal change disease and focal segmental glomerulosclerosis, but their molecular identification remains elusive, possibly due to the nonhomogeneous nature of the underlying diseases. As an example, focal segmental glomerulosclerosis possibly can be caused by the sporadic mutation of some genes for podocyte proteins, increased production of glomerular permeability factor (possibly by T lymphocytes), or the loss of inhibitors of glomerular permeability factors in nephrotic urine. Clearly the factors causing increased glomerular permeability and factors perpetuating glomerular sclerosis are not necessarily the same. Proteinuria does not seem to be only the consequence of glomerular damage, but it may possibly cause tubular damage and initiate interstitial fibrosis and thus contribute to the progression of chronic renal failure in proteinuric renal diseases. Recent insights into the mechanisms of tubular protein reabsorption may give new tools for preventing the progression of chronic renal disease. Cubilin inhibitors could potentially ameliorate tubular and interstitial damage in patients with heavy proteinuria refractory to treatment. Nephrotic hyperlipidemia is accompanied with increased risk of cardiovascular complications and should be treated in all patients with persistent nephrotic syndrome. The putative positive effect of hypolipidemic drugs (namely statins) on the cardiovascular risk and potentially also on the rate of progression of chronic renal failure remains to be demonstrated in prospective controlled studies. Recent progress in understanding podocyte biology in rare inherited glomerular diseases gives the chance to understand in the near future the molecular pathogenesis of increased glomerular permeability in the much more common acquired forms of nephrotic syndrome.
Collapse
Affiliation(s)
- Vladimír Tesar
- First Department of Medicine, Division of Nephrology, First Faculty of Medicine and University Hospital, Prague, Czech Republic
| | | | | |
Collapse
|
20
|
Prakash S, Chung KW, Sinha S, Barmada M, Ellis D, Ferrell RE, Finegold DN, Randhawa PS, Dinda A, Vats A. Autosomal dominant progressive nephropathy with deafness: linkage to a new locus on chromosome 11q24. J Am Soc Nephrol 2003; 14:1794-803. [PMID: 12819239 DOI: 10.1097/01.asn.0000071513.73427.97] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Focal segmental glomerulosclerosis (FSGS) and Alport syndrome (AS) are two major causes of end-stage renal disease (ESRD). A few families with autosomal dominant FSGS have been reported with linkage to chromosome 19q13 or 11q22, while AS is usually linked to mutations in type IV collagen (COL4) subunit genes. A phenotype resembling AS may also be seen with myosin heavy chain-9 (MYH9) gene mutations. This study ascertained a multigeneration family (CHP-177) with clinical aspects of both FSGS and AS where we identified a new locus for the trait. A genome-wide scan was performed with 400 markers, and fine mapping was performed for chromosome 11 markers. Data were analyzed by GENEHUNTER and VITESSE under various models. CHP-177 is a 39-member kindred residing near New Delhi, India, with seven affecteds and showed male-to-male transmission. Two members had ESRD. Renal biopsies showed both FSGS lesions and thin glomerular basement membranes. Five of the affecteds also had sensorineural deafness, which involved both low and high frequency in some members. The AS loci, i.e., COL4A3/COL4A4 and MYH9 (LOD scores: -6.1 and -4.3, respectively) and FSGS loci, on 19q13 and 11q22, were excluded from linkage. A significant evidence of linkage was observed for 11q24 region, with a multipoint LOD (z-score) of 3.2 for marker D11S4464 at theta = 0. The z-1 confidence interval for the linked region spans a genetic distance of 7 cM. This study thus reports an autosomal dominant nephropathy with features of both FSGS and AS in which linkage to currently known loci for such phenotypes was excluded and a new locus on 11q24 was identified. The findings suggest further locus heterogeneity for the autosomal dominant nephropathy phenotype.
Collapse
Affiliation(s)
- Sunil Prakash
- Department of Nephrology, Northern Railway Central Hospital, New Delhi, India
| | | | | | | | | | | | | | | | | | | |
Collapse
|
21
|
|
22
|
Ohashi T, Uchida K, Uchida S, Sasaki S, Nihei H. Intracellular mislocalization of mutant podocin and correction by chemical chaperones. Histochem Cell Biol 2003; 119:257-64. [PMID: 12649741 DOI: 10.1007/s00418-003-0511-x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/18/2003] [Indexed: 10/25/2022]
Abstract
The NPHS2 gene encoding the podocin protein was causally linked to the autosomal recessive type of steroid-resistant nephrotic syndrome. In this study, we investigated the consequence of the R138Q mutation of podocin, one of the most common missense mutations in the NPHS2 gene, by examining the expression of the wild-type and R138Q mutant podocins in mammalian cells. Either myc- or FLAG-tagged wild-type podocin was strongly stained in plasma membrane, particularly in the fine processes wherein the protein was colocalized with actin stress fibers. On the other hand, the R138Q mutant podocin was completely retained intracellularly and colocalized with the endoplasmic reticulum (ER) marker, calnexin. These results suggest that the R138Q mutation affected podocin protein folding, thereby interfering with the mutant protein's departure from the ER. To determine if the ER retention of R138Q mutant is correctable, cells were incubated with the chemical chaperones glycerol, trimethylamine-N-oxide, and DMSO. Using these two methods, namely, cell surface labeling with sulfo-NHS-S-S-biotin and Alexa 488-streptavidin, and immunostaining to detect the podocin protein close to the plasma membrane, we confirmed that these chemical chaperone treatments elicit a cellular redistribution of R138Q podocin. Our results reveal defective cellular processing of the mutant podocin, and provide evidence for pharmacological correction of the processing defect.
Collapse
Affiliation(s)
- Teiko Ohashi
- Department of Medicine, Kidney Center, Tokyo Women's Medical University, 8-1 Kawada-cho Shinjuku, 162-8666, Tokyo, Japan
| | | | | | | | | |
Collapse
|
23
|
Korbet SM. Angiotensin antagonists and steroids in the treatment of focal segmental glomerulosclerosis. Semin Nephrol 2003; 23:219-28. [PMID: 12704582 DOI: 10.1053/snep.2003.50020] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The use of angiotensin converting enzyme inhibitors (ACEIs) along with good blood pressure control have been shown to significantly decrease the level of proteinuria and slow the progression of renal insufficiency in patients with nondiabetic glomerular disease including focal segmental glomerulosclerosis (FSGS). Thus, this should be part of the therapeutic approach for all proteinuric patients with FSGS and should be considered the mainstay of therapy for patients with FSGS secondary to conditions associated with hyperfiltration and/or reduced nephron mass and those patients with nonnephrotic primary FSGS. However, nephrotic patients with primary FSGS may continue to have marked proteinuria and progression of renal disease despite these measures and thus require a more aggressive approach with the use of steroids and immunosuppressive agents. Although primary FSGS was once thought to be a steroid-nonresponsive lesion, recent experience has provided a note of optimism in the use of steroids and immunosuppressive agents in treating this otherwise progressive glomerulopathy. As a result, a course of steroid therapy in primary FSGS is now warranted in nephrotic patients with reasonably well preserved renal function in whom it is not otherwise contraindicated.
Collapse
Affiliation(s)
- Stephen M Korbet
- Section of Nephrology, Department of Medicine, Rush Presbyterian St. Lukes Medical Center, 1653 W Congress Pkwy, Chicago, IL, USA
| |
Collapse
|
24
|
Affiliation(s)
- Stephen M Korbet
- Rush Presbyterian St. Luke's Medical Center, Chicago, Illinois 60612, USA.
| |
Collapse
|