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Medaer L, David D, Smits M, Levtchenko E, Sampaolesi M, Gijsbers R. Residual Cystine Transport Activity for Specific Infantile and Juvenile CTNS Mutations in a PTEC-Based Addback Model. Cells 2024; 13:646. [PMID: 38607085 PMCID: PMC11011962 DOI: 10.3390/cells13070646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2024] [Revised: 04/03/2024] [Accepted: 04/04/2024] [Indexed: 04/13/2024] Open
Abstract
Cystinosis is a rare, autosomal recessive, lysosomal storage disease caused by mutations in the gene CTNS, leading to cystine accumulation in the lysosomes. While cysteamine lowers the cystine levels, it does not cure the disease, suggesting that CTNS exerts additional functions besides cystine transport. This study investigated the impact of infantile and juvenile CTNS mutations with discrepant genotype/phenotype correlations on CTNS expression, and subcellular localisation and function in clinically relevant cystinosis cell models to better understand the link between genotype and CTNS function. Using CTNS-depleted proximal tubule epithelial cells and patient-derived fibroblasts, we expressed a selection of CTNSmutants under various promoters. EF1a-driven expression led to substantial overexpression, resulting in CTNS protein levels that localised to the lysosomal compartment. All CTNSmutants tested also reversed cystine accumulation, indicating that CTNSmutants still exert transport activity, possibly due to the overexpression conditions. Surprisingly, even CTNSmutants expression driven by the less potent CTNS and EFS promoters reversed the cystine accumulation, contrary to the CTNSG339R missense mutant. Taken together, our findings shed new light on CTNS mutations, highlighting the need for robust assessment methodologies in clinically relevant cellular models and thus paving the way for better stratification of cystinosis patients, and advocating for the development of more personalized therapy.
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Affiliation(s)
- Louise Medaer
- Laboratory of Molecular Virology and Gene Therapy, Department of Pharmacological and Pharmaceutical Sciences, Faculty of Medicine, KU Leuven, 3000 Leuven, Belgium; (L.M.); (M.S.)
| | - Dries David
- Laboratory of Molecular Virology and Gene Therapy, Department of Pharmacological and Pharmaceutical Sciences, Faculty of Medicine, KU Leuven, 3000 Leuven, Belgium; (L.M.); (M.S.)
| | - Maxime Smits
- Laboratory of Molecular Virology and Gene Therapy, Department of Pharmacological and Pharmaceutical Sciences, Faculty of Medicine, KU Leuven, 3000 Leuven, Belgium; (L.M.); (M.S.)
- Leuven Viral Vector Core, Faculty of Medicine, KU Leuven, 3000 Leuven, Belgium
| | - Elena Levtchenko
- Department of Paediatric Nephrology & Development and Regeneration, University Hospitals Leuven & KU Leuven, 3000 Leuven, Belgium;
- Department of Paediatric Nephrology, Amsterdam University Medical Centre, 1081 Amsterdam, The Netherlands
| | - Maurilio Sampaolesi
- Translational Cardiology Laboratory, Department of Development and Regeneration, Stem Cell Institute, Faculty of Medicine, KU Leuven, 3000 Leuven, Belgium;
| | - Rik Gijsbers
- Laboratory of Molecular Virology and Gene Therapy, Department of Pharmacological and Pharmaceutical Sciences, Faculty of Medicine, KU Leuven, 3000 Leuven, Belgium; (L.M.); (M.S.)
- Leuven Viral Vector Core, Faculty of Medicine, KU Leuven, 3000 Leuven, Belgium
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Mohammadi Chermahini Z, Salehi M, Gheissari A, Ahmadi Beni F, Khosravian F, Kazemi M. CTNS Mutations Causing Autosomal Recessive Cystinosis in a Subset of Iranian Population: Report of Two New Variants. Adv Biomed Res 2024; 13:2. [PMID: 38525388 PMCID: PMC10958734 DOI: 10.4103/abr.abr_149_23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 07/25/2023] [Accepted: 07/29/2023] [Indexed: 03/26/2024] Open
Abstract
Background Nephropathic cystinosis (NC) is an uncommon autosomal recessive disease with abnormality in lysosomal storage that appearances in patients with mutations in the CTNS gene encoding a lysosomal transporter cystinosin. Disrupted function of this transporter is followed by accumulation of cysteine crystals in cells of many various organs. This study aimed to investigate the mutations of the CTNS gene in 20 Iranian patients suffering from NC. Materials and Methods Twenty Iranian cystinosis patients referring to Imam Hossein Hospital of Isfahan were employed in this case-series study. After extraction of genomic DNA, the promoter and entire coding regions of CTNS were analysed using sanger sequencing in all patients. Gap-Polymerase Chain Reaction was used to detect 57 kb deletion in the CTNS gene. In silico study was performed to analyse variants. Results The large deletion was not seen in any NC patients. Molecular analysis which conducted to screen the CTNS gene of patients, identified eight different mutations, including two new mutations, c.971_972insC and c.956_956delA, which have not been reported before, and c.681G>A mutation, which was identified as a frequently founded mutation in the Middle East and was observed in 35% of patients. In this study, five other mutations including c.1015G>A, c.922G>A, c.323_323delA, c.433C>T, and c.18_21delGACT were also observed, which have been reported in previous studies. Conclusion The mutational spectrum in the Iranian patients is the same as previously reported mutations except that two new mutations were found. The present findings will present suggestions for regular molecular diagnosis of cystinosis in Iran.
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Affiliation(s)
- Zahra Mohammadi Chermahini
- Department of Genetics and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
- Reproductive Sciences and Sexual Health Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
- Cellular, Molecular and Genetics Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Mansoor Salehi
- Department of Genetics and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
- Cellular, Molecular and Genetics Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Alaleh Gheissari
- Department of Pediatrics, School of Medicine, Kidney Diseases Research Center, Imam Hossein Children’s Hospital, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Faeze Ahmadi Beni
- Department of Genetics and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Farinaz Khosravian
- Cellular, Molecular and Genetics Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Mohammad Kazemi
- Department of Genetics and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
- Reproductive Sciences and Sexual Health Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
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Algasem R, Zainy N, Alsabban E, Almojalli H, Raza S, Ali T, Broering D, Rubaya N, Aleid H. The Clinical Manifestations and Disease Burden of Cystinosis in Saudi Arabia: A Single-Tertiary Center Experience. Cureus 2024; 16:e52662. [PMID: 38380220 PMCID: PMC10877213 DOI: 10.7759/cureus.52662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/18/2024] [Indexed: 02/22/2024] Open
Abstract
BACKGROUND There is a lack of regional and local evidence that describes the nature of cystinosis, a multiorgan accumulation of cystine, and its extent of organ damage. Therefore, this study aimed to determine the outcomes of cystinosis in patients who were followed up at a large tertiary care hospital. METHODS Medical records of patients with cystinosis were retrospectively reviewed. Patients' baseline demographics, lab values, medications, comorbidities, and complications were collected and described. Univariable and multivariable logistics regression models were constructed to control for confounders and build prediction models. RESULTS In our cohort of 39 patients, the mean age was 13.8±9.9 years. Approximately 56.4% of the patients had stunted growth, and the mortality rate was 25.6%. Regarding complications, the majority of patients developed myopathy (79.5%), end-stage renal disease (ESRD) (74.4%), and hypothyroidism (71.8%). Age (odds ratio=1.14, 95% confidence interval (95% CI): 1.012, 1.285) and stunted growth (odds ratio=6.62, 95% CI: 1.024, 42.835) were found to be predictors of renal replacement therapy and renal transplantation, respectively (p<0.047). CONCLUSION This study on cystinosis patients reveals a high incidence of renal complications, with a significant mortality rate and common complications such as myopathy and ESRD. Age was found to be an independent risk factor for renal replacement therapy, while stunted growth predicted the need for transplantation. These findings underscore the urgency for early diagnosis, comprehensive treatment, and careful monitoring in managing cystinosis effectively.
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Affiliation(s)
- Reem Algasem
- Department of Pharmacy, King Faisal Specialist Hospital and Research Centre, Riyadh, SAU
| | - Nedaa Zainy
- Department of Pharmacy, King Faisal Specialist Hospital and Research Centre, Riyadh, SAU
| | - Essam Alsabban
- Department of Pediatric Nephrology, King Faisal Specialist Hospital and Research Centre, Riyadh, SAU
| | - Hamad Almojalli
- Department of Pediatric Transplant Nephrology, King Faisal Specialist Hospital and Research Centre, Riyadh, SAU
| | - Syed Raza
- Department of Kidney and Pancreas Transplant, King Faisal Specialist Hospital and Research Centre, Riyadh, SAU
| | - Tariq Ali
- Department of Kidney and Pancreas Transplant, King Faisal Specialist Hospital and Research Centre, Riyadh, SAU
| | - Deiter Broering
- Department of Kidney and Pancreas Transplant, King Faisal Specialist Hospital and Research Centre, Riyadh, SAU
| | - Nawal Rubaya
- Department of Kidney and Pancreas Transplant, King Faisal Specialist Hospital and Research Centre, Riyadh, SAU
| | - Hassan Aleid
- Department of Kidney and Pancreas Transplant, King Faisal Specialist Hospital and Research Centre, Riyadh, SAU
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Hohenfellner K, Zerell K, Haffner D. Cystinosis. Klin Monbl Augenheilkd 2023; 240:251-259. [PMID: 36977426 DOI: 10.1055/a-2022-8522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
Cystinosis is a very rare autosomal recessive lysosomal storage disorder with an incidence of 1 : 150,000 - 1 : 200,000, and is caused by mutations in the CTNS gene encoding the lysosomal membrane protein cystinosin, which transports cystine out of the lysosome into the cytoplasm. As a result, accumulation of cystine occurs in almost all cells and tissues, especially in the kidneys, leading to multiple organ involvement. Introduction of drug therapy with cysteamine in the mid 1980s, along with the availability of renal replacement therapy in childhood, have dramatically improved patient outcome. Whereas patients used to die without therapy with end-stage renal failure during the first decade of life, nowadays most patients live well into adulthood without renal replacement therapy, and several reach 40 years. There is robust evidence that early initiation and sustained lifelong therapy with cysteamine are both essential for morbidity and mortality. The rarity of the disease and the multi-organ involvement present an enormous challenge for those affected and the providers of care for this patient group.
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Affiliation(s)
- Katharina Hohenfellner
- Klinik für Kinder- und Jugendmedizin/Kindernephrologie, RoMed Kliniken, Rosenheim, Deutschland
| | - Kirstin Zerell
- Rosenheim, kbo-Heckscher-Klinikum gGmbH, München, Deutschland
| | - Dieter Haffner
- Klinik für Pädiatrische Nieren-, Leber- & Stoffwechselerkrankungen, MHH, Hannover, Deutschland
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El Younsi M, Trabelsi M, Ben Youssef S, Ouertani I, Hammi Y, Achour A, Maazoul F, Kharrat M, Gargah T, M'rad R. Clinical and genetic characteristics of Tunisian children with infantile nephropathic cystinosis. Pediatr Nephrol 2023; 38:119-129. [PMID: 35445972 DOI: 10.1007/s00467-022-05525-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 02/25/2022] [Accepted: 02/25/2022] [Indexed: 12/15/2022]
Abstract
BACKGROUND Nephropathic cystinosis is an autosomal recessive disease caused by a mutation in the CTNS gene which encodes cystinosin, a lysosomal cystine transporter. The spectrum of mutations in the CTNS gene is not well defined in the North African population. Here, we investigated twelve patients with nephropathic cystinosis belonging to eight Tunisian families in order to analyze the clinical and genetic characteristics of Tunisian children with infantile nephropathic cystinosis. METHODS Clinical data were collected retrospectively. Molecular analysis of the CTNS gene was performed by Sanger sequencing. RESULTS We describe a new splicing mutation c.971-1G > C in the homozygous state in 6/12 patients which seems to be a founder mutation. The reported deletion of 23nt c.771_793 Del (p.Gly258Serfs*30) was detected in a homozygous state in one patient and in a heterozygous compound state with the c.971-1G > C mutation in 3/12 patients. Two of 12 patients have a deletion of exons 4 and 5 of the CTNS gene. None of our patients had the most common 57-kb deletion. CONCLUSIONS The mutational spectrum in the Tunisian population is different from previously described populations. Thus, a molecular diagnostic strategy must be implemented in Tunisia, by targeting as a priority the common mutations described in this country. Such a strategy will allow a cost-effective diagnosis confirmation as well as early administration of treatment with oral cysteamine. A higher resolution version of the Graphical abstract is available as Supplementary information.
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Affiliation(s)
- Mariem El Younsi
- Laboratoire de Génétique Humaine, LR99ES10, Faculté de Médecine de Tunis, Université de Tunis El Manar, 1007, Tunis, Tunisia
| | - Médiha Trabelsi
- Service des Maladies Congénitales et Héréditaires, Hôpital Charles Nicolle, Bab Souika, 1006, Tunis, Tunisia
| | - Sandra Ben Youssef
- Service de Pédiatrie Néphrologique Hôpital Charles Nicolle, Bab Souika, 1006, Tunis, Tunisia
| | - Inès Ouertani
- Service des Maladies Congénitales et Héréditaires, Hôpital Charles Nicolle, Bab Souika, 1006, Tunis, Tunisia
| | - Yousra Hammi
- Service de Pédiatrie Néphrologique Hôpital Charles Nicolle, Bab Souika, 1006, Tunis, Tunisia
| | - Ahlem Achour
- Service des Maladies Congénitales et Héréditaires, Hôpital Charles Nicolle, Bab Souika, 1006, Tunis, Tunisia
| | - Faouzi Maazoul
- Service des Maladies Congénitales et Héréditaires, Hôpital Charles Nicolle, Bab Souika, 1006, Tunis, Tunisia
| | - Maher Kharrat
- Laboratoire de Génétique Humaine, LR99ES10, Faculté de Médecine de Tunis, Université de Tunis El Manar, 1007, Tunis, Tunisia
| | - Tahar Gargah
- Service de Pédiatrie Néphrologique Hôpital Charles Nicolle, Bab Souika, 1006, Tunis, Tunisia
| | - Ridha M'rad
- Laboratoire de Génétique Humaine, LR99ES10, Faculté de Médecine de Tunis, Université de Tunis El Manar, 1007, Tunis, Tunisia. .,Service des Maladies Congénitales et Héréditaires, Hôpital Charles Nicolle, Bab Souika, 1006, Tunis, Tunisia.
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Clinical and neurophysiological characterization of early neuromuscular involvement in children and adolescents with nephropathic cystinosis. Pediatr Nephrol 2022; 37:1555-1566. [PMID: 34791528 DOI: 10.1007/s00467-021-05343-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2021] [Revised: 10/16/2021] [Accepted: 10/18/2021] [Indexed: 10/19/2022]
Abstract
BACKGROUND Nephropathic cystinosis is a rare autosomal recessive lysosomal storage disorder characterized by kidney and extra-renal complications due to the accumulation of cystine crystals in various tissues and organs. Herein, we describe the early neuromuscular complications in a cohort of pediatric nephropathic cystinosis patients. METHODS We prospectively evaluated the clinical, biochemical, and neurophysiological data of 15 cystinosis patients. Neurophysiological evaluation was performed to confirm or exclude presence of neuropathy and/or myopathy. RESULTS Patients' age ranged between 20 and 216 months at time of examination. Nine patients were males. Three patients had early abnormal neurophysiological features consistent with neuromuscular involvement (clinically asymptomatic proximal myopathy with a patchy distribution in one patient and isolated asymptomatic sensory nerve conduction changes in two patients). A fourth patient had mixed abnormal motor and sensory axonal neuropathic changes associated with overt clinical features (predominantly motor symptoms). Patients with abnormal neuromuscular features were significantly older in age than the unaffected group (P = 0.005) and had a diagnosis of cystinosis with subsequent cysteamine therapy at a significantly older age than the unaffected group (P = 0.027 and 0.001, respectively). CONCLUSIONS We expanded the recognized phenotypes of cystinosis neuromuscular complications with early proximal skeletal myopathy and symptomatic motor and sensory axonal neuropathy. Early asymptomatic neuromuscular complications could develop in pediatric patients and would require neurophysiological studies for early detection prior to development of overt clinical manifestations. Prompt diagnosis and timely initiation of cysteamine therapy with recommended dose can delay the development of neuromuscular complications. A higher resolution version of the Graphical abstract is available as Supplementary information.
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Chkioua L, Amri Y, Saheli C, Mili W, Mabrouk S, Chabchoub I, Boudabous H, Azzouz WB, Turkia HB, Ferchichi S, Tebib N, Massoud T, Ghorbel M, Laradi S. Molecular characterization of CTNS mutations in Tunisian patients with ocular cystinosis. Diagn Pathol 2022; 17:44. [PMID: 35524314 PMCID: PMC9074260 DOI: 10.1186/s13000-022-01221-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 04/12/2022] [Indexed: 12/02/2022] Open
Abstract
Background Ocular cystinosis is a rare autosomal recessive disorder characterized by intralysosomal cystine accumulation in renal, ophthalmic (cornea, conjunctiva), and other organ abnormalities. Patients with ocular cystinosis are mostly asymptomatic and typically experience mild photophobia due to cystine crystals in the cornea observed accidently during a routine ocular examination. The ocular cystinosis is associated with different mutations in CTNS gene. Cysteamine therapy mostly corrects the organ abnormalities. Methods This study was performed in collaboration with the department of ophthalmology of Farhat Hached Hospital. The Optical Coherence Tomography (OCT) of the cornea and retinal photography were used to search cystine crystals within the corneas and conjunctiva in eight Tunisian patients. Screening for the common 57-kb deletion was performed by standard multiplex PCR, followed by direct sequencing of the entire CTNS gene. Results The studied patients were found to have cystine crystal limited anterior corneal stroma and the conjunctiva associated with retinal crystals accumulation. CTNS gene sequencing disclosed 7 mutations: three missense mutations (G308R, p.Q88K, and p.S139Y); one duplication (C.829dup), one framshift mutation (p.G258f), one splice site mutation (c.681 + 7delC) and a large deletion (20,327-bp deletion). Crystallographic structure analysis suggests that the novel mutation p.S139Y is buried in a first transmembrane helix closed to the lipid bilayer polar region, introducing a difference in hydrophobicity which could affect the hydrophobic interactions with the membrane lipids. The second novel mutation p.Q88K which is located in the lysosomal lumen close to the lipid membrane polar head region, introduced a basic amino acid in a region which tolerate only uncharged residue. The third missense mutation introduces a positive change in nonpolar tail region of the phospholipid bilayer membrane affecting the folding and stability of the protein in the lipid bilayer. Conclusions Our data demonstrate that impaired transport of cystine out of lysosomes is the most common, which is obviously associated with the mutations of transmembrane domains of cystinosine resulting from a total loss of its activity.
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Affiliation(s)
- Latifa Chkioua
- Research Laboratory of Human Genome and Multifactorial Diseases, Faculty of Pharmacy, University of Monastir, Street Avicenne, 5000, Monastir, Tunisia.
| | - Yessine Amri
- Biochemistry Laboratory (LR 00SP03), Bechir Hamza Children's Hospital, Tunis, Tunisia
| | - Chaima Saheli
- Biochemistry Laboratory (LR 00SP03), Bechir Hamza Children's Hospital, Tunis, Tunisia
| | - Wassila Mili
- Ophtalmic Department, Farhat Hached Hospital, Sousse, Tunisia
| | - Sameh Mabrouk
- Pediatric Department, Sahloul Hospital, Sousse, Tunisia
| | - Imen Chabchoub
- Pediatric Department, Hedi Chaker Hospital, Sfax, Tunisia
| | | | | | | | - Salima Ferchichi
- Biochemistry Laboratory, Farhat Hached Hospital, Sousse, Tunisia
| | - Neji Tebib
- Pediatric Department, LaRabta Hospital, Tunis, Tunisia
| | - Taieb Massoud
- Biochemistry Laboratory (LR 00SP03), Bechir Hamza Children's Hospital, Tunis, Tunisia
| | - Mohamed Ghorbel
- Ophtalmic Department, Farhat Hached Hospital, Sousse, Tunisia
| | - Sandrine Laradi
- The Auvergne-Rhône-Alpes Regional Branch of the French National Blood System EFS/GIMAP, EA 3064, 42100, Saint Etienne, France
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Gholami Yarahmadi S, Sarlaki F, Morovvati S. Cystinosis and two rare mutations in CTNS gene: two case reports. J Med Case Rep 2022; 16:181. [PMID: 35513889 PMCID: PMC9074344 DOI: 10.1186/s13256-022-03379-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Accepted: 03/18/2022] [Indexed: 11/22/2022] Open
Abstract
Background Cystinosis is an autosomal recessive disorder characterized by an accumulation of the amino acid cystine in lysosomes throughout the body. Cystinosis is an inherited disease resulting from the failure of lysosomal cystine transport. The responsible gene, Cystinosin, Lysosomal Cystine Transporter (CTNS), encodes the lysosomal cystine carrier cystinosin. Case presentation In this case report, we reviewed the genetic basis of cystinosis and investigated two Iranian cases affected by cystinosis, one of which revealed a rare mutation in the CTNS gene. Two patients, 9-year-old (patient A) and 11-year-old (patient B) symptomatic Iranian females with renal insufficiency, were diagnosed with cystinosis on the basis of their clinical features and laboratory tests. After genetic counseling, blood samples were obtained from the patients and their parents. Genomic Deoxyribonucleic Acid (DNA) was extracted from whole blood, and mutation analysis was performed using polymerase chain reaction and sequencing methods for all exons of the CTNS gene. At least 148 different pathogenic and deleterious mutations in the CTNS gene have been reported to date. Owing to our patient’s prominent clinical features of cystinosis, we carried out a targeted search for mutations in the CTNS gene. Conclusions This led us to confirm the existence of a homozygous DNA variation c.257_258deletionCT (p.Ser86PhefsTer38) in exon 6 of the gene in patient A and another homozygous DNA variation, c.323delA (p.Q108RfsTer10), in the same exon in patient B. As expected, the mentioned mutation existed in both her parents in a heterozygous state. Variations c.257_258delCT and c.323delA reported in three Iranian patients in the CTNS gene are frameshifts, and truncating mutations that affect product function result in relatively mild symptoms of cystinosis. The present finding confirms previous research and proves the importance of the association of this gene rare mutations with cystinosis. Since reported mutations are rare, their previous reports in Iranian patients indicate the high frequency of these mutations in our region.
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Affiliation(s)
- Sepideh Gholami Yarahmadi
- Department of Advanced Sciences and Technology, Islamic Azad University-Tehran Medical Sciences, Zargandeh, Shariati, Tehran, Iran
| | - Fatemeh Sarlaki
- Department of Clinical Biochemistry, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Saeid Morovvati
- Department of Advanced Sciences and Technology, Islamic Azad University-Tehran Medical Sciences, Zargandeh, Shariati, Tehran, Iran.
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Newborn Screening: Review of its Impact for Cystinosis. Cells 2022; 11:cells11071109. [PMID: 35406673 PMCID: PMC8997957 DOI: 10.3390/cells11071109] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 03/13/2022] [Accepted: 03/22/2022] [Indexed: 12/10/2022] Open
Abstract
Newborn screening (NBS) programmes are considered to be one of the most successful secondary prevention measures in childhood to prevent or reduce morbidity and/or mortality via early disease identification and subsequent initiation of therapy. However, while many rare diseases can now be detected at an early stage using appropriate diagnostics, the introduction of a new target disease requires a detailed analysis of the entire screening process, including a robust scientific background, analytics, information technology, and logistics. In addition, ethics, financing, and the required medical measures need to be considered to allow the benefits of screening to be evaluated at a higher level than its potential harm. Infantile nephropathic cystinosis (INC) is a very rare lysosomal metabolic disorder. With the introduction of cysteamine therapy in the early 1980s and the possibility of renal replacement therapy in infancy, patients with cystinosis can now reach adulthood. Early diagnosis of cystinosis remains important as this enables initiation of cysteamine at the earliest opportunity to support renal and patient survival. Using molecular technologies, the feasibility of screening for cystinosis has been demonstrated in a pilot project. This review aims to provide insight into NBS and discuss its importance for nephropathic cystinosis using molecular technologies.
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Response to Cysteamine in Osteoclasts Obtained from Patients with Nephropathic Cystinosis: A Genotype/Phenotype Correlation. Cells 2021; 10:cells10092498. [PMID: 34572146 PMCID: PMC8467406 DOI: 10.3390/cells10092498] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Revised: 09/01/2021] [Accepted: 09/15/2021] [Indexed: 02/05/2023] Open
Abstract
Bone complications of cystinosis have been recently described. The main objectives of this paper were to determine in vitro the impact of CTNS mutations and cysteamine therapy on human osteoclasts and to carry out a genotype-phenotype analysis related to osteoclastic differentiation. Human osteoclasts were differentiated from peripheral blood mononuclear cells (PBMCs) and were treated with increasing doses of cysteamine (0, 50, 200 µM) and then assessed for osteoclastic differentiation. Results are presented as median (min-max). A total of 17 patients (mainly pediatric) were included, at a median age of 14 (2–61) years, and a eGFR of 64 (23–149) mL/min/1.73 m2. Most patients (71%) were under conservative kidney management (CKM). The others were kidney transplant recipients. Three functional groups were distinguished for CTNS mutations: cystinosin variant with residual cystin efflux activity (RA, residual activity), inactive cystinosin variant (IP, inactive protein), and absent protein (AP). PBMCs from patients with residual cystinosin activity generate significantly less osteoclasts than those obtained from patients of the other groups. In all groups, cysteamine exerts an inhibitory effect on osteoclastic differentiation at high doses. This study highlights a link between genotype and osteoclastic differentiation, as well as a significant impact of cysteamine therapy on this process in humans.
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Topaloglu R. Nephropathic cystinosis: an update on genetic conditioning. Pediatr Nephrol 2021; 36:1347-1352. [PMID: 32564281 DOI: 10.1007/s00467-020-04638-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Revised: 04/24/2020] [Accepted: 06/02/2020] [Indexed: 10/24/2022]
Abstract
Cystinosis is an autosomal recessive lysosomal storage disorder caused by CTNS gene mutations. The CTNS gene encodes the protein cystinosin, which transports free cystine from lysosomes to cytoplasm. In cases of cystinosin deficiency, free cystine accumulates in lysosomes and forms toxic crystals that lead to tissue and organ damage. Since CTNS gene mutations were first described, many variations have been identified that vary according to geographic region, although the phenotype remains the same. Cystinosis is a hereditary disease that can be treated with the cystine-depleting agent cysteamine. Cysteamine slows organ deterioration, but cannot treat renal Fanconi syndrome or prevent eventual kidney failure; therefore, novel treatment modalities for cystinosis are of great interest to researchers. The present review aims to highlight the geographic differences in cystinosis-specifically in terms of its genetic aspects, clinical features, management, and long-term complications.
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Affiliation(s)
- Rezan Topaloglu
- Department of Pediatric Nephrology, School of Medicine, Hacettepe University, Ankara, Turkey.
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12
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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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13
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Oldt RF, Bussey KJ, Settles ML, Fass JN, Roberts JA, Reader JR, Komandoor S, Abrich VA, Kanthaswamy S. MYBPC3 Haplotype Linked to Hypertrophic Cardiomyopathy in Rhesus Macaques ( Macaca mulatta). Comp Med 2020; 70:358-367. [PMID: 32753092 PMCID: PMC7574221 DOI: 10.30802/aalas-cm-19-000108] [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: 11/07/2019] [Revised: 01/13/2020] [Accepted: 02/07/2020] [Indexed: 11/05/2022]
Abstract
In humans, abnormal thickening of the left ventricle of the heart clinically defines hypertrophic cardiomyopathy (HCM), a common inherited cardiovascular disorder that can precede a sudden cardiac death event. The wide range of clinical presentations in HCM obscures genetic variants that may influence an individual's susceptibility to sudden cardiac death. Although exon sequencing of major sarcomere genes can be used to detect high-impact causal mutations, this strategy is successful in only half of patient cases. The incidence of left ventricular hypertrophy (LVH) in a managed research colony of rhesus macaques provides an excellent comparative model in which to explore the genomic etiology of severe HCM and sudden cardiac death. Because no rhesus HCM-associated mutations have been reported, we used a next-generation genotyping assay that targets 7 sarcomeric rhesus genes within 63 genomic sites that are orthologous to human genomic regions known to harbor HCM disease variants. Amplicon sequencing was performed on 52 macaques with confirmed LVH and 42 unrelated, unaffected animals representing both the Indian and Chinese rhesus macaque subspecies. Bias-reduced logistic regression uncovered a risk haplotype in the rhesus MYBPC3 gene, which is frequently disrupted in both human and feline HCM; this haplotype implicates an intronic variant strongly associated with disease in either homozygous or carrier form. Our results highlight that leveraging evolutionary genomic data provides a unique, practical strategy for minimizing population bias in complex disease studies.
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Affiliation(s)
- Robert F Oldt
- School of Mathematical and Natural Sciences, Arizona State University at the West Campus, Glendale, Arizona; Evolutionary Biology Graduate Program, School of Life Sciences, Arizona State University at the West Campus, Glendale, Arizona;,
| | - Kimberly J Bussey
- School of Mathematical and Natural Sciences, Arizona State University at the West Campus, Glendale, Arizona; BEYOND Center for Fundamental Concepts in Science, Arizona State University at the West Campus, Glendale, Arizona
| | - Matthew L Settles
- Bioinformatics Core, UC Davis Genome Center, University of California, Davis, California
| | - Joseph N Fass
- Bioinformatics Core, UC Davis Genome Center, University of California, Davis, California
| | - Jeffrey A Roberts
- California National Primate Research Center, University of California, Davis, California
| | - J Rachel Reader
- California National Primate Research Center, University of California, Davis, California
| | | | - Victor A Abrich
- Division of Cardiovascular Diseases, Mayo Clinic, Scottsdale, Arizona
| | - Sreetharan Kanthaswamy
- School of Mathematical and Natural Sciences, Arizona State University at the West Campus, Glendale, Arizona; Evolutionary Biology Graduate Program, School of Life Sciences, Arizona State University at the West Campus, Glendale, Arizona; California National Primate Research Center, University of California, Davis, California
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14
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Najafi M, Tamandani DMK, Azarfar A, Bakey Z, Behjati F, Antony D, Schüle I, Sadeghi-Bojd S, Karimiani EG, Schmidts M. A 57 kB Genomic Deletion Causing CTNS Loss of Function Contributes to the CTNS Mutational Spectrum in the Middle East. Front Pediatr 2019; 7:89. [PMID: 30949462 PMCID: PMC6437787 DOI: 10.3389/fped.2019.00089] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Accepted: 02/28/2019] [Indexed: 12/03/2022] Open
Abstract
Background: Nephropathic Cystinosis, the most common cause of renal Fanconi syndrome, is a lysosomal transport disorder with an autosomal recessive inheritance pattern. A large number of mutations in CTNS have been identified as causative to date. A 57 kb deletion encompassing parts of CTNS is most commonly identified in Caucasians but this allele has not been identified in individuals of Eastern Mediterranean, Middle Eastern, Persian, or Arab origin to date. Methods and Results: Implementing whole exome sequencing (WES) in a consanguineous Iranian family, we identified this large deletion affecting CTNS in a patient initially presenting with hypokalemic metabolic alkalosis symptoms and considerable proteinuria. Conclusion: We show WES is a cost and time efficient genetic diagnostics modality to identify the underlying molecular pathology in Cystinosis individuals and provide a summary of all previously reported CTNS alleles in the Middle east population. Our work also highlights the importance to consider the 57-kb deletion as underlying genetic cause in non-European populations, including the Middle East. Limited diagnostic modalities for Cystinosis in developing countries could account for the lack of previously reported cases in these populations carrying this allele. Further, our findings emphasize the utility of WES to define genetic causes in clinically poorly defined phenotypes and demonstrate the requirement of Copy number variation (CNV) analysis of WES data.
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Affiliation(s)
- Maryam Najafi
- Genome Research Division, Human Genetics Department, Radboud University Medical Center Nijmegen and Radboud Institute for Molecular Life Sciences, Nijmegen, Netherlands.,Department of Biology, University of Sistan and Baluchestan, Zahedan, Iran
| | | | - Anoush Azarfar
- Department of Pediatrics, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Zeineb Bakey
- Genome Research Division, Human Genetics Department, Radboud University Medical Center Nijmegen and Radboud Institute for Molecular Life Sciences, Nijmegen, Netherlands.,Center for Pediatrics and Adolescent Medicine, Faculty of Medicine, University Hospital Freiburg, Freiburg University, Freiburg, Germany
| | - Farkhondeh Behjati
- Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Dinu Antony
- Genome Research Division, Human Genetics Department, Radboud University Medical Center Nijmegen and Radboud Institute for Molecular Life Sciences, Nijmegen, Netherlands.,Center for Pediatrics and Adolescent Medicine, Faculty of Medicine, University Hospital Freiburg, Freiburg University, Freiburg, Germany
| | - Isabel Schüle
- Center for Pediatrics and Adolescent Medicine, Faculty of Medicine, University Hospital Freiburg, Freiburg University, Freiburg, Germany
| | - Simin Sadeghi-Bojd
- Children and Adolescents Health Research Center, Resistant Tuberculosis Institute, Zahedan University of Medical Sciences, Zahedan, Iran
| | - Ehsan Ghayoor Karimiani
- Next Generation Genetic Polyclinic, Mashhad, Iran.,Razavi Cancer Research, Razavi Hospital, Imam Reza International University, Mashhad, Iran
| | - Miriam Schmidts
- Genome Research Division, Human Genetics Department, Radboud University Medical Center Nijmegen and Radboud Institute for Molecular Life Sciences, Nijmegen, Netherlands.,Center for Pediatrics and Adolescent Medicine, Faculty of Medicine, University Hospital Freiburg, Freiburg University, Freiburg, Germany
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15
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Reda A, Van Schepdael A, Adams E, Paul P, Devolder D, Elmonem MA, Veys K, Casteels I, van den Heuvel L, Levtchenko E. Effect of Storage Conditions on Stability of Ophthalmological Compounded Cysteamine Eye Drops. JIMD Rep 2017; 42:47-51. [PMID: 29214524 DOI: 10.1007/8904_2017_77] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 11/06/2017] [Accepted: 11/15/2017] [Indexed: 02/24/2023] Open
Abstract
Cystinosis is a hereditary genetic disease that results in the accumulation of cystine crystals in the lysosomes, leading to many clinical manifestations. One of these manifestations is the formation of corneal cystine crystals, which can cause serious ocular complications. The only available drug to treat cystinosis is cysteamine, which breaks cystine and depletes its accumulation in the lysosomes. However, the oral form of cysteamine is not effective in treating corneal manifestations. Thus, ophthalmic solutions of cysteamine are applied. Because the commercial cysteamine eye drops are not available in most countries, hospital pharmacies are responsible for preparing "homemade" drops usually without a control of stability of cysteamine in different storage conditions. Hence, we aimed in this study to investigate the effect of different storage conditions on the stability of a cysteamine ophthalmic compounded solution. Cysteamine ophthalmic solution was prepared in the hospital pharmacy and sterilized using a candle filter. The preparations are then stored either in the freezer at -20°C or in the refrigerator at +4°C for up to 52 weeks. The amount of cysteamine hydrochloride in the preparation at different time points was determined using capillary electrophoresis (CE). Storage of the cysteamine ophthalmic preparations at +4° resulted in significant loss of free cysteamine at all time points, from 1 to 52 weeks of storage, when compared with storage in the freezer (-20°C). We demonstrate that cysteamine 0.5% compounded eye drops are easily oxidized within the first week after storage at +4°C, rendering the preparation less effective. Storage at -20°C is recommended to prevent this process.
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Affiliation(s)
- Ahmed Reda
- Department of Development and Regeneration, Organ System Cluster, Group of Biomedical Sciences, KU Leuven, Leuven, Belgium.
| | | | - Erwin Adams
- Farmaceutische Analyse, KU Leuven, Leuven, Belgium
| | | | - David Devolder
- Hospital Pharmacy, University Hospitals Leuven, Leuven, Belgium
| | - Mohamed A Elmonem
- Department of Development and Regeneration, Organ System Cluster, Group of Biomedical Sciences, KU Leuven, Leuven, Belgium.,Department of Clinical and Chemical Pathology, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Koenraad Veys
- Department of Development and Regeneration, Organ System Cluster, Group of Biomedical Sciences, KU Leuven, Leuven, Belgium.,Department of Pediatrics, University Hospitals Leuven, Leuven, Belgium
| | - Ingele Casteels
- Department of Ophthalmology, University Hospitals Leuven, Leuven, Belgium
| | - Lambertus van den Heuvel
- Department of Development and Regeneration, Organ System Cluster, Group of Biomedical Sciences, KU Leuven, Leuven, Belgium.,Department of Pediatrics, University Hospitals Leuven, Leuven, Belgium.,Department of Pediatric Nephrology, Radboud UMC, Nijmegen, The Netherlands
| | - Elena Levtchenko
- Department of Development and Regeneration, Organ System Cluster, Group of Biomedical Sciences, KU Leuven, Leuven, Belgium.,Department of Pediatrics, University Hospitals Leuven, Leuven, Belgium
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16
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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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17
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Sadeghipour F, Basiratnia M, Derakhshan A, Fardaei M. Mutation analysis of the CTNS gene in Iranian patients with infantile nephropathic cystinosis: identification of two novel mutations. Hum Genome Var 2017; 4:17038. [PMID: 28983406 PMCID: PMC5628181 DOI: 10.1038/hgv.2017.38] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Revised: 07/07/2017] [Accepted: 07/09/2017] [Indexed: 12/02/2022] Open
Abstract
Nephropathic cystinosis is an inherited lysosomal transport disorder caused by mutations in the CTNS gene that encodes for a lysosomal membrane transporter, cystinosin. Dysfunction in this protein leads to cystine accumulation in the cells of different organs. The accumulation of cystine in the kidneys becomes apparent with renal tubular Fanconi syndrome between 6 and 12 months of age and leads to renal failure in the first decade of life. The aim of this study was to analyze the CTNS mutations in 20 Iranian patients, from 20 unrelated families, all of whom were afflicted with infantile nephropathic cystinosis. In these patients, seven different mutant alleles were found, including two new mutations, c.517T>C; p.Y173H and c.492_515del, that have not been previously reported. In addition, we observed that c.681G>A, the common Middle Eastern mutation, was the most common mutation in our patients. Moreover, a new minisatellite or variable number of tandem repeat marker (KX499495) was identified at the CTNS gene. Seven different alleles were found for this marker, and its allele frequency and heterozygosity degree were calculated in cystinosis patients and healthy individuals.
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Affiliation(s)
- Forough Sadeghipour
- Department of Medical Genetics, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Mitra Basiratnia
- Department of Pediatric Nephrology, Namazi Hospital, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Ali Derakhshan
- Department of Pediatric Nephrology, Namazi Hospital, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Majid Fardaei
- Department of Medical Genetics, Shiraz University of Medical Sciences, Shiraz, Iran.,Transgenic Technology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
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18
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Diagnostic challenge in a patient with nephropathic juvenile cystinosis: a case report. BMC Nephrol 2017; 18:300. [PMID: 28950840 PMCID: PMC5615464 DOI: 10.1186/s12882-017-0721-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Accepted: 09/20/2017] [Indexed: 11/25/2022] Open
Abstract
Background Cystinosis is a rare autosomal recessive lysosomal disorder characterized by the accumulation of cystine in lysosomes. Cystinosis is much rarer in Asian than Caucasian populations. There are only 14 patients have with cystinosis alive in Japan. Most cystinosis is the nephropathic infantile form, as indicated by its apparent and severe clinical manifestations, including renal and ocular symptoms. Patients with the nephropathic juvenile form account for 5% of those with cystinosis. Their diagnosis is frequently delayed and difficult because of slower progression to end-stage renal disease and fewer cystine crystals in the cornea. Molecular analysis and a cysteine-binding protein assay should be performed when patients with proximal tubulopathy of an unknown origin are encountered. Case presentation A 12-year-old boy had been suffering from Fanconi syndrome since he was 3 years old. He was only recently diagnosed despite repeated ophthalmological examinations. Corneal cystine crystals were found when he was 12 years old, and he was diagnosed with cystinosis by high free cystine content in granulocytes (6.36 nmol half-cystine/mg protein, normal: <0.15). Analysis of the CTNS gene showed two novel heterozygous single nucleotide substitutions of c.329G > C and c.329 + 2 T > C. Both were splicing site variants causing exon 6 skipping proven by transcript analysis, although the functional prediction site showed c.329G > C, p.(Gly110Ala) as a benign missense substitution. The patient’s estimated glomerular filtration rate was 66.8 mL/min/1.73 m2. He was immediately treated with cysteamine after diagnosis. Conclusions Even if no ophthalmological abnormalities are present, nephropathic juvenile cystinosis should be suspected in children with Fanconi syndrome. Transcript analysis was useful to detect pathogenic splicing variants in this patient.
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Bertholet-Thomas A, Berthiller J, Tasic V, Kassai B, Otukesh H, Greco M, Ehrich J, de Paula Bernardes R, Deschênes G, Hulton SA, Fischbach M, Soulami K, Saeed B, Valavi E, Cobenas CJ, Hacihamdioglu B, Weiler G, Cochat P, Bacchetta J. Worldwide view of nephropathic cystinosis: results from a survey from 30 countries. BMC Nephrol 2017; 18:210. [PMID: 28673276 PMCID: PMC5496396 DOI: 10.1186/s12882-017-0633-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 06/21/2017] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Nephropathic cystinosis is a rare inherited metabolic disorder leading to progressive renal failure and extra-renal comorbidity. The prognosis relies on early adherence to cysteamine treatment and symptomatic therapies. Developing nations [DiN] experience many challenges for management of cystinosis. The aim of this study was to assess the management characteristics in DiN compared with developed nations [DeN]. METHODS A questionnaire was sent between April 2010 and May 2011 to 87 members of the International Pediatric Nephrology Association, in 50 countries. RESULTS A total of 213 patients were included from 41 centres in 30 nations (109 from 17 DiN and 104 from 13 DeN). 7% of DiN patients died at a median age of 5 years whereas no death was observed in DeN. DiN patients were older at the time of diagnosis. In DiN, leukocyte cystine measurement was only available in selected cases for diagnosis but never for continuous monitoring. More patients had reached end-stage renal disease in DiN (53.2 vs. 37.9%, p = 0.03), within a shorter time of evolution (8 vs. 10 yrs., p = 0.0008). The earlier the cysteamine treatment, the better the renal outcome, since the median renal survival increased up to 16.1 [12.5-/] yrs. in patients from DeN treated before the age of 2.5 years of age (p = 0.0001). However, the renal survival was not statistically different between DeN and DiN when patients initiated cysteamine after 2.5 years of age. The number of transplantations and the time from onset of ESRD to transplantation were not different in DeN and DiN. More patients were kept under maintenance dialysis in DiN (26% vs.19%, p = 0.02); 79% of patients from DiN vs. 45% in DeN underwent peritoneal dialysis. CONCLUSIONS Major discrepancies between DiN and DeN in the management of nephropathic cystinosis remain a current concern for many patients living in countries with limited financial resources.
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Affiliation(s)
- Aurélia Bertholet-Thomas
- Centre de référence des maladies rénales rares Néphrogones, hôpital Femme–Mère–Enfant, Hospices Civils de Lyon & Université Claude-Bernard Lyon 1, Lyon, France
| | - Julien Berthiller
- 0000 0001 2163 3825grid.413852.9Hospices Civils de Lyon, Pôle Information Médicale Evaluation Recherche, Lyon, France
- Epidémiologie, Pharmacologie, Investigation Clinique CIC 1407 Inserm, Information médicale, Mère-Enfant–Bron, Bron, France
- 0000 0001 2150 7757grid.7849.2Université Lyon 1, Equipe d’Accueil 4129, Lyon, France
| | - Velibor Tasic
- Medical School, University Children’s Hospital, Skopje, Macedonia
| | - Behrouz Kassai
- 0000 0001 2163 3825grid.413852.9Hospices Civils de Lyon, Pôle Information Médicale Evaluation Recherche, Lyon, France
- Epidémiologie, Pharmacologie, Investigation Clinique CIC 1407 Inserm, Information médicale, Mère-Enfant–Bron, Bron, France
- 0000 0001 2150 7757grid.7849.2Université Lyon 1, Equipe d’Accueil 4129, Lyon, France
| | | | - Marcella Greco
- 0000 0001 0727 6809grid.414125.7Division of Nephrology and Dialysis, Children’s Hospital Bambino Gesù, IRCCS, Roma, Italy
| | - Jochen Ehrich
- 0000 0000 9529 9877grid.10423.34Children’s Hospital, Hannover Medical School, Hannover, Germany
| | | | - Georges Deschênes
- 0000 0004 1788 6194grid.469994.fService de néphrologie pédiatrique, Hôpital Robert Debré, Université Sorbonne Paris, Paris, France
| | - Sally-Ann Hulton
- 0000 0004 0399 7272grid.415246.0Birmingham Children’s Hospital, Birmingham, England
| | - Michel Fischbach
- 0000 0004 0593 6932grid.412201.4Service de néphrologie pédiatrique, Hôpital Hautepierre, Strasbourg, France
| | - Kenza Soulami
- Pediatric Nephrology, 295 Bd Abdelmoumen, Casablanca, Morocco
| | | | - Ehsan Valavi
- 0000 0000 9296 6873grid.411230.5Department of Nephrology, Jundishapur University of Medical Sciences, Ahvaz, Iran
| | | | | | - Gabrielle Weiler
- 0000 0000 9402 6172grid.414148.cDivision of nephrology, Children’s hospital of Eastern Ontario, Ottawa, Canada
| | - Pierre Cochat
- Centre de référence des maladies rénales rares Néphrogones, hôpital Femme–Mère–Enfant, Hospices Civils de Lyon & Université Claude-Bernard Lyon 1, Lyon, France
| | - Justine Bacchetta
- Centre de référence des maladies rénales rares Néphrogones, hôpital Femme–Mère–Enfant, Hospices Civils de Lyon & Université Claude-Bernard Lyon 1, Lyon, France
- Centre de référence des maladies rénales rares - Néphrogones, Hôpital Femme–Mère-Enfant, 59, boulevard Pinel, 69677 Bron cedex, France
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20
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Ghazi F, Hosseini R, Akouchekian M, Teimourian S, Ataei Kachoei Z, Otukesh H, Gahl WA, Behnam B. CTNS molecular genetics profile in a Persian nephropathic cystinosis population. Nefrologia 2017; 37:301-310. [PMID: 28238446 DOI: 10.1016/j.nefro.2016.11.024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Revised: 09/18/2016] [Accepted: 11/22/2016] [Indexed: 11/27/2022] Open
Abstract
PURPOSE In this report, we document the CTNS gene mutations of 28 Iranian patients with nephropathic cystinosis age 1-17 years. All presented initially with severe failure to thrive, polyuria, and polydipsia. METHODS Cystinosis was primarily diagnosed by a pediatric nephrologist and then referred to the Iran University of Medical Sciences genetics clinic for consultation and molecular analysis, which involved polymerase chain reaction (PCR) amplification to determine the presence or absence of the 57-kb founder deletion in CTNS, followed by direct sequencing of the coding exons of CTNS. RESULTS The common 57-kb deletion was not observed in any of the 28 Iranian patients. In 14 of 28 patients (50%), mutations were observed in exons 6 and 7. No mutation was detected in exon 5, and only one (3.6%) patient with cystinosis showed a previously reported 4-bp deletion in exon 3 of CTNS. Four patients (14.3%) had a previously reported mutation (c.969C>A; p.N323K) in exon 11, and five (18%) had novel homozygous deletions in exon 6 leading to premature truncation of the protein. These deletions included c.323delA; p.Q108RfsX10 in three individuals and c.257-258delCT; p.S86FfsX37 in two cases. Other frame-shift mutations were all novel homozygous single base pair deletion/insertions including one in CTNS exon 9 (c.661insT; p.V221CfsX6), and four (14.3%) in exon 4, i.e., c.92insG; p.V31GfsX28 in two and c.120delC; p.T40TfsX10 in two. In total, we identified eight previously reported mutations and eight novel mutations in our patients. The only detected splice site mutation (IVS3-2A>C) was associated with the insertion mutation in the exon 9. CONCLUSION This study, the first molecular genetic analysis of non-ethnic-specific Iranian nephropathic cystinosis patients, may provide guidance for molecular diagnostics of cystinosis in Iran.
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Affiliation(s)
- Farideh Ghazi
- Department of Medical Genetics and Molecular Biology, Faculty of Medicine, Iran University of Medical Sciences (IUMS), Tehran, Iran
| | - Rozita Hosseini
- Department of Pediatrics, Faculty of Medicine, Ali Asghar Children Hospital, Iran University of Medical Sciences (IUMS), Tehran, Iran
| | - Mansoureh Akouchekian
- Department of Medical Genetics and Molecular Biology, Faculty of Medicine, Iran University of Medical Sciences (IUMS), Tehran, Iran
| | - Shahram Teimourian
- Department of Medical Genetics and Molecular Biology, Faculty of Medicine, Iran University of Medical Sciences (IUMS), Tehran, Iran
| | - Zohreh Ataei Kachoei
- Department of Medical Genetics and Molecular Biology, Faculty of Medicine, Iran University of Medical Sciences (IUMS), Tehran, Iran
| | - Hassan Otukesh
- Department of Pediatrics, Faculty of Medicine, Ali Asghar Children Hospital, Iran University of Medical Sciences (IUMS), Tehran, Iran
| | - William A Gahl
- Section on Human Biochemical Genetics, Medical Genetics Branch, National Human Genome Research Institute, NIH, Bethesda, MD, USA; NIH Undiagnosed Diseases Program, Common Fund, Office of the Director, NIH, Bethesda, MD, USA
| | - Babak Behnam
- Department of Medical Genetics and Molecular Biology, Faculty of Medicine, Iran University of Medical Sciences (IUMS), Tehran, Iran; Department of Pediatrics, Faculty of Medicine, Ali Asghar Children Hospital, Iran University of Medical Sciences (IUMS), Tehran, Iran; Section on Human Biochemical Genetics, Medical Genetics Branch, National Human Genome Research Institute, NIH, Bethesda, MD, USA; NIH Undiagnosed Diseases Program, Common Fund, Office of the Director, NIH, Bethesda, MD, USA.
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Cherqui S, Courtoy PJ. The renal Fanconi syndrome in cystinosis: pathogenic insights and therapeutic perspectives. Nat Rev Nephrol 2016; 13:115-131. [PMID: 27990015 DOI: 10.1038/nrneph.2016.182] [Citation(s) in RCA: 94] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Cystinosis is an autosomal recessive metabolic disease that belongs to the family of lysosomal storage disorders. It is caused by a defect in the lysosomal cystine transporter, cystinosin, which results in an accumulation of cystine in all organs. Despite the ubiquitous expression of cystinosin, a renal Fanconi syndrome is often the first manifestation of cystinosis, usually presenting within the first year of life and characterized by the early and severe dysfunction of proximal tubule cells, highlighting the unique vulnerability of this cell type. The current therapy for cystinosis, cysteamine, facilitates lysosomal cystine clearance and greatly delays progression to kidney failure but is unable to correct the Fanconi syndrome. This Review summarizes decades of studies that have fostered a better understanding of the pathogenesis of the renal Fanconi syndrome associated with cystinosis. These studies have unraveled some of the early molecular changes that occur before the onset of tubular atrophy and identified a role for cystinosin beyond cystine transport, in endolysosomal trafficking and proteolysis, lysosomal clearance, autophagy and the regulation of energy balance. These studies have also led to the identification of new potential therapeutic targets and here, we outline the potential role of stem cell therapy for cystinosis and provide insights into the mechanism of haematopoietic stem cell-mediated kidney protection.
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Affiliation(s)
- Stephanie Cherqui
- Department of Pediatrics, Division of Genetics, University of California San Diego, 9500 Gilman Drive, MC 0734, La Jolla, California 92093-0734, USA
| | - Pierre J Courtoy
- Cell biology, de Duve Institute and Université catholique de Louvain, UCL-Brussels, 75 Avenue Hippocrate, B-1200 Brussels, Belgium
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Elmonem MA, Mahmoud IG, Mehaney DA, Sharaf SA, Hassan SA, Orabi A, Salem F, Girgis MY, El-Badawy A, Abdelwahab M, Salah Z, Soliman NA, Hassan FA, Selim LA. Lysosomal Storage Disorders in Egyptian Children. Indian J Pediatr 2016; 83:805-13. [PMID: 26830282 DOI: 10.1007/s12098-015-2014-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 12/23/2015] [Indexed: 02/01/2023]
Abstract
OBJECTIVE To describe the spectrum, relative prevalence and molecular background of lysosomal storage disorders in Egypt. METHODS The authors evaluated the selective screening program for the diagnosis of lysosomal storage disorders in Egyptian children presenting to the inherited metabolic disease unit at Cairo University Children's Hospital, the largest tertiary care pediatric hospital in Egypt, over a six-year period (April 2008 through April 2014). During this period, 1,065 suspected children were assessed clinically, biochemically and some genetically. RESULTS Two hundred and eleven children (aged 44 ± 32 mo; 56 % boys, 82 % with consanguineous parents) were confirmed with 21 different lysosomal disorders. The diagnostic gap ranged between 2 mo and 14 y (average 25 mo). Mucopolysaccharidoses were the most common group of diseases diagnosed (44.5 %), while Maroteaux-Lamy, Gaucher and nephropathic cystinosis were the most commonly detected syndromes (17.1, 14.7 and 13.7 %, respectively). Eighty mutant alleles and 17 pathogenic mutations were detected in 48 genetically assessed confirmed patients (30 Gaucher, 16 cystinosis and two Niemann-Pick type C patients). CONCLUSIONS This report is the first to describe relative frequency and spectrum of clinical and molecular data in a large cohort of Egyptian lysosomal patients. The crude estimate denotes that over 80 % of Egyptian lysosomal patients do not have access to optimal diagnosis. Upgrading diagnostic and genetic services for lysosomal storage disorders in Egypt is absolutely necessary.
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Affiliation(s)
- Mohamed A Elmonem
- Department of Clinical and Chemical Pathology, Faculty of Medicine, Cairo University, Cairo, Egypt. .,Inherited Metabolic Disease Unit (IMDU), Cairo University Children's Hospital, Cairo, Egypt. .,Clinical and Chemical Pathology Department, Inherited Metabolic Disease Laboratory, Faculty of Medicine, Cairo University, 2 Ali Pasha Ibrahim Street, Center of Social and Preventive Medicine, Room 409, Monira, Cairo, 11628, Egypt.
| | - Iman G Mahmoud
- Inherited Metabolic Disease Unit (IMDU), Cairo University Children's Hospital, Cairo, Egypt.,Department of Pediatric Neurology, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Dina A Mehaney
- Department of Clinical and Chemical Pathology, Faculty of Medicine, Cairo University, Cairo, Egypt.,Inherited Metabolic Disease Unit (IMDU), Cairo University Children's Hospital, Cairo, Egypt
| | - Sahar A Sharaf
- Department of Clinical and Chemical Pathology, Faculty of Medicine, Cairo University, Cairo, Egypt.,Inherited Metabolic Disease Unit (IMDU), Cairo University Children's Hospital, Cairo, Egypt
| | - Sawsan A Hassan
- Inherited Metabolic Disease Unit (IMDU), Cairo University Children's Hospital, Cairo, Egypt.,Department of Pediatric Genetics, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Azza Orabi
- Inherited Metabolic Disease Unit (IMDU), Cairo University Children's Hospital, Cairo, Egypt.,Department of Pediatric Neurology, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Fadia Salem
- Inherited Metabolic Disease Unit (IMDU), Cairo University Children's Hospital, Cairo, Egypt.,Department of Pediatric Genetics, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Marian Y Girgis
- Inherited Metabolic Disease Unit (IMDU), Cairo University Children's Hospital, Cairo, Egypt.,Department of Pediatric Neurology, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Amira El-Badawy
- Inherited Metabolic Disease Unit (IMDU), Cairo University Children's Hospital, Cairo, Egypt.,Department of Pediatric Neurology, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Magy Abdelwahab
- Department of Pediatric Hematology, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Zeinab Salah
- Department of Pediatric Cardiology, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Neveen A Soliman
- Center for Pediatric Nephrology and Transplantation (CPNT), Department of Pediatrics, Faculty of Medicine, Cairo University, Cairo, Egypt.,Egyptian Group of Orphan Renal Diseases (EGORD), Cairo, Egypt
| | - Fayza A Hassan
- Department of Clinical and Chemical Pathology, Faculty of Medicine, Cairo University, Cairo, Egypt.,Inherited Metabolic Disease Unit (IMDU), Cairo University Children's Hospital, Cairo, Egypt
| | - Laila A Selim
- Inherited Metabolic Disease Unit (IMDU), Cairo University Children's Hospital, Cairo, Egypt.,Department of Pediatric Neurology, Faculty of Medicine, Cairo University, Cairo, Egypt
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23
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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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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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Elmonem MA, Makar SH, van den Heuvel L, Abdelaziz H, Abdelrahman SM, Bossuyt X, Janssen MC, Cornelissen EA, Lefeber DJ, Joosten LA, Nabhan MM, Arcolino FO, Hassan FA, Gaide Chevronnay HP, Soliman NA, Levtchenko E. Clinical utility of chitotriosidase enzyme activity in nephropathic cystinosis. Orphanet J Rare Dis 2014; 9:155. [PMID: 25407738 PMCID: PMC4269071 DOI: 10.1186/s13023-014-0155-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 09/30/2014] [Indexed: 01/02/2023] Open
Abstract
Background Nephropathic cystinosis is an inherited autosomal recessive lysosomal storage disorder characterized by the pathological accumulation and crystallization of cystine inside different cell types. WBC cystine determination forms the basis for the diagnosis and therapeutic monitoring with the cystine depleting drug (cysteamine). The chitotriosidase enzyme is a human chitinase, produced by activated macrophages. Its elevation is documented in several lysosomal storage disorders. Although, about 6% of Caucasians have enzyme deficiency due to homozygosity of 24-bp duplication mutation in the chitotriosidase gene, it is currently established as a screening marker and therapeutic monitor for Gaucher’s disease. Methods Plasma chitotriosidase activity was measured in 45 cystinotic patients, and compared with 87 healthy controls and 54 renal disease patients with different degrees of renal failure (CKD1-5). Chitotriosidase levels were also correlated with WBC cystine in 32 treated patients. Furthermore, we incubated control human macrophages in-vitro with different concentrations of cystine crystals and monitored the response of tumor necrosis factor-alpha (TNF-α) and chitotriosidase activity. We also compared plasma chitotriosidase activity in cystinotic knocked-out (n = 10) versus wild-type mice (n = 10). Results Plasma chitotriosidase activity in cystinotic patients (0–3880, median 163 nmol/ml/h) was significantly elevated compared to healthy controls (0–90, median 18 nmol/ml/h) and to CKD patients (0–321, median 52 nmol/ml/h), P < 0.001 for both groups. Controls with decreased renal function had mild to moderate chitotriosidase elevations; however, their levels were significantly lower than in cystinotic patients with comparable degree of renal insufficiency. Chitotriosidase activity positively correlated with WBC cystine content for patients on cysteamine therapy (r = 0.8), P < 0.001. In culture, human control macrophages engulfed cystine crystals and released TNF-α into culture supernatant in a crystal concentration dependent manner. Chitotriosidase activity was also significantly increased in macrophage supernatant and cell-lysate. Furthermore, chitotriosidase activity was significantly higher in cystinotic knocked-out than in the wild-type mice, P = 0.003. Conclusions This study indicates that cystine crystals are potent activators of human macrophages and that chitotriosidase activity is a useful marker for this activation and a promising clinical biomarker and therapeutic monitor for nephropathic cystinosis.
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Affiliation(s)
- Mohamed A Elmonem
- Department of Clinical and Chemical Pathology, Inherited Metabolic Disorder Laboratory (IMDL), Cairo University, Cairo, Egypt.
| | - Samuel H Makar
- Department of Pediatrics, Center of Pediatric Nephrology and Transplantation (CPNT), Cairo University, Cairo, Egypt. .,EGORD, Egyptian group of orphan renal diseases, Cairo, Egypt.
| | - Lambertus van den Heuvel
- Department of Pediatric Nephrology & Growth and Regeneration, University Hospital Leuven, Catholic University of Leuven, Leuven, Belgium. .,Department of Pediatric Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands.
| | - Hanan Abdelaziz
- Department of Pediatrics, Center of Pediatric Nephrology and Transplantation (CPNT), Cairo University, Cairo, Egypt. .,EGORD, Egyptian group of orphan renal diseases, Cairo, Egypt.
| | - Safaa M Abdelrahman
- Department of Pediatrics, Center of Pediatric Nephrology and Transplantation (CPNT), Cairo University, Cairo, Egypt. .,EGORD, Egyptian group of orphan renal diseases, Cairo, Egypt.
| | - Xavier Bossuyt
- University Hospitals Leuven & Department of Microbiology and Immunology, Laboratory Medicine, Catholic University of Leuven, Leuven, Belgium.
| | - Mirian C Janssen
- Department of Internal Medicine, Radboud University Medical Center, Nijmegen, The Netherlands.
| | - Elisabeth Am Cornelissen
- Department of Pediatric Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands.
| | - Dirk J Lefeber
- Department of Neurology, Laboratory for Genetic, Endocrine and Metabolic Diseases, Radboud University Medical Center, Nijmegen, The Netherlands.
| | - Leo Ab Joosten
- Department of Pediatric Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands.
| | - Marwa M Nabhan
- Department of Pediatrics, Center of Pediatric Nephrology and Transplantation (CPNT), Cairo University, Cairo, Egypt. .,EGORD, Egyptian group of orphan renal diseases, Cairo, Egypt.
| | - Fanny O Arcolino
- Department of Pediatric Nephrology & Growth and Regeneration, University Hospital Leuven, Catholic University of Leuven, Leuven, Belgium.
| | - Fayza A Hassan
- Department of Clinical and Chemical Pathology, Inherited Metabolic Disorder Laboratory (IMDL), Cairo University, Cairo, Egypt.
| | | | - Neveen A Soliman
- Department of Pediatrics, Center of Pediatric Nephrology and Transplantation (CPNT), Cairo University, Cairo, Egypt. .,EGORD, Egyptian group of orphan renal diseases, Cairo, Egypt.
| | - Elena Levtchenko
- Department of Pediatric Nephrology & Growth and Regeneration, University Hospital Leuven, Catholic University of Leuven, Leuven, Belgium.
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