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Savige J. Tips for Testing Adults With Suspected Genetic Kidney Disease. Am J Kidney Dis 2024; 83:816-824. [PMID: 38147894 DOI: 10.1053/j.ajkd.2023.10.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 10/08/2023] [Accepted: 10/14/2023] [Indexed: 12/28/2023]
Abstract
Genetic kidney disease is common but often unrecognized. It accounts for most cystic kidney diseases and tubulopathies, many forms of congenital abnormalities of the kidney and urinary tract (CAKUT), and some glomerulopathies. Genetic kidney disease is typically suspected where the disease usually has a genetic basis or there is another affected family member, a young age at onset, or extrarenal involvement, but there are also many exceptions to these "rules". Genetic testing requires the patient's written informed consent. When a patient declines testing, another later conversation may be worthwhile. Genetic testing not only indicates the diagnosis but also the inheritance pattern, likely at-risk family members, disease in other organs, clinical course, and possibly effective treatments. Sometimes genetic testing does not identify a pathogenic variant even where other evidence is strong. A variant of uncertain significance (VUS) may be reported but should not be used for clinical decision making. It may be reclassified after more information becomes available without necessarily retesting the patient. Patients should be provided with a copy of their genetic test report, the results explained, and at-risk family members offered "cascade" testing. A referral to a clinical geneticist or genetic counselor helps identify affected family members and in providing advice to assist with reproductive decisions.
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Affiliation(s)
- Judy Savige
- University of Melbourne Department of Medicine (Melbourne Health and Northern health), Royal Melbourne Hospital, Parkville, Australia.
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2
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Mabillard H, Ryan R, Tzoumas N, Gear S, Sayer JA. Explaining Alport syndrome-lessons from the adult nephrology clinic. JOURNAL OF RARE DISEASES (BERLIN, GERMANY) 2024; 3:14. [PMID: 38745975 PMCID: PMC11088994 DOI: 10.1007/s44162-024-00036-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Accepted: 02/15/2024] [Indexed: 05/16/2024]
Abstract
Alport syndrome is a genetic kidney disease that causes worsening of kidney function over time, often progressing to kidney failure. Some types of Alport syndrome cause other symptoms and signs, including hearing loss and eye abnormalities. Research now indicates that Alport syndrome (autosomal dominant inheritance) is the most common form. Alport syndrome can have X-linked or a rare form of autosomal recessive inheritance. Traditionally, a kidney biopsy was used to diagnose Alport syndrome, but genetic testing provides a more precise and less invasive means of diagnosis and reveals the underlying pattern of inheritance. At present, there are no specific curative treatments for Alport syndrome however there is a strong international effort in pursuit of future therapies. Currently, angiotensin-converting enzyme inhibitors (ACEi), or an angiotensin receptor blocker (ARB) if a patient cannot tolerate an ACEi, slow down the progression of kidney disease and can delay the onset of kidney failure by years. There are other potential treatments in research that potentially can help delay the onset of kidney issues. Early treatment of patients and identification of their at-risk relatives is a priority. People living with Alport syndrome and their doctors now benefit from an active international research community working on translating further treatments into clinical practice and providing up-to-date clinical guidelines.
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Affiliation(s)
- Holly Mabillard
- Renal Services, Newcastle Upon Tyne Hospitals NHS Foundation Trust, Newcastle Upon Tyne, UK
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Central Parkway, Newcastle Upon Tyne, UK
| | - Rebecca Ryan
- Renal Services, Newcastle Upon Tyne Hospitals NHS Foundation Trust, Newcastle Upon Tyne, UK
| | - Nik Tzoumas
- Faculty of Medical Sciences, Biosciences Institute, Newcastle University, Central Parkway, Newcastle Upon Tyne, UK
- Sunderland Eye Infirmary, Sunderland, UK
| | - Susie Gear
- Alport UK, Cirencester, Gloucestershire, UK
| | - John A. Sayer
- Renal Services, Newcastle Upon Tyne Hospitals NHS Foundation Trust, Newcastle Upon Tyne, UK
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Central Parkway, Newcastle Upon Tyne, UK
- NIHR Newcastle Biomedical Research Centre, Newcastle Upon Tyne, UK
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Lujinschi ȘN, Sorohan BM, Obrișcă B, Vrabie A, Lupușoru G, Achim C, Andronesi AG, Covic A, Ismail G. Genotype-Phenotype Correlations in Alport Syndrome-A Single-Center Experience. Genes (Basel) 2024; 15:593. [PMID: 38790222 PMCID: PMC11121304 DOI: 10.3390/genes15050593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2024] [Revised: 05/02/2024] [Accepted: 05/03/2024] [Indexed: 05/26/2024] Open
Abstract
BACKGROUND Alport syndrome (AS) is a common and heterogeneous genetic kidney disease, that often leads to end-stage kidney disease (ESKD). METHODS This is a single-center, retrospective study that included 36 adults with type IV collagen (COL4) mutations. Our main scope was to describe how genetic features influence renal survival. RESULTS A total of 24 different mutations were identified, of which eight had not been previously described. Mutations affecting each of the type IV collagen α chains were equally prevalent (33.3%). Most of the patients had pathogenic variants (61.1%). Most patients had a family history of kidney disease (71%). The most prevalent clinical picture was nephritic syndrome (64%). One-third of the subjects had extrarenal manifestations, 41.6% of patients had ESKD at referral, and another 8.3% developed ESKD during follow-up. The median renal survival was 42 years (95% CI, 29.98-54.01). The COL4A4 group displayed better renal survival than the COL4A3 group (p = 0.027). Patients with missense variants had higher renal survival (p = 0.023). Hearing loss was associated with lower renal survival (p < 0.001). CONCLUSIONS Patients with COL4A4 variants and those with missense mutations had significantly better renal survival, whereas those with COL4A3 variants and those with hearing loss had worse prognoses.
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Affiliation(s)
- Ștefan Nicolaie Lujinschi
- Department of Nephrology, “Carol Davila” University of Medicine and Pharmacy, 020021 Bucharest, Romania; (B.M.S.); (B.O.); (A.V.); (G.L.); (C.A.); (A.G.A.); (G.I.)
- Department of Nephrology, Fundeni Clinical Institute, 022328 Bucharest, Romania
| | - Bogdan Marian Sorohan
- Department of Nephrology, “Carol Davila” University of Medicine and Pharmacy, 020021 Bucharest, Romania; (B.M.S.); (B.O.); (A.V.); (G.L.); (C.A.); (A.G.A.); (G.I.)
- Department of Nephrology, Fundeni Clinical Institute, 022328 Bucharest, Romania
| | - Bogdan Obrișcă
- Department of Nephrology, “Carol Davila” University of Medicine and Pharmacy, 020021 Bucharest, Romania; (B.M.S.); (B.O.); (A.V.); (G.L.); (C.A.); (A.G.A.); (G.I.)
- Department of Nephrology, Fundeni Clinical Institute, 022328 Bucharest, Romania
| | - Alexandra Vrabie
- Department of Nephrology, “Carol Davila” University of Medicine and Pharmacy, 020021 Bucharest, Romania; (B.M.S.); (B.O.); (A.V.); (G.L.); (C.A.); (A.G.A.); (G.I.)
- Department of Nephrology, Fundeni Clinical Institute, 022328 Bucharest, Romania
| | - Gabriela Lupușoru
- Department of Nephrology, “Carol Davila” University of Medicine and Pharmacy, 020021 Bucharest, Romania; (B.M.S.); (B.O.); (A.V.); (G.L.); (C.A.); (A.G.A.); (G.I.)
- Department of Nephrology, Fundeni Clinical Institute, 022328 Bucharest, Romania
| | - Camelia Achim
- Department of Nephrology, “Carol Davila” University of Medicine and Pharmacy, 020021 Bucharest, Romania; (B.M.S.); (B.O.); (A.V.); (G.L.); (C.A.); (A.G.A.); (G.I.)
- Department of Nephrology, Fundeni Clinical Institute, 022328 Bucharest, Romania
| | - Andreea Gabriella Andronesi
- Department of Nephrology, “Carol Davila” University of Medicine and Pharmacy, 020021 Bucharest, Romania; (B.M.S.); (B.O.); (A.V.); (G.L.); (C.A.); (A.G.A.); (G.I.)
- Department of Nephrology, Fundeni Clinical Institute, 022328 Bucharest, Romania
| | - Andreea Covic
- Faculty of Medicine, “Grigore T. Popa” University of Medicine and Pharmacy, 700115 Iasi, Romania;
- Nephrology Depatment, Dialysis and Renal Transplant Center, “Dr. C. I. Parhon” Clinical Hospital, 700503 Iasi, Romania
| | - Gener Ismail
- Department of Nephrology, “Carol Davila” University of Medicine and Pharmacy, 020021 Bucharest, Romania; (B.M.S.); (B.O.); (A.V.); (G.L.); (C.A.); (A.G.A.); (G.I.)
- Department of Nephrology, Fundeni Clinical Institute, 022328 Bucharest, Romania
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Mahrous NN, Jamous YF, Almatrafi AM, Fallatah DI, Theyab A, Alanati BH, Alsagaby SA, Alenazi MK, Khan MI, Hawsawi YM. A Current Landscape on Alport Syndrome Cases: Characterization, Therapy and Management Perspectives. Biomedicines 2023; 11:2762. [PMID: 37893135 PMCID: PMC10604007 DOI: 10.3390/biomedicines11102762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2023] [Revised: 09/30/2023] [Accepted: 10/05/2023] [Indexed: 10/29/2023] Open
Abstract
Alport syndrome (AS) is a rare genetic disorder categorized by the progressive loss of kidney function, sensorineural hearing loss and eye abnormalities. It occurs due to mutations in three genes that encode for the alpha chains of type IV collagen. Globally, the disease is classified based on the pattern of inheritance into X-linked AS (XLAS), which is caused by pathogenic variants in COL4A5, representing 80% of AS. Autosomal recessive AS (ARAS), caused by mutations in either COL4A3 or COL4A4, represents 15% of AS. Autosomal dominant AS (ADAS) is rare and has been recorded in 5% of all cases due to mutations in COL4A3 or COL4A4. This review provides updated knowledge about AS including its clinical and genetic characteristics in addition to available therapies that only slow the progression of the disease. It also focuses on reported cases in Saudi Arabia and their prevalence. Moreover, we shed light on advances in genetic technologies like gene editing using CRISPR/Cas9 technology, the need for an early diagnosis of AS and managing the progression of the disease. Eventually, we provide a few recommendations for disease management, particularly in regions like Saudi Arabia where consanguineous marriages increase the risk.
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Affiliation(s)
- Nahed N. Mahrous
- Department of Biological Sciences, College of Science, University of Hafr Al-Batin, Hafr Al-Batin 39524, Saudi Arabia;
| | - Yahya F. Jamous
- The National Center of Vaccines and Bioprocessing, King Abdulaziz City for Science and Technology, Riyadh 12354, Saudi Arabia;
| | - Ahmad M. Almatrafi
- Department of Biological Sciences, College of Science, Taibah University, Madinah 42353, Saudi Arabia;
| | - Deema I. Fallatah
- Department of Medical Laboratory Sciences, College of Applied Medical Sciences, Prince Sattam Bin Abdulaziz University, Al-Kharj 11942, Saudi Arabia;
| | - Abdulrahman Theyab
- Department of Laboratory and Blood Bank, Security Forces Hospital, Makkah 11481, Saudi Arabia;
- Department of Biochemistry & Molecular Medicine, College of Medicine, Al-Faisal University, P.O. Box 50927, Riyadh 11533, Saudi Arabia
| | - Bayan H. Alanati
- Center for Synthetic Microbiology, Bioinformatics Core Facility, University of Marburg, 35032 Marburg, Germany;
| | - Suliman A. Alsagaby
- Department of Medicinal Laboratory Sciences, College of Applied Medical Sciences, Majmaah University, Al-Majmaah 11952, Saudi Arabia;
| | - Munifa K. Alenazi
- Research Center, King Faisal Specialist Hospital and Research Center, P.O. Box 40047, Jeddah 21499, Saudi Arabia; (M.K.A.); (M.I.K.)
| | - Mohammed I. Khan
- Research Center, King Faisal Specialist Hospital and Research Center, P.O. Box 40047, Jeddah 21499, Saudi Arabia; (M.K.A.); (M.I.K.)
| | - Yousef M. Hawsawi
- Department of Biochemistry & Molecular Medicine, College of Medicine, Al-Faisal University, P.O. Box 50927, Riyadh 11533, Saudi Arabia
- Research Center, King Faisal Specialist Hospital and Research Center, P.O. Box 40047, Jeddah 21499, Saudi Arabia; (M.K.A.); (M.I.K.)
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Gibson JT, de Gooyer M, Huang M, Savige J. A systematic review of pathogenic COL4A5 variants and proteinuria in women and girls with X-linked Alport syndrome. Kidney Int Rep 2022; 7:2454-2461. [DOI: 10.1016/j.ekir.2022.08.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 08/20/2022] [Accepted: 08/22/2022] [Indexed: 11/17/2022] Open
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Hay E, Cullup T, Barnicoat A. A practical approach to the genomics of kidney disorders. Pediatr Nephrol 2022; 37:21-35. [PMID: 33675412 DOI: 10.1007/s00467-021-04995-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 01/30/2021] [Accepted: 02/09/2021] [Indexed: 02/06/2023]
Abstract
Rapid technological advances in genomic testing continue to increase our understanding of the genetic basis of a wide range of kidney disorders. Establishing a molecular diagnosis benefits the individual by bringing an end to what is often a protracted diagnostic odyssey, facilitates accurate reproductive counselling for families and, in the future, is likely to lead to the delivery of more targeted management and surveillance regimens. The selection of the most appropriate testing modality requires an understanding both of the technologies available and of the genetic architecture and heterogeneity of kidney disease. Whilst we are witnessing a far greater diagnostic yield with broader genetic testing, such approaches invariably generate variants of uncertain significance and secondary incidental findings, which are not only difficult to interpret but present ethical challenges with reporting and feeding back to patients and their families. Here, we review the spectrum of nephrogenetic disorders, consider the optimal approach to genetic testing, explore the clinical utility of obtaining a molecular diagnosis, reflect on the challenges of variant interpretation and look to the future of this dynamic field.
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Affiliation(s)
- Eleanor Hay
- Department of Clinical Genetics, Great Ormond Street Hospital, London, UK.
| | - Thomas Cullup
- North Thames Genomic Laboratory Hub, Great Ormond Street Hospital, London, UK
| | - Angela Barnicoat
- Department of Clinical Genetics, Great Ormond Street Hospital, London, UK
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Wu J, Zhang J, Liu L, Zhang B, Yamamura T, Nozu K, Matsuo M, Zhao J. A disease-causing variant of COL4A5 in a Chinese family with Alport syndrome: a case series. BMC Nephrol 2021; 22:380. [PMID: 34774011 PMCID: PMC8590243 DOI: 10.1186/s12882-021-02585-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2021] [Accepted: 10/28/2021] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND Alport syndrome (AS), which is a rare hereditary disease caused by mutations of genes including COL4A3, COL4A4 and COL4A5, has a wide spectrum of phenotypes. Most disease-causing variants of AS are located in the exons or the conservative splicing sites of these genes, while little is known about the intronic disease-causing variants. METHODS A Chinese AS family was recruited in this study. All the clinical data of AS patient were collected from medical records. After pedigree analysis, the pathogenic variants were studied by the whole exome sequencing (WES). Minigene assay and in vivo RT-PCR analysis were performed to validate the functions of the variants. RESULTS Renal biopsy showed a typical histopathology changes of AS. WES revealed compound heterozygous substitution, NM_033380 c.991-14(IVS17) A > G, in the intron 17 of the COL4A5 gene, which were confirmed by Sanger sequencing. Moreover, the variant was co-segregated with the phenotype in this family. Minigene assay in cultured cell lines showed that a splicing error was induced by this intronic variant, which further confirmed by in vivo RT-PCR analysis. CONCLUSION A novel intronic disease-causing variant in COL4A5 gene was identified by WES, which was the molecular pathogenic basis of AS.
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Affiliation(s)
- Jing Wu
- Department of Nephrology, the key Laboratory for the Prevention and Treatment of Chronic Kidney Disease of Chongqing, Kidney Center of PLA, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, 400037, China
| | - Jun Zhang
- Department of Nephrology, the key Laboratory for the Prevention and Treatment of Chronic Kidney Disease of Chongqing, Kidney Center of PLA, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, 400037, China
| | - Li Liu
- Department of Nephrology, the key Laboratory for the Prevention and Treatment of Chronic Kidney Disease of Chongqing, Kidney Center of PLA, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, 400037, China
| | - Bo Zhang
- Department of Nephrology, the key Laboratory for the Prevention and Treatment of Chronic Kidney Disease of Chongqing, Kidney Center of PLA, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, 400037, China
| | - Tomohiko Yamamura
- Department of Pediatrics, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo, Kobe, Hyogo, 650-0017, Japan
| | - Kandai Nozu
- Department of Pediatrics, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo, Kobe, Hyogo, 650-0017, Japan
| | - Masafumi Matsuo
- Department of Physical Therapy, Faculty of Rehabilitation, Kobe Gakuin University, 518, Arise, Ikawadani-cho, Nishi, Kobe, Hyogo, 651-2180, Japan
| | - Jinghong Zhao
- Department of Nephrology, the key Laboratory for the Prevention and Treatment of Chronic Kidney Disease of Chongqing, Kidney Center of PLA, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, 400037, China.
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8
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Rossanti R, Horinouchi T, Yamamura T, Nagano C, Sakakibara N, Ishiko S, Aoto Y, Kondo A, Nagai S, Okada E, Ishimori S, Nagase H, Matsui S, Tamagaki K, Ubara Y, Nagahama M, Shima Y, Nakanishi K, Ninchoji T, Matsuo M, Iijima K, Nozu K. Evaluation of Suspected Autosomal Alport Syndrome Synonymous Variants. KIDNEY360 2021; 3:497-505. [PMID: 35582193 PMCID: PMC9034806 DOI: 10.34067/kid.0005252021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 10/11/2021] [Indexed: 01/10/2023]
Abstract
Background Alport syndrome is an inherited disorder characterized by progressive renal disease, variable sensorineural hearing loss, and ocular abnormalities. Although many pathogenic variants in COL4A3 and COL4A4 have been identified in patients with autosomal Alport syndrome, synonymous mutations in these genes have rarely been identified. Methods We conducted in silico splicing analysis using Human Splicing Finder (HSF) and Alamut to predict splicing domain strength and disruption of the sites. Furthermore, we performed in vitro splicing assays using minigene constructs and mRNA analysis of patient samples to determine the pathogenicity of four synonymous variants detected in four patients with suspected autosomal dominant Alport syndrome (COL4A3 [c.693G>A (p.Val231=)] and COL4A4 [c.1353C>T (p.Gly451=), c.735G>A (p.Pro245=), and c.870G>A (p.Lys290=)]). Results Both in vivo and in vitro splicing assays showed exon skipping in two out of the four synonymous variants identified (c.735G>A and c.870G>A in COL4A4). Prediction analysis of wild-type and mutated COL4A4 sequences using HSF and Alamut suggested these two variants may lead to the loss of binding sites for several splicing factors, e.g., in acceptor sites and exonic splicing enhancers. The other two variants did not induce aberrant splicing. Conclusions This study highlights the pitfalls of classifying the functional consequences of variants by a simple approach. Certain synonymous variants, although they do not alter the amino acid sequence of the encoded protein, can dramatically affect pre-mRNA splicing, as shown in two of our patients. Our findings indicate that transcript analysis should be carried out to evaluate synonymous variants detected in patients with autosomal dominant Alport syndrome.
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Affiliation(s)
- Rini Rossanti
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan,Department of Child Health, Nephrology Division, Dr. Hasan Sadikin General Hospital/Faculty of Medicine, Universitas Padjadjaran, Bandung, Indonesia
| | - Tomoko Horinouchi
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Tomohiko Yamamura
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - China Nagano
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Nana Sakakibara
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Shinya Ishiko
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Yuya Aoto
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Atsushi Kondo
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Sadayuki Nagai
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Eri Okada
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Shingo Ishimori
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Hiroaki Nagase
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Satoshi Matsui
- Department of Nephrology and Hypertension, Mitsubishi Kyoto Hospital, Kyoto, Japan
| | - Keiichi Tamagaki
- Department of Nephrology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Yoshifumi Ubara
- Nephrology Center, Okinaka Memorial Institute for Medical Research, Tokyo, Japan
| | | | - Yuko Shima
- Department of Pediatrics, Wakayama Medical University, Wakayama, Japan
| | - Koichi Nakanishi
- Department of Child Health and Welfare (Pediatrics), Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan
| | - Takeshi Ninchoji
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Masafumi Matsuo
- Research Center for Locomotion Biology, Kobe Gakuin University, Kobe, Japan
| | - Kazumoto Iijima
- Hyogo Prefectural Kobe Children’s Hospital, Kobe, Japan,Department of Advanced Pediatric Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Kandai Nozu
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
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Wang X, Zhang Y, Ding J, Wang F. mRNA analysis identifies deep intronic variants causing Alport syndrome and overcomes the problem of negative results of exome sequencing. Sci Rep 2021; 11:18097. [PMID: 34508137 PMCID: PMC8433132 DOI: 10.1038/s41598-021-97414-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 08/18/2021] [Indexed: 12/21/2022] Open
Abstract
Mutations in COL4A3, COL4A4 and COL4A5 genes lead to Alport syndrome (AS). However, pathogenic variants in some AS patients are not detected by exome sequencing. The aim of this study was to identify the underlying genetic causes of five unrelated AS probands with negative next-generation sequencing (NGS) test results. Urine COL4A3–5 mRNAs were analyzed in the probands with an uncertain inherited mode of AS, and COL4A5 mRNA of skin fibroblasts was analyzed in the probands with X-linked AS. RT-PCR and direct sequencing were performed to detect mRNA abnormalities. PCR and direct sequencing were used to analyze the exons with flanking intronic sequences corresponding to mRNA abnormalities. Six novel deep intronic splicing variants in COL4A4 and COL4A5 genes that cannot be captured by exome sequencing were identified in the four AS probands. Skipping of an exon was caused by an intronic variant, and retention of an intron fragment caused by five variants. In the remaining AS proband, COL4A5 variants c.2677 + 646 C > T and r.2678_r.2767del were detected at the DNA and RNA level, respectively, whereas it is unclear whether c.2677 + 646 C > T may not lead to r.2678_r.2767del. Our results reveal that mRNA analysis for AS genes from either urine or skin fibroblasts can resolve genetic diagnosis in AS patients with negative NGS results. We recommend analyzing COL4A3–5 mRNA from urine as the first choice for these patients because it is feasible and non-invasive.
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Affiliation(s)
- Xiaoyuan Wang
- Department of Pediatrics, Peking University First Hospital, Beijing, 100034, China
| | - Yanqin Zhang
- Department of Pediatrics, Peking University First Hospital, Beijing, 100034, China
| | - Jie Ding
- Department of Pediatrics, Peking University First Hospital, Beijing, 100034, China.
| | - Fang Wang
- Department of Pediatrics, Peking University First Hospital, Beijing, 100034, China.
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10
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Mastrangelo A, Giani M, Groppali E, Castorina P, Soldà G, Robusto M, Fallerini C, Bruttini M, Renieri A, Montini G. X-Linked Alport Syndrome in Women: Genotype and Clinical Course in 24 Cases. Front Med (Lausanne) 2020; 7:580376. [PMID: 33330536 PMCID: PMC7719790 DOI: 10.3389/fmed.2020.580376] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 10/19/2020] [Indexed: 11/30/2022] Open
Abstract
Objectives: X-linked Alport syndrome (XLAS) females are at risk of developing proteinuria and chronic kidney damage (CKD). The aim of this study is to evaluate the genotype-phenotype correlation in this rare population. Materials and Methods: This is a prospective, observational study of XLAS females, confirmed by a pathogenic mutation in COL4A5 and renal ultrastructural evaluation. Proteinuria, renal function and extrarenal involvement were monitored during follow-up. Patients were divided in 2 groups, according to mutations in COL4A5: missense (Group 1) and non-missense variants (Group 2). Results: Twenty-four XLAS females, aged 10.6 ± 10.4 years at clinical onset (mean follow-up: 13.1 ± 12.6 years) were recruited between 2000 and 2017 at a single center. In group 1 there were 10 patients and in group 2, 14 (mean age at the end of follow-up: 24.9 ± 13.6 and 23.2 ± 13.8 years, respectively). One patient in Group 1 and 9 in Group 2 (p = 0.013) developed proteinuria during follow-up. Mean eGFR at last follow-up was lower in Group 2 (p = 0.027), where two patients developed CKD. No differences in hearing loss were documented among the two groups. Two patients in Group 2 carried one mutation in both COL4A5 and COL4A3 (digenic inheritance) and were proteinuric. In one family, the mother presented only hematuria while the daughter was proteinuric and presented a greater inactivation of the X chromosome carrying the wild-type allele. Conclusions: The appearance of proteinuria and CKD is more frequent in patients with severe variants. Carrying digenic inheritance and skewed XCI seem to be additional risk factors for proteinuria in XLAS females.
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Affiliation(s)
- Antonio Mastrangelo
- Pediatric Nephrology, Dialysis and Transplant Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Marisa Giani
- Pediatric Nephrology, Dialysis and Transplant Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Elena Groppali
- Department of Pediatrics, V. Buzzi Children's Hospital, Milan, Italy
| | | | - Giulia Soldà
- Dipartimento di Scienze Biomediche, Humanitas University, Milan, Italy.,Humanitas Clinical and Research Center, Milan, Italy
| | - Michela Robusto
- Experimental Therapeutics Program, Istituto FIRC di Oncologia Molecolare-Fondazione Italiana per la Ricerca sul Cancro Institute of Molecular Oncology Foundation, Milan, Italy
| | | | - Mirella Bruttini
- Azienda Ospedaliera Universitaria Senese, Medical Genetics, University of Siena, Siena, Italy
| | - Alessandra Renieri
- Azienda Ospedaliera Universitaria Senese, Medical Genetics, University of Siena, Siena, Italy
| | - Giovanni Montini
- Pediatric Nephrology, Dialysis and Transplant Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.,Giuliana and Bernardo Caprotti Chair of Pediatrics, Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
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11
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Groopman EE, Povysil G, Goldstein DB, Gharavi AG. Rare genetic causes of complex kidney and urological diseases. Nat Rev Nephrol 2020; 16:641-656. [PMID: 32807983 PMCID: PMC7772719 DOI: 10.1038/s41581-020-0325-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/03/2020] [Indexed: 02/08/2023]
Abstract
Although often considered a single-entity, chronic kidney disease (CKD) comprises many pathophysiologically distinct disorders that result in persistently abnormal kidney structure and/or function, and encompass both monogenic and polygenic aetiologies. Rare inherited forms of CKD frequently span diverse phenotypes, reflecting genetic phenomena including pleiotropy, incomplete penetrance and variable expressivity. Use of chromosomal microarray and massively parallel sequencing technologies has revealed that genomic disorders and monogenic aetiologies contribute meaningfully to seemingly complex forms of CKD across different clinically defined subgroups and are characterized by high genetic and phenotypic heterogeneity. Investigations of prevalent genomic disorders in CKD have integrated genetic, bioinformatic and functional studies to pinpoint the genetic drivers underlying their renal and extra-renal manifestations, revealing both monogenic and polygenic mechanisms. Similarly, massively parallel sequencing-based analyses have identified gene- and allele-level variation that contribute to the clinically diverse phenotypes observed for many monogenic forms of nephropathy. Genome-wide sequencing studies suggest that dual genetic diagnoses are found in at least 5% of patients in whom a genetic cause of disease is identified, highlighting the fact that complex phenotypes can also arise from multilocus variation. A multifaceted approach that incorporates genetic and phenotypic data from large, diverse cohorts will help to elucidate the complex relationships between genotype and phenotype for different forms of CKD, supporting personalized medicine for individuals with kidney disease.
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Affiliation(s)
- Emily E Groopman
- Division of Nephrology, Columbia University College of Physicians and Surgeons, New York, NY, USA
| | - Gundula Povysil
- Institute for Genomic Medicine, Columbia University, New York, NY, USA
| | - David B Goldstein
- Institute for Genomic Medicine, Columbia University, New York, NY, USA
| | - Ali G Gharavi
- Division of Nephrology, Columbia University College of Physicians and Surgeons, New York, NY, USA.
- Institute for Genomic Medicine, Columbia University, New York, NY, USA.
- Center for Precision Medicine and Genomics, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, NY, USA.
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12
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Horinouchi T, Yamamura T, Minamikawa S, Nagano C, Sakakibara N, Nakanishi K, Shima Y, Morisada N, Ishiko S, Aoto Y, Nagase H, Takeda H, Rossanti R, Ishimori S, Kaito H, Matsuo M, Iijima K, Nozu K. Pathogenic evaluation of synonymous COL4A5 variants in X-linked Alport syndrome using a minigene assay. Mol Genet Genomic Med 2020; 8:e1342. [PMID: 32543079 PMCID: PMC7434753 DOI: 10.1002/mgg3.1342] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 05/13/2020] [Accepted: 05/19/2020] [Indexed: 12/20/2022] Open
Abstract
Background X‐linked Alport syndrome (XLAS) is a progressive, hereditary glomerular nephritis of variable severity caused by pathogenic COL4A5 variants. Currently, genetic testing is widely used for diagnosing XLAS; however, determining the pathogenicity of variants detected by such analyses can be difficult. Intronic variants or synonymous variants may cause inherited diseases by inducing aberrant splicing. Transcript analysis is necessary to confirm the pathogenicity of such variants, but it is sometimes difficult to extract mRNA directly from patient specimens. Methods In this study, we conducted in vitro splicing analysis using a hybrid minigene assay and specimens from three XLAS patients with synonymous variants causing aberrant splicing, including previously reported pathogenic mutations in the same codon. The variants were c.876 A>T (p.Gly292=), c.2358 A>G (p.Pro786=), and c.3906 A>G (p.Gln1302=). Results The results from our hybrid minigene assay were sufficient to predict splicing abnormalities; c.876 A>T cause 17‐bp del and 35‐bp del, c.2358 A>G cause exon 29 skipping, c.3906 A>G cause exon 42 skipping, which are very likely to cause pathogenicity. Further, patients carrying c.2358 A>G exhibited a mild phenotype that may have been associated with the presence of both normal and abnormally spliced transcripts. Conclusion The minigene system was shown to be a sensitive assay and a useful tool for investigating the pathogenicity of synonymous variants.
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Affiliation(s)
- Tomoko Horinouchi
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Tomohiko Yamamura
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Shogo Minamikawa
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - China Nagano
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Nana Sakakibara
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Koichi Nakanishi
- Department of Child Health and Welfare (Pediatrics), Graduate School of Medicine, University of the Ryukyus, Nishihara, Japan
| | - Yuko Shima
- Department of Pediatrics, Wakayama Medical University, Wakayama, Japan
| | - Naoya Morisada
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Shinya Ishiko
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Yuya Aoto
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Hiroaki Nagase
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Hiroki Takeda
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Rini Rossanti
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Shingo Ishimori
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Hiroshi Kaito
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Masafumi Matsuo
- Department of Physical Therapy, Faculty of Rehabilitation, Kobe Gakuin University, Kobe, Japan
| | - Kazumoto Iijima
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Kandai Nozu
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
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13
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Horinouchi T, Nozu K, Yamamura T, Minamikawa S, Nagano C, Sakakibara N, Nakanishi K, Shima Y, Morisada N, Ishiko S, Aoto Y, Nagase H, Takeda H, Rossanti R, Kaito H, Matsuo M, Iijima K. Determination of the pathogenicity of known COL4A5 intronic variants by in vitro splicing assay. Sci Rep 2019; 9:12696. [PMID: 31481700 PMCID: PMC6722096 DOI: 10.1038/s41598-019-48990-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 08/15/2019] [Indexed: 02/07/2023] Open
Abstract
X-linked Alport syndrome (XLAS) is a congenital renal disease caused by mutations in COL4A5. In XLAS cases suspected of being caused by aberrant splicing, transcript analysis needs to be conducted to determine splicing patterns and assess the pathogenicity. However, such analysis is not always available. We conducted a functional splicing assay using a hybrid minigene for seven COL4A5 intronic mutations: one was identified by us and six were found in the Human Gene Mutation Database. The minigene assay revealed exon skipping in four variants, exon skipping and a 10-bp insertion in one variant, and no change in one variant, which appeared not to be pathogenic. For one variant, our assay did not work. The results of all three cases for which transcript data were available were consistent with our assay results. Our findings may help to increase the accuracy of genetic test results and clarify the mechanisms causing aberrant splicing.
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Affiliation(s)
- Tomoko Horinouchi
- Department of Pediatrics, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo, Kobe, Hyogo, 650-0017, Japan
| | - Kandai Nozu
- Department of Pediatrics, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo, Kobe, Hyogo, 650-0017, Japan.
| | - Tomohiko Yamamura
- Department of Pediatrics, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo, Kobe, Hyogo, 650-0017, Japan
| | - Shogo Minamikawa
- Department of Pediatrics, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo, Kobe, Hyogo, 650-0017, Japan
| | - China Nagano
- Department of Pediatrics, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo, Kobe, Hyogo, 650-0017, Japan
| | - Nana Sakakibara
- Department of Pediatrics, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo, Kobe, Hyogo, 650-0017, Japan
| | - Koichi Nakanishi
- Department of Child Health and Welfare (Pediatrics), Graduate School of Medicine, University of the Ryukyus, 207, Uehara, Nishihara-cho, Tyutou, Okinawa, 903-0125, Japan
| | - Yuko Shima
- Department of Pediatrics, Wakayama Medical University, 811-1, Kimiidera, Wakayama, Wakayama Prefecture, 641-8510, Japan
| | - Naoya Morisada
- Department of Pediatrics, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo, Kobe, Hyogo, 650-0017, Japan
| | - Shinya Ishiko
- Department of Pediatrics, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo, Kobe, Hyogo, 650-0017, Japan
| | - Yuya Aoto
- Department of Pediatrics, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo, Kobe, Hyogo, 650-0017, Japan
| | - Hiroaki Nagase
- Department of Pediatrics, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo, Kobe, Hyogo, 650-0017, Japan
| | - Hiroki Takeda
- Department of Pediatrics, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo, Kobe, Hyogo, 650-0017, Japan
| | - Rini Rossanti
- Department of Pediatrics, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo, Kobe, Hyogo, 650-0017, Japan
| | - Hiroshi Kaito
- Department of Pediatrics, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo, Kobe, Hyogo, 650-0017, Japan
| | - Masafumi Matsuo
- Department of Physical Therapy, Faculty of Rehabilitation, Kobe Gakuin University, 518, Arise, Ikawadani-cho, Nishi, Kobe, Hyogo, 651-2180, Japan
| | - Kazumoto Iijima
- Department of Pediatrics, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo, Kobe, Hyogo, 650-0017, Japan
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14
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He WB, Du J, Yang XW, Li W, Tang WL, Dai C, Chen YZ, Zhang YX, Lu GX, Lin G, Gong F, Tan YQ. Novel inactivating mutations in the FSH receptor cause premature ovarian insufficiency with resistant ovary syndrome. Reprod Biomed Online 2019; 38:397-406. [DOI: 10.1016/j.rbmo.2018.11.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2018] [Revised: 08/29/2018] [Accepted: 11/29/2018] [Indexed: 02/05/2023]
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15
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Han KH, Park JE, Ki CS. De novo mutations in COL4A5 identified by whole exome sequencing in 2 girls with Alport syndrome in Korea. KOREAN JOURNAL OF PEDIATRICS 2018; 62:193-197. [PMID: 30477285 PMCID: PMC6528060 DOI: 10.3345/kjp.2018.06772] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Accepted: 11/26/2018] [Indexed: 12/12/2022]
Abstract
Alport syndrome (ATS) is an inherited glomerular disease caused by mutations in one of the type IV collagen novel chains (α3, α4, and α5). ATS is characterized by persistent microscopic hematuria that starts during infancy, eventually leading to either progressive nephritis or end-stage renal disease. There are 3 known genetic forms of ATS, namely X-linked ATS, autosomal recessive ATS, and autosomal dominant ATS. About 80% of patients with ATS have X-linked ATS, which is caused by mutations in the type IV collagen α5 chain gene, COL4A5. Although an 80% mutation detection rate is observed in men with X-linked ATS, some difficulties do exist in the genetic diagnosis of ATS. Most mutations are point mutations without hotspots in the COL4A3, COL4A4, and COL4A5 genes. Further, there are insufficient data on the detection of COL4A3 and COL4A4 mutations for their comparison between patients with autosomal recessive or dominant ATS. Therefore, diagnosis of ATS in female patients with no apparent family history can be challenging. Therefore, in this study, we used whole-exome sequencing (WES) to identify mutations in type IV collagen in 2 girls with glomerular basement membrane structural changes suspected to be associated with ATS; these patients had no relevant family history. Our results revealed de novo c.4688G>A (p.Arg1563Gln) and c.2714G>A (p.Gly905Asp) mutations in COL4A5. Therefore, we suggest that WES is an effective approach to obtain genetic information in ATS, particularly in female patients without a relevant family history, to detect unexpected DNA variations.
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Affiliation(s)
- Kyoung Hee Han
- Department of Pediatrics, Jeju National University School of Medicine, Jeju, Korea
| | - Jong Eun Park
- Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
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16
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Kashtan CE, Ding J, Garosi G, Heidet L, Massella L, Nakanishi K, Nozu K, Renieri A, Rheault M, Wang F, Gross O. Alport syndrome: a unified classification of genetic disorders of collagen IV α345: a position paper of the Alport Syndrome Classification Working Group. Kidney Int 2018; 93:1045-1051. [PMID: 29551517 DOI: 10.1016/j.kint.2017.12.018] [Citation(s) in RCA: 151] [Impact Index Per Article: 25.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 11/24/2017] [Accepted: 12/13/2017] [Indexed: 01/01/2023]
Abstract
Mutations in the genes COL4A3, COL4A4, and COL4A5 affect the synthesis, assembly, deposition, or function of the collagen IV α345 molecule, the major collagenous constituent of the mature mammalian glomerular basement membrane. These mutations are associated with a spectrum of nephropathy, from microscopic hematuria to progressive renal disease leading to ESRD, and with extrarenal manifestations such as sensorineural deafness and ocular anomalies. The existing nomenclature for these conditions is confusing and can delay institution of appropriate nephroprotective therapy. Herein we propose a new classification of genetic disorders of the collagen IV α345 molecule with the goal of improving renal outcomes through regular monitoring and early treatment.
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Affiliation(s)
- Clifford E Kashtan
- Department of Pediatrics, Division of Pediatric Nephrology, Alport Syndrome Treatments and Outcomes Registry, University of Minnesota Medical School and Masonic Children's Hospital, Minneapolis, Minnesota, USA.
| | - Jie Ding
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Guido Garosi
- Unita Operativa Complessa Nefrologia, Dialisi e Trapianto, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Laurence Heidet
- Asssitance Publique-Hôpitaux de Paris, Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte and Service de Néphrologie Pédiatrique, Hôpital Universitaire Necker-Enfants Malades, Paris, France
| | - Laura Massella
- Nephrology and Dialysis Unit, Pediatric Subspecialties Department, Bambino Gesu Children's Hospital, Istituto Di Ricovero e Cura a Carattere Scientifico, Rome, Italy
| | - Koichi Nakanishi
- Department of Child Health and Welfare (Pediatrics), Graduate School of Medicine, University of the Ryukus, Okinawa, Japan
| | - Kandai Nozu
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Alessandra Renieri
- Medical Genetics, University of Siena, Siena, Italy; Genetica Medica, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Michelle Rheault
- Department of Pediatrics, Division of Pediatric Nephrology, Alport Syndrome Treatments and Outcomes Registry, University of Minnesota Medical School and Masonic Children's Hospital, Minneapolis, Minnesota, USA
| | - Fang Wang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Oliver Gross
- Clinic of Nephrology and Rheumatology, University Medical Center Goettingen, University of Goettingen, Goettingen, Germany
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