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Zhang H, Wang F, Xiao H. Combined Alport syndrome, Klinefelter syndrome and Fanconi syndrome in a Chinese boy. Nephrology (Carlton) 2023; 28:272-275. [PMID: 36878861 DOI: 10.1111/nep.14152] [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: 12/08/2022] [Revised: 02/19/2023] [Accepted: 02/20/2023] [Indexed: 03/08/2023]
Abstract
Alport syndrome (AS) is a progressive renal disease characterized by hematuria and progressive renal failure. X-linked dominant (XLAS) is the major inheritance form, accounting for almost 80% of the cases, caused by mutations in COL4A5 genes. Klinefelter syndrome (KS) is the most common genetic cause of human male gonadal dysgenesis. AS and KS are both rare disease, there are only three cases of combined AS and KS in the literatures. Fanconi syndrome (FS) caused by AS is also very rare. We report here the first case combined AS, KS and FS in a Chinese boy. We suggest that the severe renal phenotype and FS might be due to the two homozygous COL4A5 variants in our boy, and cases of AS combined KS will be good research objects for X chromosome inactivation.
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Affiliation(s)
- Hongwen Zhang
- Department of Pediatrics, Peking University First Hospital, Beijing, People's Republic of China
| | - Fang Wang
- Department of Pediatrics, Peking University First Hospital, Beijing, People's Republic of China
| | - Huijie Xiao
- Department of Pediatrics, Peking University First Hospital, Beijing, People's Republic of China
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Gibson J, Fieldhouse R, Chan MM, Sadeghi-Alavijeh O, Burnett L, Izzi V, Persikov AV, Gale DP, Storey H, Savige J. Prevalence Estimates of Predicted Pathogenic COL4A3-COL4A5 Variants in a Population Sequencing Database and Their Implications for Alport Syndrome. J Am Soc Nephrol 2021; 32:2273-2290. [PMID: 34400539 PMCID: PMC8729840 DOI: 10.1681/asn.2020071065] [Citation(s) in RCA: 85] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 05/05/2021] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND The reported prevalence of Alport syndrome varies from one in 5000 to one in 53,000 individuals. This study estimated the frequencies of predicted pathogenic COL4A3-COL4A5 variants in sequencing databases of populations without known kidney disease. METHODS Predicted pathogenic variants were identified using filtering steps based on the ACMG/AMP criteria, which considered collagen IV α3-α5 position 1 Gly to be critical domains. The population frequencies of predicted pathogenic COL4A3-COL4A5 variants were then determined per mean number of sequenced alleles. Population frequencies for compound heterozygous and digenic combinations were calculated from the results for heterozygous variants. RESULTS COL4A3-COL4A5 variants resulting in position 1 Gly substitutions were confirmed to be associated with hematuria (for each, P<0.001). Predicted pathogenic COL4A5 variants were found in at least one in 2320 individuals. p.(Gly624Asp) represented nearly half (16 of 33, 48%) of the variants in Europeans. Most COL4A5 variants (54 of 59, 92%) had a biochemical feature that potentially mitigated the clinical effect. The predicted pathogenic heterozygous COL4A3 and COL4A4 variants affected one in 106 of the population, consistent with the finding of thin basement membrane nephropathy in normal donor kidney biopsy specimens. Predicted pathogenic compound heterozygous variants occurred in one in 88,866 individuals, and digenic variants in at least one in 44,793. CONCLUSIONS The population frequencies for Alport syndrome are suggested by the frequencies of predicted pathogenic COL4A3-COL4A5 variants, but must be adjusted for the disease penetrance of individual variants and for the likelihood of already diagnosed disease and non-Gly substitutions. Disease penetrance may depend on other genetic and environmental factors.
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Affiliation(s)
- Joel Gibson
- The University of Melbourne Department of Medicine, Melbourne Health and Northern Health, Royal Melbourne Hospital, Parkville, Victoria, Australia
| | - Rachel Fieldhouse
- Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Darlinghurst, New South Wales, Australia
| | - Melanie M.Y. Chan
- Department of Renal Medicine, University College London, London, United Kingdom,Genomics England, Queen Mary University of London, London, United Kingdom
| | - Omid Sadeghi-Alavijeh
- Department of Renal Medicine, University College London, London, United Kingdom,Genomics England, Queen Mary University of London, London, United Kingdom
| | - Leslie Burnett
- Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Darlinghurst, New South Wales, Australia
| | - Valerio Izzi
- Center for Cell-Matrix Research and Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Anton V. Persikov
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey
| | - Daniel P. Gale
- Department of Renal Medicine, University College London, London, United Kingdom,Genomics England, Queen Mary University of London, London, United Kingdom
| | - Helen Storey
- Molecular Genetics, Viapath Laboratories, Guy’s Hospital, London, United Kingdom
| | - Judy Savige
- The University of Melbourne Department of Medicine, Melbourne Health and Northern Health, Royal Melbourne Hospital, Parkville, Victoria, Australia
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Genotype-phenotype correlations and nephroprotective effects of RAAS inhibition in patients with autosomal recessive Alport syndrome. Pediatr Nephrol 2021; 36:2719-2730. [PMID: 33772369 PMCID: PMC8370956 DOI: 10.1007/s00467-021-05040-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 02/20/2021] [Accepted: 03/02/2021] [Indexed: 02/06/2023]
Abstract
BACKGROUND Autosomal recessive Alport syndrome (ARAS) is caused by pathogenic variants in both alleles of either COL4A3 or COL4A4 genes. Reports on ARAS are rare due to small patient numbers and there are no reports on renin-angiotensin-aldosterone system (RAAS) inhibition therapy in ARAS. METHODS Retrospective study in 101 patients with ARAS from Chinese Registry Database of Hereditary Kidney Diseases and European Alport Registry. Genotype-phenotype correlations and nephroprotective effects of RAAS inhibition in ARAS were evaluated. RESULTS Median age was 15 years (range 1.5-46 years). Twelve patients progressed to stage 5 chronic kidney disease (CKD5) at median age 20.5 years. Patients without missense variants had both higher prevalence and earlier onset age of hearing loss, nephrotic-range proteinuria, more rapid decline of eGFR, and earlier onset age of CKD5 compared to patients with 1 or 2 missense variants. Most patients (79/101, 78%) currently are treated with RAAS inhibitors; median age at therapy initiation was 10 years and mean duration 6.5 ± 6.0 years. Median age at CKD5 for untreated patients was 24 years. RAAS inhibition therapy delayed CKD5 onset in those with impaired kidney function (T-III) to median age 35 years, but is undefined in treated patients with proteinuria (T-II) due to low number of events. No treated patients with microalbuminuria (T-I) progressed to CKD5. ARAS patients with 1 or 2 missense variants showed better response to treatment than patients with non-missense-variants. CONCLUSIONS Our study provides the first evidence for early use of RAAS inhibition therapy in patients with ARAS. Furthermore, genotype in ARAS correlates with response to therapy in favor of missense variants.
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Savige J, Ariani F, Mari F, Bruttini M, Renieri A, Gross O, Deltas C, Flinter F, Ding J, Gale DP, Nagel M, Yau M, Shagam L, Torra R, Ars E, Hoefele J, Garosi G, Storey H. Expert consensus guidelines for the genetic diagnosis of Alport syndrome. Pediatr Nephrol 2019; 34:1175-1189. [PMID: 29987460 DOI: 10.1007/s00467-018-3985-4] [Citation(s) in RCA: 76] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 02/22/2018] [Accepted: 05/10/2018] [Indexed: 12/16/2022]
Abstract
Recent expert guidelines recommend genetic testing for the diagnosis of Alport syndrome. Here, we describe current best practice and likely future developments. In individuals with suspected Alport syndrome, all three COL4A5, COL4A3 and COL4A4 genes should be examined for pathogenic variants, probably by high throughput-targeted next generation sequencing (NGS) technologies, with a customised panel for simultaneous testing of the three Alport genes. These techniques identify up to 95% of pathogenic COL4A variants. Where causative pathogenic variants cannot be demonstrated, the DNA should be examined for deletions or insertions by re-examining the NGS sequencing data or with multiplex ligation-dependent probe amplification (MLPA). These techniques identify a further 5% of variants, and the remaining few changes include deep intronic splicing variants or cases of somatic mosaicism. Where no pathogenic variants are found, the basis for the clinical diagnosis should be reviewed. Genes in which mutations produce similar clinical features to Alport syndrome (resulting in focal and segmental glomerulosclerosis, complement pathway disorders, MYH9-related disorders, etc.) should be examined. NGS approaches have identified novel combinations of pathogenic variants in Alport syndrome. Two variants, with one in COL4A3 and another in COL4A4, produce a more severe phenotype than an uncomplicated heterozygous change. NGS may also identify further coincidental pathogenic variants in genes for podocyte-expressed proteins that also modify the phenotype. Our understanding of the genetics of Alport syndrome is evolving rapidly, and both genetic and non-genetic factors are likely to contribute to the observed phenotypic variability.
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Affiliation(s)
- Judy Savige
- Department of Medicine, Melbourne and Northern Health, The University of Melbourne, Parkville, VIC, 3050, Australia.
| | | | | | | | | | - Oliver Gross
- Clinic of Nephrology and Rheumatology, University of Gottingen, Gottingen, Germany
| | | | - Frances Flinter
- Department of Clinical Genetics, Guys' and St Thomas' NHS Foundation Trust, London, UK
| | - Jie Ding
- Peking University First Hospital, Beijing, China
| | - Daniel P Gale
- Centre for Nephrology, Royal Free Hospital, University College London, London, UK
| | - Mato Nagel
- Centre for Nephrology and Metabolic Disorders, Weisswasser, Germany
| | - Michael Yau
- Genetics, Guy's Hospital, Viapath, London, UK
| | - Lev Shagam
- Institute of Pediatrics, Pirogov Russian Medical University, Moscow, Russia
| | - Roser Torra
- Inherited Kidney Disorders, Nephrology Department, Fundacio Puigvert, Instituto de Investigacion Carlos III, Universitat Autonoma de Barcelona, Barcelona, Spain
| | - Elisabet Ars
- Molecular Biology Laboratory, Fundacio Puigvert, Instituto de Investigacion Carlos III, Universitat Autonoma de Barcelona, Barcelona, Spain
| | - Julia Hoefele
- Institute of Human Genetics, Technical University Munich, Munich, Germany
| | - Guido Garosi
- Nephrology, Dialysis and Transplantation, Azienda Ospedaliera Universitaria Senese, Siena, Italy
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Uzak AS, Tokgoz B, Dundar M, Tekin M. A novel COL4A3 mutation causes autosomal-recessive Alport syndrome in a large Turkish family. Genet Test Mol Biomarkers 2013; 17:260-4. [PMID: 23297803 DOI: 10.1089/gtmb.2012.0340] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Alport syndrome (AS) is a genetically heterogeneous disorder that is characterized by hematuria, progressive renal failure typically resulting in end-stage renal disease, sensorineural hearing loss, and variable ocular abnormalities. Only 15% of cases with AS are autosomal recessive and are caused by mutations in the COL4A3 or COL4A4 genes, encoding type IV collagen. METHODS Clinical data in a large consanguineous family with four affected members were reviewed, and genomic DNA was extracted. For mapping, 15 microsatellite markers flanking COL4A3, COL4A4, and COL4A5 in 16 family members were typed. For mutation screening, all coding exons of COL4A3 were polymerase chain reaction- amplified and Sanger-sequenced from genomic DNA. RESULTS The disease locus was mapped to chromosome 2q36.3, where COL4A3 and COL4A4 reside. Sanger sequencing revealed a novel mis-sense mutation (c.2T>C; p.M1T) in exon 1 of COL4A3. The identified nucleotide change was not found in 100 healthy ethnicity-matched controls via Sanger sequencing. CONCLUSIONS We present a large consanguineous Turkish family with AS that was found to have a COL4A3 mutation as the cause of the disease. Although the relationship between the various genotypes and phenotypes in AS has not been fully elucidated, detailed clinical and molecular analyses are helpful for providing data to be used in genetic counseling. It is important to identify new mutations to clarify their clinical importance, to assess the prognosis of the disease, and to avoid renal biopsy for final diagnosis.
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Affiliation(s)
- Asli Subasioglu Uzak
- Department of Medical Genetics, Erciyes University School of Medicine, Kayseri, Turkey
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Wang F, Zhao D, Ding J, Zhang H, Zhang Y, Yu L, Xiao H, Yao Y, Zhong X, Wang S. Skin biopsy is a practical approach for the clinical diagnosis and molecular genetic analysis of X-linked Alport's syndrome. J Mol Diagn 2012; 14:586-93. [PMID: 22921432 DOI: 10.1016/j.jmoldx.2012.06.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Revised: 05/25/2012] [Accepted: 06/08/2012] [Indexed: 11/28/2022] Open
Abstract
A total of 209 unrelated patients of predominantly Han Chinese ethnicity and with X-linked Alport's syndrome, a clinically heterogeneous hereditary nephritis, were enrolled in the present study to evaluate the ability to make a clinical diagnosis and perform molecular genetics analysis using skin biopsy. A negative or mosaic α5(IV) chain staining in the epidermal basement membrane was detected in 86.2% of male and 93.5% of female patients. COL4A5 mutations were identified in 85% of male patients with a negative α5(IV) chain staining pattern in the epidermal basement membrane. With use of skin biopsy and immunostaining, 16.4% of our patients were diagnosed before 3 years of age, and the youngest was diagnosed at 1 year of age. COL4A5 mutations were detected in 22 patients with normal epidermal basement membrane staining for the α5(IV) chain. Analysis of COL4A5 cDNA fragments from skin fibroblasts yielded a mutation detection rate of 83%, which was particularly valuable for identification of cryptic splicing mutations. Furthermore, 83% of COL4A5 mutations identified in the present study were novel. Thus, skin biopsy is a practical approach for the clinical diagnosis and molecular genetic analysis of X-linked Alport's syndrome.
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Affiliation(s)
- Fang Wang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
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Zhang H, Ding J, Wang F, Yu L. Attitudes toward genetic diagnosis and prenatal diagnosis of X-linked Alport syndrome in China. Nephrology (Carlton) 2012; 17:398-401. [PMID: 22239175 DOI: 10.1111/j.1440-1797.2012.01562.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIM Alport syndrome (AS) is a progressive renal disease characterized by hematuria and progressive renal failure. X-linked dominant AS (XLAS) is the predominant inheritance form caused by mutations in COL4A5 gene. Attitudes toward genetic diagnosis and prenatal diagnosis for Chinese AS families were investigated. Attitudes toward genetic diagnosis and prenatal diagnosis in Chinese XLAS families were evaluated in the current study. METHODS A total of 160 XLAS patients and their 126 healthy family members in China were interviewed. After providing background knowledge counselling and education on AS, their attitudes toward genetic diagnosis and prenatal diagnosis were evaluated by multiple-choice questionnaire. RESULTS Majority of the respondents cared mostly about the prognosis and treatment effects of AS (89.9% vs 81.1%) since they considered that the worst outcome of XALS was renal insufficiency (92.3%). Of all the interviewees, 99.3% were interested in genetic research for the discovery of better treatments and more appropriate diagnostic tools (positive attitudes) (89.5% vs 73.2%). About 80% of the participants would accept prenatal testing and subsequent termination of pregnancy in cases of affected foetuses (boys: 86.8% and girls: 74.6%, respectively). CONCLUSION Most Chinese XLAS families show positive attitudes and desire new discoveries in treatment and diagnosis. About 80% of respondents would approve prenatal testing with a desire for selective termination of pregnancy rather than predicting the health of a future child.
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Affiliation(s)
- Hongwen Zhang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
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