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Puapatanakul P, Miner JH. Alport syndrome and Alport kidney diseases - elucidating the disease spectrum. Curr Opin Nephrol Hypertens 2024; 33:283-290. [PMID: 38477333 PMCID: PMC10990029 DOI: 10.1097/mnh.0000000000000983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2024]
Abstract
PURPOSE OF REVIEW With the latest classification, variants in three collagen IV genes, COL4A3 , COL4A4 , and COL4A5 , represent the most prevalent genetic kidney disease in humans, exhibiting diverse, complex, and inconsistent clinical manifestations. This review breaks down the disease spectrum and genotype-phenotype correlations of kidney diseases linked to genetic variants in these genes and distinguishes "classic" Alport syndrome (AS) from the less severe nonsyndromic genetically related nephropathies that we suggest be called "Alport kidney diseases". RECENT FINDINGS Several research studies have focused on the genotype-phenotype correlation under the latest classification scheme of AS. The historic diagnoses of "benign familial hematuria" and "thin basement membrane nephropathy" linked to heterozygous variants in COL4A3 or COL4A4 are suggested to be obsolete, but instead classified as autosomal AS by recent expert consensus due to a significant risk of disease progression. SUMMARY The concept of Alport kidney disease extends beyond classic AS. Patients carrying pathogenic variants in any one of the COL4A3/A4/A5 genes can have variable phenotypes ranging from completely normal/clinically unrecognizable, hematuria without or with proteinuria, or progression to chronic kidney disease and kidney failure, depending on sex, genotype, and interplays of other genetic as well as environmental factors.
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Affiliation(s)
- Pongpratch Puapatanakul
- Division of Nephrology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
- Division of Nephrology, Department of Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Jeffrey H. Miner
- Division of Nephrology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
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Catanese L, Siwy J, Wendt R, Amann K, Beige J, Hendry B, Mischak H, Mullen W, Paterson I, Schiffer M, Wolf M, Rupprecht H. Differentiating primary and secondary FSGS using non-invasive urine biomarkers. Clin Kidney J 2024; 17:sfad296. [PMID: 38313685 PMCID: PMC10833144 DOI: 10.1093/ckj/sfad296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Indexed: 02/06/2024] Open
Abstract
Background Focal segmental glomerulosclerosis (FSGS) is divided into genetic, primary (p), uncertain cause, and secondary (s) forms. The subclasses differ in management and prognosis with differentiation often being challenging. We aimed to identify specific urine proteins/peptides discriminating between clinical and biopsy-proven pFSGS and sFSGS. Methods Sixty-three urine samples were collected in two different centers (19 pFSGS and 44 sFSGS) prior to biopsy. Samples were analysed using capillary electrophoresis-coupled mass spectrometry. For biomarker definition, datasets of age-/sex-matched normal controls (NC, n = 98) and patients with other chronic kidney diseases (CKDs, n = 100) were extracted from the urinary proteome database. Independent specificity assessment was performed in additional data of NC (n = 110) and CKD (n = 170). Results Proteomics data from patients with pFSGS were first compared to NC (n = 98). This resulted in 1179 biomarker (P < 0.05) candidates. Then, the pFSGS group was compared to sFSGS, and in a third step, pFSGS data were compared to data from different CKD etiologies (n = 100). Finally, 93 biomarkers were identified and combined in a classifier, pFSGS93. Total cross-validation of this classifier resulted in an area under the receiving operating curve of 0.95. The specificity investigated in an independent set of NC and CKD of other etiologies was 99.1% for NC and 94.7% for CKD, respectively. The defined biomarkers are largely fragments of different collagens (49%). Conclusion A urine peptide-based classifier that selectively detects pFSGS could be developed. Specificity of 95%-99% could be assessed in independent samples. Sensitivity must be confirmed in independent cohorts before routine clinical application.
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Affiliation(s)
- Lorenzo Catanese
- Department of Nephrology, Angiology and Rheumatology, Klinikum Bayreuth GmbH, Bayreuth, Germany
- Kuratorium for Dialysis and Transplantation (KfH) Bayreuth, Bayreuth, Germany
- Medizincampus Oberfranken, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | | | - Ralph Wendt
- Division of Nephrology, St. Georg Hospital Leipzig, Leipzig, Germany
| | - Kerstin Amann
- Department of Nephropathology, Institute of Pathology, University Hospital Erlangen, Friedrich-Alexander University Erlangen-Nuremberg, Erlangen, Germany
| | - Joachim Beige
- Kuratorium for Dialysis and Transplantation (KfH) Renal Unit, Leipzig, Germany
- Department of Internal Medicine II, Martin-Luther-University Halle/Wittenberg, Halle/Saale, Germany
| | | | | | - William Mullen
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, UK
| | | | - Mario Schiffer
- Department of Nephrology and Hypertension, University Hospital Erlangen, Friedrich-Alexander University (FAU) Erlangen-Nürnberg, Erlangen, Germany
- Research Center on Rare Kidney Diseases (RECORD), University Hospital Erlangen, Erlangen, Germany
| | | | - Harald Rupprecht
- Department of Nephrology, Angiology and Rheumatology, Klinikum Bayreuth GmbH, Bayreuth, Germany
- Kuratorium for Dialysis and Transplantation (KfH) Bayreuth, Bayreuth, Germany
- Medizincampus Oberfranken, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
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Du R, Liu J, Hu Y, Peng S, Fan L, Xiang R, Huang H. Novel heterozygous mutation in COL4A4 responsible for Alport syndrome in a Chinese family. Front Genet 2022; 13:899006. [PMID: 36159970 PMCID: PMC9501878 DOI: 10.3389/fgene.2022.899006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 08/08/2022] [Indexed: 11/13/2022] Open
Abstract
Background: Chronic kidney disease, a global public health problem, results in kidney damage or a gradual decline in the glomerular filtration rate. Alport syndrome is commonly characterized by chronic glomerulonephritis caused by a structural disorder in the glomerular basement membrane. Currently, three disease-causing genes, namely collagen type IV alpha 3–5 (COL4A3, COL4A4, and COL4A5), have been associated with the occurrence of Alport syndrome. Methods: We enrolled a Chinese family where the affected individuals suffered from recurrent hematuria and proteinuria. The proband was selected for whole-exome sequencing to identify the pathogenic mutations in this family. Results: After data filtering, a novel heterozygous COL4A4 variant (NM_000092: c.853G>A/p. G285A) was identified as the putative genetic lesion in the affected individuals. Further co-segregation analysis using Sanger sequencing confirmed that this novel COL4A4 mutation (c.853G>A/p. G285A) exists only in the affected individuals and is absent in other healthy family members as well as in the control cohort of 200 individuals from the same locality. According to American College of Medical Genetics and Genomics guidelines, the mutation was classified as ‘potentially pathogenic’. A bioinformatics-based prediction analysis revealed that this mutation is pathogenic and may disrupt the structure and function of type IV collagen. This variant is located at an evolutionarily conserved site of COL4A4. Conclusion: In this study, we identified a novel heterozygous COL4A4 variant (c.853G>A) in a Chinese AS family and assisted to diagnose this AS proband as autosomal-dominant Alport syndrome (ADAS). Our study expands the spectrum of Alport syndrome mutations and contributes to the genetic counseling and diagnosis of patients with Alport syndrome.
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Affiliation(s)
- Ran Du
- Department of Nephrology, The Third Xiangya Hospital Central South University, Changsha, China
- Department of Cell Biology, Hunan Key Laboratory of Animal Models for Human Diseases, School of Life Sciences, Central South University, Changsha, China
- Hunan Key Laboratory of Organ Fibrosis, Central South University, Changsha, China
| | - Jishi Liu
- Department of Nephrology, The Third Xiangya Hospital Central South University, Changsha, China
- Hunan Key Laboratory of Organ Fibrosis, Central South University, Changsha, China
| | - Yiqiao Hu
- Department of Cell Biology, Hunan Key Laboratory of Animal Models for Human Diseases, School of Life Sciences, Central South University, Changsha, China
| | - Song Peng
- Department of Radiology, The Third Xiangya Hospital Central South University, Changsha, China
| | - Liangliang Fan
- Department of Nephrology, The Third Xiangya Hospital Central South University, Changsha, China
- Department of Cell Biology, Hunan Key Laboratory of Animal Models for Human Diseases, School of Life Sciences, Central South University, Changsha, China
- Hunan Key Laboratory of Organ Fibrosis, Central South University, Changsha, China
| | - Rong Xiang
- Department of Nephrology, The Third Xiangya Hospital Central South University, Changsha, China
- Department of Cell Biology, Hunan Key Laboratory of Animal Models for Human Diseases, School of Life Sciences, Central South University, Changsha, China
- Hunan Key Laboratory of Organ Fibrosis, Central South University, Changsha, China
| | - Hao Huang
- Department of Nephrology, The Third Xiangya Hospital Central South University, Changsha, China
- Department of Cell Biology, Hunan Key Laboratory of Animal Models for Human Diseases, School of Life Sciences, Central South University, Changsha, China
- Hunan Key Laboratory of Organ Fibrosis, Central South University, Changsha, China
- *Correspondence: Hao Huang,
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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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Caliskan Y, Lee B, Whelan AM, Abualrub F, Lentine KL, Jittirat A. Evaluation of Genetic Kidney Diseases in Living Donor Kidney Transplantation: Towards Precision Genomic Medicine in Donor Risk Assessment. CURRENT TRANSPLANTATION REPORTS 2022; 9:127-142. [DOI: 10.1007/s40472-021-00340-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Abstract
Purpose of Review
To provide a comprehensive update on the role of genetic testing for the evaluation of kidney transplant recipient and living donor candidates.
Recent Findings
The evaluation of candidates for living donor transplantation and their potential donors occurs within an ever-changing landscape impacted by new evidence and risk assessment techniques. Criteria that were once considered contraindications to living kidney donation are now viewed as standard of care, while new tools identify novel risk markers that were unrecognized in past decades. Recent work suggests that nearly 10% of a cohort of patients with chronic/end-stage kidney disease had an identifiable genetic etiology, many whose original cause of renal disease was either unknown or misdiagnosed. Some also had an incidentally found genetic variant, unrelated to their nephropathy, but medically actionable. These patterns illustrate the substantial potential for genetic testing to better guide the selection of living donors and recipients, but guidance on the proper application and interpretation of novel technologies is in its infancy. In this review, we examine the utility of genetic testing in various kidney conditions, and discuss risks and unresolved challenges. Suggested algorithms in the context of related and unrelated donation are offered.
Summary
Genetic testing is a rapidly evolving strategy for the evaluation of candidates for living donor transplantation and their potential donors that has potential to improve risk assessment and optimize the safety of donation.
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Sinha R, Chaudhury AR, Sarkar S, Banerjee S, Pulai S, Dasgupta S, Muorah M, Datta D. High incidence of COL4Ageneticvariants among a cohort of childhood with steroid resistance nephrotic syndrome from Eastern India. Kidney Int Rep 2022; 7:913-915. [PMID: 35497790 PMCID: PMC9039466 DOI: 10.1016/j.ekir.2022.01.1047] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Revised: 01/06/2022] [Accepted: 01/10/2022] [Indexed: 11/25/2022] Open
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