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Cocorpus J, Hager MM, Benchimol C, Bijol V, Salem F, Punj S, Castellanos L, Singer P, Sethna CB, Basalely A. COL4A4 variant recently identified: lessons learned in variant interpretation-a case report. BMC Nephrol 2022; 23:253. [PMID: 35842573 PMCID: PMC9287857 DOI: 10.1186/s12882-022-02866-9] [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: 01/22/2022] [Accepted: 06/28/2022] [Indexed: 11/10/2022] Open
Abstract
Background Alport syndrome is a hereditary kidney disease characterized by hematuria and proteinuria. Although there have been reports of autosomal dominant COL4A4 variants, this is likely an underdiagnosed condition. Improved access to affordable genetic testing has increased the diagnosis of Alport syndrome. As genetic testing becomes ubiquitous, it is imperative that clinical nephrologists understand the benefits and challenges associated with clinical genetic testing. Case Presentation We present a family of Mexican descent with a heterozygous COL4A4 variant (c.5007delC, ClinVar accession numbers: SCV001580980.2, SCV001993731.1) not previously discussed in detail in the literature. The proband received a biopsy diagnosis suggestive of Fabry disease 18 years after she first developed hematuria and progressed to chronic kidney disease stage III. One year later, the proband was provisionally diagnosed with Alport syndrome after a variant of uncertain significance in the COL4A4 gene was identified following targeted family variant testing of her daughter. Upon review of the medical histories of the proband’s children and niece, all but one had the same variant. Of the four with the variant, three display clinical symptoms of hematuria, and/or proteinuria. The youngest of the four, only months old, has yet to exhibit clinical symptoms. Despite these findings there was a considerable delay in synthesizing this data, as patients were tested in different commercial genetic testing laboratories. Subsequently, understanding this family’s inheritance pattern, family history, and clinical symptoms, as well as the location of the COL4A4 variant resulted in the upgrade of the variant’s classification. Although the classification of this variant varied among different clinical genetic testing laboratories, the consensus was that this variant is likely pathogenic. Conclusions This COL4A4 variant (c.5007delC) not yet discussed in detail in the literature is associated with Alport syndrome. The inheritance pattern is suggestive of autosomal dominant inheritance. This report highlights the intricacies of variant interpretation and classification, the siloed nature of commercial genetic testing laboratories, and the importance of a thorough family history for proper variant interpretation. Additionally, the cases demonstrate the varied clinical presentations of Alport syndrome and suggest the utility of early screening, diagnosis, monitoring, and treatment.
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Affiliation(s)
- Jenelle Cocorpus
- Pediatric Nephrology, Cohen Children's Medical Center of New York, 269-01 76th Avenue, New Hyde Park, NY, 11040, USA
| | | | | | - Vanesa Bijol
- Renal Pathology, Northwell Health, Lake Success, NY, USA
| | - Fadi Salem
- Pathology, Molecular and Cell Based Medicine, Mount Sinai, New York, NY, USA
| | | | - Laura Castellanos
- Pediatric Nephrology, Cohen Children's Medical Center of New York, 269-01 76th Avenue, New Hyde Park, NY, 11040, USA
| | - Pamela Singer
- Pediatric Nephrology, Cohen Children's Medical Center of New York, 269-01 76th Avenue, New Hyde Park, NY, 11040, USA
| | - Christine B Sethna
- Pediatric Nephrology, Cohen Children's Medical Center of New York, 269-01 76th Avenue, New Hyde Park, NY, 11040, USA
| | - Abby Basalely
- Pediatric Nephrology, Cohen Children's Medical Center of New York, 269-01 76th Avenue, New Hyde Park, NY, 11040, USA.
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Hu X, Zhang J, Lv Y, Chen X, Feng G, Wang L, Ye Y, Jin F, Zhu Y. Preimplantation Genetic Testing Prevented Intergenerational Transmission of X-Linked Alport Syndrome. KIDNEY DISEASES (BASEL, SWITZERLAND) 2021; 7:514-520. [PMID: 34901197 PMCID: PMC8613584 DOI: 10.1159/000517796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 06/11/2021] [Indexed: 06/14/2023]
Abstract
BACKGROUND Alport syndrome (AS) is a hereditary renal basement membrane disease that can lead to end-stage renal disease in young adults. It can be diagnosed by genetic analysis, being mostly caused by mutations in COL4A3, COL-4A4, and COL4A5. To date, there is no radical cure for this disease. OBJECTIVES The aim of this study was to avoid the transmission of AS within an affected family by selecting healthy embryos for uterine transfer. The embryos were identified by preimplantation genetic testing for monogenic disorders (PGT-M). METHODS We used next-generation sequencing (NGS) to identify mutations in the proband and his parents. The results of NGS were confirmed by Sanger sequencing. Targeted NGS combined with targeted single-nucleotide polymorphism haplotyping was used for the in vitro identification of COL4A5 mutations in human embryos to prevent their intergenerational transmission. RESULTS The c.349_359delGGACCTCAAGG and c.360_361insTGC mutations in COL4A5 were identified in a family affected by X-linked AS. Whole-genome sequencing by NGS with targeted haplotyping was performed on biopsied trophectoderm cells. A healthy baby was born after transfer of a single freeze-thawed blastocyst. CONCLUSIONS The use of targeted NGS for identifying diagnostic markers combined with targeted haplotyping is an easy and efficient PGT-M method for preventing intergenerational transmission of AS.
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Affiliation(s)
- Xiaoling Hu
- Department of Reproductive Endocrinology, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Jiahui Zhang
- The MOE Key Laboratory of Biosystems Homeostasis & Protection, Life Sciences Institute, Zhejiang University, Hangzhou, China
| | - Yuan Lv
- Department of Reproductive Endocrinology, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Xijing Chen
- Department of Reproductive Endocrinology, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Guofang Feng
- Department of Reproductive Endocrinology, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Liya Wang
- Department of Reproductive Endocrinology, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Yinghui Ye
- Department of Reproductive Endocrinology, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Fan Jin
- Department of Reproductive Endocrinology, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Key Laboratory of Reproductive Genetics, Ministry of Education, Zhejiang University, Hangzhou, China
| | - Yimin Zhu
- Department of Reproductive Endocrinology, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Key Laboratory of Reproductive Genetics, Ministry of Education, Zhejiang University, Hangzhou, China
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Sienes Bailo P, Bancalero Flores JL, Lahoz Alonso R, Santamaría González M, Gutiérrez Dalmau A, Álvarez de Andrés S, Izquierdo Álvarez S. A novel variant in the COL4A3 gene: etiology of Alport syndrome type 2 in a 38-year-old male with suspected hereditary kidney disease. ADVANCES IN LABORATORY MEDICINE 2021; 2:451-462. [PMID: 37362409 PMCID: PMC10197298 DOI: 10.1515/almed-2021-0058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 05/12/2021] [Indexed: 06/28/2023]
Abstract
Objectives Patients with Alport syndrome develop progressive kidney function deterioration, sensorineural hearing loss, and ocular abnormalities. This condition is caused by mutations in COL4A5 (X-linked inheritance), COL4A3 and COL4A4 (autosomal dominant or recessive inheritance), and encoding type IV collagen α3, α4, and α5, respectively. If left untreated, clinical symptoms progress from microscopic hematuria to proteinuria, progressive kidney failure, and end-stage kidney disease. At present, kidney transplantation is the only effective approach. Next-generation sequencing is the method of choice for the diagnosis of this condition. Case presentation We report the case of a young man with chronic kidney disease who eventually underwent transplantation. Molecular testing made it possible to determine the etiology of his clinical symptoms and autosomal recessive Alport syndrome type 2. The patient was found to be a compound heterozygote for two missense variants (trans configuration) in the COL4A3 gene: A likely pathogenic variant c.4981C>T (p.Arg1661Cys) in exon 52 inherited from the mother (described elsewhere), and another variant of uncertain significance, c.943G>A (p.Gly315Ser), in exon 17 inherited from the father that has not been previously reported in the literature or found in relevant databases. Conclusions Following genetic confirmation, genetic counseling was provided to the patient and his direct relatives.
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Affiliation(s)
- Paula Sienes Bailo
- Department of Clinical Biochemistry, Hospital Universitario Miguel Servet, Zaragoza, Spain
| | | | - Raquel Lahoz Alonso
- Department of Clinical Biochemistry, Hospital Universitario Miguel Servet, Zaragoza, Spain
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Żurowska AM, Bielska O, Daca-Roszak P, Jankowski M, Szczepańska M, Roszkowska-Bjanid D, Kuźma-Mroczkowska E, Pańczyk-Tomaszewska M, Moczulska A, Drożdż D, Hadjipanagi D, Deltas C, Ostalska-Nowicka D, Rabiega A, Taraszkiewicz J, Taranta-Janusz K, Wieczorkiewicz-Plaza A, Jobs K, Mews J, Musiał K, Jakubowska A, Nosek H, Jander AE, Koutsofti C, Stanisławska-Sachadyn A, Kuleszo D, Ziętkiewicz E, Lipska-Ziętkiewicz BS. Mild X-linked Alport syndrome due to the COL4A5 G624D variant originating in the Middle Ages is predominant in Central/East Europe and causes kidney failure in midlife. Kidney Int 2020; 99:1451-1458. [PMID: 33309955 DOI: 10.1016/j.kint.2020.10.040] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 10/23/2020] [Accepted: 10/30/2020] [Indexed: 12/14/2022]
Abstract
A study of 269 children enrolled into a National Registry for children with persistent glomerular hematuria identified 131 individuals with genetically confirmed X-linked Alport Syndrome. A single variant c.1871G>A p.Gly624Asp (G624D) in COL4A5 was predominant and accounted for 39% of X-linked Alport Syndrome in unrelated Polish families (44 of 113). To evaluate its origins, the genetic variation in a 2.79 Mb segment encompassing the COL4A5 locus on chromosome X was assessed. All G624D alleles were found on the same rare haplotype background, indicating a founder effect dating back to the 12-13th century. The phenotypic data of 131 children with X-linked Alport Syndrome and their 195 affected adult relatives revealed that the G624D variant was associated with a significantly milder clinical course in comparison to other pathogenic COL4A5 variants. Furthermore the clinical course of this genetically uniform cohort was milder than that observed in individuals with other COL4A5 missense mutations. In spite of the benign clinical manifestation throughout childhood and early adulthood, the G624D variant confers significant risk for both kidney failure and deafness in males, albeit 20-30 years later than that observed in individuals with other COL4A5 pathogenic variants (50% cumulative risk of starting dialysis at 54 years (95% confidence interval: 50-62) v. 26 years (95% confidence interval: 22-30)). Thus, males with G624D are candidates for existing and emerging therapies for Alport Syndrome.
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Affiliation(s)
- Aleksandra M Żurowska
- Rare Diseases Centre, Medical University of Gdańsk, Gdańsk, Poland; Department of Pediatrics, Nephrology and Hypertension, Faculty of Medicine, Medical University of Gdańsk, Gdańsk, Poland.
| | - Olga Bielska
- Department of Pediatrics, Nephrology and Hypertension, Faculty of Medicine, Medical University of Gdańsk, Gdańsk, Poland
| | | | - Maciej Jankowski
- Department of Biology and Medical Genetics, Faculty of Medicine, Medical University of Gdańsk, Gdańsk, Poland
| | - Maria Szczepańska
- Department of Pediatrics, Faculty of Medical Sciences in Zabrze, Medical University of Silesia in Katowice, Zabrze, Poland
| | - Dagmara Roszkowska-Bjanid
- Pediatric Nephrology Ward With Dialysis Division for Children, Public Clinical Hospital, Zabrze, Poland
| | | | | | - Anna Moczulska
- Department of Pediatric Nephrology and Hypertension, Jagiellonian University Medical College, Cracow, Poland
| | - Dorota Drożdż
- Department of Pediatric Nephrology and Hypertension, Jagiellonian University Medical College, Cracow, Poland
| | - Despina Hadjipanagi
- Center of Excellence in Biobanking and Biomedical Research, Molecular Medicine Research Center, University of Cyprus Medical School, Nicosia, Cyprus
| | - Constantinos Deltas
- Center of Excellence in Biobanking and Biomedical Research, Molecular Medicine Research Center, University of Cyprus Medical School, Nicosia, Cyprus
| | - Danuta Ostalska-Nowicka
- Department of Pediatric Cardiology and Hypertensiology, Poznan University of Medical Sciences, Poznań, Poland
| | - Alina Rabiega
- Department of Pediatric Cardiology and Hypertensiology, Poznan University of Medical Sciences, Poznań, Poland
| | - Janina Taraszkiewicz
- Department of Pediatric Nephrology, Team of Municipal Hospitals in Chorzów, Chorzów, Poland
| | | | | | - Katarzyna Jobs
- Department of Pediatrics, Pediatric Nephrology and Allergology, Military Institute of Medicine, Warsaw, Poland
| | - Judyta Mews
- Department of Pediatrics, Pediatric Nephrology and Allergology, Military Institute of Medicine, Warsaw, Poland
| | - Kinga Musiał
- Department of Pediatric Nephrology, Wrocław Medical University, Wrocław, Poland
| | - Anna Jakubowska
- Department of Pediatric Nephrology, Wrocław Medical University, Wrocław, Poland
| | - Hanna Nosek
- Department of Pediatrics, Gastroenterology and Nutrition, University of Warmia and Mazury, Olsztyn, Poland
| | - Anna E Jander
- Department of Pediatrics, Immunology and Nephrology, Polish Mothers Memorial Hospital Research Institute, Łódź, Poland
| | - Constantina Koutsofti
- Center of Excellence in Biobanking and Biomedical Research, Molecular Medicine Research Center, University of Cyprus Medical School, Nicosia, Cyprus
| | | | - Dominka Kuleszo
- Department of Biology and Medical Genetics, Faculty of Medicine, Medical University of Gdańsk, Gdańsk, Poland
| | - Ewa Ziętkiewicz
- Institute of Human Genetics, Polish Academy of Sciences, Poznań, Poland
| | - Beata S Lipska-Ziętkiewicz
- Rare Diseases Centre, Medical University of Gdańsk, Gdańsk, Poland; Clinical Genetics Unit, Department of Biology and Medical Genetics, Faculty of Medicine, Medical University of Gdańsk, Gdańsk, Poland.
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Matthaiou A, Poulli T, Deltas C. Prevalence of clinical, pathological and molecular features of glomerular basement membrane nephropathy caused by COL4A3 or COL4A4 mutations: a systematic review. Clin Kidney J 2020; 13:1025-1036. [PMID: 33391746 PMCID: PMC7769542 DOI: 10.1093/ckj/sfz176] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Accepted: 11/06/2019] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Patients heterozygous for COL4A3 or COL4A4 mutations show a wide spectrum of disease, extending from familial isolated microscopic haematuria, as a result of thin basement membranes (TBMs), to autosomal dominant Alport syndrome (ADAS) and end-stage renal disease (ESRD). Many patients are mentioned in the literature under the descriptive diagnosis of TBM nephropathy (TBMN), in which case it actually describes a histological finding that represents the carriers of autosomal recessive Alport syndrome (ARAS), a severe glomerulopathy, as most patients reach ESRD at a mean age of 25 years. METHODS We performed a systematic literature review for patients with heterozygous COL4A3/A4 mutations with the aim of recording the spectrum and frequency of pathological features. We searched three databases (PubMed, Embase and Scopus) using the keywords 'Autosomal Dominant Alport Syndrome' OR 'Thin Basement Membrane Disease' OR 'Thin Basement Membrane Nephropathy'. We identified 48 publications reporting on 777 patients from 258 families. RESULTS In total, 29% of the patients developed chronic kidney disease (CKD) and 15.1% reached ESRD at a mean age of 52.8 years. Extrarenal features and typical Alport syndrome (AS) findings had a low prevalence in patients as follows: hearing loss, 16%; ocular lesions, 3%; basement membrane thickening, 18.4%; and podocyte foot process effacement, 6.9%. Data for 76 patients from 54 families emphasize extensive inter- and intrafamilial heterogeneity, with age at onset of ESRD ranging between 21 and 84 years (mean 52.8). CONCLUSIONS The analysis enabled a comparison of the clinical course of patients with typical ARAS or X-linked AS with those with heterozygous COL4A mutations diagnosed with TBMN or ADAS. Despite the consequence of a potential ascertainment bias, an important outcome is that TBM poses a global high risk of developing severe CKD, over a long follow-up, with a variable spectrum of other findings. The results are useful to practicing nephrologists for better evaluation of patients.
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Affiliation(s)
| | | | - Constantinos Deltas
- Molecular Medicine Research Center and Laboratory of Molecular and Medical Genetics, Department of Biological Sciences, University of Cyprus, Nicosia, Cyprus
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He C, Song W, Weston TA, Tran C, Kurtz I, Zuckerman JE, Guagliardo P, Miner JH, Ivanov SV, Bougoure J, Hudson BG, Colon S, Voziyan PA, Bhave G, Fong LG, Young SG, Jiang H. Peroxidasin-mediated bromine enrichment of basement membranes. Proc Natl Acad Sci U S A 2020; 117:15827-15836. [PMID: 32571911 PMCID: PMC7354931 DOI: 10.1073/pnas.2007749117] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Bromine and peroxidasin (an extracellular peroxidase) are essential for generating sulfilimine cross-links between a methionine and a hydroxylysine within collagen IV, a basement membrane protein. The sulfilimine cross-links increase the structural integrity of basement membranes. The formation of sulfilimine cross-links depends on the ability of peroxidasin to use bromide and hydrogen peroxide substrates to produce hypobromous acid (HOBr). Once a sulfilimine cross-link is created, bromide is released into the extracellular space and becomes available for reutilization. Whether the HOBr generated by peroxidasin is used very selectively for creating sulfilimine cross-links or whether it also causes oxidative damage to bystander molecules (e.g., generating bromotyrosine residues in basement membrane proteins) is unclear. To examine this issue, we used nanoscale secondary ion mass spectrometry (NanoSIMS) imaging to define the distribution of bromine in mammalian tissues. We observed striking enrichment of bromine (79Br, 81Br) in basement membranes of normal human and mouse kidneys. In peroxidasin knockout mice, bromine enrichment of basement membranes of kidneys was reduced by ∼85%. Proteomic studies revealed bromination of tyrosine-1485 in the NC1 domain of α2 collagen IV from kidneys of wild-type mice; the same tyrosine was brominated in collagen IV from human kidney. Bromination of tyrosine-1485 was reduced by >90% in kidneys of peroxidasin knockout mice. Thus, in addition to promoting sulfilimine cross-links in collagen IV, peroxidasin can also brominate a bystander tyrosine. Also, the fact that bromine enrichment is largely confined to basement membranes implies that peroxidasin activity is largely restricted to basement membranes in mammalian tissues.
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Affiliation(s)
- Cuiwen He
- Department of Medicine, University of California, Los Angeles, CA 90095
| | - Wenxin Song
- Department of Medicine, University of California, Los Angeles, CA 90095
| | - Thomas A Weston
- Department of Medicine, University of California, Los Angeles, CA 90095
| | - Caitlyn Tran
- Department of Medicine, University of California, Los Angeles, CA 90095
| | - Ira Kurtz
- Department of Medicine, University of California, Los Angeles, CA 90095
| | - Jonathan E Zuckerman
- Department of Pathology and Laboratory Medicine, University of California, Los Angeles, CA 90095
| | - Paul Guagliardo
- Centre for Microscopy, Characterisation and Analysis, University of Western Australia, 6009 Perth, Australia
| | - Jeffrey H Miner
- Division of Nephrology, Washington University School of Medicine, St. Louis, MO 63110
| | - Sergey V Ivanov
- Vanderbilt Center for Matrix Biology, Vanderbilt University Medical Center, Nashville, TN 37212
- Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232
| | - Jeremy Bougoure
- Centre for Microscopy, Characterisation and Analysis, University of Western Australia, 6009 Perth, Australia
| | - Billy G Hudson
- Vanderbilt Center for Matrix Biology, Vanderbilt University Medical Center, Nashville, TN 37212
- Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232
- Vanderbilt Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, TN 37232
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN 37232
| | - Selene Colon
- Vanderbilt Center for Matrix Biology, Vanderbilt University Medical Center, Nashville, TN 37212
- Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN 37232
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37212
| | - Paul A Voziyan
- Vanderbilt Center for Matrix Biology, Vanderbilt University Medical Center, Nashville, TN 37212
- Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232
| | - Gautam Bhave
- Vanderbilt Center for Matrix Biology, Vanderbilt University Medical Center, Nashville, TN 37212
- Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37212
- Center for Kidney Disease, Vanderbilt University Medical Center, Nashville, TN 37232
| | - Loren G Fong
- Department of Medicine, University of California, Los Angeles, CA 90095
| | - Stephen G Young
- Department of Medicine, University of California, Los Angeles, CA 90095;
- Department of Human Genetics, University of California, Los Angeles, CA 90095
| | - Haibo Jiang
- School of Molecular Sciences, University of Western Australia, 6009 Perth, Australia;
- Department of Chemistry, The University of Hong Kong, Hong Kong, China
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Clinicopathological Implications of Proteinuria after Long-Term Isolated Hematuria due to Thin Basement Membrane Nephropathy and Focal Segmental Glomerulosclerosis. Case Rep Nephrol 2019; 2019:1627392. [PMID: 31976098 PMCID: PMC6959157 DOI: 10.1155/2019/1627392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Revised: 10/02/2019] [Accepted: 10/25/2019] [Indexed: 11/17/2022] Open
Abstract
A 45-year-old obese man presented with persistent hematuria for 21 years. At the age of 37, he developed hypertension and proteinuria which later increased up to 1.6 g/g creatinine. Kidney biopsy revealed thin basement membrane nephropathy (TBMN) and focal segmental glomerulosclerosis (FSGS), which explained his urinary abnormalities. Although a subgroup of TBMN can be complicated by FSGS, his FSGS was associated with obesity because of its histological features. Reduction of body weight and increasing a dose of angiotensin-receptor blocker could transiently reduce the amount of proteinuria. Clinicopathological implications of proteinuria after long-term hematuria by TBMN and FSGS were further discussed.
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Pathologic glomerular characteristics and glomerular basement membrane alterations in biopsy-proven thin basement membrane nephropathy. Clin Exp Nephrol 2019; 23:638-649. [PMID: 30687875 DOI: 10.1007/s10157-018-01687-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Accepted: 12/26/2018] [Indexed: 01/16/2023]
Abstract
BACKGROUND Thin basement membrane nephropathy (TBMN) is diagnosed by diffuse thinning of the glomerular basement membrane (GBM) without any clinical and pathologic findings of Alport syndrome and the other renal diseases. TBMN is characterized clinically by benign familial hematuria but rarely develops into end-stage renal disease. METHODS In 27 cases of biopsy-proven TBMN, we evaluated the pathologic characteristics of TBMN, and examined the correlation between these pathologic characterizations and renal dysfunction. RESULTS All patients had hematuria, and 21 patients (77.8%) had proteinuria. In six patients (28.6%) who were more than 50 years of age, the estimated glomerular filtration rate (eGFR) decreased from G3a to G4 in the chronic kidney disease stage. Pathologically, an irregular decrease in intensity of type IV collagen α5(IV) chain was seen in GBM, and irregular thinning with diffuse rough etched images was observed on the GBM surface with several sizes of holes by low-vacuum scanning electron microscopy. The glomerular morphology of TBMN was characterized by an increased number of small glomerular capillaries with an increased extracellular matrix (ECM). These characteristic morphologic alterations were evident from a young age in patients with TBMN, but were not correlated directly with the decrease of eGFR, the degree of hematuria, and proteinuria. The decrease of eGFR in patients with TBMN who were more than 50 years of age might be primarily mediated by arteriolosclerosis-associated glomerulosclerosis and interstitial fibrosis. CONCLUSION Characteristic pathological glomerular findings and GBM alterations occurred from a young age but were not associated directly with renal impairment in biopsy-proven TBMN.
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Germline mosaicism is a pitfall in the diagnosis of “sporadic” X-linked Alport syndrome. J Nephrol 2018; 32:155-159. [DOI: 10.1007/s40620-018-0518-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 07/15/2018] [Indexed: 12/13/2022]
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10
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Gettelfinger JD, Dahl JP. Syndromic Hearing Loss: A Brief Review of Common Presentations and Genetics. J Pediatr Genet 2018; 7:1-8. [PMID: 29441214 PMCID: PMC5809162 DOI: 10.1055/s-0037-1617454] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 11/29/2017] [Indexed: 02/07/2023]
Abstract
Congenital hearing loss is one of the most common birth defects worldwide, with around 1 in 500 people experiencing some form of severe hearing loss. While over 400 different syndromes involving hearing loss have been described, it is important to be familiar with a wide range of syndromes involving hearing loss so an early diagnosis can be made and early intervention can be pursued to maximize functional hearing and speech-language development in the setting of verbal communication. This review aims to describe the presentation and genetics for some of the most frequently occurring syndromes involving hearing loss, including neurofibromatosis type 2, branchio-oto-renal syndrome, Treacher Collins syndrome, Stickler syndrome, Waardenburg syndrome, Pendred syndrome, Jervell and Lange-Nielsen syndrome, Usher syndromes, Refsum disease, Alport syndrome, MELAS, and MERRF.
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Affiliation(s)
- John D. Gettelfinger
- Department of Otolaryngology – Head and Neck Surgery, Indiana University School of Medicine, Indianapolis, Indiana, United States
| | - John P. Dahl
- Department of Otolaryngology – Head and Neck Surgery, Indiana University School of Medicine, Indianapolis, Indiana, United States
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