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Medaer L, David D, Smits M, Levtchenko E, Sampaolesi M, Gijsbers R. Residual Cystine Transport Activity for Specific Infantile and Juvenile CTNS Mutations in a PTEC-Based Addback Model. Cells 2024; 13:646. [PMID: 38607085 PMCID: PMC11011962 DOI: 10.3390/cells13070646] [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] [Received: 03/10/2024] [Revised: 04/03/2024] [Accepted: 04/04/2024] [Indexed: 04/13/2024] Open
Abstract
Cystinosis is a rare, autosomal recessive, lysosomal storage disease caused by mutations in the gene CTNS, leading to cystine accumulation in the lysosomes. While cysteamine lowers the cystine levels, it does not cure the disease, suggesting that CTNS exerts additional functions besides cystine transport. This study investigated the impact of infantile and juvenile CTNS mutations with discrepant genotype/phenotype correlations on CTNS expression, and subcellular localisation and function in clinically relevant cystinosis cell models to better understand the link between genotype and CTNS function. Using CTNS-depleted proximal tubule epithelial cells and patient-derived fibroblasts, we expressed a selection of CTNSmutants under various promoters. EF1a-driven expression led to substantial overexpression, resulting in CTNS protein levels that localised to the lysosomal compartment. All CTNSmutants tested also reversed cystine accumulation, indicating that CTNSmutants still exert transport activity, possibly due to the overexpression conditions. Surprisingly, even CTNSmutants expression driven by the less potent CTNS and EFS promoters reversed the cystine accumulation, contrary to the CTNSG339R missense mutant. Taken together, our findings shed new light on CTNS mutations, highlighting the need for robust assessment methodologies in clinically relevant cellular models and thus paving the way for better stratification of cystinosis patients, and advocating for the development of more personalized therapy.
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Affiliation(s)
- Louise Medaer
- Laboratory of Molecular Virology and Gene Therapy, Department of Pharmacological and Pharmaceutical Sciences, Faculty of Medicine, KU Leuven, 3000 Leuven, Belgium; (L.M.); (M.S.)
| | - Dries David
- Laboratory of Molecular Virology and Gene Therapy, Department of Pharmacological and Pharmaceutical Sciences, Faculty of Medicine, KU Leuven, 3000 Leuven, Belgium; (L.M.); (M.S.)
| | - Maxime Smits
- Laboratory of Molecular Virology and Gene Therapy, Department of Pharmacological and Pharmaceutical Sciences, Faculty of Medicine, KU Leuven, 3000 Leuven, Belgium; (L.M.); (M.S.)
- Leuven Viral Vector Core, Faculty of Medicine, KU Leuven, 3000 Leuven, Belgium
| | - Elena Levtchenko
- Department of Paediatric Nephrology & Development and Regeneration, University Hospitals Leuven & KU Leuven, 3000 Leuven, Belgium;
- Department of Paediatric Nephrology, Amsterdam University Medical Centre, 1081 Amsterdam, The Netherlands
| | - Maurilio Sampaolesi
- Translational Cardiology Laboratory, Department of Development and Regeneration, Stem Cell Institute, Faculty of Medicine, KU Leuven, 3000 Leuven, Belgium;
| | - Rik Gijsbers
- Laboratory of Molecular Virology and Gene Therapy, Department of Pharmacological and Pharmaceutical Sciences, Faculty of Medicine, KU Leuven, 3000 Leuven, Belgium; (L.M.); (M.S.)
- Leuven Viral Vector Core, Faculty of Medicine, KU Leuven, 3000 Leuven, Belgium
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Mohammadi Chermahini Z, Salehi M, Gheissari A, Ahmadi Beni F, Khosravian F, Kazemi M. CTNS Mutations Causing Autosomal Recessive Cystinosis in a Subset of Iranian Population: Report of Two New Variants. Adv Biomed Res 2024; 13:2. [PMID: 38525388 PMCID: PMC10958734 DOI: 10.4103/abr.abr_149_23] [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: 05/01/2023] [Revised: 07/25/2023] [Accepted: 07/29/2023] [Indexed: 03/26/2024] Open
Abstract
Background Nephropathic cystinosis (NC) is an uncommon autosomal recessive disease with abnormality in lysosomal storage that appearances in patients with mutations in the CTNS gene encoding a lysosomal transporter cystinosin. Disrupted function of this transporter is followed by accumulation of cysteine crystals in cells of many various organs. This study aimed to investigate the mutations of the CTNS gene in 20 Iranian patients suffering from NC. Materials and Methods Twenty Iranian cystinosis patients referring to Imam Hossein Hospital of Isfahan were employed in this case-series study. After extraction of genomic DNA, the promoter and entire coding regions of CTNS were analysed using sanger sequencing in all patients. Gap-Polymerase Chain Reaction was used to detect 57 kb deletion in the CTNS gene. In silico study was performed to analyse variants. Results The large deletion was not seen in any NC patients. Molecular analysis which conducted to screen the CTNS gene of patients, identified eight different mutations, including two new mutations, c.971_972insC and c.956_956delA, which have not been reported before, and c.681G>A mutation, which was identified as a frequently founded mutation in the Middle East and was observed in 35% of patients. In this study, five other mutations including c.1015G>A, c.922G>A, c.323_323delA, c.433C>T, and c.18_21delGACT were also observed, which have been reported in previous studies. Conclusion The mutational spectrum in the Iranian patients is the same as previously reported mutations except that two new mutations were found. The present findings will present suggestions for regular molecular diagnosis of cystinosis in Iran.
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Affiliation(s)
- Zahra Mohammadi Chermahini
- Department of Genetics and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
- Reproductive Sciences and Sexual Health Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
- Cellular, Molecular and Genetics Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Mansoor Salehi
- Department of Genetics and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
- Cellular, Molecular and Genetics Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Alaleh Gheissari
- Department of Pediatrics, School of Medicine, Kidney Diseases Research Center, Imam Hossein Children’s Hospital, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Faeze Ahmadi Beni
- Department of Genetics and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Farinaz Khosravian
- Cellular, Molecular and Genetics Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Mohammad Kazemi
- Department of Genetics and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
- Reproductive Sciences and Sexual Health Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
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Hohenfellner K, Zerell K, Haffner D. Cystinosis. Klin Monbl Augenheilkd 2023; 240:251-259. [PMID: 36977426 DOI: 10.1055/a-2022-8522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
Cystinosis is a very rare autosomal recessive lysosomal storage disorder with an incidence of 1 : 150,000 - 1 : 200,000, and is caused by mutations in the CTNS gene encoding the lysosomal membrane protein cystinosin, which transports cystine out of the lysosome into the cytoplasm. As a result, accumulation of cystine occurs in almost all cells and tissues, especially in the kidneys, leading to multiple organ involvement. Introduction of drug therapy with cysteamine in the mid 1980s, along with the availability of renal replacement therapy in childhood, have dramatically improved patient outcome. Whereas patients used to die without therapy with end-stage renal failure during the first decade of life, nowadays most patients live well into adulthood without renal replacement therapy, and several reach 40 years. There is robust evidence that early initiation and sustained lifelong therapy with cysteamine are both essential for morbidity and mortality. The rarity of the disease and the multi-organ involvement present an enormous challenge for those affected and the providers of care for this patient group.
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Affiliation(s)
- Katharina Hohenfellner
- Klinik für Kinder- und Jugendmedizin/Kindernephrologie, RoMed Kliniken, Rosenheim, Deutschland
| | - Kirstin Zerell
- Rosenheim, kbo-Heckscher-Klinikum gGmbH, München, Deutschland
| | - Dieter Haffner
- Klinik für Pädiatrische Nieren-, Leber- & Stoffwechselerkrankungen, MHH, Hannover, Deutschland
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La Cognata V, Cavallaro S. Detection of Structural Variants by NGS: Revealing Missing Alleles in Lysosomal Storage Diseases. Biomedicines 2022; 10:biomedicines10081836. [PMID: 36009380 PMCID: PMC9405548 DOI: 10.3390/biomedicines10081836] [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: 06/17/2022] [Revised: 07/22/2022] [Accepted: 07/26/2022] [Indexed: 11/16/2022] Open
Abstract
Lysosomal storage diseases (LSDs) are a heterogeneous group of rare multisystem metabolic disorders occurring mostly in infancy and childhood, characterized by a gradual accumulation of non-degraded substrates inside the cells. Although biochemical enzymatic assays are considered the gold standard for diagnosis of symptomatic patients, genotyping is a requirement for inclusion in enzyme replacement programs and is a prerequisite for carrier tests in relatives and DNA-based prenatal diagnosis. The emerging next-generation sequencing (NGS) technologies are now offering a powerful diagnostic tool for genotyping LSDs patients by providing faster, cheaper, and higher-resolution testing options, and are allowing to unravel, in a single integrated workflow SNVs, small insertions and deletions (indels), as well as major structural variations (SVs) responsible for the pathology. Here, we summarize the current knowledge about the most recurrent and private SVs involving LSDs-related genes, review advantages and drawbacks related to the use of the NGS in the SVs detection, and discuss the challenges to bring this type of analysis in clinical diagnostics.
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Savostyanov KV, Pushkov AA, Shchagina OA, Maltseva VV, Suleymanov EA, Zhanin IS, Mazanova NN, Fisenko AP, Mishakova PS, Polyakov AV, Balanovska EV, Zinchenko RA, Tsygin AN. Genetic Landscape of Nephropathic Cystinosis in Russian Children. Front Genet 2022; 13:863157. [PMID: 35571017 PMCID: PMC9096100 DOI: 10.3389/fgene.2022.863157] [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: 01/26/2022] [Accepted: 03/18/2022] [Indexed: 11/13/2022] Open
Abstract
Nephropathic cystinosis is a rare autosomal recessive disorder characterized by amino acid cystine accumulation and caused by biallelic mutations in the CTNS gene. The analysis methods are as follows: tandem mass spectrometry to determine the cystine concentration in polymorphonuclear blood leukocytes, Sanger sequencing for the entire coding sequence and flanking intron regions of the CTNS gene, multiplex PCR to detect a common mutation—a 57 kb deletion, and multiplex ligation-dependent probe amplification to analyze the number of exon copies in the CTNS gene. Haplotype analysis of chromosomes with major mutations was carried out using microsatellite markers D17S831, D17S1798, D17S829, D17S1828, and D17S1876. In this study, we provide clinical, biochemical, and molecular genetic characteristics of 40 Russian patients with mutations in the CTNS gene, among whom 30 patients were selected from a high-risk group of 85 people as a result of selective screening, which was carried out through cystine concentration measurement in polymorphonuclear blood leukocytes. The most common pathogenic variant, as in most described studies to date, was the 57 kb deletion, which represented 25% of all affected alleles. Previously non-described variants represented 22.5% of alleles. The founder effect in the Karachay and Chechen ethnic groups was shown for the following major variants: c.1015G > A and c.518A > G.
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Affiliation(s)
- K. V. Savostyanov
- National Medical Research Center for Children’s Health Federal State Autonomous Institution of the Ministry of Health of the Russian Federation, Moscow, Russia
- *Correspondence: K. V. Savostyanov,
| | - A. A. Pushkov
- National Medical Research Center for Children’s Health Federal State Autonomous Institution of the Ministry of Health of the Russian Federation, Moscow, Russia
| | | | - V. V. Maltseva
- National Medical Research Center for Children’s Health Federal State Autonomous Institution of the Ministry of Health of the Russian Federation, Moscow, Russia
| | | | - I. S. Zhanin
- National Medical Research Center for Children’s Health Federal State Autonomous Institution of the Ministry of Health of the Russian Federation, Moscow, Russia
| | - N. N. Mazanova
- National Medical Research Center for Children’s Health Federal State Autonomous Institution of the Ministry of Health of the Russian Federation, Moscow, Russia
| | - A. P. Fisenko
- National Medical Research Center for Children’s Health Federal State Autonomous Institution of the Ministry of Health of the Russian Federation, Moscow, Russia
| | | | | | | | | | - A. N. Tsygin
- National Medical Research Center for Children’s Health Federal State Autonomous Institution of the Ministry of Health of the Russian Federation, Moscow, Russia
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Newborn Screening: Review of its Impact for Cystinosis. Cells 2022; 11:cells11071109. [PMID: 35406673 PMCID: PMC8997957 DOI: 10.3390/cells11071109] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 03/13/2022] [Accepted: 03/22/2022] [Indexed: 12/10/2022] Open
Abstract
Newborn screening (NBS) programmes are considered to be one of the most successful secondary prevention measures in childhood to prevent or reduce morbidity and/or mortality via early disease identification and subsequent initiation of therapy. However, while many rare diseases can now be detected at an early stage using appropriate diagnostics, the introduction of a new target disease requires a detailed analysis of the entire screening process, including a robust scientific background, analytics, information technology, and logistics. In addition, ethics, financing, and the required medical measures need to be considered to allow the benefits of screening to be evaluated at a higher level than its potential harm. Infantile nephropathic cystinosis (INC) is a very rare lysosomal metabolic disorder. With the introduction of cysteamine therapy in the early 1980s and the possibility of renal replacement therapy in infancy, patients with cystinosis can now reach adulthood. Early diagnosis of cystinosis remains important as this enables initiation of cysteamine at the earliest opportunity to support renal and patient survival. Using molecular technologies, the feasibility of screening for cystinosis has been demonstrated in a pilot project. This review aims to provide insight into NBS and discuss its importance for nephropathic cystinosis using molecular technologies.
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Response to Cysteamine in Osteoclasts Obtained from Patients with Nephropathic Cystinosis: A Genotype/Phenotype Correlation. Cells 2021; 10:cells10092498. [PMID: 34572146 PMCID: PMC8467406 DOI: 10.3390/cells10092498] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Revised: 09/01/2021] [Accepted: 09/15/2021] [Indexed: 02/05/2023] Open
Abstract
Bone complications of cystinosis have been recently described. The main objectives of this paper were to determine in vitro the impact of CTNS mutations and cysteamine therapy on human osteoclasts and to carry out a genotype-phenotype analysis related to osteoclastic differentiation. Human osteoclasts were differentiated from peripheral blood mononuclear cells (PBMCs) and were treated with increasing doses of cysteamine (0, 50, 200 µM) and then assessed for osteoclastic differentiation. Results are presented as median (min-max). A total of 17 patients (mainly pediatric) were included, at a median age of 14 (2–61) years, and a eGFR of 64 (23–149) mL/min/1.73 m2. Most patients (71%) were under conservative kidney management (CKM). The others were kidney transplant recipients. Three functional groups were distinguished for CTNS mutations: cystinosin variant with residual cystin efflux activity (RA, residual activity), inactive cystinosin variant (IP, inactive protein), and absent protein (AP). PBMCs from patients with residual cystinosin activity generate significantly less osteoclasts than those obtained from patients of the other groups. In all groups, cysteamine exerts an inhibitory effect on osteoclastic differentiation at high doses. This study highlights a link between genotype and osteoclastic differentiation, as well as a significant impact of cysteamine therapy on this process in humans.
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Atmis B, K Bayazit A, Cevizli D, Kor D, Fidan HB, Bisgin A, Kilavuz S, Unal I, Erdogan KE, Melek E, Gonlusen G, Anarat A, Onenli Mungan N. More than tubular dysfunction: cystinosis and kidney outcomes. J Nephrol 2021; 35:831-840. [PMID: 34097292 DOI: 10.1007/s40620-021-01078-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 05/20/2021] [Indexed: 10/21/2022]
Abstract
BACKGROUND Cystinosis is a lysosomal storage disease that affects many tissues. Its prognosis depends predominantly on kidney involvement. Cystinosis has three clinical forms: nephropathic infantile, nephropathic juvenile and non-nephropathic adult. Proximal tubular dysfunction is prominent in the infantile form, whereas a combination of glomerular and tubular alterations are observed in the juvenile form. METHODS Thirty-six children with nephropathic cystinosis were included in the study. Clinical features, molecular genetic diagnoses, and kidney outcomes of the patients were evaluated. RESULTS Twenty-one children (58.3%) were male. The median age at diagnosis was 18.5 months. Twenty-eight patients (77.8%) had infantile nephropathic cystinosis, while eight (22.2%) had juvenile nephropathic cystinosis. An acute rapid deterioration of the kidney function with proteinuria, hypoalbuminemia, and nephrotic syndrome, was observed in 37.5% of patients with the juvenile form. The mean estimated glomerular filtration rate (eGFR) was 82.31 ± 37.45 ml/min/1.73m2 at diagnosis and 63.10 ± 54.60 ml/min/1.73m2 at the last visit (p = 0.01). Six patients (16.6%) had kidney replacement therapy (KRT) at the last visit. The median age of patients with kidney failure was 122 months. Patients with a spot urine protein/creatinine ratio < 6 mg/mg at the time of diagnosis had better kidney outcomes (p = 0.01). The most common allele was c.451A>G (32.6%). The patients with the most common mutation tended to have higher mean eGFR and lower leukocyte cystine levels than patients with other mutations. CONCLUSION Glomerulonephritis may be a frequent finding in addition to the well-known tubular dysfunction in patients with cystinosis. Furthermore, our results highlight that the presence of severe proteinuria at the time of diagnosis is a relevant prognostic factor for kidney survival.
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Affiliation(s)
- Bahriye Atmis
- Department of Pediatric Nephrology, Cukurova University Faculty of Medicine, Adana, Turkey.
| | - Aysun K Bayazit
- Department of Pediatric Nephrology, Cukurova University Faculty of Medicine, Adana, Turkey
| | - Derya Cevizli
- Department of Pediatric Nephrology, Cukurova University Faculty of Medicine, Adana, Turkey
| | - Deniz Kor
- Department of Pediatric Metabolism and Nutrition, Cukurova University Faculty of Medicine, Adana, Turkey
| | - Hatice Busra Fidan
- Department of Pediatrics, Cukurova University Faculty of Medicine, Adana, Turkey
| | - Atil Bisgin
- Department of Medical Genetics, Cukurova University Faculty of Medicine, Adana, Turkey.,Cukurova University AGENTEM (Adana Genetic Diseases Diagnosis and Treatment Center), Adana, Turkey.,Medical Genetics Department of Balcali Clinics and Hospital, Faculty of Medicine, Adana, Turkey
| | - Sebile Kilavuz
- Department of Pediatric Metabolism and Nutrition, Cukurova University Faculty of Medicine, Adana, Turkey
| | - Ilker Unal
- Department of Biostatistics, Cukurova University Faculty of Medicine, Adana, Turkey
| | | | - Engin Melek
- Department of Pediatric Nephrology, Cukurova University Faculty of Medicine, Adana, Turkey
| | - Gulfiliz Gonlusen
- Department of Pathology, Cukurova University Faculty of Medicine, Adana, Turkey
| | - Ali Anarat
- Department of Pediatric Nephrology, Cukurova University Faculty of Medicine, Adana, Turkey
| | - Neslihan Onenli Mungan
- Department of Pediatric Metabolism and Nutrition, Cukurova University Faculty of Medicine, Adana, Turkey
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Next generation sequencing as second-tier test in high-throughput newborn screening for nephropathic cystinosis. Eur J Hum Genet 2019; 28:193-201. [PMID: 31570786 DOI: 10.1038/s41431-019-0521-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 09/11/2019] [Accepted: 09/17/2019] [Indexed: 01/20/2023] Open
Abstract
Nephropathic cystinosis is a rare autosomal recessive lysosomal storage disorder, which causes loss of renal proximal tubular function and progressive loss of glomerular function, finally leading to end stage renal failure at school age. In the course of the disease most patients will need kidney transplantation if treatment has not been started before clinical manifestation. With an effective treatment available, a newborn screening assay is highly demanded. Since newborns with cystinosis usually do not show symptoms within the first months of life and no biochemical markers are easily detectable, a DNA-based method seems to be an obvious tool for early diagnosis. Screening was performed using high-throughput nucleic acid extraction followed by 384-well qPCR and melting analysis for the three most frequent variants (57 kb deletion NC_000017.11:g.3600934_3658165del (GRCh38); c.18_21del GACT; c.926dupG) responsible for the defective lysosomal membrane protein cystinosin (CTNS). To increase sensitivity, all heterozygous samples identified in qPCR assay were verified and screened for additional variants by applying next generation sequencing. From January 2018 to July 2019 nearly 292,000 newborns were successfully screened. We identified two newborns with a homozygous 57 kb deletion and a second one with heterozygous 57 kb deletion and a G>C substitution at position c.-512 on the second allele. Cystinosis is an example for diseases caused by a limited number of high prevalence and a high number of low prevalence variants. We have shown that qPCR combined with NGS can be used as a high throughput, cost effective tool in newborn screening for such diseases.
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Li XQ, Wu D, Liang XJ, Li WJ, Liu M, Cao BY, Su C, Meng X, Gong CX. The diagnosis of cystinosis in patients reveals new CTNS gene mutations in the Chinese population. J Pediatr Endocrinol Metab 2019; 32:375-382. [PMID: 30849045 DOI: 10.1515/jpem-2018-0263] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 01/30/2019] [Indexed: 11/15/2022]
Abstract
Background Cystinosis is a rare autosomal-recessive disorder caused by a defective transport of cystine across the lysosomal membrane. Previous studies have mapped cystinosis to the CTNS gene which is located on chromosome 17p13, and various CTNS mutations have been identified to correlate them with this disease. Methods We analyzed six patients from five unrelated families who were diagnosed with cystinosis in our hospital. We described the diagnostic procedures for all the patients and proposed alternative therapies for cystinosis patients instead of using cysteamine, an orphan drug which was commercially unavailable in China. Moreover, genetic analysis of all patients' samples was carried out to identify novel CTNS gene mutations. Results and conclusions The patients in this study were followed up from 1 to more than 10 years to monitor their growth and development, which indicated that the alternative therapies we used were helpful to ameliorate the complications of the cystinosis patients without cysteamine. Furthermore, by sequencing the patients' genome, we identified novel mutations in the CTNS gene including: c.477C > G (p.S159R), c.274C > T (p.Q92X) and c.680A > T (p.E227V); these mutations were only observed in cystinosis patients and had never been reported in any other populations, suggesting they might be specific to Chinese cystinosis patients.
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Affiliation(s)
- Xiao-Qiao Li
- Department of Endocrinology, Genetics and Metabolism, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing, China
| | - Di Wu
- Department of Endocrinology, Genetics and Metabolism, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing, China
| | - Xue-Jun Liang
- Department of Endocrinology, Genetics and Metabolism, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing, China
| | - Wen-Jing Li
- Department of Endocrinology, Genetics and Metabolism, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing, China
| | - Min Liu
- Department of Endocrinology, Genetics and Metabolism, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing, China
| | - Bing-Yan Cao
- Department of Endocrinology, Genetics and Metabolism, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing, China
| | - Chang Su
- Department of Endocrinology, Genetics and Metabolism, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing, China
| | - Xi Meng
- Department of Endocrinology, Genetics and Metabolism, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing, China
| | - Chun-Xiu Gong
- Department of Endocrinology, Genetics and Metabolism, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing, China
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Slow progression of renal failure in a child with infantile cystinosis. CEN Case Rep 2018; 7:153-157. [PMID: 29446030 DOI: 10.1007/s13730-018-0316-3] [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: 09/25/2017] [Accepted: 02/07/2018] [Indexed: 10/18/2022] Open
Abstract
Cystinosis is a rare autosomal recessive lysosomal transport disorder, characterized by the accumulation of the aminoacid cystine and progressive dysfunction of several organs. Kidneys are severely affected, and the most frequent form, infantile nephropathic cystinosis, presents with growth failure in infancy, renal Fanconi syndrome and end-stage renal disease by the first decade of life. We report of a girl with infantile nephropathic cystinosis that has reached adolescence without the need of renal replacement therapy and without extrarenal manifestations despite her delayed diagnosis and treatment initiation. The girl with this intermediate phenotype was found to have compound heterozygosity of one known (1015G > A) and one novel (587_588insA) mutation in CTNS gene. Our case points to the wide clinical presentation of infantile nephropathic cystinosis and suggest that long-term outcome is not always ominous as generally thought.
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Topaloglu R, Gulhan B, İnözü M, Canpolat N, Yilmaz A, Noyan A, Dursun İ, Gökçe İ, Gürgöze MK, Akinci N, Baskin E, Serdaroğlu E, Demircioğlu Kiliç B, Yüksel S, Övünç Hacihamdioğlu D, Korkmaz E, Hayran M, Ozaltin F. The Clinical and Mutational Spectrum of Turkish Patients with Cystinosis. Clin J Am Soc Nephrol 2017; 12:1634-1641. [PMID: 28793998 PMCID: PMC5628704 DOI: 10.2215/cjn.00180117] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 06/26/2017] [Indexed: 01/24/2023]
Abstract
BACKGROUND AND OBJECTIVES Infantile nephropathic cystinosis is a severe disease that occurs due to mutations in the cystinosis gene, and it is characterized by progressive dysfunction of multiple organs; >100 cystinosis gene mutations have been identified in multiple populations. Our study aimed to identify the clinical characteristics and spectrum of cystinosis gene mutations in Turkish pediatric patients with cystinosis. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS We identified the clinical characteristics and spectrum of cystinosis gene mutations in Turkish patients with cystinosis in a multicenter registry that was established for data collection. The data were extracted from this registry and analyzed. RESULTS In total, 136 patients (75 men and 61 women) were enrolled in the study. The most common clinical findings were growth retardation, polyuria, and loss of appetite. None of the patients had the 57-kb deletion, but seven novel mutations were identified. The most common mutations identified were c.681G>A (p.Glu227Glu; 31%), c.1015G>A (p.Gly339Arg; 22%), and c.18_21 del (p.Thr7Phefs*7; 14%). These mutations were associated with earlier age of disease onset than the other mutations. To understand the effects of these allelic variants on clinical progression, the mutations were categorized into two major groups (missense versus deletion/duplication/splice site). Although patients with missense mutations had a better eGFR at the last follow-up visit, the difference was not significant. Patients in whom treatment began at age <2 years old had later onset of ESRD (P=0.02). Time to ESRD did not differ between the patients with group 1 and group 2 mutations. CONCLUSIONS The most common cystinosis gene mutations identified in Turkey were c.681G>A (p.Glu227Glu), c.1015G>A (p.Gly339Arg), and c.18_21 del (p.Thr7Phefs*7). Patients with less severe cystinosis gene mutations tend to have better kidney outcome.
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Affiliation(s)
- Rezan Topaloglu
- Due to the number of contributing authors, the affiliations are provided in the Supplemental Material
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Abstract
PURPOSE OF REVIEW Over the past few decades, cystinosis, a rare lysosomal storage disorder, has evolved into a treatable metabolic disease. The increasing understanding of its pathophysiology has made cystinosis a prototype disease, delivering new insights into several fundamental biochemical and cellular processes. RECENT FINDINGS In this review, we aim to provide an overview of the latest advances in the pathogenetic, clinical, and therapeutic aspects of cystinosis. SUMMARY The development of alternative therapeutic monitoring strategies and new systemic and ocular cysteamine formulations might improve outcome of cystinosis patients in the near future. With the dawn of stem cell based therapy and new emerging gene-editing technologies, novel tools have become available in the search for a cure for cystinosis.
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Doğan M, Bulan K, Kaba S, Cesur Y, Ceylaner S, Ustyol L. Cystinosis in Eastern Turkey. J Pediatr Endocrinol Metab 2016; 29:965-9. [PMID: 27269891 DOI: 10.1515/jpem-2014-0477] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 04/21/2016] [Indexed: 11/15/2022]
Abstract
BACKGROUND This study was conducted to investigate CTNS (cystinosin, lysosomal cystine transporter) gene mutations and the clinical spectrum of nephropathic cystinosis among patients diagnosed with the disease in a single center in Turkey. METHODS Patients' clinical and laboratory data were extracted from an electronic health registry. Molecular CTNS gene analysis was performed using either next-generation sequencing or Sanger sequencing. RESULTS Eleven patients (age range: 1.5-12 years) from nine families were identified. The presenting complaint was growth retardation in seven patients; polydipsia and polyuria in three patients; and vomiting in two patients. At presentation, electrolyte loss was noted in all patients, of which eight patients presented with metabolic acidosis, and three patients presented with metabolic alkalosis. All patients also presented with proteinuria and glucosuria, and four patients developed varying degrees of renal insufficiency, for which peritoneal dialysis was initiated in one patient. Cystine crystals were detected via ocular examination in one patient at presentation. No cystine crystals were detected among patients who underwent bone marrow aspiration. In the CTNS gene, a p.T7FX7 (c.18-21del4bp) mutation was detected in three patients, whereas a p.E227E (c.681 G>A) (homozygous) mutation was detected in eight patients. CONCLUSIONS We detected two distinct mutations, p.T7FX7 (c.18-21del4bp) and p.E227E (c.681 G>A) (homozygous), in the CTNS gene in 11 patients with cystinosis from the East Anatolian region of Turkey. Patients with a homozygous c.681 G>A (p.E227E) mutation are more likely to develop chronic renal failure and should be monitored closely, whereas patients with a p.T7FX7 (c.18-21del4bp) mutation have a milder phenotype. Additionally, metabolic alkalosis does not exclude cystinosis, although cystinosis is a cause of proximal renal tubular acidosis.
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Jaradat S, Al-Rababah B, Hazza I, Akl K, Saca E, Al-Younis D. Molecular analysis of the CTNS gene in Jordanian families with nephropathic cystinosis. Nefrologia 2015; 35:547-53. [DOI: 10.1016/j.nefro.2015.09.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 06/10/2015] [Indexed: 10/22/2022] Open
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Genetic basis of cystinosis in Tunisian patients: Identification of novel mutation in CTNS gene. Meta Gene 2015; 5:144-9. [PMID: 26266097 PMCID: PMC4528043 DOI: 10.1016/j.mgene.2015.07.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 07/07/2015] [Accepted: 07/09/2015] [Indexed: 12/24/2022] Open
Abstract
Nephropathic cystinosis (NC) is an autosomal recessive disorder characterized by defective transport of cystine across the lysosomal membrane and resulting in renal, ophthalmic, and other organ abnormalities. Mutations in the CTNS gene cause a deficiency of the transport protein, cystinosin. This study was performed to investigate mutations of the CTNS gene in three Tunisian families with NC. Polymerase chain reaction (PCR), ARMS multiplex PCR and direct sequencing were performed for molecular characterization of the CTNS gene in 3 unrelated Tunisian patients and their parents. Based on family history, prenatal diagnosis (PND) was performed in fetal DNA isolated from chorionic villi obtained at 10-12 weeks of gestation. None of the patients showed the most common 57-kb deletion in heterozygous or homozygous status. One patient was homozygous for the previously reported mutation c.1515G > A (p.G308R). One patient presented the novel gross deletion of 20,327 bp. One was homozygote for the previously reported mutation c.771_793del (p.Gly258Serfs*30). In addition, eight polymorphisms were identified in the 3 patients and their parents. The prenatal diagnosis in one family showed that the fetus DNA was heterozygous for the c.771_793del (p.Gly258Serfs*30) mutation. This study expands the mutational and population spectrum of NC, representing the first molecular diagnosis of NC in Tunisian population. The mutation screening of the CTNS gene was used for prenatal diagnosis to prevent and/or limit this inheritable disease in our country where the families are particularly large and have a high rate of consanguinity.
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Soliman NA, Elmonem MA, van den Heuvel L, Abdel Hamid RH, Gamal M, Bongaers I, Marie S, Levtchenko E. Mutational Spectrum of the CTNS Gene in Egyptian Patients with Nephropathic Cystinosis. JIMD Rep 2014; 14:87-97. [PMID: 24464559 DOI: 10.1007/8904_2013_288] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 12/02/2013] [Accepted: 12/05/2013] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Nephropathic cystinosis is a rare autosomal recessive disorder caused by mutations in the CTNS gene, encoding for cystinosin, a carrier protein transporting cystine out of lysosomes. Its deficiency leads to cystine accumulation and cell damage in multiple organs, especially in the kidney. In this study, we aimed to provide the first report describing the mutational spectrum of Egyptian patients with nephropathic cystinosis and their genotype-phenotype correlation. METHODS Fifteen Egyptian patients from 13 unrelated families with infantile nephropathic cystinosis were evaluated clinically, biochemically, and genetically. Screening for the common 57-kb deletion was performed by standard multiplex PCR, followed by direct sequencing of the ten coding exons, exon-intron interfaces, and promoter region. RESULTS None of the 15 Egyptian patients had the 57-kb deletion. Twenty-seven mutant alleles and 12 pathogenic mutations were detected including six novel mutations: two frameshift (c.260_261delTT; p.F87SfsX36, c.1032delCinsTG; p.F345CfsX19), one nonsense (c.734G>A; p.W245fsX), two missense (c.1084G>A; pG362R, c.560A>G; p.K187R), and one intronic splicing mutation (IVS3+5g>t). A novel promoter region mutation (1-593-41C>T) seemed to be detected but was excluded as a pathogenic mutation by quantitative real-time PCR analysis. CONCLUSIONS This study could be the basis for future genetic counseling and prenatal diagnosis of patients with nephropathic cystinosis in Egyptian and surrounding populations. The screening for the 57-kb deletion is not recommended anymore outside its geographical distribution, especially in the region of the Middle East. A common Middle Eastern mutation (c.681G>A; E227E) was pointed out and discussed.
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Affiliation(s)
- Neveen A Soliman
- Department of Pediatrics, Center of Pediatric Nephrology and Transplantation (CPNT), Cairo University, Cairo, Egypt
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Kiehntopf M, Varga RE, Koch HG, Beetz C. A homemade MLPA assay detects known CTNS mutations and identifies a novel deletion in a previously unresolved cystinosis family. Gene 2012; 495:89-92. [DOI: 10.1016/j.gene.2011.12.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Revised: 11/23/2011] [Accepted: 12/06/2011] [Indexed: 12/01/2022]
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Genetic basis of cystinosis in Turkish patients: a single-center experience. Pediatr Nephrol 2012; 27:115-21. [PMID: 21786142 PMCID: PMC3501933 DOI: 10.1007/s00467-011-1942-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2010] [Revised: 04/28/2011] [Accepted: 06/01/2011] [Indexed: 10/18/2022]
Abstract
We report the molecular findings for the CTNS gene in 12 Turkish cystinosis patients aged 7-29 years. All presented initially with severe failure to thrive, polyuria, and polydipsia. Cystinosis was diagnosed at age 1 month to 9 years. Seven patients reached end-stage renal failure at ages ranging from 6.5 to 15 years. Whereas three of the remaining five have renal Fanconi syndrome with proteinuria, two have had kidney failure of varying degrees. Molecular analyses involved an initial multiplex polymerase chain reaction (PCR) to determine the presence or absence of the 57-kb northern European founder deletion in CTNS, followed by sequencing of the ten coding exons of CTNS. Comprehensive mutation analysis verified that none of the 12 patients carried the common 57-kb deletion. We identified four previously reported nucleotide variations associated with cystinosis and five new variants: a 10-kb deletion, three missense variants, and a nucleotide substitution in a potential branch point site of intron 4. This study is the first molecular analysis of Turkish cystinosis patients and provides guidance for the molecular diagnosis of cystinosis in this population.
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Macías-Vidal J, Rodés M, Hernández-Pérez JM, Vilaseca MA, Coll MJ. Analysis of the CTNS gene in 32 cystinosis patients from Spain. Clin Genet 2010; 76:486-9. [PMID: 19863563 DOI: 10.1111/j.1399-0004.2009.01222.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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Taranta A, Wilmer MJ, van den Heuvel LP, Bencivenga P, Bellomo F, Levtchenko EN, Emma F. Analysis of CTNS gene transcripts in nephropathic cystinosis. Pediatr Nephrol 2010; 25:1263-7. [PMID: 20352457 PMCID: PMC2874020 DOI: 10.1007/s00467-010-1502-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Revised: 02/23/2010] [Accepted: 03/01/2010] [Indexed: 11/30/2022]
Abstract
Nephropathic cystinosis (NC) is an autosomal recessive disorder caused by mutations of the CTNS gene that encodes for a cystine transmembrane transporter. Several mutations have been described in the coding and promoter regions of the CTNS gene in affected individuals. We selected three patients with NC from two unrelated families, in whom sequence analysis of the CTNS gene detected only one or no mutations. Total RNA was isolated from peripheral blood mononuclear cells or fibroblasts and CTNS transcripts were analyzed. We observed a skipping of exon 5 (85 bp) in two siblings and an intron 9 retention of 75 bp associated with partial replication of exon 9 in the third patient. Genomic DNA analysis of intron regions surrounding exon 5 showed a point mutation in the hypothetical lariat branch site of intron 4 at position -24 (c.141-24 T > C) in the first two patients and a duplication of 266 bp including a part of exon and intron 9 in the third patient. Analysis of CTNS gene transcripts allowed identification of mutations in patients in whom CTNS mutations could not be detected by traditional DNA sequencing. These results support the hypothesis that cystinosis is a monogenic disorder.
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Affiliation(s)
- Anna Taranta
- Department of Nephrology and Urology, Division of Nephrology, Bambino Gesù Children's Hospital and Research Institute, Piazza S. Onofrio, 4, 00165, Rome, Italy.
| | - Martijn J. Wilmer
- Laboratory of Pediatrics and Neurology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Lambert P. van den Heuvel
- Laboratory of Pediatrics and Neurology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands ,Department of Pediatrics/Pediatric Nephrology, University Hospital Gasthuisberg, Leuven, Belgium
| | - Paola Bencivenga
- Laboratory of Scientific Research, Bambino Gesù Children’s Hospital and Research Institute, Rome, Italy
| | - Francesco Bellomo
- Department of Nephrology and Urology, Division of Nephrology, Bambino Gesù Children’s Hospital and Research Institute, Piazza S. Onofrio, 4, 00165 Rome, Italy
| | - Elena N. Levtchenko
- Department of Pediatrics/Pediatric Nephrology, University Hospital Gasthuisberg, Leuven, Belgium
| | - Francesco Emma
- Department of Nephrology and Urology, Division of Nephrology, Bambino Gesù Children’s Hospital and Research Institute, Piazza S. Onofrio, 4, 00165 Rome, Italy
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Alcántara-Ortigoza MA, Belmont-Martínez L, Vela-Amieva M, González-Del Angel A. Analysis of the CTNS gene in nephropathic cystinosis Mexican patients: report of four novel mutations and identification of a false positive 57-kb deletion genotype with LDM-2/exon 4 multiplex PCR assay. ACTA ACUST UNITED AC 2008; 12:409-14. [PMID: 18752449 DOI: 10.1089/gte.2008.0014] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
OBJECTIVE Identify CTNS gene mutations in nephropathic cystinosis Mexican patients. SUBJECTS AND METHODS Eleven patients were included, nine presenting infantile nephropathic cystinosis and two siblings with the juvenile phenotype. The common 57-kb deletion was detected by multiplex PCR using large deletion marker-2 (LDM-2)/exon 4 set primers. Those alleles negative for 57-kb deletion were screened by single strand confirmation polymorphism (SSCP) and subsequent direct sequencing. RESULTS In our sample, five mutations previously reported are identified: 57-kb deletion, EX4_EX5del, c.985_986insA, c.357_360delGACT, and c.537_557del. We detect a false assignation of 57-kb deletion homozygous genotype by using the LDM-2/exon 4 primers. In addition, four novel and severe mutations are identified: c.379delC, c.1090_1093delACCAinsCG, c.986C>G (p.T216R), and c.400+5G>A. CONCLUSIONS Our sample of Mexican patients display allelic heterogeneity as compared to European or North American cystinosis cases. The identification of novel mutations might suggest the presence of exclusive American CTNS alleles in Mexican population. In order to prevent the false positive assignation of 57-kb deletion genotype, as caused by the presence of another type of intragenic CTNS gross deletion, we propose to analyze a different control CTNS exon to those originally reported in both LDM multiplex PCR assays, especially when parental DNA samples are not available.
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Soledad Martínez Llamas M, Cabrera Morales CM, Antonio Bravo Soto J, Cantón J, Pedrinaci S. Cistinosis: diagnóstico mediante la determinación del contenido de cistina intraleucocitaria por cromatografía líquida de alta resolución. Med Clin (Barc) 2004. [DOI: 10.1016/s0025-7753(04)74425-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Mason S, Pepe G, Dall'Amico R, Tartaglia S, Casciani S, Greco M, Bencivenga P, Murer L, Rizzoni G, Tenconi R, Clementi M. Mutational spectrum of the CTNS gene in Italy. Eur J Hum Genet 2003; 11:503-8. [PMID: 12825071 DOI: 10.1038/sj.ejhg.5200993] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Classic nephropathic or infantile cystinosis (NC) is an autosomal recessive disorder; the gene coding for the integral membrane protein cystinosin, which is responsible for membrane transport of cystine (CTNS), was cloned. Mutation analysis of the CTNS gene of Caucasian patients revealed a common 57-kb deletion, and several other mutations spread throughout the entire gene. In the present study, we report the CTNS mutations identified in 42 of 46 Italian families with NC. The percentage of mutations characterized in this study is 86%. The mutational spectrum of the Italian population is different from that of populations of North European origin: the 57-kb deletion is present in a lower percentage, while the splicing mutations represent 30% of mutation detected in our sample. In all, six novel mutations have been identified, and the origin of one recurrent mutation has been traced.
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Affiliation(s)
- Silvia Mason
- Clinical Genetics, Department of Pediatrics, University of Padua, Italy
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