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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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2
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Biesecker LG, Byrne AB, Harrison SM, Pesaran T, Schäffer AA, Shirts BH, Tavtigian SV, Rehm HL. ClinGen guidance for use of the PP1/BS4 co-segregation and PP4 phenotype specificity criteria for sequence variant pathogenicity classification. Am J Hum Genet 2024; 111:24-38. [PMID: 38103548 PMCID: PMC10806742 DOI: 10.1016/j.ajhg.2023.11.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 11/21/2023] [Accepted: 11/21/2023] [Indexed: 12/19/2023] Open
Abstract
The 2015 American College of Medical Genetics and Genomics and the Association for Molecular Pathology variant classification publication established a standard employed internationally to guide laboratories in variant assessment. Those recommendations included both pathogenic (PP1) and benign (BS4) criteria for evaluating the inheritance patterns of variants, but details of how to apply those criteria at appropriate evidence levels were sparse. Several publications have since attempted to provide additional guidance, but anecdotally, this issue is still challenging. Additionally, it is not clear that those prior efforts fully distinguished disease-gene identification considerations from variant pathogenicity considerations nor did they address autosomal-recessive and X-linked inheritance. Here, we have taken a mixed inductive and deductive approach to this problem using real diseases as examples. We have developed a practical heuristic for genetic co-segregation evidence and have also determined that the specific phenotype criterion (PP4) is inseparably coupled to the co-segregation criterion. We have also determined that negative evidence at one locus constitutes positive evidence for other loci for disorders with locus heterogeneity. Finally, we provide a points-based system for evaluating phenotype and co-segregation as evidence types to support or refute a locus and show how that can be integrated into the Bayesian framework now used for variant classification and consistent with the 2015 guidelines.
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Affiliation(s)
- Leslie G Biesecker
- Center for Precision Health Research, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA.
| | - Alicia B Byrne
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Steven M Harrison
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA; Ambry Genetics, Aliso Viejo, CA, USA
| | | | - Alejandro A Schäffer
- Cancer Data Science Laboratory, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Brian H Shirts
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA
| | - Sean V Tavtigian
- Department of Oncological Sciences, University of Utah School of Medicine and Huntsman Cancer Institute at the University of Utah, Salt Lake City, UT, USA
| | - Heidi L Rehm
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA; Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
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3
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Bondue T, Kouraich A, Berlingerio SP, Veys K, Marie S, Alsaad KO, Al-Sabban E, Levtchenko E, van den Heuvel L. The Pitfall of White Blood Cell Cystine Measurement to Diagnose Juvenile Cystinosis. Int J Mol Sci 2023; 24:ijms24021253. [PMID: 36674769 PMCID: PMC9864853 DOI: 10.3390/ijms24021253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 01/05/2023] [Accepted: 01/05/2023] [Indexed: 01/11/2023] Open
Abstract
Cystinosis is an autosomal recessive lysosomal storage disease, caused by mutations in the CTNS gene, resulting in multi-organ cystine accumulation. Three forms of cystinosis are distinguished: infantile and juvenile nephropathic cystinosis affecting kidneys and other organs such as the eyes, endocrine system, muscles, and brain, and adult ocular cystinosis affecting only the eyes. Currently, elevated white blood cell (WBC) cystine content is the gold standard for the diagnosis of cystinosis. We present a patient with proteinuria at adolescent age and corneal cystine crystals, but only slightly elevated WBC cystine levels (1.31 ½ cystine/mg protein), precluding the diagnosis of nephropathic cystinosis. We demonstrate increased levels of cystine in skin fibroblasts and urine-derived kidney cells (proximal tubular epithelial cells and podocytes), that were higher than the values observed in the WBC and healthy control. CTNS gene analysis shows the presence of a homozygous missense mutation (c.590 A > G; p.Asn177Ser), previously described in the Arab population. Our observation underlines that low WBC cystine levels can be observed in patients with juvenile cystinosis, which may delay the diagnosis and timely administration of cysteamine. In such patients, the diagnosis can be confirmed by cystine measurement in slow-dividing cells and by molecular analysis of the CTNS gene.
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Affiliation(s)
- Tjessa Bondue
- Laboratory of Pediatric Nephrology, Department of Development and Regeneration, KU Leuven Campus Gasthuisberg, 3000 Leuven, Belgium
| | - Anas Kouraich
- Laboratory of Pediatric Nephrology, Department of Development and Regeneration, KU Leuven Campus Gasthuisberg, 3000 Leuven, Belgium
| | - Sante Princiero Berlingerio
- Laboratory of Pediatric Nephrology, Department of Development and Regeneration, KU Leuven Campus Gasthuisberg, 3000 Leuven, Belgium
| | - Koenraad Veys
- Laboratory of Pediatric Nephrology, Department of Development and Regeneration, KU Leuven Campus Gasthuisberg, 3000 Leuven, Belgium
- Department of Pediatrics, AZ Delta Campus Torhout, 8820 Torhout, Belgium
| | - Sandrine Marie
- Laboratory of Inherited Metabolic Diseases/Biochemical Genetics, Cliniques Universitaires Saint-Luc, UC Louvain, 1200 Brussels, Belgium
| | - Khaled O. Alsaad
- Section of Histopathology, Department of Pathology and Laboratory Medicine, King Faisal Specialist Hospital and Research Centre, Riyadh 11533, Saudi Arabia
| | - Essam Al-Sabban
- Section of Pediatric Nephrology, Department of Pediatrics, King Faisal Specialist Hospital and Research Centre, Riyadh 11533, Saudi Arabia
| | - Elena Levtchenko
- Laboratory of Pediatric Nephrology, Department of Development and Regeneration, KU Leuven Campus Gasthuisberg, 3000 Leuven, Belgium
- Department of Pediatrics, University Hospitals Leuven Campus Gasthuisberg, 3000 Leuven, Belgium
| | - Lambertus van den Heuvel
- Laboratory of Pediatric Nephrology, Department of Development and Regeneration, KU Leuven Campus Gasthuisberg, 3000 Leuven, Belgium
- Department of Pediatrics, Division of Pediatric Nephrology, Amalia Children’s Hospital, Radboud University Medical Center, HB-6524 Nijmegen, The Netherlands
- Correspondence:
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4
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Sullivan S, Grant N, Hammond C, David WS, Eichler F, Sadjadi R. Longitudinal dysphagia assessment in adult patients with nephropathic cystinosis using the Modified Barium Swallow Impairment Profile. Muscle Nerve 2022; 66:223-226. [PMID: 35616433 DOI: 10.1002/mus.27642] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 05/19/2022] [Accepted: 05/20/2022] [Indexed: 11/12/2022]
Abstract
INTRODUCTION/AIMS Nephropathic cystinosis is a lysosomal storage disorder with known myopathic features, including dysphagia. Evaluation of oropharyngeal swallowing physiology can be standardized using the Modified Barium Swallow Impairment Profile (MBSImP), a validated assessment tool used to analyze and rate swallowing across 17 distinct physiologic domains. Our objective was to better characterize swallowing impairments in nephropathic cystinosis using MBSImP analysis. METHODS We retrospectively evaluated 40 video fluoroscopic swallowing studies performed at two time points over 1 y in patients with nephropathic cystinosis with various levels of oral and pharyngeal stage dysphagia. Patients completed two self-administered dysphagia outcome measures (the M. D. Anderson Dysphagia Inventory [MDADI] and the 10-item Eating Assessment Tool [EAT-10]). RESULTS We demonstrated oral stage and pharyngeal stage dysphagia across domains that impacted bolus control, transit, and clearance through both the oral cavity and pharyngeal lumen. Also captured were deficits related to onset and completeness of laryngeal closure that impact airway protection during swallow. There were significant correlations between pharyngeal total score and EAT-10 (r = 0.5, p < 0.001) and between oral total score and EAT-10 (r = 0.7, p < 0.001), MDADI-e (r = -0.6, p < 0.001), MDADI-p (r = -0.5, p < 0.001) and MDADI-c (r = -0.6, p < 0.001). There were no differences in oral or pharyngeal total scores across the 1-y time span. DISCUSSION This study identifies oral and pharyngeal stage dysphagia as crucial to patients with nephropathic cystinosis and paves the path for future studies of treatment targets.
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Affiliation(s)
- Stacey Sullivan
- Department of Speech, Language and Swallowing Disorders, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Natalie Grant
- Department of Neurology, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Colleen Hammond
- Cystinosis Adult Care Excellence Initiative, Reading, Massachusetts, USA
| | - William S David
- Department of Neurology, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Florian Eichler
- Department of Neurology, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Reza Sadjadi
- Department of Neurology, Massachusetts General Hospital, Boston, Massachusetts, USA
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5
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Tokhmafshan F, Dickinson K, Akpa MM, Brasell E, Huertas P, Goodyer PR. A no-nonsense approach to hereditary kidney disease. Pediatr Nephrol 2020; 35:2031-2042. [PMID: 31807928 DOI: 10.1007/s00467-019-04394-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 07/05/2019] [Accepted: 10/07/2019] [Indexed: 01/12/2023]
Abstract
The advent of a new class of aminoglycosides with increased translational readthrough of nonsense mutations and reduced toxicity offers a new therapeutic strategy for a subset of patients with hereditary kidney disease. The renal uptake and retention of aminoglycosides at a high intracellular concentration makes the kidney an ideal target for this approach. In this review, we explore the potential of aminoglycoside readthrough therapy in a number of hereditary kidney diseases and discuss the therapeutic window of opportunity for subclasses of each disease, when caused by nonsense mutations.
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Affiliation(s)
- Fatima Tokhmafshan
- Research Institute of the McGill University Health Center, 1001 Décarie Boulevard, EM1.2232, Montreal, QC, H4A 3J1, Canada
| | - Kyle Dickinson
- Research Institute of the McGill University Health Center, 1001 Décarie Boulevard, EM1.2232, Montreal, QC, H4A 3J1, Canada.,Department of Experimental Medicine, McGill University, Montreal, Canada
| | - Murielle M Akpa
- Research Institute of the McGill University Health Center, 1001 Décarie Boulevard, EM1.2232, Montreal, QC, H4A 3J1, Canada
| | - Emma Brasell
- Department of Human Genetics, McGill University, Montreal, Canada
| | | | - Paul R Goodyer
- Research Institute of the McGill University Health Center, 1001 Décarie Boulevard, EM1.2232, Montreal, QC, H4A 3J1, Canada. .,Department of Experimental Medicine, McGill University, Montreal, Canada. .,Department of Human Genetics, McGill University, Montreal, Canada. .,Department of Pediatrics, McGill University, Montreal, Canada.
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6
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Sadjadi R, Sullivan S, Grant N, Thomas SE, Doyle M, Hammond C, Corre C, Mello N, David WS, Eichler F. Clinical trial readiness study of distal myopathy and dysphagia in nephropathic cystinosis. Muscle Nerve 2020; 62:681-687. [PMID: 32737993 DOI: 10.1002/mus.27039] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 07/23/2020] [Accepted: 07/27/2020] [Indexed: 12/20/2022]
Abstract
BACKGROUND Nephropathic cystinosis is a lysosomal storage disorder with late-onset systemic complications, such as myopathy and dysphagia. Currently employed outcome measures lack sensitivity and responsiveness for dysphagia and myopathy, a limitation to clinical trial readiness. METHODS We evaluated 20 patients with nephropathic cystinosis in two visits over the course of a year to identify outcomes sensitive to detect changes over time. Patients also underwent an expiratory muscle strength training program to assess any effects on aspiration and dysphagia. RESULTS There were significant differences in the Timed Up and Go Test (TUG) and Timed 25-Foot Walk (25-FW) between baseline and 1-y follow-up (P < .05). Maximum expiratory pressure (MEP) and peak cough flow (PCF) significantly improved following respiratory training (P < .05). CONCLUSIONS Improved respiratory outcomes may enhance patients ability to expel aspirated material from the airway, stave off pulmonary sequelae associated with chronic aspiration, and yield an overall improvement in physical health and well-being.
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Affiliation(s)
- Reza Sadjadi
- Department of Neurology, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Stacey Sullivan
- Department of Speech, Language and Swallowing Disorders, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Natalie Grant
- Center for Rare Neurological Diseases, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Susan E Thomas
- Division of Pediatric Nephrology, Department of Pediatrics and Communicable Diseases, University of Michigan School of Medicine, Ann Arbor, Michigan, USA
| | - Maya Doyle
- Department of Social Work, School of Health Sciences, Quinnipiac University, Hamden, Connecticut, USA
| | - Colleen Hammond
- Cystinosis Adult Care Excellence Initiative, Reading, Massachusetts, USA
| | - Camille Corre
- Center for Rare Neurological Diseases, Department of Neurology, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Nicholas Mello
- Center for Rare Neurological Diseases, Department of Neurology, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - William S David
- Department of Neurology, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Florian Eichler
- Center for Rare Neurological Diseases, Department of Neurology, Massachusetts General Hospital, Boston, Massachusetts, USA
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7
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Papizh S, Serzhanova V, Filatova A, Skoblov M, Tabakov V, van den Heuvel L, Levtchenko E, Prikhodina L. CTNS mRNA molecular analysis revealed a novel mutation in a child with infantile nephropathic cystinosis: a case report. BMC Nephrol 2019; 20:400. [PMID: 31672123 PMCID: PMC6822415 DOI: 10.1186/s12882-019-1589-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 10/13/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Cystinosis is an autosomal recessive lysosomal storage disorder characterized by accumulation of cystine in lysosomes throughout the body. Cystinosis is caused by mutations in the CTNS gene that encodes the lysosomal cystine carrier protein cystinosin. CTNS mutations result in either complete absence or reduced cystine transporting function of the protein. The diagnosis of nephropathic cystinosis is generally based on measuring leukocyte cystine level, demonstration of corneal cystine crystals by the slit lamp examination and confirmed by genetic analysis of the CTNS gene. CASE PRESENTATION A boy born to consanguineous Caucasian parents had the characteristic clinical features of the infantile nephropathic cystinosis including renal Fanconi syndrome (polydipsia/polyuria, metabolic acidosis, hypokalemia, hypophosphatemia, low molecular weight proteinuria, glycosuria, cystine crystals in the cornea) and elevated WBC cystine levels. Initially we performed RFLP analysis of the common in the Northern European population 57-kb deletion of proband's DNA, then a direct Sanger sequencing which revealed no mutations in the coding part of the CTNS gene. To confirm the diagnosis we performed RT-PCR analysis of total RNA obtained from patient-derived fibroblasts in combination with cDNA sequencing. This revealed the skipping of exon 4 and exon 5 in the CTNS in our patient. Therefore, we detected a novel 9-kb homozygous deletion in the CTNS gene at genomic DNA level, spanning region from intron 3 to intron 5. In order to identify the inheritance pattern of the deletion we analyzed DNA of proband's mother and father. Both parents were found to be heterozygous carriers of the CTNS mutation. CONCLUSIONS Analysis of CTNS gene transcript allowed to identify a large homozygous deletion in the patient with infantile nephropathic cystinosis. Mutational detection at RNA level may be an efficient tool to establish the genetic defect in some cystinosis patients.
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Affiliation(s)
- Svetlana Papizh
- Department of hereditary and acquired kidney diseases, Research and Clinical Institute for Pediatrics at the Pirogov Russian National Research Medical University, 125412, Taldomskaya st., 2, Moscow, Russia.
| | | | | | - Mikhail Skoblov
- Research Centre for Medical Genetics, 115522, Russia, Moscow
| | | | - Lambert van den Heuvel
- Department of Pediatrics/Pediatric Nephrology, University Hospital Gasthuisberg, Leuven, Belgium
| | - Elena Levtchenko
- Department of Pediatrics/Pediatric Nephrology, University Hospital Gasthuisberg, Leuven, Belgium
| | - Larisa Prikhodina
- Department of hereditary and acquired kidney diseases, Research and Clinical Institute for Pediatrics at the Pirogov Russian National Research Medical University, 125412, Taldomskaya st., 2, Moscow, Russia
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8
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Sadjadi R, Sullivan S, Grant N, Thomas SE, Doyle M, Hammond C, Duong R, Corre C, David W, Eichler F. Clinical myopathy in patients with nephropathic cystinosis. Muscle Nerve 2019; 61:74-80. [PMID: 31588568 DOI: 10.1002/mus.26726] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 09/16/2019] [Accepted: 09/17/2019] [Indexed: 12/20/2022]
Abstract
BACKGROUND Nephropathic cystinosis is a lysosomal storage disorder. Patient survival years after renal transplantation has revealed systemic complications including distal myopathy and dysphagia. METHODS We evaluated 20 adult patients with nephropathic cystinosis using patient-reported and clinical outcome measures. Standard motor measures, video fluoroscopy swallow studies, and tests of respiratory function were performed. We also used Rasch analysis of an initial survey to design a 16-item survey focused on upper and lower extremity function, which was completed by 31 additional patients. RESULTS Distal myopathy and dysphagia were common in patients with nephropathic cystinosis. Muscle weakness ranges from mild involvement of intrinsic hand muscles to prominent distal greater than proximal weakness and contractures. CONCLUSIONS In addition to further characterization of underlying dysphagia and muscle weakness, we propose a new psychometrically devised, disease specific, functional outcome measures for distal myopathy in patients with nephropathic cystinosis.
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Affiliation(s)
- Reza Sadjadi
- Center for Rare Neurological Diseases, Department of Neurology, Massachusetts General Hospital, Massachusetts
| | - Stacey Sullivan
- Department of Neurology, Massachusetts General Hospital, Boston, Massachusetts
| | - Natalie Grant
- Center for Rare Neurological Diseases, Department of Neurology, Massachusetts General Hospital, Massachusetts
| | - Susan E Thomas
- Division of Pediatric Nephrology, Department of Pediatrics and Communicable Diseases, University of Michigan School of Medicine, Ann Arbor, Michigan
| | - Maya Doyle
- Department of Social Work, School of Health Sciences, Quinnipiac University, Hamden, Connecticut
| | - Colleen Hammond
- Cystinosis Adult Care Excellence Initiative, Reading, Massachusetts
| | - Rachel Duong
- Center for Rare Neurological Diseases, Department of Neurology, Massachusetts General Hospital, Massachusetts
| | - Camille Corre
- Center for Rare Neurological Diseases, Department of Neurology, Massachusetts General Hospital, Massachusetts
| | - William David
- Department of Neurology, Massachusetts General Hospital, Boston, Massachusetts
| | - Florian Eichler
- Center for Rare Neurological Diseases, Department of Neurology, Massachusetts General Hospital, Massachusetts
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9
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Lueck JD, Yoon JS, Perales-Puchalt A, Mackey AL, Infield DT, Behlke MA, Pope MR, Weiner DB, Skach WR, McCray PB, Ahern CA. Engineered transfer RNAs for suppression of premature termination codons. Nat Commun 2019; 10:822. [PMID: 30778053 PMCID: PMC6379413 DOI: 10.1038/s41467-019-08329-4] [Citation(s) in RCA: 81] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2018] [Accepted: 12/21/2018] [Indexed: 12/28/2022] Open
Abstract
Premature termination codons (PTCs) are responsible for 10–15% of all inherited disease. PTC suppression during translation offers a promising approach to treat a variety of genetic disorders, yet small molecules that promote PTC read-through have yielded mixed performance in clinical trials. Here we present a high-throughput, cell-based assay to identify anticodon engineered transfer RNAs (ACE-tRNA) which can effectively suppress in-frame PTCs and faithfully encode their cognate amino acid. In total, we identify ACE-tRNA with a high degree of suppression activity targeting the most common human disease-causing nonsense codons. Genome-wide transcriptome ribosome profiling of cells expressing ACE-tRNA at levels which repair PTC indicate that there are limited interactions with translation termination codons. These ACE-tRNAs display high suppression potency in mammalian cells, Xenopus oocytes and mice in vivo, producing PTC repair in multiple genes, including disease causing mutations within cystic fibrosis transmembrane conductance regulator (CFTR). Premature termination codon suppression therapy could be used to treat a range of genetic disorders. Here the authors present a high-throughput cell-based assay to identify anticodon engineered tRNAs with high suppression activity.
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Affiliation(s)
- John D Lueck
- Department of Physiology and Pharmacology, University of Rochester School of Medicine and Dentistry, Rochester, NY, 14642, USA.
| | - Jae Seok Yoon
- CFFT Lab, Cystic Fibrosis Foundation Therapeutics, Lexington, 02421, MA, USA
| | | | - Adam L Mackey
- Department of Molecular Physiology and Biophysics, Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA
| | - Daniel T Infield
- Department of Molecular Physiology and Biophysics, Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA
| | - Mark A Behlke
- Integrated DNA Technologies Inc., Coralville, IA, 52241, USA
| | - Marshall R Pope
- Department of Molecular Physiology and Biophysics, Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA
| | | | - William R Skach
- CFFT Lab, Cystic Fibrosis Foundation Therapeutics, Lexington, 02421, MA, USA.,Cystic Fibrosis Foundation, Bethesda, 20814, MD, USA
| | - Paul B McCray
- Stead Family Department of Pediatrics, Pappajohn Biomedical Institute, University of Iowa, Iowa City, IA, 52242, USA
| | - Christopher A Ahern
- Department of Molecular Physiology and Biophysics, Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA.
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10
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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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11
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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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Medeiros M, Enciso S, Hernández AM, García Hernández HR, Toussaint G, Pinto C, Navarrete Rodríguez EM, del-Rio-Navarro BE, Saucedo-Ramírez OJ, Medina Bravo P, Miranda S, Worona L, Sosa G, Belmont Martinez L, Alcántara Ortigoza MÁ, Escobar L, Muñoz Arizpe R. Informe de casos de acidosis tubular renal y errores de diagnóstico. Nefrologia 2016; 36:323-5. [DOI: 10.1016/j.nefro.2015.10.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Revised: 08/26/2015] [Accepted: 10/19/2015] [Indexed: 11/26/2022] Open
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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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Common mutation causes cystinosis in the majority of black South African patients. Pediatr Nephrol 2015; 30:595-601. [PMID: 25326109 DOI: 10.1007/s00467-014-2980-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Revised: 09/03/2014] [Accepted: 09/29/2014] [Indexed: 01/01/2023]
Abstract
BACKGROUND The mutations responsible for cystinosis in South African patients are currently unknown. A pertinent question is whether they are similar to those described elsewhere in the world. METHODS Children who were being managed for cystinosis in the Western Cape Province of South Africa between 2002 and 2013 were studied. All underwent molecular analysis to detect sequence variations in the cystinosis gene. RESULTS This cohort study included 20 patients, 13 of whom were Xhosa-speaking black South Africans and seven were Cape Coloureds (mixed race); none were Caucasian. All had nephropathic infantile-type cystinosis with evidence of proximal tubulopathy, with glycosuria and renal phosphate wasting. Diagnosis was confirmed in 19 cases by demonstrating an elevated cystine concentration in leukocytes. Molecular analysis of the cystinosin gene revealed that 19 patients had a G > A mutation in intron 11 (CTNS-c.971-12G > A p.D324AfsX44) which caused an out-of-frame 10-bp insertion. Of these 19 patients, 16 were homozygous for this mutation, which was the most frequent mutation identified in the alleles of the black South African and Cape Coloured patients (96 and 71 %, respectively). CONCLUSION We recommend that black South African and Cape Coloured patients presenting with cystinosis be tested for CTNS-c.971-12G > A in the first instance, with the possibility of prenatal testing being offered to at-risk families.
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Shams F, Livingstone I, Oladiwura D, Ramaesh K. Treatment of corneal cystine crystal accumulation in patients with cystinosis. Clin Ophthalmol 2014; 8:2077-84. [PMID: 25336909 PMCID: PMC4199850 DOI: 10.2147/opth.s36626] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Cystinosis is a rare autosomal recessive disorder characterized by the accumulation of cystine within the cells of different organs. Infantile nephropathic cystinosis is the most common and severe phenotype. With the success of renal transplantation, these patients are now living longer and thus more long-term complications within different organs are becoming apparent. Ophthalmic manifestations range from corneal deposits of cystine crystals to pigmentary retinopathy. With increasing age, more severe ocular complications have been reported. Photophobia is a prominent symptom for patients. With prolonged survival and increasing age, this symptom, along with corneal erosions and blepharospasm, can become debilitating. This review revisits the basic pathogenesis of cystinosis, the ocular manifestations of the disease, and the treatment of corneal crystals.
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Affiliation(s)
- Fatemeh Shams
- Department of Ophthalmology, Gartnavel General Hospital, Glasgow, Scotland
| | - Iain Livingstone
- Department of Ophthalmology, Gartnavel General Hospital, Glasgow, Scotland
| | - Dilys Oladiwura
- Department of Ophthalmology, Gartnavel General Hospital, Glasgow, Scotland
| | - Kanna Ramaesh
- Department of Ophthalmology, Gartnavel General Hospital, Glasgow, Scotland
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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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Chiavérini C, Kang HY, Sillard L, Berard E, Niaudet P, Guest G, Cailliez M, Bahadoran P, Lacour JP, Ballotti R, Ortonne JP. In vivo reflectance confocal microscopy of the skin: A noninvasive means of assessing body cystine accumulation in infantile cystinosis. J Am Acad Dermatol 2013; 68:e111-e116. [DOI: 10.1016/j.jaad.2011.08.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2010] [Revised: 08/05/2011] [Accepted: 08/07/2011] [Indexed: 11/27/2022]
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Rangel-Filho A, Lazar J, Moreno C, Geurts A, Jacob HJ. Rab38 modulates proteinuria in model of hypertension-associated renal disease. J Am Soc Nephrol 2013; 24:283-92. [PMID: 23291471 DOI: 10.1681/asn.2012090927] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
We previously reported that the fawn-hooded hypertensive (FHH) rat is a natural Rab38 knockout, supported by a congenic animal (FHH.BN-Rab38) having less proteinuria than FHH animals. Because these congenic animals contain Brown Norway (BN) alleles for five other named genes; however, a causal role for Rab38 in the FHH phenotype remains uncertain. Here, we used transgenic and knockout models to validate Rab38 and to exclude other genes within the 1.5 Mb congenic region from involvement in causing the FHH phenotype. Transgenic rats homozygous for the wild-type Rab38 BN allele on the FHH background exhibited phenotypic rescue, having 43% lower proteinuria and 75% lower albuminuria than nontransgenic FHH littermates. Conversely, knockout of the Rab38 gene on the FHH.BN-Rab38 congenic line recapitulated a proteinuric phenotype indistinguishable from the FHH strain. In addition, in cultured proximal tubule LLC-PK1 cells, knockdown of Rab38 mRNA significantly decreased endocytosis of colloidal gold-coupled albumin, supporting the hypothesis that Rab38 modulates proteinuria through effects on tubular re-uptake and not by altering glomerular permeability. Taken together, these findings validate Rab38 as a gene having a causal role in determining the phenotype of the FHH rat, which models hypertension-associated renal disease. Furthermore, our data suggest that Rab38 affects urinary protein excretion via effects in the proximal tubule.
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Affiliation(s)
- Artur Rangel-Filho
- Human and Molecular Genetics Center, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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Langman CB, Greenbaum LA, Sarwal M, Grimm P, Niaudet P, Deschênes G, Cornelissen E, Morin D, Cochat P, Matossian D, Gaillard S, Bagger MJ, Rioux P. A randomized controlled crossover trial with delayed-release cysteamine bitartrate in nephropathic cystinosis: effectiveness on white blood cell cystine levels and comparison of safety. Clin J Am Soc Nephrol 2012; 7:1112-20. [PMID: 22554716 DOI: 10.2215/cjn.12321211] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
BACKGROUND AND OBJECTIVES Immediate-release cysteamine bitartrate (Cystagon; Mylan Pharmaceuticals, Canonsburg, PA) may prevent or delay kidney transplantation and other serious outcomes in patients with cystinosis, but has never been subjected to a prospective clinical trial. Cystagon efficacy requires strict lifelong dosing every 6 hours. Such a dosing schedule and Cystagon-associated side effects are often cited by patients as reasons for nonadherence. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS This open-label, randomized, controlled, crossover trial was powered to show that a new delayed-release formulation of cysteamine bitartrate, RP103, taken every 12 hours, was noninferior to Cystagon for maintenance of white blood cell (WBC) cystine at levels associated with optimal outcomes in the disease. RESULTS Forty-three patients were randomized. Using a mixed-effects statistical analysis model, the least-squares mean peak value of WBC cystine level was 0.62±0.05 nmol 1/2 cystine/mg protein after 12 hours under RP103 and 0.54±0.05 nmol 1/2 cystine/mg protein after 6 hours under Cystagon, a difference of 0.08±0.04 nmol 1/2 cystine/mg protein (95.8% confidence interval, 0-0.16). The average steady-state total daily dose of RP103 was 82% of the incoming steady-state total daily dose of Cystagon. There were three-fold more gastrointestinal side effects compared with using Cystagon. CONCLUSIONS A new delayed-release Q12H formulation of cysteamine bitartrate is not inferior to the Q6H formulation (Cystagon) in maintaining low WBC cystine levels in patients with cystinosis but at a lower total daily dose.
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Affiliation(s)
- Craig B Langman
- Division of Kidney Diseases, Department of Pediatrics, Feinberg School of Medicine, Northwestern University, Chicago, IL 60614, USA.
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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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Brodin-Sartorius A, Tête MJ, Niaudet P, Antignac C, Guest G, Ottolenghi C, Charbit M, Moyse D, Legendre C, Lesavre P, Cochat P, Servais A. Cysteamine therapy delays the progression of nephropathic cystinosis in late adolescents and adults. Kidney Int 2011; 81:179-89. [PMID: 21900880 DOI: 10.1038/ki.2011.277] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Nephropathic cystinosis is a multisystem autosomal recessive disease caused by cystine accumulation, which is usually treated by oral cysteamine. In order to determine long-term effects of this therapy, we enrolled 86 adult patients (mean age 26.7 years) diagnosed with nephropathic cystinosis, 75 of whom received cysteamine. Therapy was initiated at a mean age of 9.9 years with a mean duration of 17.4 years. By last follow-up, 78 patients had end-stage renal disease (mean age 11.1 years), 62 had hypothyroidism (mean age 13.4), 48 developed diabetes (mean age 17.1 years), and 32 had neuromuscular disorders (mean age 23.3 years). Initiating cysteamine therapy before 5 years of age significantly decreased the incidence and delayed the onset of end-stage renal disease, and significantly delayed the onset of hypothyroidism, diabetes, and neuromuscular disorders. The development of diabetes and hypothyroidism was still significantly delayed, however, in patients in whom therapy was initiated after 5 years of age, compared with untreated patients. The life expectancy was significantly improved in cysteamine-treated versus untreated patients. Thus, cysteamine decreases and delays the onset of complications and improves life expectancy in cystinosis. Hence, cysteamine therapy should be introduced as early as possible during childhood and maintained lifelong.
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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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Aldahmesh MA, Humeidan A, Almojalli HA, Khan AO, Rajab M, AL-Abbad AA, Meyer BF, Alkuraya FS. Characterization of CTNS mutations in Arab patients with cystinosis. Ophthalmic Genet 2010; 30:185-9. [PMID: 19852576 DOI: 10.3109/13816810903200953] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND Cystinosis is an autosomal recessive disease characterized by impaired transport of free cystine out of lysosomes with resulting renal and ophthalmic manifestations. Mutations in CTNS, encoding cystinosin, are the only known cause of this autosomal recessive disorder with more than 85 different mutations described so far. PURPOSE To identify CTNS mutations in Arab cystinosis patients. METHODS In this study, we have analyzed the mutational spectrum of CTNS in a population of 21 patients from 13 families of Arab origin. The entire coding region and flanking intronic regions of CTNS were analyzed by direct sequencing. RESULTS Eight mutations were identified, four of which are novel (c.530A>G, c.681G>A, 1013T>G, and c.1018_1041del). CONCLUSION These alleles will provide the basis for routine molecular diagnosis of cystinosis in the region.
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Affiliation(s)
- Mohammed A Aldahmesh
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
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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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Ulmer FF, Landolt MA, Vinh RH, Huisman TAGM, Neuhaus TJ, Latal B, Laube GF. Intellectual and motor performance, quality of life and psychosocial adjustment in children with cystinosis. Pediatr Nephrol 2009; 24:1371-8. [PMID: 19294426 DOI: 10.1007/s00467-009-1149-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2008] [Revised: 02/05/2009] [Accepted: 02/06/2009] [Indexed: 12/18/2022]
Abstract
Cystinosis is a rare multisystemic progressive disorder mandating lifelong medical treatment. Knowledge on the intellectual and motor functioning, health-related quality of life and psychosocial adjustment in children with cystinosis is limited. We have investigated nine patients (four after renal transplantation) at a median age of 9.7 years (range 5.3-19.9 years). Intellectual performance (IP) was analysed with the Wechsler Intelligence Scale for Children-III (seven children) and the Kaufman Assessment Battery for Children (two children). Motor performance (MP) was evaluated using the Zurich Neuromotor Assessment Test, and quality of life (QOL) was studied by means of the Netherlands Organization for Applied Scientific Research Academical Medical Center Child Quality of Life Questionnaire. Psychosocial adjustment was assessed by the Child Behavior Checklist. The overall intelligence quotient (IQ) of our patient cohort (median 92, range 71-105) was significantly lower than that of the healthy controls (p = 0.04), with two patients having an IQ < 85. Verbal IQ (93, range 76-118) was significantly higher than performance IQ (90, range 68-97; p = 0.03). The MP was significantly below the norm for pure motor, pegboard and static balance, as well as for movement quality. The patients' QOL was normal for six of seven dimensions (exception being positive emotions), whereas parents reported significant impairment in positive emotions, autonomy, social and cognitive functions. Significant disturbance was noted in terms of psychosocial adjustment. Based on the results from our small patient cohort, we conclude that intellectual and motor performance, health-related QOL and psychosocial adjustment are significantly impaired in children and adolescents with cystinosis.
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Affiliation(s)
- Francis F Ulmer
- Nephrology Unit, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland
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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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Servais A, Morinière V, Grünfeld JP, Noël LH, Goujon JM, Chadefaux-Vekemans B, Antignac C. Late-onset nephropathic cystinosis: clinical presentation, outcome, and genotyping. Clin J Am Soc Nephrol 2008; 3:27-35. [PMID: 18178779 DOI: 10.2215/cjn.01740407] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
BACKGROUND AND OBJECTIVES Cystinosis is an autosomal recessive disease characterized by the intralysosomal accumulation of cystine, as a result of a defect in cystine transport across the lysosomal membrane. Three clinical forms have been described on the basis of severity of symptoms and age of onset: infantile cystinosis, characterized by renal proximal tubulopathy and progression to end-stage renal disease before 12 yr of age; juvenile form, with a markedly slower rate of progression; and adult form, with only ocular abnormalities. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Fourteen patients in nine unrelated families with noninfantile cystinosis were studied. Information about clinical outcome, biochemical data, renal histopathologic data, and genotyping was collected. RESULTS Eight patients had Fanconi syndrome. Proteinuria was present in all patients. Serum creatinine at last follow-up, without specific treatment, ranged between 69 and 450 mumol/L, at an age of 12 to 56 yr. Four patients reached end-stage renal disease by 12 to 28 yr. Renal biopsies, available in four cases, disclosed focal segmental glomerulosclerosis in three and crystals in three. Genetic screening showed that patients were compound heterozygous for mutations in the CTNS gene in four families and homozygous in two families. Patients had at least one "mild" mutation. A single heterozygous mutation was identified in one family and none in two families (only 72% mutations found). CONCLUSION Renal involvement is heterogeneous in patients with noninfantile cystinosis even within families, and renal disease should be assessed even in families of patients with seemingly isolated ocular forms.
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Affiliation(s)
- Aude Servais
- Department of Nephrology, Necker Hospital, 149 rue de Sèvres, 75015 Paris, France.
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Abstract
Information theory-based software tools have been useful in interpreting noncoding sequence variation within functional sequence elements such as splice sites. Individual information analysis detects activated cryptic splice sites and associated splicing regulatory sites and is capable of distinguishing null from partially functional alleles. We present a server (https://splice.cmh.edu) designed to analyze splicing mutations in binding sites in either human genes, genome-mapped mRNAs, user-defined sequences, or dbSNP entries. Standard HUGO-approved gene symbols and HGVS-approved systematic mutation nomenclature (or dbSNP format) are entered via a web portal. After verifying the accuracy of input variant(s), the surrounding interval is retrieved from the human genome or user-supplied reference sequence. The server then computes the information contents (Ri) of all potential constitutive and/or regulatory splice sites in both the reference and variant sequences. Changes in information content are color-coded, tabulated, and visualized as sequence walkers, which display the binding sites with the reference sequence. The software was validated by analyzing approximately 1,300 mutations from Human Mutation as well as eight mapped SNPs from dbSNP designated as splice site variants. All of the splicing mutations and variants affected splice site strength or activated cryptic splice sites. The server also detected several missense mutations that were unexpectedly predicted to have concomitant effects on splicing or appeared to activate cryptic splicing.
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Affiliation(s)
- Vijay K Nalla
- Laboratory of Human Molecular Genetics, Children's Mercy Hospital and Clinics, University of Missouri-Kansas City, Kansas City, Missouri, USA
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Wilmer MJG, de Graaf-Hess A, Blom HJ, Dijkman HBPM, Monnens LA, van den Heuvel LP, Levtchenko EN. Elevated oxidized glutathione in cystinotic proximal tubular epithelial cells. Biochem Biophys Res Commun 2005; 337:610-4. [PMID: 16202976 DOI: 10.1016/j.bbrc.2005.09.094] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2005] [Accepted: 09/09/2005] [Indexed: 11/17/2022]
Abstract
Cystinosis, the most frequent cause of inborn Fanconi syndrome, is characterized by the lysosomal cystine accumulation, caused by mutations in the CTNS gene. To elucidate the pathogenesis of cystinosis, we cultured proximal tubular cells from urine of cystinotic patients (n = 9) and healthy controls (n = 9), followed by immortalization with human papilloma virus (HPV E6/E7). Obtained cell lines displayed basolateral polarization, alkaline phosphatase activity, and presence of aminopeptidase N (CD-13) and megalin, confirming their proximal tubular origin. Cystinotic cell lines exhibited elevated cystine levels (0.86 +/- 0.95 nmol/mg versus 0.09 +/- 0.01 nmol/mg protein in controls, p = 0.03). Oxidized glutathione was elevated in cystinotic cells (1.16 +/- 0.83 nmol/mg versus 0.29 +/- 0.18 nmol/mg protein, p = 0.04), while total glutathione, free cysteine, and ATP contents were normal in these cells. In conclusion, elevated oxidized glutathione in cystinotic proximal tubular epithelial cell lines suggests increased oxidative stress, which may contribute to tubular dysfunction in cystinosis.
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Affiliation(s)
- Martijn J G Wilmer
- Laboratory of Pediatrics and Neurology, Radboud University Nijmegen Medical Centre, The Netherlands
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Rangel-Filho A, Sharma M, Datta YH, Moreno C, Roman RJ, Iwamoto Y, Provoost AP, Lazar J, Jacob HJ. RF-2 gene modulates proteinuria and albuminuria independently of changes in glomerular permeability in the fawn-hooded hypertensive rat. J Am Soc Nephrol 2005; 16:852-6. [PMID: 15758045 DOI: 10.1681/asn.2005010029] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Affiliation(s)
- Artur Rangel-Filho
- Human and Molecular Genetics Center, Department of Physiology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
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Chol M, Nevo N, Cherqui S, Antignac C, Rustin P. Glutathione precursors replenish decreased glutathione pool in cystinotic cell lines. Biochem Biophys Res Commun 2004; 324:231-5. [PMID: 15465007 DOI: 10.1016/j.bbrc.2004.09.033] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2004] [Indexed: 12/13/2022]
Abstract
Cystinosis is an inherited disorder due to mutations in the CTNS gene which encodes cystinosin, a lysosomal transmembrane protein involved in cystine export to the cytosol. Both accumulation of cystine in the lysosome and decreased cystine in the cytosol may participate in the pathogenic mechanism underlying the disease. We observed that cystinotic cell lines have moderate decrease of glutathione content during exponential growth phase. This resulted in increased solicitation of oxidative defences of the cell denoted by concurrent superoxide dismutase induction, although without major oxidative insult under our experimental conditions. Finally, decreased glutathione content in cystinotic cell lines could be counterbalanced by a series of exogenous precursors of cysteine, denoting that lysosomal cystine export is a natural source of cellular cysteine in the studied cell lines.
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Affiliation(s)
- Marie Chol
- INSERM U574, Néphropathies Héréditaires et Rein en Développement, Hôpital Necker-Enfants Malades, rue de Sèvres, 75015 Paris, France
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Abstract
We report the excellent clinical outcomes of siblings with nephropathic cystinosis treated diligently with cysteamine starting at 20 months and 2 months of age. Now 15 and 8 years old, they have glomerular filtration rates of 78 and 105 mL/min/1.73m 2 , respectively. These cases illustrate the critical importance of early diagnosis and treatment.
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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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Kalatzis V, Antignac C. New aspects of the pathogenesis of cystinosis. Pediatr Nephrol 2003; 18:207-15. [PMID: 12644911 DOI: 10.1007/s00467-003-1077-5] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2002] [Revised: 11/04/2002] [Accepted: 11/08/2002] [Indexed: 10/25/2022]
Abstract
Cystinosis is a lysosomal transport disorder characterized by an intra-lysosomal accumulation of cystine, the disulfide of the amino acid cysteine. It is the most common inherited cause of the renal Fanconi syndrome. There are various clinical forms, infantile, juvenile, and ocular, based on age of onset and severity of symptoms. The first clinical description appeared in the early 1900s, but it was not until 1998 that the causative gene, CTNS, was identified. CTNS encodes cystinosin, a novel seven transmembrane domain (TM) protein. Cystinosin is a lysosomal membrane protein that requires two lysosomal targeting signals: a classic GYDQL motif in its C-terminal tail and a novel conformational motif, the core of which is YFPQA, situated in the fifth inter-TM loop. Cystinosin is the lysosomal cystine transporter and its activity is H(+)-driven. A mouse model of cystinosis was recently generated and Ctns(-/-) mice accumulate cystine in all tissues. A high level of cystine accumulates in the kidney, but these mice do not present with proximal tubulopathy or renal dysfunction. The Ctns(-/-) mouse model may provide clues to the cause of the Fanconi syndrome associated with cystinosis, the origin of which remains poorly understood.
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