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Mitrotti A, Giliberti M, Di Leo V, di Bari I, Pontrelli P, Gesualdo L. Hidden genetics behind glomerular scars: an opportunity to understand the heterogeneity of focal segmental glomerulosclerosis? Pediatr Nephrol 2024; 39:1685-1707. [PMID: 37728640 PMCID: PMC11026212 DOI: 10.1007/s00467-023-06046-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 05/02/2023] [Accepted: 05/30/2023] [Indexed: 09/21/2023]
Abstract
Focal segmental glomerulosclerosis (FSGS) is a complex disease which describes different kinds of kidney defects, not exclusively linked with podocyte defects. Since nephrin mutation was first described in association with early-onset nephrotic syndrome (NS), many advancements have been made in understanding genetic patterns associated with FSGS. New genetic causes of FSGS have been discovered, displaying unexpected genotypes, and recognizing possible site of damage. Many recent large-scale sequencing analyses on patients affected by idiopathic chronic kidney disease (CKD), kidney failure (KF) of unknown origin, or classified as FSGS, have revealed collagen alpha IV genes, as one of the most frequent sites of pathogenic mutations. Also, recent interest in complex and systemic lysosomal storage diseases, such as Fabry disease, has highlighted GLA mutations as possible causes of FSGS. Tubulointerstitial disease, recently classified by KDIGO based on genetic subtypes, when associated with UMOD variants, may phenotypically gain FSGS features, as well as ciliopathy genes or others, otherwise leading to completely different phenotypes, but found carrying pathogenic variants with associated FSGS phenotype. Thus, glomerulosclerosis may conceal different heterogeneous conditions. When a kidney biopsy is performed, the principal objective is to provide an accurate diagnosis. The broad spectrum of phenotypic expression and genetic complexity is demonstrating that a combined path of management needs to be applied. Genetic investigation should not be reserved only to selected cases, but rather part of medical management, integrating with clinical and renal pathology records. FSGS heterogeneity should be interpreted as an interesting opportunity to discover new pathways of CKD, requiring prompt genotype-phenotype correlation. In this review, we aim to highlight how FSGS represents a peculiar kidney condition, demanding multidisciplinary management, and in which genetic analysis may solve some otherwise unrevealed idiopathic cases. Unfortunately there is not a uniform correlation between specific mutations and FSGS morphological classes, as the same variants may be identified in familial cases or sporadic FSGS/NS or manifest a variable spectrum of the same disease. These non-specific features make diagnosis challenging. The complexity of FSGS genotypes requires new directions. Old morphological classification does not provide much information about the responsible cause of disease and misdiagnoses may expose patients to immunosuppressive therapy side effects, mistaken genetic counseling, and misguided kidney transplant programs.
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Affiliation(s)
- Adele Mitrotti
- Precision and Regenerative Medicine and Ionian Area, Nephrology, Dialysis and Transplantation Unit, Department of Emergency and Organ Transplantation, University of Bari Aldo Moro, Bari, Italy.
| | - Marica Giliberti
- Precision and Regenerative Medicine and Ionian Area, Nephrology, Dialysis and Transplantation Unit, Department of Emergency and Organ Transplantation, University of Bari Aldo Moro, Bari, Italy
| | - Vincenzo Di Leo
- Precision and Regenerative Medicine and Ionian Area, Nephrology, Dialysis and Transplantation Unit, Department of Emergency and Organ Transplantation, University of Bari Aldo Moro, Bari, Italy
| | - Ighli di Bari
- Precision and Regenerative Medicine and Ionian Area, Nephrology, Dialysis and Transplantation Unit, Department of Emergency and Organ Transplantation, University of Bari Aldo Moro, Bari, Italy
| | - Paola Pontrelli
- Precision and Regenerative Medicine and Ionian Area, Nephrology, Dialysis and Transplantation Unit, Department of Emergency and Organ Transplantation, University of Bari Aldo Moro, Bari, Italy
| | - Loreto Gesualdo
- Precision and Regenerative Medicine and Ionian Area, Nephrology, Dialysis and Transplantation Unit, Department of Emergency and Organ Transplantation, University of Bari Aldo Moro, Bari, Italy
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Esson G, Logan I, Wood K, Browning AC, Sayer JA. Diverse retinal-kidney phenotypes associated with NPHP1 homozygous whole-gene deletions in patients with kidney failure. JOURNAL OF RARE DISEASES (BERLIN, GERMANY) 2024; 3:7. [PMID: 38433745 PMCID: PMC10904492 DOI: 10.1007/s44162-024-00031-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Accepted: 01/19/2024] [Indexed: 03/05/2024]
Abstract
A precise diagnosis in medicine allows appropriate disease-specific management. Kidney failure of unknown aetiology remains a frequent diagnostic label within the haemodialysis unit and kidney transplant clinic, accounting for 15-20% of these patients. Approximately 10% of such cases may have an underlying monogenic cause of kidney failure. Modern genetic approaches can provide a precise diagnosis for patients and their families. A search for extra-renal disease manifestations is also important as this may point to a specific genetic diagnosis. Here, we present two patients where molecular genetic testing was performed because of kidney failure of unknown aetiology and associated retinal phenotypes. The first patient reached kidney failure at 16 years of age but only presented with a retinal phenotype at 59 years of age and was found to have evidence of rod-cone dystrophy. The second patient presented with childhood kidney failure at the age of 15 years and developed visual difficulties and photophobia at the age of 32 years and was diagnosed with cone dystrophy. In both cases, genetic tests were performed which revealed a homozygous whole-gene deletion of NPHP1-encoding nephrocystin-1, providing the unifying diagnosis of Senior-Løken syndrome type 1. We conclude that reviewing kidney and extra-renal phenotypes together with targeted genetic testing was informative in these cases of kidney failure of unknown aetiology and associated retinal phenotypes. The involvement of an interdisciplinary team is advisable when managing such patients and allows referral to other relevant specialities. The long time lag and lack of diagnostic clarity and clinical evaluation in our cases should encourage genetic investigations for every young patient with unexplained kidney failure. For these and similar patients, a more timely genetic diagnosis would allow for improved management, a risk assessment of kidney disease in relatives, and the earlier identification of extra-renal disease manifestations. Supplementary Information The online version contains supplementary material available at 10.1007/s44162-024-00031-4.
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Affiliation(s)
- Gavin Esson
- Renal Services, The Newcastle Upon Tyne Hospitals NHS Foundation Trust, Newcastle Upon Tyne, UK
| | - Ian Logan
- Renal Services, The Newcastle Upon Tyne Hospitals NHS Foundation Trust, Newcastle Upon Tyne, UK
| | - Katrina Wood
- Histopathology Department, The Newcastle Upon Tyne Hospitals NHS Foundation Trust, Newcastle Upon Tyne, NE1 4LP UK
| | - Andrew C. Browning
- Ophthalmology Department, The Newcastle Upon Tyne Hospitals NHS Foundation Trust, Newcastle Upon Tyne, NE1 4LP UK
| | - John A. Sayer
- Renal Services, The Newcastle Upon Tyne Hospitals NHS Foundation Trust, Newcastle Upon Tyne, UK
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Central Parkway, Newcastle Upon Tyne, NE1 3BZ UK
- NIHR Newcastle Biomedical Research Centre, Newcastle Upon Tyne, UK
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Differential Expression of microRNAs in Serum of Patients with Chronic Painful Polyneuropathy and Healthy Age-Matched Controls. Biomedicines 2023; 11:biomedicines11030764. [PMID: 36979743 PMCID: PMC10045018 DOI: 10.3390/biomedicines11030764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 02/24/2023] [Accepted: 02/28/2023] [Indexed: 03/06/2023] Open
Abstract
Polyneuropathies (PNP) are the most common type of disorder of the peripheral nervous system in adults. However, information on microRNA expression in PNP is lacking. Following microRNA sequencing, we compared the expression of microRNAs in the serum of patients experiencing chronic painful PNP with healthy age-matched controls. We have been able to identify four microRNAs (hsa-miR-3135b, hsa-miR-584-5p, hsa-miR-12136, and hsa-miR-550a-3p) that provide possible molecular links between degenerative processes, blood flow regulation, and signal transduction, that eventually lead to PNP. In addition, these microRNAs are discussed regarding the targeting of proteins that are involved in high blood flow/pressure and neural activity dysregulations/disbalances, presumably resulting in PNP-typical symptoms such as chronical numbness/pain. Within our study, we have identified four microRNAs that may serve as potential novel biomarkers of chronic painful PNP, and that may potentially bear therapeutic implications.
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Which patients with CKD will benefit from genomic sequencing? Synthesizing progress to illuminate the future. Curr Opin Nephrol Hypertens 2022; 31:541-547. [PMID: 36093902 PMCID: PMC9594128 DOI: 10.1097/mnh.0000000000000836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
PURPOSE OF REVIEW This review will summarize and synthesize recent findings in regard to monogenic kidney disorders, including how that evidence is being translated into practice. It will add to existing key knowledge to provide context for clinicians in consolidating existing practice and approaches. RECENT FINDINGS Whilst there are long established factors, which indicate increased likelihood of identifying a monogenic cause for kidney disease, these can now be framed in terms of the identification of new genes, new indications for genomic testing and new evidence for clinical utility of genomic testing in nephrology. Further, inherent in the use of genomics in nephrology are key concepts including robust informed consent, variant interpretation and return of results. Recent findings of variants in genes related to complex or broader kidney phenotypes are emerging in addition to understanding of de novo variants. Phenocopy phenomena are indicating a more pragmatic use of broader gene panels whilst evidence is emerging of a role in unexplained kidney disease. Clinical utility is evolving but is being successfully demonstrated across multiple domains of outcome and practice. SUMMARY We provide an updated framework of evidence to guide application of genomic testing in chronic kidney disease (CKD), building upon existing principles and knowledge to indicate how the practice and implementation of this can be applied today. There are clearly established roles for genomic testing for some patients with CKD, largely those with suspected heritable forms, with these continuing to expand as new evidence emerges.
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Wang D, Chen X, Wen Q, Li Z, Chen W, Chen W, Wang X. A single heterozygous nonsense mutation in the TTC21B gene causes adult-onset nephronophthisis 12: A case report and review of literature. Mol Genet Genomic Med 2022; 10:e2076. [PMID: 36263627 PMCID: PMC9747551 DOI: 10.1002/mgg3.2076] [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: 06/16/2022] [Revised: 09/25/2022] [Accepted: 09/30/2022] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND Nephronophthisis type 12 (NPHP 12) is a rare cilia-related cystic kidney disease, caused by TTC21B mutation, mainly involving the kidneys, which generally occurs in children. Our study aimed to illustrate its clinical, pathological and genetic characteristics by reporting an adult-onset case of NPHP 12 caused by a single heterozygous nonsense mutation of TTC21B confirmed by renal histology and whole exome sequencing and reviewing related literature with a comparative analysis of the clinical features of each case. It will further increase the recognition of this rare kidney genetic disease, which sometimes can manifest as an adult disease. RESULTS A 33-years-old man showed a chronic disease course, and he exhibited slight renal dysfunction (CKD stage 3, eGFR = 49 ml/[min* 1.73 m2]) with renal tubular proteinuria, without any extrarenal manifestations, congenital malformation history of kidney disease, or family hereditary disease. Renal histological findings showed substantial interstitial fibrosis with some irregular and tortuous tubules with complex branches and segmental thickening and splitting of the tubular basement membrane. The patient was diagnosed with chronic interstitial nephritis for an unknown reason clinically. Further genetic analysis revealed a single heterozygous nonsense mutation in the TTC21B gene and NPHP 12 was diagnosed finally. CONCLUSION A single heterozygous mutation in the TTC21B gene may cause atypical NPHP12, which had a relatively later onset and milder clinical symptoms without developmental abnormalities. Therefore, for unexplained adult-onset chronic interstitial nephritis with unusual changes of renal tubules and interstitial fibrosis, even without a clear history of hereditary kidney disease, genetic testing is still recommended. The correct diagnosis of this rare adult-onset hereditary nephropathy can avoid unnecessary treatment.
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Affiliation(s)
- Dan Wang
- Department of NephrologyThe First Affiliated Hospital, Sun Yat‐sen UniversityGuangzhouChina,NHC Key Laboratory of Clinical Nephrology (Sun Yat‐sen University) and Guangdong Provincial Key Laboratory of NephrologySun Yat‐sen UniversityGuangzhouChina
| | - Xionghui Chen
- Department of NephrologyThe First Affiliated Hospital, Sun Yat‐sen UniversityGuangzhouChina,NHC Key Laboratory of Clinical Nephrology (Sun Yat‐sen University) and Guangdong Provincial Key Laboratory of NephrologySun Yat‐sen UniversityGuangzhouChina
| | - Qiong Wen
- Department of NephrologyThe First Affiliated Hospital, Sun Yat‐sen UniversityGuangzhouChina,NHC Key Laboratory of Clinical Nephrology (Sun Yat‐sen University) and Guangdong Provincial Key Laboratory of NephrologySun Yat‐sen UniversityGuangzhouChina
| | - Zhijian Li
- Department of NephrologyThe First Affiliated Hospital, Sun Yat‐sen UniversityGuangzhouChina,NHC Key Laboratory of Clinical Nephrology (Sun Yat‐sen University) and Guangdong Provincial Key Laboratory of NephrologySun Yat‐sen UniversityGuangzhouChina
| | - Wei Chen
- Department of NephrologyThe First Affiliated Hospital, Sun Yat‐sen UniversityGuangzhouChina,NHC Key Laboratory of Clinical Nephrology (Sun Yat‐sen University) and Guangdong Provincial Key Laboratory of NephrologySun Yat‐sen UniversityGuangzhouChina
| | - Wenfang Chen
- Department of NephrologyThe First Affiliated Hospital, Sun Yat‐sen UniversityGuangzhouChina,Department of PathologyThe First Affiliated Hospital, Sun Yat‐sen UniversityGuangzhouChina
| | - Xin Wang
- Department of NephrologyThe First Affiliated Hospital, Sun Yat‐sen UniversityGuangzhouChina,NHC Key Laboratory of Clinical Nephrology (Sun Yat‐sen University) and Guangdong Provincial Key Laboratory of NephrologySun Yat‐sen UniversityGuangzhouChina
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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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