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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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Goodman S, Khan M, Sharma J, Li Z, Cano J, Castellanos C, Estrada MV, Gertsman I, Cherqui S. Deficiency of the sedoheptulose kinase (Shpk) does not alter the ability of hematopoietic stem cells to rescue cystinosis in the mouse model. Mol Genet Metab 2021; 134:309-316. [PMID: 34823997 PMCID: PMC8935660 DOI: 10.1016/j.ymgme.2021.11.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 11/09/2021] [Accepted: 11/10/2021] [Indexed: 11/21/2022]
Abstract
Cystinosis is an autosomal recessive lysosomal storage disorder caused by mutations in the CTNS gene encoding the lysosomal cystine transporter, cystinosin, and leading to multi-organ degeneration including kidney failure. A clinical trial for cystinosis is ongoing to test the safety and efficacy of transplantation of autologous hematopoietic stem and progenitor cells (HSPCs) ex vivo gene-modified to introduce functional CTNS cDNA. Preclinical studies in Ctns-/- mice previously showed that a single HSPC transplantation led to significant tissue cystine decrease and long-term tissue preservation. The main mechanism of action involves the differentiation of the transplanted HSPCs into macrophages within tissues and transfer of cystinosin-bearing lysosomes to the diseased cells via tunneling nanotubes. However, a major concern was that the most common cystinosis-causing mutation in humans is a 57-kb deletion that eliminates not only CTNS but also the adjacent sedopheptulose kinase SHPK/CARKL gene encoding a metabolic enzyme that influences macrophage polarization. Here, we investigated if absence of Shpk could negatively impact the efficiency of transplanted HSPCs to differentiate into macrophages within tissues and then to prevent cystinosis rescue. We generated Shpk knockout mouse models and detected a phenotype consisting of perturbations in the pentose phosphate pathway (PPP), the metabolic shunt regulated by SHPK. Shpk-/- mice also recapitulated the urinary excretion of sedoheptulose and erythritol found in cystinosis patients homozygous for the 57-kb deletion. Transplantation of Shpk-/--HSPCs into Ctns-/- mice resulted in significant reduction in tissue cystine load and restoration of Ctns expression, as well as improved kidney architecture comparable to WT-HSPC recipients. Altogether, these data demonstrate that absence of SHPK does not alter the ability of HSPCs to rescue cystinosis, and then patients homozygous for the 57-kb deletion should benefit from ex vivo gene therapy and can be enrolled in the ongoing clinical trial. However, because of the limits inherent to animal models, outcomes of this patient population will be carefully compared to the other enrolled subjects.
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Affiliation(s)
- Spencer Goodman
- Department of Pediatrics, Division of Genetics, University of California, San Diego, La Jolla, CA, USA
| | - Meisha Khan
- Department of Pediatrics, Division of Genetics, University of California, San Diego, La Jolla, CA, USA
| | - Jay Sharma
- Department of Pediatrics, Division of Genetics, University of California, San Diego, La Jolla, CA, USA
| | - Zijie Li
- Department of Pediatrics, Division of Genetics, University of California, San Diego, La Jolla, CA, USA
| | - Jose Cano
- Department of Pediatrics, Division of Genetics, University of California, San Diego, La Jolla, CA, USA
| | - Carlos Castellanos
- Department of Pediatrics, Division of Genetics, University of California, San Diego, La Jolla, CA, USA
| | - Monica V Estrada
- Tissue Technology Shared Resource, Biorepository and Tissue Technology, Moores Cancer Center, University of California, San Diego, La Jolla, CA, USA
| | | | - Stephanie Cherqui
- Department of Pediatrics, Division of Genetics, University of California, San Diego, La Jolla, CA, USA.
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Linden S, Klank S, Harms E, Grüneberg M, Park JH, Marquardt T. Cystinosis: Therapy adherence and metabolic monitoring in patients treated with immediate-release cysteamine. Mol Genet Metab Rep 2020; 24:100620. [PMID: 32685378 PMCID: PMC7358454 DOI: 10.1016/j.ymgmr.2020.100620] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Accepted: 06/21/2020] [Indexed: 01/02/2023] Open
Abstract
Background Cystinosis is a metabolic disease caused by intracellular accumulation of cystine within lysosomes. Development of symptoms can be delayed significantly by a life-long therapy with cysteamine, a drug that enters the lysosome and reacts with cystine thereby enabling its export from the organelle. Methods During a period of 16 years, blood samples of 330 cystinosis patients were analyzed to investigate therapeutic adherence and metabolic control in patients treated with immediate-release cysteamine. The accepted therapeutic goal is to measure intracellular cystine levels in white blood cells every 3 months and to keep them below 0.5 nmol cystine/mg protein (= 1 nmol hemicystine/mg protein). Results 42% of measurements were within the desired 3-month interval, 38% were done every 3–5 months, 11% every 6–8 months, 5% every 9–12 months and 4% after a 12-month interval only. 64.4% of the measurements were higher than the therapeutic target value. Median cystine levels increased with longer control intervals. Conclusions The majority of the cystinosis patients showed insufficient metabolic adjustment. Intracellular cystine levels were not done as often as recommended and were not within therapeutic range. Poor therapy adherence is likely to be caused by gastrointestinal side effects of immediate-release cysteamine. Incorrect intervals between drug intake and blood sampling could contribute to the results.
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Affiliation(s)
- Simone Linden
- Department of General Pediatrics, Metabolic Diseases, University Children's Hospital, Albert-Schweitzer-Campus 1, Münster, NRW DE 48149, Germany
| | - Sabrina Klank
- Department of General Pediatrics, Metabolic Diseases, University Children's Hospital, Albert-Schweitzer-Campus 1, Münster, NRW DE 48149, Germany
| | - Erik Harms
- Department of General Pediatrics, Metabolic Diseases, University Children's Hospital, Albert-Schweitzer-Campus 1, Münster, NRW DE 48149, Germany
| | - Marianne Grüneberg
- Department of General Pediatrics, Metabolic Diseases, University Children's Hospital, Albert-Schweitzer-Campus 1, Münster, NRW DE 48149, Germany
| | - Julien H Park
- Department of General Pediatrics, Metabolic Diseases, University Children's Hospital, Albert-Schweitzer-Campus 1, Münster, NRW DE 48149, Germany
| | - Thorsten Marquardt
- Department of General Pediatrics, Metabolic Diseases, University Children's Hospital, Albert-Schweitzer-Campus 1, Münster, NRW DE 48149, Germany
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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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Nevo N, Thomas L, Chhuon C, Andrzejewska Z, Lipecka J, Guillonneau F, Bailleux A, Edelman A, Antignac C, Guerrera IC. Impact of Cystinosin Glycosylation on Protein Stability by Differential Dynamic Stable Isotope Labeling by Amino Acids in Cell Culture (SILAC). Mol Cell Proteomics 2017; 16:457-468. [PMID: 28082515 DOI: 10.1074/mcp.m116.063867] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 01/11/2017] [Indexed: 11/06/2022] Open
Abstract
Cystinosis is a rare autosomal recessive lysosomal storage disorder characterized by intralysosomal accumulation of cystine. The causative gene for cystinosis is CTNS, which encodes the protein cystinosin, a lysosomal proton-driven cystine transporter. Over 100 mutations have been reported, leading to varying disease severity, often in correlation with residual cystinosin activity as a transporter and with maintenance of its protein-protein interactions. In this study, we focus on the ΔITILELP mutation, the only mutation reported that sometimes leads to severe forms, inconsistent with its residual transported activity. ΔITILELP is a deletion that eliminates a consensus site on N66, one of the protein's seven glycosylation sites. Our hypothesis was that the ΔITILELP mutant is less stable and undergoes faster degradation. Our dynamic stable isotope labeling by amino acids in cell culture (SILAC) study clearly showed that wild-type cystinosin is very stable, whereas ΔITILELP is degraded three times more rapidly. Additional lysosome inhibition experiments confirmed ΔITILELP instability and showed that the degradation was mainly lysosomal. We observed that in the lysosome, ΔITILELP is still capable of interacting with the V-ATPase complex and some members of the mTOR pathway, similar to the wild-type protein. Intriguingly, our interactomic and immunofluorescence studies showed that ΔITILELP is partially retained at the endoplasmic reticulum (ER). We proposed that the ΔITILELP mutation causes protein misfolding, ER retention and inability to be processed in the Golgi apparatus, and we demonstrated that ΔITILELP carries high-mannose glycans on all six of its remaining glycosylation sites. We found that the high turnover of ΔITILELP, because of its immature glycosylation state in combination with low transport activity, might be responsible for the phenotype observed in some patients.
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Affiliation(s)
- Nathalie Nevo
- From the ‡INSERM U1163, Laboratory of Hereditary Kidney Diseases, Imagine Institute, Paris, France.,‡‡Paris Descartes-Sorbonne Paris Cité University, Paris, France
| | - Lucie Thomas
- From the ‡INSERM U1163, Laboratory of Hereditary Kidney Diseases, Imagine Institute, Paris, France.,‡‡Paris Descartes-Sorbonne Paris Cité University, Paris, France
| | - Cerina Chhuon
- §Plateforme Protéomique Paris Descartes Necker, PPN, 3P5-Necker, SFR Necker, US24, 75014 Paris, France.,‡‡Paris Descartes-Sorbonne Paris Cité University, Paris, France
| | - Zuzanna Andrzejewska
- From the ‡INSERM U1163, Laboratory of Hereditary Kidney Diseases, Imagine Institute, Paris, France.,‡‡Paris Descartes-Sorbonne Paris Cité University, Paris, France
| | - Joanna Lipecka
- ¶The CPN Proteomics Facility - 3P5, Center of Psychiatry and Neuroscience, UMR INSERM 894, 75014 Paris, France.,‡‡Paris Descartes-Sorbonne Paris Cité University, Paris, France
| | - François Guillonneau
- ‖Plateforme Protéomique Paris Descartes Cochin, 3P5-Cochin, 75014 Paris, France.,‡‡Paris Descartes-Sorbonne Paris Cité University, Paris, France
| | - Anne Bailleux
- From the ‡INSERM U1163, Laboratory of Hereditary Kidney Diseases, Imagine Institute, Paris, France.,‡‡Paris Descartes-Sorbonne Paris Cité University, Paris, France
| | - Aleksander Edelman
- §Plateforme Protéomique Paris Descartes Necker, PPN, 3P5-Necker, SFR Necker, US24, 75014 Paris, France.,**INSERM U1151, 75015 Paris, France
| | - Corinne Antignac
- From the ‡INSERM U1163, Laboratory of Hereditary Kidney Diseases, Imagine Institute, Paris, France.,‡‡Paris Descartes-Sorbonne Paris Cité University, Paris, France.,§§Assistance Publique - Hôpitaux de Paris (AP-HP), Department of Genetics, Necker Hospital, Paris, France
| | - Ida Chiara Guerrera
- §Plateforme Protéomique Paris Descartes Necker, PPN, 3P5-Necker, SFR Necker, US24, 75014 Paris, France; .,‡‡Paris Descartes-Sorbonne Paris Cité University, Paris, France
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Buntinx L, Voets T, Morlion B, Vangeel L, Janssen M, Cornelissen E, Vriens J, de Hoon J, Levtchenko E. TRPV1 dysfunction in cystinosis patients harboring the homozygous 57 kb deletion. Sci Rep 2016; 6:35395. [PMID: 27734949 PMCID: PMC5062165 DOI: 10.1038/srep35395] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 09/27/2016] [Indexed: 11/12/2022] Open
Abstract
Cystinosis is a rare autosomal recessive disorder characterized by lysosomal cystine accumulation due to loss of function of the lysosomal cystine transporter (CTNS). The most common mutation in cystinosis patients of Northern Europe consists of a 57-kb deletion. This deletion not only inactivates the CTNS gene but also extends into the non-coding region upstream of the start codon of the TRPV1 gene, encoding the capsaicin- and heat-sensitive ion channel TRPV1. To evaluate the consequences of the 57-kb deletion on functional TRPV1 expression, we compared thermal, mechanical and chemical sensitivity of cystinosis patients with matched healthy controls. Whereas patients heterozygous for the 57-kb deletion showed normal sensory responses, homozygous subjects exhibited a 60% reduction in vasodilation and pain evoked by capsaicin, as well as an increase in heat detection threshold. Responses to cold, mechanical stimuli or cinnamaldehyde, an agonist of the related nociceptor channel TRPA1, were unaltered. We conclude that cystinosis patients homozygous for the 57-kb deletion exhibit a strong reduction of TRPV1 function, leading to sensory deficiencies akin to the phenotype of TRPV1-deficient mice. These deficits may account for the reported sensory alterations and thermoregulatory deficits in these patients, and provide a paradigm for life-long TRPV1 deficiency in humans.
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Affiliation(s)
- L Buntinx
- Center for Clinical Pharmacology, Department of Pharmaceutical and Pharmacological Sciences, KULeuven, Herestraat 49, 3000 Leuven, Belgium
| | - T Voets
- Department of Cellular and Molecular Medicine, KULeuven, Herestraat 49, 3000 Leuven, Belgium
| | - B Morlion
- Center for algology and pain management, Department of Cardiovascular Sciences, KULeuven, Weligerveld 1, 3212 Pellenberg, Belgium
| | - L Vangeel
- Department of Cellular and Molecular Medicine, KULeuven, Herestraat 49, 3000 Leuven, Belgium
| | - M Janssen
- Department of internal medicine, Radboud UMC Nijmegen, Geert Grooteplein-Zuid 22, 6525 GA Nijmegen, The Netherlands
| | - E Cornelissen
- Department of Pediatric Nephrology, Radboud UMC Nijmegen, Geert Grooteplein-Zuid 22, 6525 GA Nijmegen, The Netherlands
| | - J Vriens
- Department of Development and Regeneration, KULeuven, Herestraat 49, 3000 Leuven, Belgium
| | - J de Hoon
- Center for Clinical Pharmacology, Department of Pharmaceutical and Pharmacological Sciences, KULeuven, Herestraat 49, 3000 Leuven, Belgium
| | - E Levtchenko
- Department of Development and Regeneration, KULeuven, Herestraat 49, 3000 Leuven, Belgium
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7
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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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8
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Elmonem MA, Veys KR, Soliman NA, van Dyck M, van den Heuvel LP, Levtchenko E. Cystinosis: a review. Orphanet J Rare Dis 2016; 11:47. [PMID: 27102039 PMCID: PMC4841061 DOI: 10.1186/s13023-016-0426-y] [Citation(s) in RCA: 144] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 04/15/2016] [Indexed: 01/01/2023] Open
Abstract
Cystinosis is the most common hereditary cause of renal Fanconi syndrome in children. It is an autosomal recessive lysosomal storage disorder caused by mutations in the CTNS gene encoding for the carrier protein cystinosin, transporting cystine out of the lysosomal compartment. Defective cystinosin function leads to intra-lysosomal cystine accumulation in all body cells and organs. The kidneys are initially affected during the first year of life through proximal tubular damage followed by progressive glomerular damage and end stage renal failure during mid-childhood if not treated. Other affected organs include eyes, thyroid, pancreas, gonads, muscles and CNS. Leucocyte cystine assay is the cornerstone for both diagnosis and therapeutic monitoring of the disease. Several lines of treatment are available for cystinosis including the cystine depleting agent cysteamine, renal replacement therapy, hormonal therapy and others; however, no curative treatment is yet available. In the current review we will discuss the most important clinical features of the disease, advantages and disadvantages of the current diagnostic and therapeutic options and the main topics of future research in cystinosis.
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Affiliation(s)
- Mohamed A Elmonem
- Department of Pediatric Nephrology & Growth and Regeneration, University Hospitals Leuven & KU Leuven, UZ Herestraat 49-3000, Leuven, Belgium.,Department of Clinical and Chemical Pathology, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Koenraad R Veys
- Department of Pediatric Nephrology & Growth and Regeneration, University Hospitals Leuven & KU Leuven, UZ Herestraat 49-3000, Leuven, Belgium
| | - Neveen A Soliman
- Department of Pediatrics, Center of Pediatric Nephrology and Transplantation (CPNT), Faculty of Medicine, Cairo University, Cairo, Egypt.,EGORD, Egyptian group of orphan renal diseases, Cairo, Egypt
| | - Maria van Dyck
- Department of Pediatric Nephrology & Growth and Regeneration, University Hospitals Leuven & KU Leuven, UZ Herestraat 49-3000, Leuven, Belgium
| | - Lambertus P van den Heuvel
- Department of Pediatric Nephrology & Growth and Regeneration, University Hospitals Leuven & KU Leuven, UZ Herestraat 49-3000, Leuven, Belgium.,Department of Pediatric Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Elena Levtchenko
- Department of Pediatric Nephrology & Growth and Regeneration, University Hospitals Leuven & KU Leuven, UZ Herestraat 49-3000, Leuven, Belgium.
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9
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Wamelink MMC, Ramos RJJF, van den Elzen APM, Ruijter GJG, Bonte R, Diogo L, Garcia P, Neves N, Nota B, Haschemi A, Tavares de Almeida I, Salomons GS. First two unrelated cases of isolated sedoheptulokinase deficiency: A benign disorder? J Inherit Metab Dis 2015; 38:889-94. [PMID: 25647543 PMCID: PMC4551550 DOI: 10.1007/s10545-014-9809-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2014] [Revised: 12/29/2014] [Accepted: 12/30/2014] [Indexed: 12/13/2022]
Abstract
We present the first two reported unrelated patients with an isolated sedoheptulokinase (SHPK) deficiency. The first patient presented with neonatal cholestasis, hypoglycemia, and anemia, while the second patient presented with congenital arthrogryposis multiplex, multiple contractures, and dysmorphisms. Both patients had elevated excretion of erythritol and sedoheptulose, and each had a homozygous nonsense mutation in SHPK. SHPK is an enzyme that phosphorylates sedoheptulose to sedoheptulose-7-phosphate, which is an important intermediate of the pentose phosphate pathway. It is questionable whether SHPK deficiency is a causal factor for the clinical phenotypes of our patients. This study illustrates the necessity of extensive functional and clinical workup for interpreting a novel variant, including nonsense variants.
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Affiliation(s)
- Mirjam M C Wamelink
- Department of Clinical Chemistry, Neuroscience Campus Amsterdam, VU University Medical Center, De Boelelaan 1117, 1081HV, Amsterdam, The Netherlands,
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10
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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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11
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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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12
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Peeters K, Wilmer MJ, Schoeber JP, Reijnders D, Heuvel LPVD, Masereeuw R, Levtchenko E. Role of p-glycoprotein expression and function in cystinotic renal proximal tubular cells. Pharmaceutics 2011; 3:782-92. [PMID: 24309308 PMCID: PMC3857058 DOI: 10.3390/pharmaceutics3040782] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Revised: 10/11/2011] [Accepted: 10/20/2011] [Indexed: 11/16/2022] Open
Abstract
P-glycoprotein (P-gp) is an ATP-dependent transporter localized at the apical membrane of the kidney proximal tubules, which plays a role in the efflux of cationic and amphipathic endogenous waste products and xenobiotics, such as drugs, into urine. Studies in mice deficient in P-gp showed generalized proximal tubular dysfunction similar to the phenotype of patients with cystinosis, an autosomal recessive disorder caused by mutations in the lysosomal cystine transporter cystinosin. Renal disease in cystinosis is characterized by generalized dysfunction of the apical proximal tubular influx transporters (so-called renal Fanconi syndrome) developing during infancy and gradually progressing towards end-stage renal disease before the 10th birthday in the majority of patients that are not treated with the cystine-depleting drug cysteamine. Here, we investigated whether the proximal tubular efflux transporter P-gp is affected in cystinosis and whether this might contribute to the development of renal Fanconi syndrome. We used conditionally immortalized (ci) proximal tubular epithelial cells (ciPTEC) derived from cystinotic patients and healthy volunteers. P-gp-mediated transport was measured by using the P-gp substrate calcein-AM in the presence and absence of the P-gp-inhibitor PSC833. P-gp activity was normal in cystinotic cells as compared to controls. Additionally, the effect of cysteamine on P-gp transport activity and phosphate uptake was determined; demonstrating increased P-gp activity in cystinotic cells, and further decrease of proximal tubular phosphate uptake. This observation is compatible with the persistence of renal Fanconi syndrome in vivo under cysteamine therapy. In summary, P-gp expression and activity are normal in cystinotic ciPTEC, indicating that P-gp dysfunction is not involved in the pathogenesis of cystinosis.
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Affiliation(s)
- Karen Peeters
- Pediatric Nephrology, Katholieke Universiteit Leuven, Herestraat 49 Box 817, Leuven, Belgium.
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13
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Natural history of adolescent-onset cystinosis. Pediatr Nephrol 2011; 26:1335-7. [PMID: 21553323 DOI: 10.1007/s00467-011-1904-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2011] [Revised: 04/04/2011] [Accepted: 04/05/2011] [Indexed: 10/18/2022]
Abstract
Cystinosis is a rare autosomal recessive disease caused by mutations of the CTNS gene in which cystine accumulates throughout the body as a result of a defective efflux of cystine from lysosomes. Three phenotypic forms have been described according to the age of onset and the severity of the clinical symptoms: infantile, intermediate, and ocular non-nephropathic cystinosis. Here we report the natural history of cystinosis in a 55-year-old man with intermediate nephropathic cystinosis diagnosed at 9 years of age. Although tubulopathy was unnoticed in the early years, he required transplantation at age 16. Sequencing analysis of all the CTNS exons revealed that the proband is homozygous for a 21-bp in-frame deletion in exon 5 (c. 198_218del21), resulting in an in-frame deletion of 7 amino acids from the N-terminal domain of the cystinosin protein. Our patient has had relatively mild extra-renal disease despite lack of early cysteamine therapy. He has been able to attend university and pursue a professional career into the 6th decade.
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14
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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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15
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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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Wamelink MMC, Struys EA, Jansen EEW, Levtchenko EN, Zijlstra FSM, Engelke U, Blom HJ, Jakobs C, Wevers RA. Sedoheptulokinase deficiency due to a 57-kb deletion in cystinosis patients causes urinary accumulation of sedoheptulose: elucidation of the CARKL gene. Hum Mutat 2008; 29:532-6. [PMID: 18186520 DOI: 10.1002/humu.20685] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The most common mutation in the nephropathic cystinosis (CTNS) gene is a homozygous 57-kb deletion that also includes an adjacent gene carbohydrate kinase-like (CARKL). The latter gene encodes a protein that is predicted to function as a carbohydrate kinase. Cystinosis patients with the common 57-kb deletion had strongly elevated urinary concentrations of sedoheptulose (28-451 mmol/mol creatinine; controls and other cystinosis patients <9) and erythritol (234-1110 mmol/mol creatinine; controls and other cystinosis patients <148). Enzyme studies performed on fibroblast homogenates derived from patients carrying the 57-kb deletion revealed 80% reduction in their sedoheptulose phosphorylating activity compared to cystinosis patients with other mutations and controls. This indicates that the CARKL-encoded protein, sedoheptulokinase (SHK), is responsible for the reaction: sedoheptulose + ATP --> sedoheptulose-7-phosphate + ADP and that deletion of CARKL causes urinary accumulation of sedoheptulose and erythritol.
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Affiliation(s)
- Mirjam M C Wamelink
- Department of Clinical Chemistry, Metabolic Unit, VU University Medical Center, Amsterdam, The Netherlands.
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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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