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Uedono H, Mori K, Nakatani S, Watanabe K, Nakaya R, Morioka F, Sone K, Ono C, Hotta J, Tsuda A, Morisada N, Seto T, Nozu K, Emoto M. Novel Digenic Variants in COL4A4 and COL4A5 Causing X-Linked Alport Syndrome: A Case Report. Case Rep Nephrol Dial 2024; 14:1-9. [PMID: 38179179 PMCID: PMC10764090 DOI: 10.1159/000535493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Accepted: 11/18/2023] [Indexed: 01/06/2024] Open
Abstract
Introduction Alport syndrome (AS) is a hereditary, progressive kidney disease characterized by structural abnormalities and dysfunction of the glomerular basement membrane (GBM). AS is classified as X-linked, autosomal, and digenic. The number of cases of digenic AS has increased, but the genotype-phenotype correlation of patient with digenic AS is still unclear. Here, we present a case of digenic AS with novel digenic missense variants in COL4A4 (c.827G>C, p.Gly276Ala) and COL4A5 (c.4369G>C, p.Gly1457Arg). Case Presentation The patient was a 29-year-old Japanese man suffering from persistent microscopic hematuria and proteinuria without kidney function impairment. Kidney biopsy showed focal interstitial foam cell infiltration, global and segmental glomerulosclerosis. Immunofluorescence staining for collagen IV α5 was almost negative in the GBM and Bowman's capsule. Electron microscopy revealed irregular thickening with lamellation and segmental thinning of the GBM. Clinical and pathological findings were consistent with AS. Comprehensive next-generation sequencing revealed a heterozygous missense variant in COL4A4 (c.827G>C, p.Gly276Ala) in exon 1 and a hemizygous missense variant in COL4A5 (c.4369G>C, p.Gly1457Arg) in exon 49 on the patient's paternal and maternal alleles, respectively. The same digenic variants were detected in his sister, and she also showed a similar phenotype. After treatment with angiotensin-converting enzyme inhibitors, proteinuria decreased from 2.3 to 1.1 g/g creatinine, but occult blood persisted. During follow-up, kidney function has been preserved. Conclusion The novel genotype of our case provides more information on the genotype-phenotype correlation of digenic XLAS, although long-term follow-up is required. The findings in the present case also indicate the importance of genetic tests for family members of a patient diagnosed with digenic AS.
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Affiliation(s)
- Hideki Uedono
- Department of Metabolism, Endocrinology and Molecular Medicine, Osaka Metropolitan University Graduate School of Medicine, Osaka, Japan
| | - Katsuhito Mori
- Department of Nephrology, Osaka Metropolitan University Graduate School of Medicine, Osaka, Japan
| | - Shinya Nakatani
- Department of Metabolism, Endocrinology and Molecular Medicine, Osaka Metropolitan University Graduate School of Medicine, Osaka, Japan
| | - Kohei Watanabe
- Department of Metabolism, Endocrinology and Molecular Medicine, Osaka Metropolitan University Graduate School of Medicine, Osaka, Japan
| | - Rino Nakaya
- Department of Metabolism, Endocrinology and Molecular Medicine, Osaka Metropolitan University Graduate School of Medicine, Osaka, Japan
| | - Fumiyuki Morioka
- Department of Metabolism, Endocrinology and Molecular Medicine, Osaka Metropolitan University Graduate School of Medicine, Osaka, Japan
| | - Kazuma Sone
- Department of Metabolism, Endocrinology and Molecular Medicine, Osaka Metropolitan University Graduate School of Medicine, Osaka, Japan
| | - Chie Ono
- Department of Medical Genetics, Osaka Metropolitan University Graduate School of Medicine, Osaka, Japan
| | - Junko Hotta
- Department of Medical Genetics, Osaka Metropolitan University Graduate School of Medicine, Osaka, Japan
| | - Akihiro Tsuda
- Department of Metabolism, Endocrinology and Molecular Medicine, Osaka Metropolitan University Graduate School of Medicine, Osaka, Japan
| | - Naoya Morisada
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Toshiyuki Seto
- Department of Medical Genetics, Osaka Metropolitan University Graduate School of Medicine, Osaka, Japan
| | - Kandai Nozu
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Masanori Emoto
- Department of Metabolism, Endocrinology and Molecular Medicine, Osaka Metropolitan University Graduate School of Medicine, Osaka, Japan
- Department of Nephrology, Osaka Metropolitan University Graduate School of Medicine, Osaka, Japan
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Beadell I, Quinlan C. A decision-making framework for genomic testing in paediatric nephrology. J Paediatr Child Health 2023; 59:1304-1310. [PMID: 37975548 DOI: 10.1111/jpc.16514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 10/17/2023] [Accepted: 10/27/2023] [Indexed: 11/19/2023]
Abstract
AIM Technological advances and increased access have led to genomics expanding beyond the genetics clinic. Consequently, nephrologists can now order genomic testing for their patients. Consistent decision-making around patient and test selection is required to ensure equitable access while maximising the utility of genomic testing. However, there are currently no frameworks to guide decision-making for testing in this context. We aimed to develop an ethical decision-making framework for genomic testing in paediatric nephrology. METHODS A three-stage approach was used: (i) review of the literature on decision-making for genomic testing in nephrology and other disciplines; (ii) ethnographic observation of approaches to genomic testing in the general nephrology and renal genetics clinics at an Australian paediatric hospital; (iii) review and revision of the framework with key stakeholders, including clinical geneticists, genetic counsellors, paediatric nephrologists and families from the renal genetics service. The initial framework was modified until consensus from key stakeholders was reached. RESULTS A decision-making framework was created with questions designed to explore the impact of genomic testing on patient management, clinical validity, patient characteristics, alternatives to genomic testing, genetic counselling, resource availability, implications for family members, psychosocial considerations, patient autonomy, research, support services and insurance. Case studies were developed to demonstrate the framework's application. CONCLUSIONS This framework was designed to guide decisions around patient selection for genomic testing in nephrology in the Australian health-care setting, with potential utility in other institutions and medical disciplines. It may help facilitate consistent approaches to genomic testing, to maximise equity and utility.
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Affiliation(s)
- Inez Beadell
- Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
| | - Catherine Quinlan
- Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
- Kidney Flagship, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
- Department of Paediatric Nephrology, The Royal Children's Hospital, Melbourne, Victoria, Australia
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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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Kohler J, Omachi K, Charu V, Miner JH, Bhalla V. A COL4A4-G394S Variant and Impaired Collagen IV Trimerization in a Patient with Mild Alport Syndrome. KIDNEY360 2022; 3:1899-1908. [PMID: 36514391 PMCID: PMC9717634 DOI: 10.34067/kid.0005472022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Accepted: 10/18/2022] [Indexed: 04/14/2023]
Abstract
Background Missense variants in COL4A genes are often found in patients with an Alport syndrome-like presentation, but their pathogenicity is not always clear. We encountered a woman with microscopic hematuria and proteinuria at 33 years of age with a diagnosis of thin basement membrane disease who was approaching end stage kidney disease at 59 years of age. We hypothesized that this patient's kidney disease was within the spectrum of Alport syndrome. Methods We used histologic, genetic, and biochemical approaches to investigate the mechanisms of kidney disease. By immunofluorescence, we investigated collagen IV chain composition of the glomerular basement membrane (GBM). We employed targeted sequencing to search for pathogenic variants in COL4A and other relevant genes. We utilized N- and C-terminal split NanoLuciferase assays to determine the effect of a novel COL4A4 variant of uncertain significance (VUS) on collagen IV heterotrimer formation in vitro. We transfected COL4A4 expression constructs with split NanoLuciferase fragment-fused COL4A3 and COL4A5 constructs into human embryonic kidney 293T cells. To assay for α3α4α5(IV) heterotrimer formation and secretion, we measured luminescence in cell lysates and culture supernatants from transfected cells. Results Immunostaining suggested that the collagen α3α4α5(IV) network was present throughout the patient's GBMs. DNA sequencing revealed a novel homozygous VUS: COL4A4 c.1180G>A (p. Gly394Ser). In the C-terminal split luciferase-based α3α4α5(IV) heterotrimer formation assays, luminescence levels for G394S were comparable to WT, but in the N-terminal tag assays, the extracellular luminescence levels for G394S were decreased by approximately 50% compared with WT. Conclusions Our cell-based assay provides a platform to test COL4 VUS and shows that G394S impairs assembly of the α3α4α5(IV) N-terminus and subsequent trimer secretion. These data suggest that the COL4A4-G394S variant is pathogenic and causes an atypical mild form of autosomal recessive Alport syndrome.
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Affiliation(s)
- Jennefer Kohler
- Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, California
| | - Kohei Omachi
- Division of Nephrology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Vivek Charu
- Department of Pathology, Stanford University School of Medicine, Stanford, California
| | - Jeffrey H. Miner
- Division of Nephrology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Vivek Bhalla
- Division of Nephrology, Department of Medicine, Stanford School of Medicine, Stanford, California
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5
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Mastrangelo A, Madeira C, Castorina P, Giani M, Montini G. Heterozygous COL4A3/COL4A4 mutations: the hidden part of the iceberg? Nephrol Dial Transplant 2022; 37:2398-2407. [PMID: 35090027 DOI: 10.1093/ndt/gfab334] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Single mutations in COL4A3/COL4A4 genes have been described in patients with autosomal dominant Alport syndrome and thin basement membrane nephropathy, without a shared definition of these patients within the medical community. We aimed to better categorize this clinical entity by examining clinical manifestations, family history, pathological features and genetics. METHODS We retrospectively analyzed patients with causative heterozygous COL4A3/COL4A4 mutations referred to us between 1990 and 2019. Index cases were defined as children who were the first to be diagnosed in their families. RESULTS The study included 24 index cases and 29 affected relatives, belonging to 25 families with a heterozygous mutation in the COL4A3/COL4A4 genes. During the follow-up, nine patients developed proteinuria [median age 15.7 years (range 5.6-33)], six at clinical diagnosis and four with progression toward chronic kidney disease (CKD) (three required kidney replacement therapy at 25, 45 and 53 years and one had CKD Stage 2 at 46 years). Extrarenal involvement was observed in 24.5% of patients. Hematuria was transmitted in consecutive generations, while CKD was reported in nonconsecutive generations of 11 families [median age 53 years (range 16-80)]. Seventeen patients (32%) underwent kidney biopsy: findings were consistent with Alport syndrome in 12 cases and with thin basement membrane nephropathy in 5 cases. CONCLUSIONS Despite the benign course for these patients described in the literature, a significant percentage is at risk for disease progression. Consequently, we suggest that the assessment of these patients must take into account family history, genetic analysis and pathologic findings. After comparison with the literature, our data suggest that a different definition for Alport syndrome must be considered.
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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
| | - Giovanni Montini
- Pediatric Nephrology, Dialysis, and Transplant Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.,Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
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Caliskan Y, Lentine KL. Approach to genetic testing to optimize the safety of living donor transplantation in Alport syndrome spectrum. Pediatr Nephrol 2022; 37:1981-1994. [PMID: 35088158 DOI: 10.1007/s00467-022-05430-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 11/26/2021] [Accepted: 12/06/2021] [Indexed: 10/19/2022]
Abstract
Alport syndrome spectrum can be considered as a group of genetic diseases affecting the major basement membrane collagen type IV network in various organs including the ear, eye, and kidney. The living donor candidate evaluation is an ever-changing landscape. Recently, next-generation sequence (NGS) panels have become readily available and provide opportunities to genetically screen recipient and donor candidates for collagen network gene variants. In this review, our aim is to provide a comprehensive update on the role of genetic testing for the evaluation of potential living kidney donors to kidney candidates with Alport syndrome spectrum. We examine the utility of genetic testing in the evaluation of potential donors for recipients with Alport syndrome spectrum, and discuss risks and unresolved challenges. Suggested algorithms in the context of related and unrelated donation are offered. In contemporary practice, an approach to the evaluation of living donor candidates for transplant candidates with Alport syndrome spectrum can incorporate genetic testing in algorithms tailored for donor-recipient relationship status. Ongoing research is needed to inform optimal practice.
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Affiliation(s)
- Yasar Caliskan
- Saint Louis University Center for Abdominal Transplantation, 1201 S. Grand Blvd, St. Louis, MO, 63110, USA.
| | - Krista L Lentine
- Saint Louis University Center for Abdominal Transplantation, 1201 S. Grand Blvd, St. Louis, MO, 63110, USA
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7
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Wang FM, Yang Y, Zhang XL, Wang YL, Tu Y, Liu BC, Wang B. Combination of a Novel Genetic Variant in CFB Gene and a Pathogenic Variant in COL4A5 Gene in a Sibling Renal Disease: A Case Report. Front Genet 2021; 12:690952. [PMID: 34349783 PMCID: PMC8326751 DOI: 10.3389/fgene.2021.690952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 06/07/2021] [Indexed: 12/02/2022] Open
Abstract
Complement factor B (CFB) variants have been described to play a causative role in auto-immune associated C3 glomerulopathy (C3G) and/or atypical hemolytic uremic syndrome (aHUS) by affecting the dysregulations of alternative pathway activation. However, CFB variant concomitant with COL4A5 variant is scarce. Here, we depict two intriguing cases with concurrent novel heterozygosity for CFB c.2054_2057del (p.Ser687Profs∗16) variant and a previous reported COL4A5 c.2999G > T (p.Gly1000Val) variant in a pair of siblings. The clinical feature of either paternal CFB variant or maternal COL4A5 variant is just mild microscopic hematuria. Interestingly, their two children with paternal CFB c.2054_2057del (p.Ser687Profs∗16) variant and maternal COL4A5 c.2999G > T (p.Gly1000Val) variant presented with massive proteinuria, hematuria, and progressive renal failure with poor treatment response. Moreover, complement pathway activation in renal tissue further supports and strengthens the pathogenic role of CFB variant in the development of renal injury in the presence of COL4A5 variant. In conclusion, the rare sibling cases highlight that the extension of genetic analyses in the proband is helpful for the diagnosis and understanding of some family cluster renal diseases.
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Affiliation(s)
- Feng-Mei Wang
- Institute of Nephrology, Zhongda Hospital, Southeast University School of Medicine, Nanjing, China
| | - Yan Yang
- Institute of Nephrology, Zhongda Hospital, Southeast University School of Medicine, Nanjing, China
| | - Xiao-Liang Zhang
- Institute of Nephrology, Zhongda Hospital, Southeast University School of Medicine, Nanjing, China
| | - Yan-Li Wang
- Institute of Nephrology, Zhongda Hospital, Southeast University School of Medicine, Nanjing, China
| | - Yan Tu
- Institute of Nephrology, Zhongda Hospital, Southeast University School of Medicine, Nanjing, China
| | - Bi-Cheng Liu
- Institute of Nephrology, Zhongda Hospital, Southeast University School of Medicine, Nanjing, China
| | - Bin Wang
- Institute of Nephrology, Zhongda Hospital, Southeast University School of Medicine, Nanjing, China
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Patient engagement in preclinical laboratory research: A scoping review. EBioMedicine 2021; 70:103484. [PMID: 34280783 PMCID: PMC8318845 DOI: 10.1016/j.ebiom.2021.103484] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 06/24/2021] [Accepted: 06/25/2021] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND 'Patient engagement' involves meaningful collaboration between researchers and 'patient partners' to co-create research. It helps ensure that research being conducted is relevant to its ultimate end-users. Although patient engagement within clinical research has been well documented, the prevalence and effects of patient engagement in translational preclinical laboratory research remain unclear. The aim of this scoping review is to present current patient engagement activities reported in preclinical laboratory research. METHODS MEDLINE, Embase, and grey literature were systematically searched from inception to April 2021. Studies that described or investigated patient engagement in preclinical laboratory research were included. Patient engagement activities where patients (i.e. patients, family members, caregivers or community members) provided input, or consultation on at least one element of the research process were eligible for inclusion. Study characteristics and outcomes were extracted and organized thematically. FINDINGS 32 reports were included (30 primary studies, 1 narrative review, and 1 researcher guide). Most studies engaged patients at the education or priority setting stages (n=26). The most frequently reported benefit of patient engagement was 'providing a mutual learning opportunity'. Reported barriers to patient engagement reflected concerns around 'differences in knowledge and research experience' and how this may challenge communication and limit meaningful collaboration. INTERPRETATION Patient engagement is feasible and beneficial for preclinical laboratory research. Future work should focus on assessing the impacts of patient engagement in this area of research.
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Tang S, Yonezawa T, Maeda Y, Ono M, Maeba T, Miyoshi T, Momota R, Tomono Y, Oohashi T. Lack of collagen α6(IV) chain in mice does not cause severe-to-profound hearing loss or cochlear malformation, a distinct phenotype from nonsyndromic hearing loss with COL4A6 missense mutation. PLoS One 2021; 16:e0249909. [PMID: 33848312 PMCID: PMC8043391 DOI: 10.1371/journal.pone.0249909] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2020] [Accepted: 03/26/2021] [Indexed: 11/18/2022] Open
Abstract
Congenital hearing loss affects 1 in every 1000 births, with genetic mutations contributing to more than 50% of all cases. X-linked nonsyndromic hereditary hearing loss is associated with six loci (DFNX1-6) and five genes. Recently, the missense mutation (c.1771G>A, p.Gly591Ser) in COL4A6, encoding the basement membrane (BM) collagen α6(IV) chain, was shown to be associated with X-linked congenital nonsyndromic hearing loss with cochlear malformation. However, the mechanism by which the COL4A6 mutation impacts hereditary hearing loss has not yet been elucidated. Herein, we investigated Col4a6 knockout (KO) effects on hearing function and cochlear formation in mice. Immunohistochemistry showed that the collagen α6(IV) chain was distributed throughout the mouse cochlea within subepithelial BMs underlying the interdental cells, inner sulcus cells, basilar membrane, outer sulcus cells, root cells, Reissner's membrane, and perivascular BMs in the spiral limbus, spiral ligament, and stria vascularis. However, the click-evoked auditory brainstem response analysis did not show significant changes in the hearing threshold of Col4a6 KO mice compared with wild-type (WT) mice with the same genetic background. In addition, the cochlear structures of Col4a6 KO mice did not exhibit morphological alterations, according to the results of high-resolution micro-computed tomography and histology. Hence, loss of Col4a6 gene expression in mice showed normal click ABR thresholds and normal cochlear formation, which differs from humans with the COL4A6 missense mutation c.1771G>A, p.Gly591Ser. Therefore, the deleterious effects in the auditory system caused by the missense mutation in COL4A6 are likely due to the dominant-negative effects of the α6(IV) chain and/or α5α6α5(IV) heterotrimer with an aberrant structure that would not occur in cases with loss of gene expression.
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Affiliation(s)
- Shaoying Tang
- Department of Molecular Biology and Biochemistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Tomoko Yonezawa
- Department of Molecular Biology and Biochemistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
- * E-mail:
| | - Yukihide Maeda
- Department of Otolaryngology-Head and Neck Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Mitsuaki Ono
- Department of Molecular Biology and Biochemistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Takahiro Maeba
- Department of Molecular Biology and Biochemistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Toru Miyoshi
- Department of Cardiovascular Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Ryusuke Momota
- Department of Human Morphology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Yasuko Tomono
- Division of Molecular and Cell Biology, Shigei Medical Research Institute, Okayama, Japan
| | - Toshitaka Oohashi
- Department of Molecular Biology and Biochemistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
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Long-term outcome among females with Alport syndrome from a single pediatric center. Pediatr Nephrol 2021; 36:945-951. [PMID: 33048202 PMCID: PMC7914153 DOI: 10.1007/s00467-020-04748-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 07/23/2020] [Accepted: 08/27/2020] [Indexed: 10/23/2022]
Abstract
BACKGROUND Alport syndrome (AS) is a multisystem condition which can result in progressive kidney disease, hearing loss, and ocular changes. X-linked inheritance is observed in 85% of affected individuals. As a result, most prior studies have focused on males. Girls with AS can also be symptomatic although historically thought to have few clinical manifestations in childhood. The objective of the study was to describe the clinical presentation and course of females with AS. METHODS A single-center retrospective study of all young females with AS between January 1, 1987, and May 20, 2019. Subjects were identified using ICD-9/10 diagnosis codes for AS, familial hematuria, or nephritis. Clinical data were extracted by retrospective chart review. RESULTS Thirty-six female patients were included in the analysis. Mean age at presentation was 5.58 ± 3.0 years, and mean follow-up was 5.9 ± 3.9 years. Twenty-nine patients (80%) had a family history of AS. At end of the follow-up period, gross hematuria was observed in 15 patients (42%), 20 (56%) developed proteinuria, and 2 (6.7%) had an estimated glomerular filtration rate (eGFR) < 90 ml/min/1.73m2 with one patient developing stage 5 chronic kidney disease. Four of the twenty-seven (14.8%) who underwent audiologic testing had an abnormal exam. CONCLUSIONS Known family histories of AS or gross hematuria were the most common reasons for the initial presentation in our cohort. Development of proteinuria, eGFR < 90 ml/min/1.73m2, and abnormal audiology exam are not exceptional findings, suggesting that close monitoring of young females into adulthood is warranted.
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Weinstock BA, Feldman DL, Fornoni A, Gross O, Kashtan CE, Lagas S, Lennon R, Miner JH, Rheault MN, Simon JF. Clinical trial recommendations for potential Alport syndrome therapies. Kidney Int 2020; 97:1109-1116. [PMID: 32386680 PMCID: PMC7614298 DOI: 10.1016/j.kint.2020.02.029] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 02/04/2020] [Accepted: 02/12/2020] [Indexed: 12/26/2022]
Abstract
Alport syndrome is experiencing a remarkable increase in preclinical investigations. To proactively address the needs of the Alport syndrome community, as well as offer clarity for future clinical research sponsors, the Alport Syndrome Foundation hosted a workshop to generate consensus recommendations for prospective trials for conventional drugs. Opinions of key stakeholders were carefully considered, including those of the biopharmaceutical industry representatives, academic researchers, clinicians, regulatory agency representatives, and-most critically-patients with Alport syndrome. Recommendations were established for preclinical researchers, the use and selection of biomarkers, standards of care, clinical trial designs, trial eligibility criteria and outcomes, pediatric trial considerations, and considerations for patient engagement, recruitment, and treatment. This paper outlines their recommendations.
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Affiliation(s)
| | | | - Alessia Fornoni
- Katz Family Division of Nephrology and Hypertension, Miller School of Medicine, University of Miami, Miami, Florida, USA
| | - Oliver Gross
- Department of Nephrology and Rheumatology, Universitätsmedizin Göttingen, Göttingen, Germany
| | - Clifford E Kashtan
- Department of Pediatrics, University of Minnesota Medical School, Minneapolis, Minnesota, USA
| | - Sharon Lagas
- Alport Syndrome Foundation, Phoenix, Arizona, USA
| | - Rachel Lennon
- Division of Cell Matrix Biology & Regenerative Medicine, University of Manchester, Manchester, England, UK.
| | - Jeffrey H Miner
- Division of Nephrology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Michelle N Rheault
- Department of Pediatrics, University of Minnesota Medical School, Minneapolis, Minnesota, USA
| | - James F Simon
- Department of Nephrology and Hypertension, The Cleveland Clinic, Cleveland, Ohio, USA
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