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Żuber Z, Kieć-Wilk B, Kałużny Ł, Wierzba J, Tylki-Szymańska A. Diagnosis and Management of Mucopolysaccharidosis Type II (Hunter Syndrome) in Poland. Biomedicines 2023; 11:1668. [PMID: 37371763 DOI: 10.3390/biomedicines11061668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 05/12/2023] [Accepted: 05/31/2023] [Indexed: 06/29/2023] Open
Abstract
Mucopolysaccharidosis type II (MPS II; also known as Hunter syndrome) is a rare, inherited lysosomal storage disease. The disease is caused by deficiency of the lysosomal enzyme iduronate-2-sulphatase (I2S) due to mutations in the IDS gene, which leads to accumulation of glycosaminoglycans (GAGs). Deficiency of I2S enzyme activity in patients with MPS II leads to progressive lysosomal storage of GAGs in the liver, spleen, heart, bones, joints, and respiratory tract. This process disturbs cellular functioning and leads to multisystemic disease manifestations. Symptoms and their time of onset differ among patients. Diagnosis of MPS II involves assessment of clinical features, biochemical parameters, and molecular characteristics. Life-long enzyme replacement therapy with idursulfase (recombinant human I2S) is the current standard of care. However, an interdisciplinary team of specialists is required to monitor and assess the patient's condition to ensure optimal care. An increasing number of patients with this rare disease reach adulthood and old age. The transition from pediatric care to the adult healthcare system should be planned and carried out according to guidelines to ensure maximum benefit for the patient.
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Affiliation(s)
- Zbigniew Żuber
- Department of Pediatrics, Faculty of Medicine and Health Sciences, Andrzej Frycz Modrzewski Krakow University, 30-705 Krakow, Poland
| | - Beata Kieć-Wilk
- Unit of Rare Metabolic Diseases, Department of Metabolic Diseases, Jagiellonian University Medical College, 31-008 Krakow, Poland
| | - Łukasz Kałużny
- Department of Pediatric Gastroenterology and Metabolic Diseases, Poznan University of Medical Sciences, 61-701 Poznan, Poland
| | - Jolanta Wierzba
- Department of Pediatrics, Hematology and Oncology, Medical University of Gdansk, 80-210 Gdansk, Poland
| | - Anna Tylki-Szymańska
- Department of Pediatrics, Nutrition and Metabolic Diseases, The Children's Memorial Health Institute, 04-730 Warsaw, Poland
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Zhong L, Gao X, Wang Y, Qiu W, Han L, Gu X, Zhang H. Clinical characteristics and genotypes of 201 patients with mucopolysaccharidosis type II in China: A retrospective, observational study. Clin Genet 2023; 103:655-662. [PMID: 36945845 DOI: 10.1111/cge.14329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 03/09/2023] [Accepted: 03/12/2023] [Indexed: 03/23/2023]
Abstract
Mucopolysaccharidosis type II (MPS II) is an X-linked recessive lysosomal storage disease caused by a disease-associated variant in the IDS gene, which encodes iduronate 2-sulfatase (IDS). We aimed to characterize the clinical characteristics and genotypes of the largest cohort of Chinese patients with MPS II and so gain a deeper understanding of natural disease progression. Patients with confirmed MPS II and without treatment were included. The disease was classified as severe in patients with neurological impairment, and as attenuated in patients aged >6 years without neurological impairment. Of the 201 male patients, 78.1% had severe MPS II. Cognitive regression occurred before age 6 years in 94.3% of patients. Of 122 IDS variants identified, 37 were novel. Among the large gene alteration types identified, only the frequency of IDS-IDS2 recombination was significantly higher in severe versus attenuated MPS II (P = 0.032). Some identified point variants could inform the understanding of genotype-phenotype correlations. In conclusion, this study showed that classification of the disease as attenuated should only be made in patients aged >6 years. Our findings expand the understanding of the genotype-phenotype relationship, inform the diagnostic process, and provide an indication of the likely prognosis.
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Affiliation(s)
- Lin Zhong
- Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiao Tong University School of Medicine, 1665 Kongjiang Road, Shanghai, 200092, People's Republic of China
| | - Xiaolan Gao
- Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiao Tong University School of Medicine, 1665 Kongjiang Road, Shanghai, 200092, People's Republic of China
| | - Yu Wang
- Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiao Tong University School of Medicine, 1665 Kongjiang Road, Shanghai, 200092, People's Republic of China
| | - Wenjuan Qiu
- Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiao Tong University School of Medicine, 1665 Kongjiang Road, Shanghai, 200092, People's Republic of China
| | - Lianshu Han
- Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiao Tong University School of Medicine, 1665 Kongjiang Road, Shanghai, 200092, People's Republic of China
| | - Xuefan Gu
- Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiao Tong University School of Medicine, 1665 Kongjiang Road, Shanghai, 200092, People's Republic of China
| | - Huiwen Zhang
- Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiao Tong University School of Medicine, 1665 Kongjiang Road, Shanghai, 200092, People's Republic of China
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Tang J, Chang G, Wei M, Li X, Chen H, Qin Y, Wang J, Wang X, Chen R, Li N. Diagnosis of patients with mucopolysaccharidosis type II via RNA sequencing. Clin Chim Acta 2022; 537:38-45. [DOI: 10.1016/j.cca.2022.10.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 09/29/2022] [Accepted: 10/10/2022] [Indexed: 11/03/2022]
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Genotype-phenotype spectrum of 130 unrelated Indian families with Mucopolysaccharidosis type II. Eur J Med Genet 2022; 65:104447. [PMID: 35144014 DOI: 10.1016/j.ejmg.2022.104447] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 12/20/2021] [Accepted: 02/06/2022] [Indexed: 11/22/2022]
Abstract
MPS II is an X linked recessive lysosomal storage disorder with multi-system involvement and marked molecular heterogeneity. In this study, we explored the clinical and molecular spectrum of 144 Indian patients with MPS II from 130 unrelated families. Clinical information was collected on a predesigned clinical proforma. Sanger method was employed to sequence all the exons and exon/intron boundaries of the IDS gene. In cases where causative variation was not detected by Sanger sequencing, MLPA and RFLP were performed to identify large deletions/duplications and complex rearrangements. Cytogenetic microarray was done in one patient to see the breakpoints and extent of deletion. In one patient with no detectable likely pathogenic or pathogenic variation, whole-genome sequencing was also performed. Novel variants were systematically assessed by in silico prediction software and protein modelling. The pathogenicity of variants was established based on ACMG criteria. An attempt was also made to establish a genotype-phenotype correlation. Positive family history was present in 31% (41/130) of patients. Developmental delay and intellectual disability were the main reasons for referral. Macrocephaly, coarse facies and dysostosis were present in almost all patients. Hepatosplenomegaly, joint contractures and short stature were the characteristic features, seen in 87% (101/116), 67.8% (74/109) and 41.4% (41/99) patients respectively. Attenuated phenotype was seen in 32.6% (47/144) patients, while severe phenotype was seen in 63% (91/144) patients. The detection rate for likely pathogenic or pathogenic variants in our cohort is 95.5% (107/112) by Sanger sequencing, MLPA and RFLP. We also found two variants of unknown significance, one each by Sanger sequencing and WGS. Total of 71 variants were identified by Sanger sequencing and 29 of these variants were found to be novel. Amongst the novel variants, there was a considerable proportion (51%) of frameshift variants (15/29). Almost half of the causative variants were located in exon 3,8 and 9. A significant genotype-phenotype correlation was also noted for both known and novel variants. This information about the genotype spectrum and phenotype will be helpful for diagnostic and prognostic purposes.
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A molecular genetics view on Mucopolysaccharidosis Type II. MUTATION RESEARCH. REVIEWS IN MUTATION RESEARCH 2021; 788:108392. [PMID: 34893157 DOI: 10.1016/j.mrrev.2021.108392] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 06/03/2021] [Accepted: 08/05/2021] [Indexed: 02/07/2023]
Abstract
Mucopolysaccharidosis Type II (MPS II) is an X-linked recessive genetic disorder that primarily affects male patients. With an incidence of 1 in 100,000 male live births, the disease is one of the orphan diseases. MPS II symptoms are caused by mutations in the lysosomal iduronate-2-sulfatase (IDS) gene. The mutations cause a loss of enzymatic performance and result in the accumulation of glycosaminoglycans (GAGs), heparan sulfate and dermatan sulfate, which are no longer degradable. This inadvertent accumulation causes damage in multiple organs and leads either to a severe neurological course or to an attenuated course of the disease, although the exact relationship between mutation, extent of GAG accumulation and disease progression is not yet fully understood. This review is intended to present current diagnostic procedures and therapeutic interventions. In times when the genetic profile of patients plays an increasingly important role in the assessment of therapeutic success and future drug design, we chose to further elucidate the impact of genetic diversity within the IDS gene on disease phenotype and potential implications in current diagnosis, prognosis and therapy. We report recent advances in the structural biological elucidation of I2S enzyme that that promises to improve our future understanding of the molecular damage of the hundreds of IDS gene variants and will aid damage prediction of novel mutations in the future.
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Josahkian JA, Brusius-Facchin AC, Netto ABO, Leistner-Segal S, Málaga DR, Burin MG, Michelin-Tirelli K, Trapp FB, Cardoso-Dos-Santos AC, Ribeiro EM, Kim CA, de Siqueira ACM, Santos ML, do Valle DA, da Silva RTB, Horovitz DDG, de Medeiros PFV, de Souza CFM, Giuliani LDR, Miguel DSCG, Santana-da-Silva LC, Galera MF, Giugliani R. Genotype-phenotype studies in a large cohort of Brazilian patients with Hunter syndrome. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2021; 187:349-356. [PMID: 33960103 DOI: 10.1002/ajmg.c.31915] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 02/25/2021] [Accepted: 04/18/2021] [Indexed: 11/05/2022]
Abstract
Mucopolysaccharidosis type II (MPS II) is an X-linked inherited disease caused by pathogenic variants in the IDS gene, leading to deficiency of the lysosomal enzyme iduronate-2-sulfatase and consequent widespread storage of glycosaminoglycans, leading to several clinical consequences, with progressive manifestations which most times includes cognitive decline. MPS II has wide allelic and clinical heterogeneity and a complex genotype-phenotype correlation. We evaluated data from 501 Brazilian patients diagnosed with MPS II from 1982 to 2020. We genotyped 280 of these patients (55.9%), which were assigned to 206 different families. Point mutations were present in 70% of our patients, being missense variants the most frequent. We correlated the IDS pathogenic variants identified with the phenotype (neuronophatic or non-neuronopathic). Except for two half-brothers, there was no discordance in the genotype-phenotype correlation among family members, nor among MPS II patients from different families with the same single base-pair substitution variant. Mothers were carriers in 82.0% of the cases. This comprehensive study of the molecular profile of the MPS II cases in Brazil sheds light on the genotype-phenotype correlation and helps the better understanding of the disease and the prediction of its clinical course, enabling the provision of a more refined genetic counseling to the affected families.
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Affiliation(s)
- Juliana Alves Josahkian
- Department of Clinical Medicine, Hospital Universitário de Santa Maria (HUSM), Santa Maria, Rio Grande do Sul, Brazil.,Postgraduate Program in Genetics and Molecular Biology, UFRGS, Porto Alegre, Rio Grande do Sul, Brazil
| | | | - Alice Brinckmann Oliveira Netto
- Medical Genetics Service, HCPA, Porto Alegre, Rio Grande do Sul, Brazil.,National Institute on Population Medical Genetics, INAGEMP, Porto Alegre, Rio Grande do Sul, Brazil.,Graduate in Biological Sciences, UFRGS, Porto Alegre, Rio Grande do Sul, Brazil
| | - Sandra Leistner-Segal
- Medical Genetics Service, HCPA, Porto Alegre, Rio Grande do Sul, Brazil.,National Institute on Population Medical Genetics, INAGEMP, Porto Alegre, Rio Grande do Sul, Brazil
| | - Diana Rojas Málaga
- Medical Genetics Service, HCPA, Porto Alegre, Rio Grande do Sul, Brazil.,Research and Development, Grupo Fleury, São Paulo, São Paulo, Brazil
| | | | | | | | - Augusto César Cardoso-Dos-Santos
- Postgraduate Program in Genetics and Molecular Biology, UFRGS, Porto Alegre, Rio Grande do Sul, Brazil.,National Institute on Population Medical Genetics, INAGEMP, Porto Alegre, Rio Grande do Sul, Brazil
| | | | - Chong Ae Kim
- Genetic Unit, Pediatric Department, HC-FMUSP, São Paulo University, São Paulo, São Paulo, Brazil
| | | | - Mara Lucia Santos
- Neuropediatric Division, Hospital Pequeno Príncipe, Curitiba, Paraná, Brazil
| | | | | | - Dafne Dain Gandelman Horovitz
- Medical Genetics Department, National Institute of Women, Children and Adolescents Health Fernandes Figueira-Fiocruz/Reference Center for Rare Diseases, Rio de Janeiro, Rio de Janeiro, Brazil
| | | | | | - Liane de Rosso Giuliani
- Hospital Universitário Maria Aparecida Pedrossian (HUMAP), UFMS, Campo Grande, Mato Grosso do Sul, Brazil
| | | | - Luiz Carlos Santana-da-Silva
- Laboratory of Innate Errors of Metabolism, Institute of Biological Sciences, Federal University of Pará, Belém, Pará, Brazil
| | - Marcial Francis Galera
- Department of Pediatrics, Faculty of Medicine, Federal University of Mato Grosso, Cuiabá, Mato Grosso, Brazil
| | - Roberto Giugliani
- Medical Genetics Service, HCPA, Porto Alegre, Rio Grande do Sul, Brazil.,National Institute on Population Medical Genetics, INAGEMP, Porto Alegre, Rio Grande do Sul, Brazil.,Department of Genetics, UFRGS, Porto Alegre, Rio Grande do Sul, Brazil
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Chkioua L, Grissa O, Leban N, Gribaa M, Boudabous H, Turkia HB, Ferchichi S, Tebib N, Laradi S. The mutational spectrum of hunter syndrome reveals correlation between biochemical and clinical profiles in Tunisian patients. BMC MEDICAL GENETICS 2020; 21:111. [PMID: 32448126 PMCID: PMC7247178 DOI: 10.1186/s12881-020-01051-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/25/2019] [Accepted: 05/14/2020] [Indexed: 11/10/2022]
Abstract
Background Mucopolysaccharidosis type II (MPS II) or Hunter syndrome is an X-linked recessive lysosomal storage disorder resulting from deficient activity of iduronate 2-sulfatase (IDS) and the progressive lysosomal accumulation of sulfated glycosaminoglycans (GAGs). Methods A diagnosis of MPS II or Hunter syndrome was performed based on the following approach after a clinical and paraclinical suspicion. Two biochemical and molecular tests were carried out separately and according to the availability of the biological material. Results All patients in this cohort presented the most common MPS II clinical features. Electrophoresis of GAGs on a cellulose acetate plate in the presence of a high concentration of heparane sulfate showed an abnormal dermatan sulfate band in the patients compared with that in a control case. Furthermore, leukocyte IDS activity ranged from 0.00 to 0.75 nmol/h/mg of leukocyte protein in patients. Five previously reported mutations were identified in this study patients: one splice site mutation, c.240 + 1G > A; two missense mutations, p.R88P and p.G94D; a large deletion of exon 1 to exon 7; and one nonsense mutation, p.Q396*. In addition, two novel alterations were identified in the MPS II patients: one frame shift mutation, p.D450Nfs*95 and one nonsense mutation, p.Q204*. Additionally, five known IDS polymorphisms were identified in the patients: c.419–16 delT, c.641C > T (p.T214M), c.438 C > T (p.T146T), c.709-87G > A, and c.1006 + 38 T > C. Conclusions The high level of urine GAGs and the deficiency of iduronate 2-sulfatase activity was associated with the phenotype expression of Hunter syndrome. Molecular testing was useful for the patients’ phenotypic classification and the detection of carriers.
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Affiliation(s)
- L Chkioua
- Research Laboratory of Human Genome and Multifactorial Diseases, Faculty of Pharmacy, University of Monastir, Street Avicenne, 5000, Monastir, Tunisie.
| | - O Grissa
- Research Laboratory of Human Genome and Multifactorial Diseases, Faculty of Pharmacy, University of Monastir, Street Avicenne, 5000, Monastir, Tunisie
| | - N Leban
- Research Laboratory of Human Genome and Multifactorial Diseases, Faculty of Pharmacy, University of Monastir, Street Avicenne, 5000, Monastir, Tunisie
| | - M Gribaa
- Department of Cytogenetic and Reproductive Biology Farhat HACHED Hospital, Sousse, Tunisia
| | - H Boudabous
- Laboratory of pediatrics, La Rabta Hospital Tunis, Tunis, Tunisia
| | - H Ben Turkia
- Laboratory of pediatrics, La Rabta Hospital Tunis, Tunis, Tunisia
| | - S Ferchichi
- Biochemistry Laboratory, Farhat HACHED Hospital Sousse, Sousse, Tunisia
| | - N Tebib
- Laboratory of pediatrics, La Rabta Hospital Tunis, Tunis, Tunisia
| | - S 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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D’Avanzo F, Rigon L, Zanetti A, Tomanin R. Mucopolysaccharidosis Type II: One Hundred Years of Research, Diagnosis, and Treatment. Int J Mol Sci 2020; 21:E1258. [PMID: 32070051 PMCID: PMC7072947 DOI: 10.3390/ijms21041258] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 02/10/2020] [Accepted: 02/11/2020] [Indexed: 12/11/2022] Open
Abstract
Mucopolysaccharidosis type II (MPS II, Hunter syndrome) was first described by Dr. Charles Hunter in 1917. Since then, about one hundred years have passed and Hunter syndrome, although at first neglected for a few decades and afterwards mistaken for a long time for the similar disorder Hurler syndrome, has been clearly distinguished as a specific disease since 1978, when the distinct genetic causes of the two disorders were finally identified. MPS II is a rare genetic disorder, recently described as presenting an incidence rate ranging from 0.38 to 1.09 per 100,000 live male births, and it is the only X-linked-inherited mucopolysaccharidosis. The complex disease is due to a deficit of the lysosomal hydrolase iduronate 2-sulphatase, which is a crucial enzyme in the stepwise degradation of heparan and dermatan sulphate. This contributes to a heavy clinical phenotype involving most organ-systems, including the brain, in at least two-thirds of cases. In this review, we will summarize the history of the disease during this century through clinical and laboratory evaluations that allowed its definition, its correct diagnosis, a partial comprehension of its pathogenesis, and the proposition of therapeutic protocols. We will also highlight the main open issues related to the possible inclusion of MPS II in newborn screenings, the comprehension of brain pathogenesis, and treatment of the neurological compartment.
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Affiliation(s)
- Francesca D’Avanzo
- Laboratory of Diagnosis and Therapy of Lysosomal Disorders, Department of Women’s and Children ‘s Health, University of Padova, Via Giustiniani 3, 35128 Padova, Italy; (F.D.); (A.Z.)
- Fondazione Istituto di Ricerca Pediatrica “Città della Speranza”, Corso Stati Uniti 4, 35127 Padova, Italy;
| | - Laura Rigon
- Fondazione Istituto di Ricerca Pediatrica “Città della Speranza”, Corso Stati Uniti 4, 35127 Padova, Italy;
- Molecular Developmental Biology, Life & Medical Science Institute (LIMES), University of Bonn, 53115 Bonn, Germany
| | - Alessandra Zanetti
- Laboratory of Diagnosis and Therapy of Lysosomal Disorders, Department of Women’s and Children ‘s Health, University of Padova, Via Giustiniani 3, 35128 Padova, Italy; (F.D.); (A.Z.)
- Fondazione Istituto di Ricerca Pediatrica “Città della Speranza”, Corso Stati Uniti 4, 35127 Padova, Italy;
| | - Rosella Tomanin
- Laboratory of Diagnosis and Therapy of Lysosomal Disorders, Department of Women’s and Children ‘s Health, University of Padova, Via Giustiniani 3, 35128 Padova, Italy; (F.D.); (A.Z.)
- Fondazione Istituto di Ricerca Pediatrica “Città della Speranza”, Corso Stati Uniti 4, 35127 Padova, Italy;
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Brusius-Facchin AC, Rojas Malaga D, Leistner-Segal S, Giugliani R. Recent advances in molecular testing to improve early diagnosis in children with mucopolysaccharidoses. Expert Rev Mol Diagn 2018; 18:855-866. [DOI: 10.1080/14737159.2018.1523722] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
| | - Diana Rojas Malaga
- Medical Genetics Service, HCPA, Porto Alegre, RS, Brazil
- Postgraduate Program of Genetics and Molecular Biology, UFRGS, Porto Alegre, RS, Brazil
| | - Sandra Leistner-Segal
- Medical Genetics Service, HCPA, Porto Alegre, RS, Brazil
- Postgraduate Program in Medical Science, UFRGS, Porto Alegre, RS, Brazil
| | - Roberto Giugliani
- Medical Genetics Service, HCPA, Porto Alegre, RS, Brazil
- Postgraduate Program of Genetics and Molecular Biology, UFRGS, Porto Alegre, RS, Brazil
- Postgraduate Program in Medical Science, UFRGS, Porto Alegre, RS, Brazil
- Department of Genetics, UFRGS, Porto Alegre, RS, Brazil
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Ngiwsara L, Rojnueangnit K, Wattanasirichaigoon D, Tim-Aroon T, Sawangareetrakul P, Champattanachai V, Ketudat-Cairns JR, Svasti J. Molecular analysis of the novel IDS allele in a Thai family with mucopolysaccharidosis type II: The c.928C>T (p.Gln310*) transcript is sensitive to nonsense-mediated mRNA decay. Exp Ther Med 2017; 13:2989-2996. [PMID: 28588666 PMCID: PMC5450777 DOI: 10.3892/etm.2017.4303] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 01/26/2017] [Indexed: 11/06/2022] Open
Abstract
Hunter syndrome (or mucopolysaccharidosis type II, MPS II) is an X-linked recessive disorder induced by a deficiency of the iduronate 2-sulfatase (IDS) enzyme, resulting in the accumulation of glycosaminoglycan substrates, heparan sulfate and dermatan sulfate, in the lysosomes. The progressive accumulation of undegraded metabolites induces cell and tissue dysfunction, leading to multi-systemic pathology. The heterogeneity of clinical phenotypes, ranging from mild to severe forms, results from different mutations in the IDS gene. To date, >550 MPS II causal mutations have been reported in the IDS gene, of which ~10% are nonsense mutations that lead to premature protein termination. In the present study, the IDS mutation causing MPS II in an extended Thai family was identified using IDS enzyme assay and IDS gene exon sequencing. Three family members were enzymatically confirmed to have MPS II and to carry the novel IDS nonsense allele c.928C>T (p.Gln310*). The IDS mRNA levels were evaluated by reverse transcription-quantitative polymerase chain reaction, which demonstrated that all patients exhibited a reduction of IDS mRNA, suggesting its degradation by nonsense-mediated mRNA decay. Expression of wild type and mutant IDS in COS-7 cells revealed that the IDS p.Gln310* mutant lacked IDS activity, consistent with production of a nonfunctional, prematurely truncated protein. Taken together, these results indicate that the IDS c.928C>T (p.Gln310*) mutation is a severe disease-causing mutation for MPS II.
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Affiliation(s)
- Lukana Ngiwsara
- Laboratory of Biochemistry, Chulaborn Research Institute, Bangkok 10210, Thailand
| | - Kitiwan Rojnueangnit
- Pediatrics Department, Faculty of Medicine, Thammasat University, Bangkok 10200, Thailand
| | - Duangrurdee Wattanasirichaigoon
- Department of Pediatrics, Division of Medical Genetics, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok 10400, Thailand
| | - Thipwimol Tim-Aroon
- Department of Pediatrics, Division of Medical Genetics, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok 10400, Thailand
| | | | | | - James R. Ketudat-Cairns
- Laboratory of Biochemistry, Chulaborn Research Institute, Bangkok 10210, Thailand
- School of Chemistry, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand
| | - Jisnuson Svasti
- Laboratory of Biochemistry, Chulaborn Research Institute, Bangkok 10210, Thailand
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Hui WWI, Jiang P, Tong YK, Lee WS, Cheng YKY, New MI, Kadir RA, Chan KCA, Leung TY, Lo YMD, Chiu RWK. Universal Haplotype-Based Noninvasive Prenatal Testing for Single Gene Diseases. Clin Chem 2017; 63:513-524. [DOI: 10.1373/clinchem.2016.268375] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Accepted: 11/17/2016] [Indexed: 01/02/2023]
Abstract
Abstract
BACKGROUND
Researchers have developed approaches for the noninvasive prenatal testing of single gene diseases. One approach that allows for the noninvasive assessment of both maternally and paternally inherited mutations involves the analysis of single nucleotide polymorphisms (SNPs) in maternal plasma DNA with reference to parental haplotype information. In the past, parental haplotypes were resolved by complex experimental methods or inferential approaches, such as through the analysis of DNA from other affected family members. Recently, microfluidics-based linked-read sequencing technology has become available and allows the direct haplotype phasing of the whole genome rapidly. We explored the feasibility of applying this direct haplotyping technology in noninvasive prenatal testing.
METHODS
We first resolved the haplotypes of parental genomes with the use of linked-read sequencing technology. Then, we identified SNPs within and flanking the genes of interest in maternal plasma DNA by targeted sequencing. Finally, we applied relative haplotype dosage analysis to deduce the mutation inheritance status of the fetus.
RESULTS
Haplotype phasing and relative haplotype dosage analysis of 12 out of 13 families were successfully achieved. The mutational status of these 12 fetuses was correctly classified.
CONCLUSIONS
High-throughput linked-read sequencing followed by maternal plasma-based relative haplotype dosage analysis represents a streamlined approach for noninvasive prenatal testing of inherited single gene diseases. The approach bypasses the need for mutation-specific assays and is not dependent on the availability of DNA from other affected family members. Thus, the approach is universally applicable to pregnancies at risk for the inheritance of a single gene disease.
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Affiliation(s)
- Winnie W I Hui
- Department of Chemical Pathology, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Peiyong Jiang
- Department of Chemical Pathology, The Chinese University of Hong Kong, Hong Kong SAR, China
- Centre for Research into Circulating Fetal Nucleic Acids, Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, China
| | - Yu K Tong
- Department of Chemical Pathology, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Wing-Shan Lee
- Department of Chemical Pathology, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Yvonne K Y Cheng
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Maria I New
- Department of Pediatrics, Icahn School of Medicine at Mount Sinai, NY
| | - Rezan A Kadir
- Department of Obstetrics and Gynaecology, Royal Free London NHS Foundation Trust, London, UK
- Katharine Dormandy Haemophilia Centre and Thrombosis Unit, Royal Free London NHS Foundation Trust, London, UK
| | - K C Allen Chan
- Department of Chemical Pathology, The Chinese University of Hong Kong, Hong Kong SAR, China
- Centre for Research into Circulating Fetal Nucleic Acids, Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, China
| | - Tak Y Leung
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Y M Dennis Lo
- Department of Chemical Pathology, The Chinese University of Hong Kong, Hong Kong SAR, China
- Centre for Research into Circulating Fetal Nucleic Acids, Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, China
| | - Rossa W K Chiu
- Department of Chemical Pathology, The Chinese University of Hong Kong, Hong Kong SAR, China
- Centre for Research into Circulating Fetal Nucleic Acids, Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, China
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12
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Detailed molecular characterization of a novel IDS exonic mutation associated with multiple pseudoexon activation. J Mol Med (Berl) 2016; 95:299-309. [PMID: 27837218 DOI: 10.1007/s00109-016-1484-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 10/12/2016] [Accepted: 11/01/2016] [Indexed: 12/21/2022]
Abstract
Mutations affecting splicing underlie the development of many human genetic diseases, but rather rarely through mechanisms of pseudoexon activation. Here, we describe a novel c.1092T>A mutation in the iduronate-2-sulfatase (IDS) gene detected in a patient with significantly decreased IDS activity and a clinical diagnosis of mild mucopolysaccharidosis II form. The mutation created an exonic de novo acceptor splice site and resulted in a complex splicing pattern with multiple pseudoexon activation in the patient's fibroblasts. Using an extensive series of minigene splicing experiments, we showed that the competition itself between the de novo and authentic splice site led to the bypass of the authentic one. This event then resulted in activation of several cryptic acceptor and donor sites in the upstream intron. As this was an unexpected and previously unreported mechanism of aberrant pseudoexon inclusion, we systematically analysed and disproved that the patient's mutation induced any relevant change in surrounding splicing regulatory elements. Interestingly, all pseudoexons included in the mature transcripts overlapped with the IDS alternative terminal exon 7b suggesting that this sequence represents a key element in the IDS pre-mRNA architecture. These findings extend the spectrum of mechanisms enabling pseudoexon activation and underscore the complexity of mutation-induced splicing aberrations. KEY MESSAGE Novel exonic IDS gene mutation leads to a complex splicing pattern. Mutation activates multiple pseudoexons through a previously unreported mechanism. Multiple cryptic splice site (ss) activation results from a bypass of authentic ss. Authentic ss bypass is due to a competition between de novo and authentic ss.
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13
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Alcántara-Ortigoza MA, García-de Teresa B, González-Del Angel A, Berumen J, Guardado-Estrada M, Fernández-Hernández L, Navarrete-Martínez JI, Maza-Morales M, Rius-Domínguez R. Wide allelic heterogeneity with predominance of large IDS gene complex rearrangements in a sample of Mexican patients with Hunter syndrome. Clin Genet 2016; 89:574-83. [PMID: 26762690 DOI: 10.1111/cge.12738] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Revised: 12/26/2015] [Accepted: 01/11/2016] [Indexed: 11/29/2022]
Abstract
Hunter syndrome or mucopolysaccharidosis type II (MPSII) is caused by pathogenic variants in the IDS gene. This is the first study that examines the mutational spectrum in 25 unrelated Mexican MPSII families. The responsible genotype was identified in 96% of the families (24/25) with 10 novel pathogenic variants: c.133G>C, c.1003C>T, c.1025A>C, c.463_464delinsCCGTATAGCTGG, c.754_767del, c.1132_1133del, c.1463del, c.508-1G>C, c.1006+1G>T and c.(-217_103del). Extensive IDS gene deletions were identified in four patients; using DNA microarray analysis two patients showed the loss of the entire AFF2 gene, and epilepsy developed in only one of them. Wide allelic heterogeneity was noted, with large gene alterations (e.g. IDS/IDSP1 gene inversions, partial to extensive IDS deletions, and one chimeric IDS-IDSP1 allele) that occurred at higher frequencies than previously reported (36% vs 18.9-29%). The frequency of carrier mothers (80%) is consistent with previous descriptions (>70%). Carrier assignment allowed molecular prenatal diagnoses. Notably, somatic and germline mosaicism was identified in one family, and two patients presented thrombocytopenic purpura and pancytopenia after idursulfase enzyme replacement treatment. Our findings suggest a wide allelic heterogeneity in Mexican MPSII patients; DNA microarray analysis contributes to further delineation of the resulting phenotype for IDS and neighboring loci deletions.
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Affiliation(s)
- M A Alcántara-Ortigoza
- Laboratorio de Biología Molecular, Departamento de Genética Humana, Instituto Nacional de Pediatría, Distrito Federal, México
| | - B García-de Teresa
- Laboratorio de Biología Molecular, Departamento de Genética Humana, Instituto Nacional de Pediatría, Distrito Federal, México
| | - A González-Del Angel
- Laboratorio de Biología Molecular, Departamento de Genética Humana, Instituto Nacional de Pediatría, Distrito Federal, México
| | - J Berumen
- Departamento de Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México, Distrito Federal, México.,Unidad de Medicina Genómica, Hospital General de México, Distrito Federal, México
| | - M Guardado-Estrada
- Unidad de Medicina Genómica, Hospital General de México, Distrito Federal, México
| | - L Fernández-Hernández
- Laboratorio de Biología Molecular, Departamento de Genética Humana, Instituto Nacional de Pediatría, Distrito Federal, México
| | - J I Navarrete-Martínez
- Servicio de Genética. Hospital de Alta Especialidad PEMEX Picacho Sur, Distrito Federal, México
| | - M Maza-Morales
- Médico Residente de Pediatría, Instituto Nacional de Pediatría, Distrito Federal, México
| | - R Rius-Domínguez
- Médico Residente de Genética Médica, Departamento de Genética Humana, Instituto Nacional de Pediatría, Distrito Federal, México
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14
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Abstract
BACKGROUND Mucopolysaccharidosis type II (MPSII), also known as Hunter syndrome, is an X-linked disorder caused by mutations in the iduronate 2 sulfatase (IDS) gene. This enzyme catalyzes the initial step in the catabolism of heparan sulfate and dermatan sulfate; thus, its deficiency leads to the accumulation of these glycosaminoglycans. MPS II has significant allelic heterogeneity, making the establishment of genotype-phenotype correlations difficult. This study assessed clinical features in combination with deep genotyping of a group of Colombian patients with MPS II and attempted to establish a degree of genotype-phenotype correlation by employing bioinformatic tools. METHODS Eighteen patients were included in this study, 11% of whom were non-neuronopathic, and the other 89% were neuronopathic. Samples were all analyzed using three molecular methodologies: MLPA, direct exon sequencing, and RFLP analysis. RESULTS A total of 13 mutations were identified, 6 of which were novel (c.548_564dup16, c.477insT, c.595_607del12, c. 549_562del13, c.182delC, and a complete deletion of exon 7). The frequency of common mutations (R468Q, Q465X, K347Q, K236N, S71N, R88H, and a conversion phenomenon) was 53.85%. The S71N mutation was frequent among the attenuated phenotype, while private frameshift mutations and rearrangements were seen in patients with severe phenotypes. Molecular docking was performed on the wild-type and mutant IDS proteins, which revealed changes in the enzyme-substrate interaction for the mutant IDS. CONCLUSION The frequency of novel mutations (46.15%) is similar to what has been reported elsewhere. The use of bioinformatic tools showed differences in enzyme-substrate interactions. Studies with larger groups of patients are needed.
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15
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Lonardo F, Di Natale P, Lualdi S, Acquaviva F, Cuoco C, Scarano F, Maioli M, Pavone LM, Di Gregorio G, Filocamo M, Scarano G. Mucopolysaccharidosis type II in a female patient with a reciprocal X;9 translocation and skewed X chromosome inactivation. Am J Med Genet A 2014; 164A:2627-32. [PMID: 25044788 DOI: 10.1002/ajmg.a.36667] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2014] [Accepted: 06/09/2014] [Indexed: 11/08/2022]
Abstract
Mucopolysaccharidosis type II (MPS II or Hunter syndrome) is a rare X-linked disorder caused by deficient activity of the lysosomal enzyme, iduronate-2-sulfatase (IDS). Phenotypic expression of MPS II in female patients rarely occurs and may be the result of (i) structural abnormalities of the X chromosome, (ii) homozygosity for disease-causing mutations, or (iii) skewed X-chromosome inactivation, in which the normal IDS allele is preferentially inactivated and the abnormal IDS allele is active. We report here on a female patient with clinical MPS II manifestations, deficiency of IDS enzyme activity and a de novo balanced reciprocal X;9 translocation. As our patient has a skewed XCI pattern, but neither genomic IDS mutations nor abnormal IDS transcripts were detected, we speculate about the possible role of the chromosomal rearrangement in reducing the IDS translation efficiency.
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16
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Chistiakov DA, Savost'anov KV, Kuzenkova LM, Gevorkyan AK, Pushkov AA, Nikitin AG, Pakhomov AV, Vashakmadze ND, Zhurkova NV, Podkletnova TV, Mayansky NA, Namazova-Baranova LS, Baranov AA. Molecular characteristics of patients with glycosaminoglycan storage disorders in Russia. Clin Chim Acta 2014; 436:112-20. [PMID: 24875751 DOI: 10.1016/j.cca.2014.05.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2014] [Revised: 05/16/2014] [Accepted: 05/18/2014] [Indexed: 02/09/2023]
Abstract
BACKGROUND The mucopolysaccharidoses (MPSs) are rare genetic disorders caused by mutations in lysosomal enzymes involved in the degradation of glycosaminoglycans (GAGs). In this study, we analyzed a total of 48 patients including MPSI (n=6), MPSII (n=18), MPSIIIA (n=11), MPSIVA (n=3), and MPSVI (n=10). METHODS In MPS patients, urinary GAGs were colorimetrically assayed. Enzyme activity was quantified by colorimetric and fluorimetric assays. To find mutations, all IDUA, IDS, SGSH, GALNS, and ARSB exons and intronic flanks were sequenced. New mutations were functionally assessed by reconstructing mutant alleles with site-directed mutagenesis followed with expression of wild-type and mutant genetic variants in CHO cells, measuring enzymatic activity, and Western blot analysis of protein expression of normal and mutated enzymes in cell lysates. RESULTS A total of five novel mutations were found including p.Asn348Lys (IDUA) in MPSI, p.Tyr240Cys (GALNS) in MPSIVA, and three ARSB mutations (p.Gln110*, p.Asn262Lysfs*14, and pArg315*) in MPSVI patients. In case of mutations p.Asn348Lys, p.Asn262Lysfs*14, and p.Gln110*, no mutant protein was detected while activity of the mutant protein was <1% of that of the normal enzyme. For p.Tyr240Cys, a trace of mutant protein was observed with a remnant activity of 3.6% of the wild-type GALNS activity. For pArg315*, a truncated 30-kDa protein that had 7.9% of activity of the normal ARSB was detected. CONCLUSIONS These data further enrich our knowledge of the genetic background of MPSs.
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Affiliation(s)
- Dimitry A Chistiakov
- Department of Medical Nanobiotechnology, Pirogov Russian State Medical University, 117997 Moscow, Russia; Department of Molecular Genetic Diagnostics, Division of Laboratory Medicine, Institute of Pediatrics, Research Center for Children's Health, 119991 Moscow, Russia.
| | - Kirill V Savost'anov
- Department of Molecular Genetic Diagnostics, Division of Laboratory Medicine, Institute of Pediatrics, Research Center for Children's Health, 119991 Moscow, Russia
| | - Lyudmila M Kuzenkova
- Department of Psychoneurology and Psychosomatic Pathology, Institute of Pediatrics, Research Center for Children's Health, 119991 Moscow, Russia
| | - Anait K Gevorkyan
- Institute of Preventive Pediatrics and Rehabilitation, Research Center for Children's Health, 119991 Moscow, Russia
| | - Alexander A Pushkov
- Department of Molecular Genetic Diagnostics, Division of Laboratory Medicine, Institute of Pediatrics, Research Center for Children's Health, 119991 Moscow, Russia
| | - Alexey G Nikitin
- Department of Molecular Genetic Diagnostics, Division of Laboratory Medicine, Institute of Pediatrics, Research Center for Children's Health, 119991 Moscow, Russia
| | - Alexander V Pakhomov
- Department of Molecular Genetic Diagnostics, Division of Laboratory Medicine, Institute of Pediatrics, Research Center for Children's Health, 119991 Moscow, Russia
| | - Nato D Vashakmadze
- Department of Psychoneurology and Psychosomatic Pathology, Institute of Pediatrics, Research Center for Children's Health, 119991 Moscow, Russia
| | - Natalia V Zhurkova
- Department of Molecular Genetic Diagnostics, Division of Laboratory Medicine, Institute of Pediatrics, Research Center for Children's Health, 119991 Moscow, Russia
| | - Tatiana V Podkletnova
- Department of Psychoneurology and Psychosomatic Pathology, Institute of Pediatrics, Research Center for Children's Health, 119991 Moscow, Russia
| | - Nikolai A Mayansky
- Department of Experimental Immunology and Virology, Division of Laboratory Medicine, Institute of Pediatrics, Research Center for Children's Health, 119991 Moscow, Russia
| | - Leila S Namazova-Baranova
- Institute of Preventive Pediatrics and Rehabilitation, Research Center for Children's Health, 119991 Moscow, Russia
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17
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Brusius-Facchin AC, Schwartz IVD, Zimmer C, Ribeiro MG, Acosta AX, Horovitz D, Monlleó IL, Fontes MIB, Fett-Conte A, Sobrinho RPO, Duarte AR, Boy R, Mabe P, Ascurra M, de Michelena M, Tylee KL, Besley GTN, Garreton MCV, Giugliani R, Leistner-Segal S. Mucopolysaccharidosis type II: identification of 30 novel mutations among Latin American patients. Mol Genet Metab 2014; 111:133-8. [PMID: 24125893 DOI: 10.1016/j.ymgme.2013.08.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Accepted: 08/23/2013] [Indexed: 10/26/2022]
Abstract
In this study, 103 unrelated South-American patients with mucopolysaccharidosis type II (MPS II) were investigated aiming at the identification of iduronate-2-sulfatase (IDS) disease causing mutations and the possibility of some insights on the genotype-phenotype correlation The strategy used for genotyping involved the identification of the previously reported inversion/disruption of the IDS gene by PCR and screening for other mutations by PCR/SSCP. The exons with altered mobility on SSCP were sequenced, as well as all the exons of patients with no SSCP alteration. By using this strategy, we were able to find the pathogenic mutation in all patients. Alterations such as inversion/disruption and partial/total deletions of the IDS gene were found in 20/103 (19%) patients. Small insertions/deletions/indels (<22 bp) and point mutations were identified in 83/103 (88%) patients, including 30 novel mutations; except for a higher frequency of small duplications in relation to small deletions, the frequencies of major and minor alterations found in our sample are in accordance with those described in the literature.
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Affiliation(s)
| | - I V D Schwartz
- Post Graduation Program in Medical Sciences, UFRGS, Porto Alegre, RS, Brazil; Department of Genetics, UFRGS, Porto Alegre, Brazil; Medical Genetics Service, Hospital de Clínicas de Porto Alegre, Brazil
| | - C Zimmer
- Medical Genetics Service, Hospital de Clínicas de Porto Alegre, Brazil
| | - M G Ribeiro
- Clinical Genetics Service, IPPMG, UFRJ, Rio de Janeiro, Brazil
| | - A X Acosta
- Department of Pediatrics, UFBA, Salvador, Brazil
| | - D Horovitz
- Instituto Fernandes Figueira, FIOCRUZ, Rio de Janeiro, Brazil
| | - I L Monlleó
- Department of Pediatrics, UNCISAL, Maceió, Brazil
| | - M I B Fontes
- Department of Pediatrics, UNCISAL, Maceió, Brazil
| | - A Fett-Conte
- Department of Molecular Biology, FAMERP, São José do Rio Preto, Brazil
| | | | - A R Duarte
- Medical Genetics Service, IMIP, Recife, Brazil
| | - R Boy
- Mother and Child Department, UERJ, Rio de Janeiro, Brazil
| | - P Mabe
- Genetics and Metabolic Diseases Unit, INTA, University of Chile, Chile
| | - M Ascurra
- Department of Genetics, ILCS-UNA, Asunción, Paraguay
| | | | - K L Tylee
- Willink Biochemical Genetics Unit, Royal Manchester Children's Hospital, Manchester, UK
| | - G T N Besley
- Willink Biochemical Genetics Unit, Royal Manchester Children's Hospital, Manchester, UK
| | - M C V Garreton
- Unidad de Genética Clínica, Hospital Roberto del Río, Santiago, Chile
| | - R Giugliani
- Post Graduation Program in Medical Sciences, UFRGS, Porto Alegre, RS, Brazil; Department of Genetics, UFRGS, Porto Alegre, Brazil; Medical Genetics Service, Hospital de Clínicas de Porto Alegre, Brazil
| | - S Leistner-Segal
- Post Graduation Program in Medical Sciences, UFRGS, Porto Alegre, RS, Brazil; Department of Genetics, UFRGS, Porto Alegre, Brazil; Medical Genetics Service, Hospital de Clínicas de Porto Alegre, Brazil.
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18
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Zanetti A, Tomanin R, Rampazzo A, Rigon C, Gasparotto N, Cassina M, Clementi M, Scarpa M. A Hunter Patient with a Severe Phenotype Reveals Two Large Deletions and Two Duplications Extending 1.2 Mb Distally to IDS Locus. JIMD Rep 2014; 17:13-21. [PMID: 25059704 PMCID: PMC4241202 DOI: 10.1007/8904_2014_317] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 04/16/2014] [Accepted: 04/22/2014] [Indexed: 03/24/2023] Open
Abstract
Mucopolysaccharidosis type II (Hunter syndrome, MPS II) is an X-linked lysosomal storage disorder caused by the deficit of iduronate 2-sulfatase (IDS), an enzyme involved in the glycosaminoglycans (GAGs) degradation. We here report the case of a 9-year-old boy who was diagnosed with an extremely severe form of MPS II at 10 months of age. Sequencing of the IDS gene revealed the deletion of exons 1-7, extending distally and removing the entire pseudogene IDSP1. The difficulty to define the boundaries of the deletion and the particular severity of the patient phenotype suggested to verify the presence of pathological copy number variations (CNVs) in the genome, by the array CGH (aCGH) technology. The examination revealed the presence of two deletions alternate with two duplications, overall affecting a region of about 1.2 Mb distally to IDS gene. This is the first complex rearrangement involving IDS and extending to a large region located distally to it described in a severe Hunter patient, as evidenced by the CNVs databases interrogated. The analysis of the genes involved in the rearrangement and of the disorders correlated with them did not help to clarify the phenotype observed in our patient, except for the deletion of the IDS gene, which explains per se the Hunter phenotype. However, this cannot exclude a potential "contiguous gene syndrome" as well as the future rising of additional pathological symptoms associated with the other extra genes involved in the identified rearrangement.
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Affiliation(s)
- Alessandra Zanetti
- Laboratory of Diagnosis and Therapy of Lysosomal Disorders, Department of Women’s and Children’s Health, University of Padova, Padova, Italy
| | - Rosella Tomanin
- Laboratory of Diagnosis and Therapy of Lysosomal Disorders, Department of Women’s and Children’s Health, University of Padova, Padova, Italy
| | - Angelica Rampazzo
- Laboratory of Diagnosis and Therapy of Lysosomal Disorders, Department of Women’s and Children’s Health, University of Padova, Padova, Italy
| | - Chiara Rigon
- Clinical Genetics Unit, Department of Women’s and Children’s Health, University of Padova, Padova, Italy
| | - Nicoletta Gasparotto
- Laboratory of Diagnosis and Therapy of Lysosomal Disorders, Department of Women’s and Children’s Health, University of Padova, Padova, Italy
| | - Matteo Cassina
- Clinical Genetics Unit, Department of Women’s and Children’s Health, University of Padova, Padova, Italy
| | - Maurizio Clementi
- Clinical Genetics Unit, Department of Women’s and Children’s Health, University of Padova, Padova, Italy
| | - Maurizio Scarpa
- Laboratory of Diagnosis and Therapy of Lysosomal Disorders, Department of Women’s and Children’s Health, University of Padova, Padova, Italy
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Brusius-Facchin AC, Abrahão L, Schwartz IVD, Lourenço CM, Santos ES, Zanetti A, Tomanin R, Scarpa M, Giugliani R, Leistner-Segal S. Extension of the molecular analysis to the promoter region of the iduronate 2-sulfatase gene reveals genomic alterations in mucopolysaccharidosis type II patients with normal coding sequence. Gene 2013; 526:150-4. [PMID: 23707223 DOI: 10.1016/j.gene.2013.05.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Revised: 04/25/2013] [Accepted: 05/04/2013] [Indexed: 11/15/2022]
Abstract
Hunter disease or mucopolysaccharidosis type II (MPS II) is an X-linked recessive lysosomal disorder caused by the deficit of the enzyme iduronate-2-sulfatase (IDS), involved in the catabolism of the glycosaminoglycans heparan and dermatan sulfate. Our aim was to search for molecular defects in the promoter region of the IDS gene in patients with previous biochemical diagnosis of MPS II and after we sequenced the whole IDS coding region and the exon/intron boundaries without detecting any pathogenic mutations. Screening of the promoter region of four patients detected in two of them a 178 bp deletion and in the other two a single nucleotide substitution 818 bp upstream of the coding region. The latter had never been described before in MPS II patients and it turned out to be a polymorphism. Our experience suggests that MPS II patients with no mutations detected in the IDS coding region should be screened in the promoter region of the gene. Findings will hopefully help to clarify the relationship between genotype and phenotype and will be useful for the correct molecular diagnosis of Hunter patients and the identification of female carriers, the latter particularly important for genetic counseling.
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20
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Abstract
Lysosomal storage disorders (LSDs) are a large group of more than 50 different inherited metabolic diseases which, in the great majority of cases, result from the defective function of specific lysosomal enzymes and, in cases, of non-enzymatic lysosomal proteins or non-lysosomal proteins involved in lysosomal biogenesis. The progressive lysosomal accumulation of undegraded metabolites results in generalised cell and tissue dysfunction, and, therefore, multi-systemic pathology. Storage may begin during early embryonic development, and the clinical presentation for LSDs can vary from an early and severe phenotype to late-onset mild disease. The diagnosis of most LSDs--after accurate clinical/paraclinical evaluation, including the analysis of some urinary metabolites--is based mainly on the detection of a specific enzymatic deficiency. In these cases, molecular genetic testing (MGT) can refine the enzymatic diagnosis. Once the genotype of an individual LSD patient has been ascertained, genetic counselling should include prediction of the possible phenotype and the identification of carriers in the family at risk. MGT is essential for the identification of genetic disorders resulting from non-enzymatic lysosomal protein defects and is complementary to biochemical genetic testing (BGT) in complex situations, such as in cases of enzymatic pseudodeficiencies. Prenatal diagnosis is performed on the most appropriate samples, which include fresh or cultured chorionic villus sampling or cultured amniotic fluid. The choice of the test--enzymatic and/or molecular--is based on the characteristics of the defect to be investigated. For prenatal MGT, the genotype of the family index case must be known. The availability of both tests, enzymatic and molecular, enormously increases the reliability of the entire prenatal diagnostic procedure. To conclude, BGT and MGT are mostly complementary for post- and prenatal diagnosis of LSDs. Whenever genotype/phenotype correlations are available, they can be helpful in predicting prognosis and in making decisions about therapy.
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Affiliation(s)
- Mirella Filocamo
- S.S.D. Lab. Diagnosi Pre-Postnatale Malattie Metaboliche, Dipartimento di Neuroscienze, IRCCS G. Gaslini, Largo G. Gaslini 5, Genova, Italy.
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21
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Zhang H, Li J, Zhang X, Wang Y, Qiu W, Ye J, Han L, Gao X, Gu X. Analysis of the IDS gene in 38 patients with Hunter syndrome: the c.879G>A (p.Gln293Gln) synonymous variation in a female create exonic splicing. PLoS One 2011; 6:e22951. [PMID: 21829674 PMCID: PMC3150403 DOI: 10.1371/journal.pone.0022951] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2011] [Accepted: 07/01/2011] [Indexed: 11/18/2022] Open
Abstract
Background Hunter syndrome (mucopolysaccharidosis type II, MPS II) is a rare disease inherited in an X-linked autosomal recessive pattern. It is the prevailing form of the mucopolysaccharidoses in China. Here we investigated mutations of IDS (iduronate 2-sulfatase) gene in 38 unrelated Chinese patients, one of which is a female. Methods Peripheral leucocytes were collected from the patients and the IDS gene was amplified to looking for the variations. For a female patient, the X chromosome status was analyzed by androgen receptor X-inactivation assay and the mutation impact on RNA level was further performed by reverse transcription polymerase chain reaction. Results We discovered that point mutations constituted the major form while mutations in codon p.R468 defined the largest number of patients in our cohort. Consistent with data from other ethnic groups, exons 9 and 3 had comparatively more mutations, while exon 2 had quite a few mutations unique to Chinese patients. Of the 30 different mutations identified, only 9 were novel: one was a premature termination mutation, i.e., c.196C>T (p.Gln66X); three were missense mutations, i.e., c.200T>C (p.Leu67Pro), c.215T>C (p.Leu72Pro), c.389C>T (p.Thr130Ile); one was a small deletion, i.e., c.1104_1122del19 (p.Ser369ArgfsX16); and one was a deletion that spanned both exons 8 and 9 deletion leading to gross structural changes in the IDS gene. In addition, a synonymous mutation c.879G>A (p.Gln293Gln) was identified in a female Hunter disease patient, which resulted in loss of the original splicing site, activated a cryptic splicing site upstream, leading to a 28 bp deletion and a premature termination at p. Tyr285GlufsX47. Together with concurrent skewed X-inactivation this was believed to facilitate the development of Hunter disease in this girl. Conclusions In conclusion, the molecular analysis of IDS gene in Chinese patients confirmed the Hunter disease diagnosis and expanded the mutation and clinical spectrum of this devastating disorder.
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Affiliation(s)
- Huiwen Zhang
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- * E-mail: (HZ); (XG)
| | - Jing Li
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xinshun Zhang
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yu Wang
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Wenjuan Qiu
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jun Ye
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Lianshu Han
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xiaolan Gao
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xuefan Gu
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- * E-mail: (HZ); (XG)
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22
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Oshima J, Lee JA, Breman AM, Fernandes PH, Babovic-Vuksanovic D, Ward PA, Wolfe LA, Eng CM, Del Gaudio D. LCR-initiated rearrangements at the IDS locus, completed with Alu-mediated recombination or non-homologous end joining. J Hum Genet 2011; 56:516-23. [PMID: 21593745 DOI: 10.1038/jhg.2011.51] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Mucopolysaccharidosis type II (MPS II) is caused by mutations in the IDS gene, which encodes the lysosomal enzyme iduronate-2-sulfatase. In ∼20% of MPS II patients the disorder is caused by gross IDS structural rearrangements. We identified two male cases harboring complex rearrangements involving the IDS gene and the nearby pseudogene, IDSP1, which has been annotated as a low-copy repeat (LCR). In both cases the rearrangement included a partial deletion of IDS and an inverted insertion of the neighboring region. In silico analyses revealed the presence of repetitive elements as well as LCRs at the junctions of rearrangements. Our models illustrate two alternative consequences of rearrangements initiated by non-allelic homologous recombination of LCRs: resolution by a second recombination event (that is, Alu-mediated recombination), or resolution by non-homologous end joining repair. These complex rearrangements have the potential to be recurrent and may be present among those MSP II cases with previously uncharacterized aberrations involving IDS.
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Affiliation(s)
- Junko Oshima
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
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23
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Sohn YB, Ki CS, Kim CH, Ko AR, Yook YJ, Lee SJ, Kim SJ, Park SW, Yeau S, Kwon EK, Han SJ, Choi EW, Lee SY, Kim JW, Jin DK. Identification of 11 novel mutations in 49 Korean patients with mucopolysaccharidosis type II. Clin Genet 2011; 81:185-90. [PMID: 21291454 DOI: 10.1111/j.1399-0004.2011.01641.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mucopolysaccharidosis type II (MPS II) or Hunter syndrome is a rare lysosomal storage disorder caused by a deficiency of iduronate-2-sulfatase (IDS). As MPS II is X-linked, patients are usually males with heterogeneous mutations ranging from point mutations to gross deletions and recombination. In 2003, we reported a mutation analysis of 25 patients with MPS II. In this study, 31 mutations in another 49 Korean patients (45 families) with MPS II are reported: 12 missense, nine deletions, four splicing, two nonsense, two insertions, one deletion/insertion, and IDS-IDS2 recombination mutations. Among these mutations, 11 were novel ones (4 missense mutations: Ser61Pro, Pro97Arg, Pro228Ala, and Pro261Ala; 5 deletions: c.344delA, c.420delG, c.768delT, c.1112delC and c.1402delC; 1 deletion/insertion: c.1222delinsTA; and 1 insertion mutation: c.359_360insATCC). The IDS-IDS2 recombination mutations were most frequently observed; all patients with this mutation had the severe MPS II phenotype. However, most of the patients (5/7) with the G374G splicing mutation had an attenuated phenotype, except for two sibling cases with the severe phenotype. Except for a few recurrent mutations such as the G374G, R443X, L522P, and recombination mutations, each patient had a unique individual mutation. Therefore, careful interpretation of genotype-phenotype correlations is warranted.
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Affiliation(s)
- Y B Sohn
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
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24
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[Identification of a novel mutation of IDS gene from a Chinese pedigree with MPS II]. YI CHUAN = HEREDITAS 2010; 31:1101-6. [PMID: 19933090 DOI: 10.3724/sp.j.1005.2009.01101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The purpose of this study was to understand the molecular genetic mechanism of mucopolysaccharidosis type II (MPS II) and to provide a prerequisite for future prenatal gene diagnosis. A preliminary diagnosis was made by qualitative detection of Urinary Glycosaminoglycans of the suspected MPS II proband. Then, mutation detection was performed on the proband and his family members with PCR and direct sequencing of PCR products. After the novel mutation of c.876 del 2 in IDS gene was detected, sequence analysis was performed on exon 6 of IDS gene of the 135 cases, which consisted of 120 randomly selected normal controls, and other 15 patients with MPS I, IV, and VI other than MPS II. Besides, the patho-genicity of the novel mutation was analyzed with the following 2 methods: conservative analysis of the sequence of muta-tion spots of different species and the direct test of the IDS enzyme activity of the patient and his relative family members. The result of uroscopy of the proband was strong positive (GAGs +++). There was a novel deletion mutation of c.876-877 del TC in the coding region of exon 6 of IDS gene, which was a hemizygous mutation. However, the mutation of his mother and sister was a heterozygous mutation. Detection of the exon 6 of IDS gene showed that the mutation was not found among normal controls and other patients with MPS I, IV, and VI other than MPS II. Homology comparison of amino acid sequences from different species showed that the phenylalanine (F) glutamine (Q) of the mutation site of c.876-877 del TC located in p.292-293 was highly conserved. The activity of IDS enzyme of the proband was only 2.3 nmol/4 h/mL, which was much lower than normal; but the activity of IDS enzyme of his father, mother and sister was 641.9 nmol/4 h/mL, 95.8 nmol/4h/mL and 103.2 nmol/4h/mL, respectively. These results illustrated that the deletion and frame-shift mutation of c.876-877 del TC detected was a novel pathologic mutation, which was the underlying cause of MPS II of this patient.
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25
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Keeratichamroen S, Cairns JRK, Wattanasirichaigoon D, Wasant P, Ngiwsara L, Suwannarat P, Pangkanon S, Kuptanon J, Tanpaiboon P, Rujirawat T, Liammongkolkul S, Svasti J. Molecular analysis of the iduronate-2-sulfatase gene in Thai patients with Hunter syndrome. J Inherit Metab Dis 2008; 31 Suppl 2:S303-11. [PMID: 18500569 DOI: 10.1007/s10545-008-0876-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2008] [Revised: 02/29/2008] [Accepted: 03/03/2008] [Indexed: 10/22/2022]
Abstract
Molecular defects in the gene encoding the enzyme iduronate-2-sulfatase (IDS) result in Hunter disease (mucopolysaccharidosis type II, MPS II). To determine the molecular basis of MPS II in Thailand, the IDS gene was analysed in 20 Thai patients with Hunter syndrome from 18 unrelated families. A total of 19 different mutations, including 9 missense mutations, 3 nonsense mutations, 3 splice site alterations, 1 deletion, 2 indels, and 1 rearrangement were identified, 8 of which were novel (p.R101C, p.D148V, p.G224A, p.K227E, p.E254X, p.W337X, c.440_442delinsTT and c.720_731delinsTTTCAGATGTTCTCCCCAG). Evaluation of the IDS activity of two hemizygous variants identified in the same patient, p.R101C and p.R468Q, by expression of IDS with the individual mutations in COS 7 cells indicated that only the p.R468Q mutation affected IDS protein activity. Two exonic mutations, c.257C>T (p.P86L) and c.418G>A, were found to activate multiple cryptic splice sites, resulting in aberrantly spliced transcripts. Thus, MPS II in Thailand is caused by a diverse set of defects affecting both IDS protein production and activity.
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Affiliation(s)
- S Keeratichamroen
- Laboratory of Biochemistry, Chulabhorn Research Institute, Bangkok, 10210, Thailand
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26
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Alves S, Mangas M, Prata MJ, Ribeiro G, Lopes L, Ribeiro H, Pinto-Basto J, Lima MR, Lacerda L. Molecular characterization of Portuguese patients with mucopolysaccharidosis type II shows evidence that the IDS gene is prone to splicing mutations. J Inherit Metab Dis 2006; 29:743-54. [PMID: 17063374 DOI: 10.1007/s10545-006-0403-z] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2006] [Revised: 08/09/2006] [Accepted: 08/31/2006] [Indexed: 11/30/2022]
Abstract
Mucopolysaccharidosis type II (MPS II) is an X-linked recessive lysosomal storage disease caused by a defect in the iduronate-2-sulfatase gene (IDS). Alternative splicing of the IDS gene can occur and the underlying regulatory mechanism may be rather complex. Nevertheless, little information is available on the role of variations at the IDS locus in the splicing process. Here we report that splice mutations at the IDS locus are an important source of MPS II pathogenicity, accounting for almost 56% of Portuguese cases. Among 16 unrelated Portuguese MPS II patients, 15 different mutations were identified: six intronic splice mutations (c.104-2AG, c.241-2A>G, c.241-1G>A, c.418+1G>A, c.880-8AG and c.1181-1G>C); two exonic splice mutations (c.1006G>lC and c.1122C>T); five missense mutations (D269V, D69V, D148N, R88C and P86L); one nonsense mutation (Q465Ter); one total IDS gene deletion; and one rearrangement involving a IDS gene inversion. Furthermore, nine of the 15 detected mutations affected the usual splicing pattern at the locus. Some of them are responsible for dramatic changes in the splicing mechanism. For example, the substitution mutation, c.418+1G>A, revealed the presence of an exonic sequence inside intron 3. Our study provides evidence that the IDS locus is prone to splicing mutations and that such susceptibility is particularly high in exon 3 and neighbouring regions. Consequently, mutation screening of the IDS gene cannot be restricted to gDNA examination. Unless cDNA analysis is also conducted, misclassifications as silent or missense mutations can be produced and even uncharacteristic splice-site mutations can be misinterpreted as classic splicing defects that may generate severe, unconventional splicing alterations.
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Affiliation(s)
- S Alves
- Institute of Medical Genetics Jacinto Magalhães, Porto, Portugal.
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27
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Lualdi S, Di Rocco M, Corsolini F, Spada M, Bembi B, Cotugno G, Battini R, Stroppiano M, Gabriela Pittis M, Filocamo M. Identification of nine new IDS alleles in mucopolysaccharidosis II. Quantitative evaluation by real-time RT-PCR of mRNAs sensitive to nonsense-mediated and nonstop decay mechanisms. Biochim Biophys Acta Mol Basis Dis 2006; 1762:478-84. [PMID: 16495038 DOI: 10.1016/j.bbadis.2006.01.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2005] [Revised: 01/05/2006] [Accepted: 01/06/2006] [Indexed: 10/25/2022]
Abstract
The present study aimed to characterize mutant alleles in Mucopolysaccharidosis II and evaluate possible reduction of mRNA amount consequent to nonsense-mediated or nonstop mRNA decay pathways. A combination of different approaches, including real-time RT-PCR, were used to molecularly characterize seventeen patients. Fifteen alleles were identified and nine of them were new. The novel alleles consisted of three missense mutations (p.S71R, p.P197R, p.C432R), two nonsense (p.Q66X, p.L359X), two frameshifts (p.V136fs75X, p.C432fs8X), one allele carrying two in-cis mutations [p.D252N;p.S369X], and a large deletion (p.G394_X551). Analysing these results it emerged that most of the alterations resulted in mutants leading to mRNAs with premature termination codons, and therefore, potentially sensitive to mRNA surveillance pathway. By using real-time RT-PCR, the mRNAs resulting (i) from substitutions that changed one amino acid to a stop codon (L359X, and S369X), or caused the shifted reading frame with premature introduction of a stop codon (C432fs8X), (ii) from large deletion (p.G394_X551) that included the termination codon, seemed to be subject to degradation by nonsense-mediated (i) or nonstop decay (ii) mechanisms, as mRNA was strongly underexpressed. On the contrary, two mutations (Q66X and V136fs75X) produced transcripts evading mRNA surveillance pathway despite both of them fulfilled the known criteria. These results confirm the wide variability of the mRNA expression levels previously reported and represent a further exception to the rules governing susceptibility to nonsense-mediated decay. A close examination of the molecular basis of the disease is becoming increasingly important for optimising the choices of available or forthcoming therapies such as, enzyme replacement therapy or enzyme enhancement therapy.
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Affiliation(s)
- Susanna Lualdi
- Laboratorio Diagnosi Pre-Postnatale Malattie Metaboliche, IRCCS G.Gaslini-Largo G.Gaslini-16147 Genova, Italy
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28
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Detection of a new mutation (1467-A) for the pedigree with mucopolysaccharidosis type II from a chinese family. CHINESE SCIENCE BULLETIN-CHINESE 2005. [DOI: 10.1007/bf03183645] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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