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Li Y, Dai L, Xu H, Huang J, Zhang J, Mei Z, Zhang R. Clinical report and genetic analysis of rare premature infant nephronophthisis caused by biallelic TTC21B variants. Mol Genet Genomic Med 2024; 12:e2399. [PMID: 38439578 PMCID: PMC10912793 DOI: 10.1002/mgg3.2399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 08/24/2023] [Accepted: 02/05/2024] [Indexed: 03/06/2024] Open
Abstract
BACKGROUND Nephronophthisis (NPHP) is a genetically heterogeneous disease that can lead to end-stage renal disease (ESRD) in children. The TTC21B variant is associated with NPHP12 and mainly characterized by cystic kidney disease, skeletal malformation, liver fibrosis, and retinopathy. Affected patients range from children to adults. Some patients experience ESRD in infancy or early childhood, but clinical reports on neonatal patients are rare. We report a case of NPHP12 in a premature infant and analyze its genetic etiology. METHODS Trio-whole exome sequencing analysis was performed on the patient and her parents; bioinformatics software was used to predict and analyze the hazards of the variants. Sanger sequencing was performed to verify variants. We calculated the free energy between mutant IFT139 and the IFT121-IFT122-IFT43 complex structure using molecular dynamics (MD). Finally, the clinical and genetic characteristics of patients with hotspot variant Cys518Arg were reviewed. RESULTS Genetic analysis revealed compound-heterozyous TTC21B variants in the patient, c.497delA (p.Lys166fs*36) and c.1552T>C (p.Cys518Arg). Her father and mother had heterozygous c.497delA (p.Lys166fs*36) and heterozygous c.1552T>C (p.Cys518Arg), respectively. Cys518Arg represents a hotspot variant, and the MD calculation results show that this can reduce the structural stability of the IFT121-IFT122-IFT139-IFT43 complex structure. A literature review showed that Cys518Arg might lead to the early occurrence of ESRD. CONCLUSIONS Compound-heterozygous TTC21B variants underlie the phenotype in this patient. Thus, Cys518Arg may be a hotspot variant in the Chinese population. Genetic testing should be recommended for NPHP in neonates and early infants.
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Affiliation(s)
- Yingying Li
- Department of NeonatologySuzhou Hospital of Anhui Medical University (Suzhou Municipal Hospital of Anhui Province)SuzhouAnhuiChina
| | - Liying Dai
- Department of NeonatologyAnhui Province Children's HospitalHefeiAnhuiChina
| | - Hong Xu
- Department of NeonatologySuzhou Hospital of Anhui Medical University (Suzhou Municipal Hospital of Anhui Province)SuzhouAnhuiChina
| | - Jin Huang
- Department of NeonatologySuzhou Hospital of Anhui Medical University (Suzhou Municipal Hospital of Anhui Province)SuzhouAnhuiChina
| | - Jinqiu Zhang
- Department of NeonatologySuzhou Hospital of Anhui Medical University (Suzhou Municipal Hospital of Anhui Province)SuzhouAnhuiChina
| | - Zhenzhu Mei
- Department of NeonatologySuzhou Hospital of Anhui Medical University (Suzhou Municipal Hospital of Anhui Province)SuzhouAnhuiChina
| | - Rui Zhang
- Department of NeonatologySuzhou Hospital of Anhui Medical University (Suzhou Municipal Hospital of Anhui Province)SuzhouAnhuiChina
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Zhao X, Jiang LJ, Rong ZH, Dou ZY, Su QX, Liang YH, Qi XJ. [Clinical phenotype characteristics and genetic analysis in children with nephronophthisis and related syndromes caused by different gene mutations]. ZHONGGUO DANG DAI ER KE ZA ZHI = CHINESE JOURNAL OF CONTEMPORARY PEDIATRICS 2023; 25:831-836. [PMID: 37668031 PMCID: PMC10484077 DOI: 10.7499/j.issn.1008-8830.2303020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 03/05/2023] [Accepted: 06/12/2023] [Indexed: 09/06/2023]
Abstract
OBJECTIVES To improve the understanding of the clinical phenotypes and genetic characteristics of nephronophthisis (NPHP) and related syndromes in children. METHODS A retrospective analysis was performed on the medical data of eight children with NPHP and related syndromes who were diagnosed and treated in the Department of Pediatrics of the Second Hospital of Hebei Medical University, from January 2018 to November 2022. The clinical characteristics and genetic testing results were analyzed. RESULTS Among these eight children, there were five boys and three girls, with an age of onset ranging from 15 months to 12 years. All 8 children exhibited different degrees of renal function abnormalities when they attended the hospital. Among the eight children, two had the initial symptom of delayed development, two had the initial symptom of anemia, and two were found to have abnormal renal function during physical examination. The extrarenal manifestations included cardiovascular abnormalities in two children, skeletal dysplasia in two children, liver dysfunction in one child, retinitis pigmentosa in one child, and visceral translocation in one child. All eight children had renal structural changes on ultrasound, and four children had mild to moderate proteinuria based on routine urine test. Of all eight children, five had NPHP1 gene mutations and one each had a gene mutation in the NPHP3, IFT140, and TTC21B genes, and four new mutation sites were discovered. CONCLUSIONS Children with NPHP and related syndromes often have the initial symptom of delayed development or anemia, and some children also have extrarenal manifestations. NPHP and related syndromes should be considered for children with unexplained renal dysfunction, and high-throughput sequencing may help to make a confirmed diagnosis.
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Affiliation(s)
- Xue Zhao
- Department of Pediatrics, Second Hospital of Hebei Medical University, Shijiazhuang 050000, China
| | - Li-Jun Jiang
- Department of Pediatrics, Second Hospital of Hebei Medical University, Shijiazhuang 050000, China
| | - Zan-Hua Rong
- Department of Pediatrics, Second Hospital of Hebei Medical University, Shijiazhuang 050000, China
| | - Zhi-Yan Dou
- Department of Pediatrics, Second Hospital of Hebei Medical University, Shijiazhuang 050000, China
| | - Qing-Xiao Su
- Department of Pediatrics, Second Hospital of Hebei Medical University, Shijiazhuang 050000, China
| | - Yu-Heng Liang
- Department of Pediatrics, Second Hospital of Hebei Medical University, Shijiazhuang 050000, China
| | - Xing-Jie Qi
- Department of Pediatrics, Second Hospital of Hebei Medical University, Shijiazhuang 050000, China
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3
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Sambharia M, Rastogi P, Thomas CP. Monogenic focal segmental glomerulosclerosis: A conceptual framework for identification and management of a heterogeneous disease. AMERICAN JOURNAL OF MEDICAL GENETICS. PART C, SEMINARS IN MEDICAL GENETICS 2022; 190:377-398. [PMID: 35894442 PMCID: PMC9796580 DOI: 10.1002/ajmg.c.31990] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 05/31/2022] [Accepted: 06/30/2022] [Indexed: 01/29/2023]
Abstract
Focal segmental glomerulosclerosis (FSGS) is not a disease, rather a pattern of histological injury occurring from a variety of causes. The exact pathogenesis has yet to be fully elucidated but is likely varied based on the type of injury and the primary target of that injury. However, the approach to treatment is often based on the degree of podocyte foot process effacement and clinical presentation without sufficient attention paid to etiology. In this regard, there are many monogenic causes of FSGS with variable presentation from nephrotic syndrome with histological features of primary podocytopathy to more modest degrees of proteinuria with limited evidence of podocyte foot process injury. It is likely that genetic causes are largely underdiagnosed, as the role and the timing of genetic testing in FSGS is not established and genetic counseling, testing options, and interpretation of genotype in the context of phenotype may be outside the scope of practice for both nephrologists and geneticists. Yet most clinicians believe that a genetic diagnosis can lead to targeted therapy, limit the use of high-dose corticosteroids as a therapeutic trial, and allow the prediction of the natural history and risk for recurrence in the transplanted kidney. In this manuscript, we emphasize that genetic FSGS is not monolithic in its presentation, opine on the importance of genetic testing and provide an algorithmic approach to deployment of genetic testing in a timely fashion when faced with a patient with FSGS.
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Affiliation(s)
- Meenakshi Sambharia
- Division of Nephrology, Department of Internal MedicineUniversity of IowaIowa CityIowaUSA
| | - Prerna Rastogi
- Department of PathologyUniversity of IowaIowa CityIowaUSA
| | - Christie P. Thomas
- Division of Nephrology, Department of Internal MedicineUniversity of IowaIowa CityIowaUSA,Department of PediatricsUniversity of IowaIowa CityIowaUSA,The Iowa Institute of Human GeneticsUniversity of IowaIowa CityIowaUSA,Medical ServiceVeterans Affairs Medical CenterIowa CityIowaUSA
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Olinger E, Phakdeekitcharoen P, Caliskan Y, Orr S, Mabillard H, Pickles C, Tse Y, Wood K, Sayer JA. Biallelic variants in TTC21B as a rare cause of early-onset arterial hypertension and tubuloglomerular kidney disease. AMERICAN JOURNAL OF MEDICAL GENETICS. PART C, SEMINARS IN MEDICAL GENETICS 2022; 190:109-120. [PMID: 35289079 PMCID: PMC9314882 DOI: 10.1002/ajmg.c.31964] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 02/21/2022] [Accepted: 03/01/2022] [Indexed: 12/13/2022]
Abstract
Monogenic disorders of the kidney typically affect either the glomerular or tubulointerstitial compartment producing a distinct set of clinical phenotypes. Primary focal segmental glomerulosclerosis (FSGS), for instance, is characterized by glomerular scarring with proteinuria and hypertension while nephronophthisis (NPHP) is associated with interstitial fibrosis and tubular atrophy, salt wasting, and low- to normal blood pressure. For both diseases, an expanding number of non-overlapping genes with roles in glomerular filtration or primary cilium homeostasis, respectively, have been identified. TTC21B, encoding IFT139, however has been associated with disorders of both the glomerular and tubulointerstitial compartment, and linked with defective podocyte cytoskeleton and ciliary transport, respectively. Starting from a case report of extreme early-onset hypertension, proteinuria, and progressive kidney disease, as well as data from the Genomics England 100,000 Genomes Project, we illustrate here the difficulties in assigning this mixed phenotype to the correct genetic diagnosis. Careful literature review supports the notion that biallelic, often hypomorph, missense variants in TTC21B are commonly associated with early-onset hypertension and histological features of both FSGS and NPHP. Increased clinical recognition of this mixed glomerular and tubulointerstitial disease with often mild or absent features of a typical ciliopathy as well as inclusion of TTC21B on gene panels for early-onset arterial hypertension might shorten the diagnostic odyssey for patients affected by this rare tubuloglomerular kidney disease.
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Affiliation(s)
- Eric Olinger
- Translational and Clinical Research Institute, Faculty of Medical SciencesNewcastle UniversityNewcastle upon TyneUK
| | - Pran Phakdeekitcharoen
- Translational and Clinical Research Institute, Faculty of Medical SciencesNewcastle UniversityNewcastle upon TyneUK
| | - Yasar Caliskan
- Division of NephrologySaint Louis University Center for Abdominal TransplantationSt. LouisMissouriUSA
| | - Sarah Orr
- Translational and Clinical Research Institute, Faculty of Medical SciencesNewcastle UniversityNewcastle upon TyneUK
| | - Holly Mabillard
- Translational and Clinical Research Institute, Faculty of Medical SciencesNewcastle UniversityNewcastle upon TyneUK
| | - Charles Pickles
- Paediatric Nephrology, Great North Children's HospitalNewcastle upon Tyne Hospitals NHS Foundation TrustNewcastle upon TyneUK
| | - Yincent Tse
- Paediatric Nephrology, Great North Children's HospitalNewcastle upon Tyne Hospitals NHS Foundation TrustNewcastle upon TyneUK
| | - Katrina Wood
- Department of Cellular PathologyNewcastle upon Tyne Hospitals NHS Foundation TrustNewcastle upon TyneUK
| | | | - John A. Sayer
- Translational and Clinical Research Institute, Faculty of Medical SciencesNewcastle UniversityNewcastle upon TyneUK,Renal ServicesNewcastle upon Tyne Hospitals NHS Foundation TrustNewcastle upon TyneUK,NIHR Newcastle Biomedical Research CentreNewcastle upon TyneUK
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Gambino G, Catalano C, Marangoni M, Geers C, Moine AL, Boon N, Smits G, Ghisdal L. Case Report: Homozygous Pathogenic Variant P209L in the TTC21B Gene: A Rare Cause of End Stage Renal Disease and Biliary Cirrhosis Requiring Combined Liver-Kidney Transplantation. A Case Report and Literature Review. Front Med (Lausanne) 2021; 8:795216. [PMID: 34957165 PMCID: PMC8702958 DOI: 10.3389/fmed.2021.795216] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 11/12/2021] [Indexed: 01/09/2023] Open
Abstract
Background: Ciliopathies are rare diseases causing renal and extrarenal manifestations. Here, we report the case of a ciliopathy induced by a homozygous pathogenic variant in the TTC21B gene. Case Description: A 47-year-old patient started hemodialysis for chronic kidney disease (CKD) of unknown origin. She presented with early onset of hypertension, pre-eclampsia, myopia and cirrhosis. Renal biopsy showed mild interstitial fibrosis, tubular atrophy, and moderate arteriosclerosis while liver pathology demonstrates grade B biliary cirrhosis. Family history revealed several cases of early-onset severe hypertension and one case of end-stage renal disease (ESRD) needing kidney transplantation at twenty years of age. Clinical exome sequencing showed homozygosis for the pathogenic variant c.626C>T (p.Pro209Leu) in the TTC21B gene. The patient underwent combined liver-renal transplantation with an excellent renal and hepatic graft outcome. Conclusions:TTC21B gene mutations can lead heterogeneous to clinical manifestations and represent an underappreciated cause of ESRD. The paradigm in diagnosis of CKD of early onset and/or of unknown origin is changing and genetic counseling should be performed in all patients and families that meet those criteria. Renal or combined liver-renal transplantation represents the best option for patients suffering from those diseases in terms of prognosis and quality of life.
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Affiliation(s)
- Giuseppe Gambino
- Department of Nephrology, Dialysis and Renal Transplantation, Erasmus Erasme Hospital, Free University of Brussels, Brussels, Belgium
| | - Concetta Catalano
- Department of Nephrology, Dialysis and Renal Transplantation, Erasmus Erasme Hospital, Free University of Brussels, Brussels, Belgium
- *Correspondence: Concetta Catalano
| | - Martina Marangoni
- Department of Genetics, Erasme Hospital, Free University of Brussels, Brussels, Belgium
| | - Caroline Geers
- Department of Nephropathology, Universitair Ziekenhuis Brussel, Brussels, Belgium
- Department of Nephropathology, Brugmann University Hospital, Brussels, Belgium
| | - Alain Le Moine
- Department of Nephrology, Dialysis and Renal Transplantation, Erasme Hospital, Free University of Brussels, Brussels, Belgium
| | - Nathalie Boon
- Department of Gastroenterology, Erasme Hospital, Free University of Brussels, Brussels, Belgium
| | - Guillaume Smits
- Department of Genetics, Erasme Hospital, Free University of Brussels, Brussels, Belgium
| | - Lidia Ghisdal
- Department of Nephrology, Dialysis and Renal Transplantation, Erasmus Erasme Hospital, Free University of Brussels, Brussels, Belgium
- Department of Nephrology and Dialysis, Epicura Hospital, Saint-Ghislain, Belgium
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Bezdíčka M, Zemková D, Skálová S, Hovorková E, Podhola M, Burkert J, Zieg J. Tubuloglomerular Disease With Cone-Shaped Epiphyses Associated With Hypomorphic Variant and a Novel p.Cys14Arg in the TTC21B Gene: A Case Report. Front Pediatr 2021; 9:752878. [PMID: 34805047 PMCID: PMC8603824 DOI: 10.3389/fped.2021.752878] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 10/12/2021] [Indexed: 11/13/2022] Open
Abstract
Monogenic nephrotic syndrome (NS) is associated with a resistance to initial glucocorticoid therapy and causative variants, which may be found in several genes influencing podocyte stability and kidney development. The TTC21B gene, which encodes the retrograde intraflagellar transport protein IFT139, is found mostly in association with ciliopathies in humans. The role of this protein in podocyte cytoskeleton stability was confirmed later and the mutated TTC21B also may be associated with proteinuric diseases, such as nephrotic syndrome. Our patient manifested as an infant with brachydactyly, nephrotic-range proteinuria, and renal tubular acidosis, and a kidney biopsy revealed focal segmental glomerulosclerosis (FSGS). Multiple phalangeal cone-shaped epiphyses of the hand were seen on X-ray. Next-generation sequencing revealed the well-described p.Pro209Leu heterozygous variant and a novel heterozygous p.Cys14Arg variant in the TTC21B gene. Our finding confirmed that the causative variants in the TTC21B gene may contribute to a spectrum of clinical features, such as glomerular proteinuric disease with tubulointerstitial involvement and skeletal abnormalities.
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Affiliation(s)
- Martin Bezdíčka
- Vera Vavrova Lab/VIAL, Department of Pediatrics, Second Faculty of Medicine, Charles University and Motol University Hospital, Prague, Czechia
| | - Dana Zemková
- Department of Pediatrics, Second Faculty of Medicine, Charles University and Motol University Hospital, Prague, Czechia
| | - Sylva Skálová
- Department of Pediatrics, Faculty of Medicine in Hradec Králové, Charles University and Hospital Hradec Králové, Hradec Králové, Czechia
| | - Eva Hovorková
- Department of Pathology, Faculty of Medicine in Hradec Králové, Charles University and Hospital Hradec Králové, Hradec Králové, Czechia
| | - Miroslav Podhola
- Department of Pathology, Faculty of Medicine in Hradec Králové, Charles University and Hospital Hradec Králové, Hradec Králové, Czechia
| | - Jan Burkert
- Department of Cardiovascular Surgery, Second Faculty of Medicine, Charles University and Motol University Hospital, Prague, Czechia
| | - Jakub Zieg
- Department of Pediatrics, Second Faculty of Medicine, Charles University and Motol University Hospital, Prague, Czechia
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Torra R, Furlano M, Ortiz A, Ars E. Genetic kidney diseases as an underrecognized cause of chronic kidney disease: the key role of international registry reports. Clin Kidney J 2021; 14:1879-1885. [PMID: 34345410 PMCID: PMC8323147 DOI: 10.1093/ckj/sfab056] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Indexed: 01/01/2023] Open
Abstract
Inherited kidney diseases (IKDs) are among the leading causes of early-onset chronic kidney disease (CKD) and are responsible for at least 10-15% of cases of kidney replacement therapy (KRT) in adults. Paediatric nephrologists are very aware of the high prevalence of IKDs among their patients, but this is not the case for adult nephrologists. Recent publications have demonstrated that monogenic diseases account for a significant percentage of adult cases of CKD. A substantial number of these patients have received a non-specific/incorrect diagnosis or a diagnosis of CKD of unknown aetiology, which precludes correct treatment, follow-up and genetic counselling. There are a number of reasons why genetic kidney diseases are difficult to diagnose in adulthood: (i) adult nephrologists, in general, are not knowledgeable about IKDs; (ii) existence of atypical phenotypes; (iii) genetic testing is not universally available; (iv) family history is not always available or may be negative; (v) lack of knowledge of various genotype-phenotype relationships and (vi) conflicting interpretation of the pathogenicity of many sequence variants. Registries can contribute to visualize the burden of IKDs by regularly grouping all IKDs in their annual reports, as is done for glomerulonephritis or interstitial diseases, rather than reporting only cystic disease and hiding other IKDs under labels such as 'miscellaneous' or 'other'. Any effort to reduce the percentage of patients needing KRT with a diagnosis of 'nephropathy of unknown etiology' or an unspecific/incorrect diagnosis should be encouraged as a step towards precision nephrology. Genetic testing may be of value in this context but should not be used indiscriminately, but rather on the basis of a deep knowledge of IKDs.
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Affiliation(s)
- Roser Torra
- Department of Nephrology, Inherited Kidney Diseases, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau (IIB-Sant Pau), Medicine Department-Universitat Autónoma de Barcelona, REDinREN, Instituto de Investigación Carlos III, Barcelona, Spain
| | - Mónica Furlano
- Department of Nephrology, Inherited Kidney Diseases, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau (IIB-Sant Pau), Medicine Department-Universitat Autónoma de Barcelona, REDinREN, Instituto de Investigación Carlos III, Barcelona, Spain
| | - Alberto Ortiz
- IIS-Fundación Jimenez Diaz, School of Medicine, Universidad Autónoma de Madrid, Fundación Renal Iñigo Alvarez de Toledo-IRSIN, REDinREN, Instituto de Investigación Carlos III, Madrid, Spain
| | - Elisabet Ars
- Molecular Biology Laboratory, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau (IIB-Sant Pau), Universitat Autónoma de Barcelona, REDinREN, Instituto de Investigación Carlos III, Barcelona, Spain
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8
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Ben-Yosef T, Asia Batsir N, Ali Nasser T, Ehrenberg M. Retinal dystrophy as part of TTC21B-associated ciliopathy. Ophthalmic Genet 2021; 42:329-333. [PMID: 33599192 DOI: 10.1080/13816810.2021.1888131] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Background: TCC21B is a ciliary protein. The most common phenotypic features associated with TCC21B biallelic mutations are nephronophthisis and skeletal abnormalities. To date, retinal dystrophy has been reported in only one patient.Materials and Methods: Clinical evaluation included best-corrected visual acuity, cycloplegic refraction, fundus examination, fundus photography, retinal imaging by optical coherence tomography, full-field electroretinography, multifocal electroretinography, and visual evoked potentials. Genetic analysis included Whole Exome Sequencing and confirmation of the identified mutations in the patient and his parents by PCR amplification and direct sequencing.Results: A ten-year-old Caucasian male presented with nephronophthisis, high myopia and nycatalopia. Best-corrected visual acuity was preserved to 20/20 in each eye with significant myopic correction. Visual fields were constricted. Optical coherence tomography confirmed the lack of outer retinal layers in the perifoveal area on both eyes. Electroretinography confirmed significant retinal dystrophy. Whole Exome Sequencing revealed compound heterozygous mutations in the TTC21B gene.Conclusions: TTC21B is associated with ciliopathy, but retinal dystrophy is a rare finding in these patients. We report retinal dystrophy secondary to TTC21B mutations, and provide for the first time detailed clinical information of the ophthalmic phenotype.
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Affiliation(s)
- Tamar Ben-Yosef
- The Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Haifa, Israel
| | - Nurit Asia Batsir
- Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.,Pediatric Genetics Clinic, Schneider Children's Medical Center of Israel, Petach Tikva, Israel
| | - Tahleel Ali Nasser
- The Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Haifa, Israel
| | - Miriam Ehrenberg
- Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.,Department of Ophthalmology, Schneider Children's Medical Center of Israel, Petach Tikva, Israel
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9
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Tang X, Liu C, Liu X, Chen J, Fan X, Liu J, Ma D, Cao G, Chen Z, Xu D, Zhu Y, Jiang X, Cheng L, Wu Y, Hou L, Li Y, Shao X, Zheng S, Zhang A, Zheng B, Jian S, Rong Z, Su Q, Gao X, Rao J, Shen Q, Xu H. Phenotype and genotype spectra of a Chinese cohort with nephronophthisis-related ciliopathy. J Med Genet 2020; 59:147-154. [PMID: 33323469 DOI: 10.1136/jmedgenet-2020-107184] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 10/23/2020] [Accepted: 11/11/2020] [Indexed: 12/28/2022]
Abstract
BACKGROUND Nephronophthisis-related ciliopathies (NPHP-RC) account for the majority of cases of monogenetically caused end-stage renal disease (ESRD) in children. Exploring the correlation between the phenotype and genotype of NPHP-RC is helpful for early diagnosis and management. We investigated the phenotype and genotype spectra of NPHP-RC in a Chinese multicentre cohort. METHODS Crosss-ectional and longitudinal data of 60 patients from 57 families with pathogenic NPHP-RC gene mutations distributed in 22 regions of China were collected into a unified, anonymous database. The mean observation time of this cohort was 3.5±3.1 years. RESULTS Mutations in NPHP1 and NPHP3 were the most common genetic defects. Overall, 45% of patients presented with isolated nephronophthisis (NPH), and 55% exhibited the extrarenal phenotype, which frequently involved the liver (41.7%, n=25), central nervous system (26.7%, n=16), eyes (26.7%, n=16) and skeletal system (11.7%, n=7). Accidental detection of elevated serum creatinine and non-specific symptoms caused by chronic kidney disease occurred in 65% of patients. Patients carrying NPHP1 mutations mainly presented with isolated NPH (90%, 18/20) and progressed to ESRD at a mean age of 12.9±0.5 years. The mean age of ESRD onset in the non-NPHP1 group was lower than that in the NPHP1 group (6.2±1.4 years, p<0.001), especially for patients carrying NPHP3 mutations (3.1±1.2 years), showing a heterogeneous phenotype characterised by Bardet-Biedl syndrome (12.5%, n=5), Joubert syndrome (7.5%, n=3), COACH syndrome (2.5%, n=1), Mainzer-Saldino syndrome (2.5%, n=1), short-rib thoracic dysplasia (2.5%, n=1) and unclassified symptoms (32.5%, n=13). CONCLUSIONS The Chinese Children Genetic Kidney Disease Database registry characterised the spectrum of the phenotype and genotype of NPHP-RC in the Chinese population. NPHP1 and NPHP3 were the most common pathogenic genes. Rapid progression to ESRD and liver involvement were noted in patients with NPHP3 mutations.
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Affiliation(s)
- Xiaoshan Tang
- Department of Nephrology, Children's Hospital of Fudan University, Shanghai, China.,Shanghai Kidney Development and Pediatric Kidney Disease Research Center, Children's Hospital of Fudan University, Shanghai, China
| | - Cuihua Liu
- Nephrology and Rheumatology, Children's Hospital Affiliated to Zhengzhou University, Zhengzhou, China
| | - Xiaorong Liu
- Nephrology, Bejing Children's Hospital, Beijing, China.,Beijing Children's Key Laboratory of Chronic Kidney Disease and Blood Purification, Beijing Children's Hospital, Beijing, China
| | - Jing Chen
- Department of Nephrology, Children's Hospital of Fudan University, Shanghai, China.,Shanghai Kidney Development and Pediatric Kidney Disease Research Center, Children's Hospital of Fudan University, Shanghai, China
| | - Xiaoyan Fan
- Department of Nephrology, Children's Hospital of Fudan University, Shanghai, China.,Shanghai Kidney Development and Pediatric Kidney Disease Research Center, Children's Hospital of Fudan University, Shanghai, China
| | - Jialu Liu
- Department of Nephrology, Children's Hospital of Fudan University, Shanghai, China.,Shanghai Kidney Development and Pediatric Kidney Disease Research Center, Children's Hospital of Fudan University, Shanghai, China
| | - Duan Ma
- Key Laboratory of Metabolism and Molecular Medicine, Ministry of Education, Department of Biochemistry and Molecular Biology, Institutes of Biomedical Sciences, Fudan University School of Basic Medical Sciences, Shanghai, China
| | - Guanghai Cao
- Nephrology and Rheumatology, Children's Hospital Affiliated to Zhengzhou University, Zhengzhou, China
| | - Zhi Chen
- Nephrology, Bejing Children's Hospital, Beijing, China.,Beijing Children's Key Laboratory of Chronic Kidney Disease and Blood Purification, Beijing Children's Hospital, Beijing, China
| | - Daliang Xu
- Nephrology, Anhui Provincial Children's Hospital, Hefei, China
| | - Ying Zhu
- Nephrology, Anhui Provincial Children's Hospital, Hefei, China
| | - Xiaoyun Jiang
- Pediatric, Sun Yat-sen University First Affiliated Hospital, Guangzhou, Guangdong, China
| | - Lizhi Cheng
- Pediatric, Sun Yat-sen University First Affiliated Hospital, Guangzhou, Guangdong, China
| | - Yubing Wu
- Pediatric Nephrology and Rheumatology, Shengjing Hospital of China Medical University, Shenyang, Liaoning, China
| | - Ling Hou
- Pediatric Nephrology and Rheumatology, Shengjing Hospital of China Medical University, Shenyang, Liaoning, China
| | - Yuhong Li
- Nephrology and Rheumatology, Guiyang Children's Hospital, Guiyang, China
| | - Xiaoshan Shao
- Nephrology and Rheumatology, Guiyang Children's Hospital, Guiyang, China
| | - Shasha Zheng
- Nephrology and Rheumatology, Guiyang Children's Hospital, Guiyang, China
| | - Aihua Zhang
- Nephrology, Nanjing Medical University Affiliated Nanjing Children's Hospital, Nanjing, China
| | - Bixia Zheng
- Nanjing Key Laboratory of Pediatrics, Nanjing Medical University Affiliated Nanjing Children's Hospital, Nanjing, Jiangsu, China
| | - Shan Jian
- Pediatrics, Peking Union Medical College Hospital, Beijing, China
| | - Zanhua Rong
- Pediatrics, Second Hospital of Hebei Medical University, Shijiazhuang, China
| | - Qingxiao Su
- Pediatrics, Second Hospital of Hebei Medical University, Shijiazhuang, China
| | - Xia Gao
- Nephrology, Guangzhou Children's Hospital, Guangzhou, China
| | - Jia Rao
- Department of Nephrology, Children's Hospital of Fudan University, Shanghai, China .,State Key Laboratory of Medical Neurobiology, Institutes of Brain Science and School of Basic Medical Science,Fudan University, Shanghai, China.,Shanghai Key Lab of Birth Defect, Children's Hospital of Fudan University, Shanghai, China, Shanghai, China
| | - Qian Shen
- Department of Nephrology, Children's Hospital of Fudan University, Shanghai, China .,Shanghai Kidney Development and Pediatric Kidney Disease Research Center, Children's Hospital of Fudan University, Shanghai, China
| | - Hong Xu
- Department of Nephrology, Children's Hospital of Fudan University, Shanghai, China .,Shanghai Kidney Development and Pediatric Kidney Disease Research Center, Children's Hospital of Fudan University, Shanghai, China.,Shanghai Key Lab of Birth Defect, Children's Hospital of Fudan University, Shanghai, China, Shanghai, China
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10
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Hibino S, Morisada N, Takeda A, Tanaka K, Nozu K, Yamakawa S, Iijima K, Fujita N. Medullary Cystic Kidney Disease and Focal Segmental Glomerulosclerosis Caused by a Compound Heterozygous Mutation in TTC21B. Intern Med 2020; 59:1735-1738. [PMID: 32238723 PMCID: PMC7434538 DOI: 10.2169/internalmedicine.4266-19] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Mutations in the TTC21B gene have been identified in patients with nephronophthisis and were recently found in some patients with focal segmental glomerulosclerosis. We herein report a Japanese boy with end-stage renal disease due to medullary polycystic kidney disease and primary focal segmental glomerulosclerosis. Next-generation sequencing detected a new compound heterozygous missense mutation in the TTC21B gene. His renal pathological findings and gene mutations have not been previously reported in patients with ciliopathy. For children with severe renal dysfunction, mutations in the TTC21B gene cause both ciliopathy characterized by bilateral polycystic kidney disease and primary focal segmental glomerulosclerosis.
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Affiliation(s)
- Satoshi Hibino
- Pediatric Nephrology, Aichi Children's Health & Medical Center, Japan
| | | | - Asami Takeda
- Department of Nephrology, Nagoya Second Red Cross Hospital, Japan
| | - Kazuki Tanaka
- Pediatric Nephrology, Aichi Children's Health & Medical Center, Japan
| | - Kandai Nozu
- Department of Pediatrics, Kobe University, Japan
| | - Satoshi Yamakawa
- Pediatric Nephrology, Aichi Children's Health & Medical Center, Japan
| | | | - Naoya Fujita
- Pediatric Nephrology, Aichi Children's Health & Medical Center, Japan
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11
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Abo El Fotoh WMM, Al-Fiky AF. A Compound Heterozygous Mutation in the Ciliary Gene TTC21B Causes Nephronophthisis Type 12. J Pediatr Genet 2019; 9:198-202. [PMID: 32714622 DOI: 10.1055/s-0039-1700804] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 09/25/2019] [Indexed: 12/31/2022]
Abstract
Nephronophthisis (NPHP) is one of the renal ciliopathies and is also a cystic renal disorder with an autosomal recessive inheritance, which usually progresses to end-stage renal disease (ESRD). It affects children, adolescents, and young adults. In approximately 15% of cases, the features of a ciliopathy syndrome, which include liver fibrosis, skeletal anomalies, retinal abnormalities, and neurodevelopmental delay, will be present. We describe a case of a 2-year-old male child with ESRD on hemodialysis and a family record of a similar condition (his brother). The clinical features of this child are succinctly summarized. The genetic study was conducted using whole exome sequencing. TTC21B mutational variants were detected in our patient who exhibited nephrotic-range proteinuria, focal segmental glomerulosclerosis, and tubulointerstitial lesions that evolved to ESRD. Compound heterozygous mutations, c.626c > t (p.P209L) in exon 6 and c.450 g > a (p.W150Ter) in exon 5, were uncovered. These findings are in line with the description of autosomal recessive NPHP type 12. Both clinical and pathological diagnoses of NPHP are critical, bearing in mind ESRD as well as its related extrarenal defining features. Identification of the pathogenic variants in the TTC21B gene assisted in the successful proof of the clinical diagnosis NPHP12 as well as providing information for formal suitable prenatal counseling.
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Affiliation(s)
| | - Amira Fathy Al-Fiky
- Department of Pediatrics, Faculty of Medicine, Menoufia University Hospitals, Menoufia, Egypt
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12
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Jian S, Wei QJ, Liu YT, Wang W, Zhou Y, Quan MY, He YY, Song HM, Wei M. [Clinical features and TTC21B genotype of a child with nephronophthisis type 12]. ZHONGGUO DANG DAI ER KE ZA ZHI = CHINESE JOURNAL OF CONTEMPORARY PEDIATRICS 2019. [PMID: 31208513 DOI: 10.7499/j.issn.1008-8830.2019.06.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Nephronophthisis (NPHP) is a group of autosomal recessive tubulointerstitial cystic kidney disorders. This article reports a case of NPHP type 12 caused by TTC21B mutations. The girl had an insidious onset, with moderate proteinuria, renal dysfunction, stage 2 hypertension, situs inversus, and short phalanges when she visited the hospital for the first time at the age of 3 years and 6 months. The renal lesions progressed to end-stage renal disease (ESRD) before she was 4 years old. Urine protein electrophoresis showed glomerular proteinuria. There were significant increases in urinary β2-microglobulin and α1-microglobulin. Gene detection revealed two compound heterozygous mutations, c.1552T>C (p.C518R) and c.752T>G (p.M251R), in the TTC21B gene, which came from her father and mother respectively. The c.752T>G mutation was a novel mutation. It is concluded that besides typical tubular changes of NPHP, marked glomerular damage is also observed in patients with TTC21B gene mutations.
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Affiliation(s)
- Shan Jian
- Department of Pediatrics, Peking Union Medical College Hospital, Beijing 100730, China.
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13
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Chen L, Wei Y, Chi W, Fang D, Jiang X, Zhang S. Potential Mutations in Chinese Pathologic Myopic Patients and Contributions to Phenotype. Curr Mol Med 2019; 18:689-697. [PMID: 30747064 PMCID: PMC6635424 DOI: 10.2174/1566524019666190211120016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2018] [Revised: 01/07/2019] [Accepted: 01/07/2019] [Indexed: 12/02/2022]
Abstract
Purpose Pathologic myopia is a leading cause of visual impairment in East Asia. The aim of this study was to investigate the potential mutations in Chinese pathologic myopic patients and to analyze the correlations between genotype and clinical phenotype. Method One hundred and three patients with pathologic myopia and one hundred and nine unrelated healthy controls were recruited from Zhongshan Ophthalmic Center. Detailed clinical data, including ultra-widefield retinal images, measurements of best-corrected visual acuity, axial length, refractive error and ophthalmic examination results, were obtained. Blood samples were collected for high-throughput DNA targeted sequencing. Based on the screening results, phenotype-genotype correlations were analyzed. Results The study included 196 eyes of 103 patients (36 men and 67 women) with an average age of 52.19 (38.92 – 65.46) years, an average refractive error of -11.80 D (-16.38 – -7.22) and a mean axial length of 28.26 mm (25.79 – 30.73). The patients were subdivided into three groups: myopic chorioretinal atrophy (190 eyes of 101 patients), myopic choroidal neovascularization (17 eyes of 15 patients), and myopic traction retinopathy (71 eyes of 61 patients). Systematic analysis of variants in the 255 genes revealed six potential pathogenic mutations: PEX7, OCA2, LRP5 (rs545382, c.1647T>C), TSPAN12 (rs41623, c.765G>T), RDH5 (rs3138142, c.423C>T) and TTC21B (rs80225158, c.2385G>C). OCA2 mutations were primarily observed in patients with myopic traction maculopathy. Conclusion Genetic alterations contribute to various clinical characteristics in Chinese pathologic myopic patients. The study may provide new insights into the etiology of pathologic myopia and potential targets for therapeutic interventions.
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Affiliation(s)
- L Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.,Shenzhen Eye Hospital, Shenzhen Eye Institute, Jinan University, Shenzhen, China
| | - Y Wei
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - W Chi
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - D Fang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - X Jiang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - S Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
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14
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Zhang H, Su B, Liu X, Xiao H, Ding J, Yao Y. Mutations in TTC21B cause different phenotypes in two childhood cases in China. Nephrology (Carlton) 2018; 23:371-376. [PMID: 28124483 DOI: 10.1111/nep.13008] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 01/17/2017] [Accepted: 01/22/2017] [Indexed: 12/22/2022]
Abstract
AIM The TTC21B gene is now known as causative of nephronophthisis-related ciliopathies (NPHP-RC). We reported two Chinese paediatric cases with end-stage renal disease and other phenotypes caused by the TTC21B gene mutations. METHODS The clinical features of Chinese paediatric cases with NPHP-RC were summarized. Mutation analysis of the TTC21B gene was performed using next-generation sequencing. RESULTS The two cases both had nephrotic proteinuria, renal failure, hypertension and abnormal liver function (or hepatic fibrosis). One case also presented situs inversus and short phalanges. They developed end-stage renal disease (ESRD) at 1 year old and 8 years old, respectively, when renal pathology both showed focal segmental glomerular sclerosis (FSGS) with tubulointerstitial lesions including interstitial fibrosis and atrophic tubules. Three novel disease-causing TTC21B mutations were identified. One case carried homozygous mutation c.2211 + 3A > G, while the other case carried compound heterozygous mutations c.1552 T > C (p.C518R) and c.1456dupA (p.R486KfsX22). CONCLUSION Mutations in TTC21B cause a range of ciliopathy phenotypes in humans. We identified 3 novel TTC21B mutations in two Chinese paediatric cases that both presented end-stage renal disease and other different features. This is the first TTC21B mutations ever reported in China.
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Affiliation(s)
- Hongwen Zhang
- Department of Pediatric, Peking University First Hospital, Beijing, China
| | - Baige Su
- Department of Pediatric, Peking University First Hospital, Beijing, China
| | - Xiaoyu Liu
- Department of Pediatric, Peking University First Hospital, Beijing, China
| | - Huijie Xiao
- Department of Pediatric, Peking University First Hospital, Beijing, China
| | - Jie Ding
- Department of Pediatric, Peking University First Hospital, Beijing, China
| | - Yong Yao
- Department of Pediatric, Peking University First Hospital, Beijing, China
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15
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The complexity of the cilium: spatiotemporal diversity of an ancient organelle. Curr Opin Cell Biol 2018; 55:139-149. [PMID: 30138887 DOI: 10.1016/j.ceb.2018.08.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 07/31/2018] [Accepted: 08/02/2018] [Indexed: 02/06/2023]
Abstract
Cilia are microtubule-based appendages present on almost all vertebrate cell types where they mediate a myriad of cellular processes critical for development and homeostasis. In humans, impaired ciliary function is associated with an ever-expanding repertoire of phenotypically-overlapping yet highly variable genetic disorders, the ciliopathies. Extensive work to elucidate the structure, function, and composition of the cilium is offering hints that the `static' representation of the cilium is a gross oversimplification of a highly dynamic organelle whose functions are choreographed dynamically across cell types, developmental, and homeostatic contexts. Understanding this diversity will require discerning ciliary versus non-ciliary roles for classically-defined `ciliary' proteins; defining ciliary protein-protein interaction networks within and beyond the cilium; and resolving the spatiotemporal diversity of ciliary structure and function. Here, focusing on one evolutionarily conserved ciliary module, the intraflagellar transport system, we explore these ideas and propose potential future studies that will improve our knowledge gaps of the oversimplified cilium and, by extension, inform the reasons that underscore the striking range of clinical pathologies associated with ciliary dysfunction.
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16
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Elisakova V, Merta M, Reiterova J, Baxova A, Kotlas J, Hirschfeldova K, Obeidova L, Tesar V, Stekrova J. Bilineal inheritance of pathogenic PKD1 and PKD2 variants in a Czech family with autosomal dominant polycystic kidney disease - a case report. BMC Nephrol 2018; 19:163. [PMID: 29973168 PMCID: PMC6032778 DOI: 10.1186/s12882-018-0978-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 06/28/2018] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary renal disorder, leading to end stage renal failure and kidney transplantation in its most serious form. The severity of the disease's manifestation depends on the genetic determination of ADPKD. The huge variability of different phenotypes (even within a single family) is not only modulated by the two main ADPKD genes (PKD1 and PKD2) but also by modifier genes and the whole genetic background. CASE PRESENTATION This is a report of an ADPKD family with co-inheritance of PKD1 and PKD2 pathogenic variants. The proband, with an extremely serious manifestation of ADPKD (the man was diagnosed in early childhood, and with end stage renal disease aged 23), underwent genetic analysis of PKD1 and PKD2, which revealed the presence of pathogenic mutations in both of these genes. The missense PKD2 mutation p.Arg420Gly came from the proband's father, with a mild ADPKD phenotype. The same mutation of the PKD2 gene and similar mild disease presentation were found in the proband's aunt (father's sister) and her son. The nonsense mutation p.Gln2196* within the PKD1 gene was probably inherited from the proband's mother, who died at the age of 45. It was only discovered post mortem, that the real cause of her death was kidney failure as a consequence of untreated ADPKD. Unfortunately, neither the DNA of the proband's mother nor the DNA of any other family members from this side of the pedigree were available for further examination. The proband underwent successful cadaveric kidney transplantation at the age of 24, and this replacement therapy lasted for the next 15 years. CONCLUSIONS Here, we present a first case of bilineal ADPKD inheritance in the Czech Republic. This report highlights the significant role of modifier genes in genetic determination of ADPKD, especially in connection with seriously deteriorated disease phenotypes. In our case, the modifying role is probably mediated by the PKD2 gene.
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Affiliation(s)
- Veronika Elisakova
- Institute of Biology and Medical Genetics, First Faculty of Medicine Charles University and General University Hospital in Prague, Albertov 4, 128 00, Prague, Czech Republic
| | - Miroslav Merta
- Institute of Biology and Medical Genetics, First Faculty of Medicine Charles University and General University Hospital in Prague, Albertov 4, 128 00, Prague, Czech Republic
| | - Jana Reiterova
- Department of Nephrology, First Faculty of Medicine Charles University and General University Hospital in Prague, U Nemocnice 2, 128 00, Prague, Czech Republic
| | - Alica Baxova
- Institute of Biology and Medical Genetics, First Faculty of Medicine Charles University and General University Hospital in Prague, Albertov 4, 128 00, Prague, Czech Republic
| | - Jaroslav Kotlas
- Institute of Biology and Medical Genetics, First Faculty of Medicine Charles University and General University Hospital in Prague, Albertov 4, 128 00, Prague, Czech Republic
| | - Katerina Hirschfeldova
- Institute of Biology and Medical Genetics, First Faculty of Medicine Charles University and General University Hospital in Prague, Albertov 4, 128 00, Prague, Czech Republic
| | - Lena Obeidova
- Institute of Biology and Medical Genetics, First Faculty of Medicine Charles University and General University Hospital in Prague, Albertov 4, 128 00, Prague, Czech Republic
| | - Vladimir Tesar
- Department of Nephrology, First Faculty of Medicine Charles University and General University Hospital in Prague, U Nemocnice 2, 128 00, Prague, Czech Republic
| | - Jitka Stekrova
- Institute of Biology and Medical Genetics, First Faculty of Medicine Charles University and General University Hospital in Prague, Albertov 4, 128 00, Prague, Czech Republic.
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17
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Solanki AK, Arif E, Morinelli T, Wilson RC, Hardiman G, Deng P, Arthur JM, Velez JC, Nihalani D, Janech MG, Budisavljevic MN. A Novel CLCN5 Mutation Associated With Focal Segmental Glomerulosclerosis and Podocyte Injury. Kidney Int Rep 2018; 3:1443-1453. [PMID: 30426109 PMCID: PMC6224352 DOI: 10.1016/j.ekir.2018.06.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 06/05/2018] [Accepted: 06/09/2018] [Indexed: 12/17/2022] Open
Abstract
Introduction Tubular dysfunction is characteristic of Dent’s disease; however, focal segmental glomerulosclerosis (FSGS) can also be present. Glomerulosclerosis could be secondary to tubular injury, but it remains uncertain whether the CLCN5 gene, which encodes an endosomal chloride and/or hydrogen exchanger, plays a role in podocyte biology. Here, we implicate a role for CLCN5 in podocyte function and pathophysiology. Methods Whole exome capture and sequencing of the proband and 5 maternally-related family members was conducted to identify X-linked mutations associated with biopsy-proven FSGS. Human podocyte cultures were used to characterize the mutant phenotype on podocyte function. Results We identified a novel mutation (L521F) in CLCN5 in 2 members of a Hispanic family who presented with a histologic diagnosis of FSGS and low-molecular-weight proteinuria without hypercalciuria. Presence of CLCN5 was confirmed in cultured human podocytes. Podocytes transfected with the wild-type or the mutant (L521F) CLCN5 constructs showed differential localization. CLCN5 knockdown in podocytes resulted in defective transferrin endocytosis and was associated with decreased cell proliferation and increased cell migration, which are hallmarks of podocyte injury. Conclusions The CLCN5 mutation, which causes Dent’s disease, may be associated with FSGS without hyercalcuria and nepthrolithiasis. The present findings supported the hypothesis that CLCN5 participates in protein trafficking in podocytes and plays a critical role in organizing the components of the podocyte slit diaphragm to help maintain normal cell physiology and a functional filtration barrier. In addition to tubular dysfunction, mutations in CLCN5 may also lead to podocyte dysfunction, which results in a histologic picture of FSGS that may be a primary event and not a consequence of tubular damage.
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Affiliation(s)
- Ashish K Solanki
- Department of Medicine, Nephrology Division, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Ehtesham Arif
- Department of Medicine, Nephrology Division, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Thomas Morinelli
- Division of Transplant Surgery, Department of Surgery, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Robert C Wilson
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Gary Hardiman
- Department of Medicine, Nephrology Division, Medical University of South Carolina, Charleston, South Carolina, USA.,MUSC Bioinformatics, Center for Genomics Medicine, Medical University of South Carolina, Charleston, South Carolina, USA.,Department of Public Health Sciences, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Peifeng Deng
- Department of Medicine, Nephrology Division, Medical University of South Carolina, Charleston, South Carolina, USA
| | - John M Arthur
- Division of Nephrology, Department of Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Juan Cq Velez
- Department of Nephrology, Ochsner Clinic Foundation, New Orleans, Louisiana, USA
| | - Deepak Nihalani
- Department of Medicine, Nephrology Division, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Michael G Janech
- Department of Medicine, Nephrology Division, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Milos N Budisavljevic
- Department of Medicine, Nephrology Division, Medical University of South Carolina, Charleston, South Carolina, USA.,Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina, USA
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18
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Abstract
Technologies such as next-generation sequencing and chromosomal microarray have advanced the understanding of the molecular pathogenesis of a variety of renal disorders. Genetic findings are increasingly used to inform the clinical management of many nephropathies, enabling targeted disease surveillance, choice of therapy, and family counselling. Genetic analysis has excellent diagnostic utility in paediatric nephrology, as illustrated by sequencing studies of patients with congenital anomalies of the kidney and urinary tract and steroid-resistant nephrotic syndrome. Although additional investigation is needed, pilot studies suggest that genetic testing can also provide similar diagnostic insight among adult patients. Reaching a genetic diagnosis first involves choosing the appropriate testing modality, as guided by the clinical presentation of the patient and the number of potential genes associated with the suspected nephropathy. Genome-wide sequencing increases diagnostic sensitivity relative to targeted panels, but holds the challenges of identifying causal variants in the vast amount of data generated and interpreting secondary findings. In order to realize the promise of genomic medicine for kidney disease, many technical, logistical, and ethical questions that accompany the implementation of genetic testing in nephrology must be addressed. The creation of evidence-based guidelines for the utilization and implementation of genetic testing in nephrology will help to translate genetic knowledge into improved clinical outcomes for patients with kidney disease.
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Affiliation(s)
- Emily E Groopman
- Division of Nephrology, Columbia University College of Physicians and Surgeons, 1150 Saint Nicholas Avenue, Russ Berrie Pavilion #412C, New York, New York 10032, USA
| | - Hila Milo Rasouly
- Division of Nephrology, Columbia University College of Physicians and Surgeons, 1150 Saint Nicholas Avenue, Russ Berrie Pavilion #412C, New York, New York 10032, USA
| | - Ali G Gharavi
- Division of Nephrology, Columbia University College of Physicians and Surgeons, 1150 Saint Nicholas Avenue, Russ Berrie Pavilion #412C, New York, New York 10032, USA
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19
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Clinical and genetic analyses of a Dutch cohort of 40 patients with a nephronophthisis-related ciliopathy. Pediatr Nephrol 2018; 33:1701-1712. [PMID: 29974258 PMCID: PMC6132874 DOI: 10.1007/s00467-018-3958-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2017] [Revised: 03/22/2018] [Accepted: 04/02/2018] [Indexed: 11/08/2022]
Abstract
BACKGROUND Nephronophthisis is an autosomal recessive ciliopathy and important cause of end-stage renal disease (ESRD) in children and young adults. Diagnostic delay is frequent. This study investigates clinical characteristics, initial symptoms, and genetic defects in a cohort with nephronophthisis-related ciliopathy, to improve early detection and genetic counseling. METHODS Forty patients from 36 families with nephronophthisis-related ciliopathy were recruited at university medical centers and online. Comprehensive clinical and genotypic data were recorded. Patients without molecular diagnosis were offered genetic analysis. RESULTS Of 40 patients, 45% had isolated nephronophthisis, 48% syndromic diagnosis, and 7% nephronophthisis with extrarenal features not constituting a recognizable syndrome. Patients developed ESRD at median 13 years (range 5-47). Median age of symptom onset was 9 years in both isolated and syndromic forms (range 5-26 vs. 5-33). Common presenting symptoms were fatigue (42%), polydipsia/polyuria (33%), and hypertension (21%). Renal ultrasound showed small-to-normal-sized kidneys, increased echogenicity (65%), cysts (43%), and abnormal corticomedullary differentiation (32%). Renal biopsies in eight patients showed nonspecific signs of chronic kidney disease (CKD). Twenty-three patients (58%) had genetic diagnosis upon inclusion. Thirteen of those without a genetic diagnosis gave consent for genetic testing, and a cause was identified in five (38%). CONCLUSIONS Nephronophthisis is genetically and phenotypically heterogeneous and should be considered in children and young adults presenting with persistent fatigue and polyuria, and in all patients with unexplained CKD. As symptom onset can occur into adulthood, presymptomatic monitoring of kidney function in syndromic ciliopathy patients should continue until at least age 30.
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20
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Ars E, Torra R. Rare diseases, rare presentations: recognizing atypical inherited kidney disease phenotypes in the age of genomics. Clin Kidney J 2017; 10:586-593. [PMID: 28980669 PMCID: PMC5622904 DOI: 10.1093/ckj/sfx051] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Accepted: 05/03/2017] [Indexed: 12/11/2022] Open
Abstract
A significant percentage of adults (10%) and children (20%) on renal replacement therapy have an inherited kidney disease (IKD). The new genomic era, ushered in by the next generation sequencing techniques, has contributed to the identification of new genes and facilitated the genetic diagnosis of the highly heterogeneous IKDs. Consequently, it has also allowed the reclassification of diseases and has broadened the phenotypic spectrum of many classical IKDs. Various genetic, epigenetic and environmental factors may explain ‘atypical’ phenotypes. In this article, we examine different mechanisms that may contribute to phenotypic variability and also provide case examples that illustrate them. The aim of the article is to raise awareness, among nephrologists and geneticists, of rare presentations that IKDs may show, to facilitate diagnosis.
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Affiliation(s)
- Elisabet Ars
- Molecular Biology Laboratory, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau (IIB-Sant Pau), Universitat Autònoma de Barcelona, REDinREN, Instituto de Investigación Carlos III, Barcelona, Spain
| | - Roser Torra
- Inherited Kidney Disorders, Nephrology Department, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau (IIB-Sant Pau), Universitat Autònoma de Barcelona, REDinREN, Instituto de Investigación Carlos III, Barcelona, Spain
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21
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Thomas CP, Mansilla MA, Sompallae R, Mason SO, Nishimura CJ, Kimble MJ, Campbell CA, Kwitek AE, Darbro BW, Stewart ZA, Smith RJH. Screening of Living Kidney Donors for Genetic Diseases Using a Comprehensive Genetic Testing Strategy. Am J Transplant 2017; 17:401-410. [PMID: 27434427 PMCID: PMC5297870 DOI: 10.1111/ajt.13970] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2016] [Revised: 06/20/2016] [Accepted: 07/12/2016] [Indexed: 01/25/2023]
Abstract
Related living kidney donors (LKDs) are at higher risk of end-stage renal disease (ESRD) compared with unrelated LKDs. A genetic panel was developed to screen 115 genes associated with renal diseases. We used this panel to screen six negative controls, four transplant candidates with presumed genetic renal disease and six related LKDs. After removing common variants, pathogenicity was predicted using six algorithms to score genetic variants based on conservation and function. All variants were evaluated in the context of patient phenotype and clinical data. We identified causal variants in three of the four transplant candidates. Two patients with a family history of autosomal dominant polycystic kidney disease segregated variants in PKD1. These findings excluded genetic risk in three of four relatives accepted as potential LKDs. A third patient with an atypical history for Alport syndrome had a splice site mutation in COL4A5. This pathogenic variant was excluded in a sibling accepted as an LKD. In another patient with a strong family history of ESRD, a negative genetic screen combined with negative comparative genomic hybridization in the recipient facilitated counseling of the related donor. This genetic renal disease panel will allow rapid, efficient and cost-effective evaluation of related LKDs.
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Affiliation(s)
- C. P. Thomas
- Department of Internal MedicineCarver College of MedicineUniversity of IowaIowa CityIA,Department of PediatricsCarver College of MedicineUniversity of IowaIowa CityIA,VA Medical CenterIowa CityIA
| | - M. A. Mansilla
- Iowa Institute of Human GeneticsCarver College of MedicineUniversity of IowaIowa CityIA
| | - R. Sompallae
- Iowa Institute of Human GeneticsCarver College of MedicineUniversity of IowaIowa CityIA
| | - S. O. Mason
- Iowa Institute of Human GeneticsCarver College of MedicineUniversity of IowaIowa CityIA
| | - C. J. Nishimura
- Iowa Institute of Human GeneticsCarver College of MedicineUniversity of IowaIowa CityIA
| | - M. J. Kimble
- Iowa Institute of Human GeneticsCarver College of MedicineUniversity of IowaIowa CityIA
| | - C. A. Campbell
- Department of Internal MedicineCarver College of MedicineUniversity of IowaIowa CityIA,Iowa Institute of Human GeneticsCarver College of MedicineUniversity of IowaIowa CityIA
| | - A. E. Kwitek
- Iowa Institute of Human GeneticsCarver College of MedicineUniversity of IowaIowa CityIA,Department of PharmacologyCarver College of MedicineUniversity of IowaIowa CityIA
| | - B. W. Darbro
- Department of PediatricsCarver College of MedicineUniversity of IowaIowa CityIA,Interdisciplinary Program in GeneticsUniversity of IowaIowa CityIA,The Holden Comprehensive Cancer CenterUniversity of IowaIowa CityIA
| | - Z. A. Stewart
- Department of SurgeryDivision of Transplant SurgeryCarver College of MedicineUniversity of IowaIowa CityIA
| | - R. J. H. Smith
- Department of Internal MedicineCarver College of MedicineUniversity of IowaIowa CityIA,Department of PediatricsCarver College of MedicineUniversity of IowaIowa CityIA,Iowa Institute of Human GeneticsCarver College of MedicineUniversity of IowaIowa CityIA,Interdisciplinary Program in GeneticsUniversity of IowaIowa CityIA,Department of OtorhinolaryngologyCarver College of MedicineUniversity of IowaIowa CityIA
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22
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The expanding phenotypic spectra of kidney diseases: insights from genetic studies. Nat Rev Nephrol 2016; 12:472-83. [PMID: 27374918 DOI: 10.1038/nrneph.2016.87] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Next-generation sequencing (NGS) has led to the identification of previously unrecognized phenotypes associated with classic kidney disease genes. In addition to improving diagnostics for genetically heterogeneous diseases and enabling a faster rate of gene discovery, NGS has enabled an expansion and redefinition of nephrogenetic disease categories. Findings from these studies raise the question of whether disease diagnoses should be made on clinical grounds, on genetic evidence or a combination thereof. Here, we discuss the major kidney disease-associated genes and gene categories for which NGS has expanded the phenotypic spectrum. For example, COL4A3-5 genes, which are classically associated with Alport syndrome, are now understood to also be involved in the aetiology of focal segmental glomerulosclerosis. DGKE, which is associated with nephrotic syndrome, is also mutated in patients with atypical haemolytic uraemic syndrome. We examine how a shared genetic background between diverse clinical phenotypes can provide insight into the function of genes and novel links with essential pathophysiological mechanisms. In addition, we consider genetic and epigenetic factors that contribute to the observed phenotypic heterogeneity of kidney diseases and discuss the challenges in the interpretation of genetic data. Finally, we discuss the implications of the expanding phenotypic spectra associated with kidney disease genes for clinical practice, genetic counselling and personalized care, and present our recommendations for the use of NGS-based tests in routine nephrology practice.
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