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Essawi ML, Fateen EM, Atia HA, Eissa NR, Aboul-Ezz EH, Ibrahim MM, Hassan HA, Temtamy SA. Quaternary diagnostics scheme for mucolipidosis II and detection of novel mutation in GNPTAB gene. J Genet Eng Biotechnol 2021; 19:111. [PMID: 34342781 PMCID: PMC8333150 DOI: 10.1186/s43141-021-00204-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 07/03/2021] [Indexed: 11/21/2022]
Abstract
Background Mucolipidosis II (ML II α/β) is an inherited lysosomal storage disorder caused by deficiency of GlcNAc-phosphotransferase enzyme and results in mis-targeting of multiple lysosomal enzymes. Affected patients are characterized by skeletal deformities and developmental delay. Homozygous or compound heterozygous mutations in GNPTAB gene are associated with the clinical presentation. This is the first study to characterize the underlying genetics of ML among a cohort of Egyptian patients. ML II diagnosis established by clinical assessment, biochemical evaluation of enzymes, electron microscopy examination of gingival inclusion bodies, and molecular study of GNPTAB gene using targeted next-generation sequencing panel in 8 patients form 8 unrelated Egyptian families. Results Sequencing revealed 3 mutations in GNPTAB gene; 1 novel frame-shift mutation in exon 19 (c.3488_3488delC) and 2 previously reported mutations (c.1759C>T in exon 13 and c.3503_3504delTC in exon 19). All patients were homozygous for their corresponding mutations and the parents were consanguineous. Conclusions According to the established quaternary diagnostic scheme, ML II was the final diagnosis in eight patients. The most common mutation was the frame shift c.3503_3504delTC mutation, found in 5 patients and associated with a severe phenotype.
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Affiliation(s)
- Mona L Essawi
- Department of Medical Molecular Genetics, Division of Human Genetics and Genome Research, Dokki, Cairo, 12311, Egypt.,National Research Centre, Cairo, Egypt
| | - Ekram M Fateen
- Department of Medical Molecular Genetics, Division of Human Genetics and Genome Research, Dokki, Cairo, 12311, Egypt.,National Research Centre, Cairo, Egypt
| | - Hanan A Atia
- Department of Pharmacology and Toxicology, College of Pharmacy, Hail University, Hail, Kingdom of Saudi Arabia.,Department of Biochemistry, Faculty of Pharmacy (Girls), Al Azhar University, Cairo, Egypt
| | - Noura R Eissa
- Department of Medical Molecular Genetics, Division of Human Genetics and Genome Research, Dokki, Cairo, 12311, Egypt. .,National Research Centre, Cairo, Egypt.
| | - Eman H Aboul-Ezz
- National Research Centre, Cairo, Egypt.,Division of Oral & Dental Research, Department of Basic Dental Sciences, Dokki, Cairo, 12311, Egypt
| | - Mona M Ibrahim
- National Research Centre, Cairo, Egypt.,Division of Human Genetics and Genome Research, Department of Biochemical Genetics, Dokki, Cairo, 12311, Egypt
| | - Heba A Hassan
- Department of Medical Molecular Genetics, Division of Human Genetics and Genome Research, Dokki, Cairo, 12311, Egypt.,National Research Centre, Cairo, Egypt
| | - Samia A Temtamy
- National Research Centre, Cairo, Egypt.,Division of Human Genetics and Genome Research, Department of Clinical Genetics, Dokki, Cairo, 12311, Egypt
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2
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Gunasekaran ND, Jayasankaran C, Justin Margret J, Krishnamoorthy M, Srisailapathy CRS. Evaluation of recurrent GNPTAB, GNPTG, and NAGPA variants associated with stuttering. ADVANCED GENETICS (HOBOKEN, N.J.) 2021; 2:e10043. [PMID: 36618124 PMCID: PMC9744500 DOI: 10.1002/ggn2.10043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 05/02/2021] [Accepted: 05/03/2021] [Indexed: 01/11/2023]
Abstract
Stuttering is a childhood-onset fluency disorder, intertwined with physiological, emotional, and anxiety factors. The present study was designed to evaluate the recurrence of the reported mutations among three previously implicated (GNPTAB, GNPTG, NAGPA) candidate genes, in persons with stuttering from south India. Mutation screening was performed among 64 probands on 12 specific exons, by Sanger sequencing. A total of 12 variants were identified, which included five nonsynonymous, five synonymous, and two noncoding variants. Three unrelated probands harbored heterozygous missense variants at conserved coding positions across species (p. Glu1200Lys in GNPTAB, p. Ile268Leu in GNPTG and p. Arg44Pro in NAGPA). Of these, only one variant (p. Glu1200Lys in GNPTAB) cosegregated with the affected status while p. Ile268Leu in GNPTG gene was found to be a rare de novo variant. Although this study identified some previously reported variants that have been claimed to have a role in stuttering, we confirmed only one of these to be a likely causal de novo variant (p.Ile268Leu) in the GNPTG gene at an allele frequency of 0.8% (1/128) in the families with stuttering.
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Affiliation(s)
- Nandhini Devi Gunasekaran
- Department of Genetics, Post Graduate Institute of Basic Medical SciencesUniversity of Madras, Taramani CampusChennaiIndia
| | - Chandru Jayasankaran
- Department of Genetics, Post Graduate Institute of Basic Medical SciencesUniversity of Madras, Taramani CampusChennaiIndia
- LifeBytes India Pvt. LtdBengaluruKarnatakaIndia
| | - Jeffrey Justin Margret
- Department of Genetics, Post Graduate Institute of Basic Medical SciencesUniversity of Madras, Taramani CampusChennaiIndia
| | - Mathuravalli Krishnamoorthy
- Department of Genetics, Post Graduate Institute of Basic Medical SciencesUniversity of Madras, Taramani CampusChennaiIndia
| | - C. R. Srikumari Srisailapathy
- Department of Genetics, Post Graduate Institute of Basic Medical SciencesUniversity of Madras, Taramani CampusChennaiIndia
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3
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Akter H, Hossain MS, Dity NJ, Rahaman MA, Furkan Uddin KM, Nassir N, Begum G, Hameid RA, Islam MS, Tusty TA, Basiruzzaman M, Sarkar S, Islam M, Jahan S, Lim ET, Woodbury-Smith M, Stavropoulos DJ, O'Rielly DD, Berdeiv BK, Nurun Nabi AHM, Ahsan MN, Scherer SW, Uddin M. Whole exome sequencing uncovered highly penetrant recessive mutations for a spectrum of rare genetic pediatric diseases in Bangladesh. NPJ Genom Med 2021; 6:14. [PMID: 33594065 PMCID: PMC7887195 DOI: 10.1038/s41525-021-00173-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 01/06/2021] [Indexed: 01/31/2023] Open
Abstract
Collectively, rare genetic diseases affect a significant number of individuals worldwide. In this study, we have conducted whole-exome sequencing (WES) and identified underlying pathogenic or likely pathogenic variants in five children with rare genetic diseases. We present evidence for disease-causing autosomal recessive variants in a range of disease-associated genes such as DHH-associated 46,XY gonadal dysgenesis (GD) or 46,XY sex reversal 7, GNPTAB-associated mucolipidosis II alpha/beta (ML II), BBS1-associated Bardet-Biedl Syndrome (BBS), SURF1-associated Leigh Syndrome (LS) and AP4B1-associated spastic paraplegia-47 (SPG47) in unrelated affected members from Bangladesh. Our analysis pipeline detected three homozygous mutations, including a novel c. 863 G > C (p.Pro288Arg) variant in DHH, and two compound heterozygous variants, including two novel variants: c.2972dupT (p.Met991Ilefs*) in GNPTAB and c.229 G > C (p.Gly77Arg) in SURF1. All mutations were validated by Sanger sequencing. Collectively, this study adds to the genetic heterogeneity of rare genetic diseases and is the first report elucidating the genetic profile of (consanguineous and nonconsanguineous) rare genetic diseases in the Bangladesh population.
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Affiliation(s)
- Hosneara Akter
- Genetics and Genomic Medicine Centre, NeuroGen Children's Healthcare, Dhaka, Bangladesh
- Department of Biochemistry and Molecular Biology, University of Dhaka, Dhaka, Bangladesh
| | | | - Nushrat Jahan Dity
- Genetics and Genomic Medicine Centre, NeuroGen Children's Healthcare, Dhaka, Bangladesh
| | - Md Atikur Rahaman
- Genetics and Genomic Medicine Centre, NeuroGen Children's Healthcare, Dhaka, Bangladesh
| | - K M Furkan Uddin
- Genetics and Genomic Medicine Centre, NeuroGen Children's Healthcare, Dhaka, Bangladesh
| | - Nasna Nassir
- College of Medicine, Mohammed Bin Rashid University of Medicine and Health Science, Dubai, UAE
| | - Ghausia Begum
- College of Medicine, Mohammed Bin Rashid University of Medicine and Health Science, Dubai, UAE
| | - Reem Abdel Hameid
- College of Medicine, Mohammed Bin Rashid University of Medicine and Health Science, Dubai, UAE
| | | | - Tahrima Arman Tusty
- Department of Genetic Engineering & Biotechnology, University of Dhaka, Dhaka, Bangladesh
| | - Mohammad Basiruzzaman
- Genetics and Genomic Medicine Centre, NeuroGen Children's Healthcare, Dhaka, Bangladesh
- Department of Child Neurology, NeuroGen Children's Healthcare, Dhaka, Bangladesh
| | - Shaoli Sarkar
- Genetics and Genomic Medicine Centre, NeuroGen Children's Healthcare, Dhaka, Bangladesh
- Department of Child Neurology, NeuroGen Children's Healthcare, Dhaka, Bangladesh
| | - Mazharul Islam
- Genetics and Genomic Medicine Centre, NeuroGen Children's Healthcare, Dhaka, Bangladesh
- Department of Child Neurology, NeuroGen Children's Healthcare, Dhaka, Bangladesh
| | - Sharmin Jahan
- Department of Endocrinology & Metabolism, Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh
| | - Elaine T Lim
- Department of Genetics, Harvard Medical School, Boston, USA
| | - Marc Woodbury-Smith
- The Centre for Applied Genomics, The Hospital for Sick Children, Toronto, Canada
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK
| | - Dimitri James Stavropoulos
- Genome Diagnostics, Department of Pediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Canada
| | | | - Bakhrom K Berdeiv
- College of Medicine, Mohammed Bin Rashid University of Medicine and Health Science, Dubai, UAE
| | - A H M Nurun Nabi
- Department of Biochemistry and Molecular Biology, University of Dhaka, Dhaka, Bangladesh
| | - Mohammed Nazmul Ahsan
- Department of Genetic Engineering & Biotechnology, University of Dhaka, Dhaka, Bangladesh
| | - Stephen W Scherer
- The Centre for Applied Genomics, The Hospital for Sick Children, Toronto, Canada
- McLaughlin Centre and Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Mohammed Uddin
- College of Medicine, Mohammed Bin Rashid University of Medicine and Health Science, Dubai, UAE.
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Ludwig NF, Sperb-Ludwig F, Randon DN, Bernardi P, Giuliani LR, Moreno CA, Cavalcanti DP, Silva LCSD, Schwartz IVD. A decade of molecular diagnosis of Mucolipidosis II and III in Brazil: a pooled analysis of 32 patients. JOURNAL OF INBORN ERRORS OF METABOLISM AND SCREENING 2021. [DOI: 10.1590/2326-4594-jiems-2020-0029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Nataniel F Ludwig
- Hospital de Clínicas de Porto Alegre, Brazil; Universidade Federal do Rio Grande do Sul, Porto Alegre, Brasil, Brazil
| | - Fernanda Sperb-Ludwig
- Hospital de Clínicas de Porto Alegre, Brazil; Universidade Federal do Rio Grande do Sul, Porto Alegre, Brasil, Brazil
| | - Dévora N Randon
- Hospital de Clínicas de Porto Alegre, Brazil; Universidade Federal do Rio Grande do Sul, Porto Alegre, Brasil, Brazil
| | | | | | | | | | | | - Ida V D Schwartz
- Hospital de Clínicas de Porto Alegre, Brazil; Universidade Federal do Rio Grande do Sul, Porto Alegre, Brasil, Brazil; Hospital de Clínicas de Porto Alegre, Brazil
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5
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Soares MB, Turchetto-Zolet AC, Schwartz IV, Sperb-Ludwig F. Haplotype analysis and origin of the most common pathogenic mutation causing Mucolipidosis II and III alpha/beta in Brazilian patients. GENE REPORTS 2020. [DOI: 10.1016/j.genrep.2020.100645] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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6
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Matos L, Vilela R, Rocha M, Santos JI, Coutinho MF, Gaspar P, Prata MJ, Alves S. Development of an Antisense Oligonucleotide-Mediated Exon Skipping Therapeutic Strategy for Mucolipidosis II: Validation at RNA Level. Hum Gene Ther 2020; 31:775-783. [PMID: 32283951 DOI: 10.1089/hum.2020.034] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Lysosomal storage disorders (LSDs) are a group of rare inherited metabolic diseases caused by the malfunction of the lysosomal system, which results in the accumulation of undergraded substrates inside the lysosomes and leads to severe and progressive pathology. Despite there currently being a broad understanding of the molecular defects behind LSDs, curative therapies have been approved for only few of these diseases, whereas existing treatments are still mostly symptomatic with several limitations. Mucolipidosis type II alpha/beta (ML II) is one of most severe LSDs, which is caused by the total deficiency of the GlcNAc-1-phosphotransferase, a key enzyme for the formation of specific targeting signals on lysosomal hydrolases to lysosomes. GlcNAc-1-phosphotransferase is a multimeric enzyme complex encoded by two genes: GNPTAB and GNPTG. One of the most frequent ML II causal mutation is a dinucleotide deletion on exon 19 of GNPTAB (c.3503_3504del) that leads to the generation of a truncated protein, loss of GlcNAc-1-phosphotransferase activity, and missorting of multiple lysosomal enzymes. Presently, there is no therapy available for ML II. In this study, we explored the possibility of an innovative therapeutic strategy for ML II based on the use of antisense oligonucleotides (AOs) capable to induce the skipping of GNPTAB exon 19 harboring the most common disease-causing mutation, c.3503_3504del. The approach confirmed the ability of specific AOs for RNA splicing modulation, thus paving the way for future studies on the therapeutic potential of this strategy.
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Affiliation(s)
- Liliana Matos
- Research and Development Unit, Department of Human Genetics, National Health Institute Doutor Ricardo Jorge, Porto, Portugal.,Center for the Study of Animal Science, CECA-ICETA, University of Porto, Porto, Portugal
| | - Regina Vilela
- Research and Development Unit, Department of Human Genetics, National Health Institute Doutor Ricardo Jorge, Porto, Portugal
| | - Melissa Rocha
- Research and Development Unit, Department of Human Genetics, National Health Institute Doutor Ricardo Jorge, Porto, Portugal
| | - Juliana I Santos
- Research and Development Unit, Department of Human Genetics, National Health Institute Doutor Ricardo Jorge, Porto, Portugal.,Biology Department, Faculty of Sciences, University of Porto, Porto, Portugal
| | - Maria Francisca Coutinho
- Research and Development Unit, Department of Human Genetics, National Health Institute Doutor Ricardo Jorge, Porto, Portugal.,Center for the Study of Animal Science, CECA-ICETA, University of Porto, Porto, Portugal
| | - Paulo Gaspar
- Newborn Screening, Metabolism and Genetics Unit, Department of Human Genetics, National Health Institute Doutor Ricardo Jorge, Porto, Portugal
| | - Maria João Prata
- Biology Department, Faculty of Sciences, University of Porto, Porto, Portugal.,i3S, Institute of Research and Innovation in Health/IPATIMUP, Institute of Molecular Pathology and Immunology of the University of Porto, Porto, Portugal
| | - Sandra Alves
- Research and Development Unit, Department of Human Genetics, National Health Institute Doutor Ricardo Jorge, Porto, Portugal.,Center for the Study of Animal Science, CECA-ICETA, University of Porto, Porto, Portugal
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7
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Human GNPTAB stuttering mutations engineered into mice cause vocalization deficits and astrocyte pathology in the corpus callosum. Proc Natl Acad Sci U S A 2019; 116:17515-17524. [PMID: 31405983 DOI: 10.1073/pnas.1901480116] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Stuttering is a common neurodevelopmental disorder that has been associated with mutations in genes involved in intracellular trafficking. However, the cellular mechanisms leading to stuttering remain unknown. Engineering a mutation in N-acetylglucosamine-1-phosphate transferase subunits α and β (GNPTAB) found in humans who stutter into the mouse Gnptab gene resulted in deficits in the flow of ultrasonic vocalizations similar to speech deficits of humans who stutter. Here we show that other human stuttering mutations introduced into this mouse gene, Gnptab Ser321Gly and Ala455Ser, produce the same vocalization deficit in 8-day-old pup isolation calls and do not affect other nonvocal behaviors. Immunohistochemistry showed a marked decrease in staining of astrocytes, particularly in the corpus callosum of the Gnptab Ser321Gly homozygote mice compared to wild-type littermates, while the staining of cerebellar Purkinje cells, oligodendrocytes, microglial cells, and dopaminergic neurons was not significantly different. Diffusion tensor imaging also detected deficits in the corpus callosum of the Gnptab Ser321Gly mice. Using a range of cell type-specific Cre-drivers and a Gnptab conditional knockout line, we found that only astrocyte-specific Gnptab-deficient mice displayed a similar vocalization deficit. These data suggest that vocalization defects in mice carrying human stuttering mutations in Gnptab derive from abnormalities in astrocytes, particularly in the corpus callosum, and provide support for hypotheses that focus on deficits in interhemispheric communication in stuttering.
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8
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Velho RV, Harms FL, Danyukova T, Ludwig NF, Friez MJ, Cathey SS, Filocamo M, Tappino B, Güneş N, Tüysüz B, Tylee KL, Brammeier KL, Heptinstall L, Oussoren E, van der Ploeg AT, Petersen C, Alves S, Saavedra GD, Schwartz IV, Muschol N, Kutsche K, Pohl S. The lysosomal storage disorders mucolipidosis type II, type III alpha/beta, and type III gamma: Update on GNPTAB and GNPTG mutations. Hum Mutat 2019; 40:842-864. [PMID: 30882951 DOI: 10.1002/humu.23748] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 02/19/2019] [Accepted: 03/14/2019] [Indexed: 01/04/2023]
Abstract
Mutations in the GNPTAB and GNPTG genes cause mucolipidosis (ML) type II, type III alpha/beta, and type III gamma, which are autosomal recessively inherited lysosomal storage disorders. GNPTAB and GNPTG encode the α/β-precursor and the γ-subunit of N-acetylglucosamine (GlcNAc)-1-phosphotransferase, respectively, the key enzyme for the generation of mannose 6-phosphate targeting signals on lysosomal enzymes. Defective GlcNAc-1-phosphotransferase results in missorting of lysosomal enzymes and accumulation of non-degradable macromolecules in lysosomes, strongly impairing cellular function. MLII-affected patients have coarse facial features, cessation of statural growth and neuromotor development, severe skeletal abnormalities, organomegaly, and cardiorespiratory insufficiency leading to death in early childhood. MLIII alpha/beta and MLIII gamma are attenuated forms of the disease. Since the identification of the GNPTAB and GNPTG genes, 564 individuals affected by MLII or MLIII have been described in the literature. In this report, we provide an overview on 258 and 50 mutations in GNPTAB and GNPTG, respectively, including 58 novel GNPTAB and seven novel GNPTG variants. Comprehensive functional studies of GNPTAB missense mutations did not only gain insights into the composition and function of the GlcNAc-1-phosphotransferase, but also helped to define genotype-phenotype correlations to predict the clinical outcome in patients.
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Affiliation(s)
- Renata Voltolini Velho
- Section Cell Biology of Rare Diseases, Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Frederike L Harms
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Tatyana Danyukova
- Section Cell Biology of Rare Diseases, Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Nataniel F Ludwig
- Department of Genetics, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.,Post-Graduation Program in Genetics and Molecular Biology, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | | | | | - Mirella Filocamo
- Laboratorio di Genetica Molecolare e Biobanche, Istituto Giannina Gaslini, Genova, Italy
| | - Barbara Tappino
- Laboratorio di Genetica Molecolare e Biobanche, Istituto Giannina Gaslini, Genova, Italy
| | - Nilay Güneş
- Department of Pediatric Genetics, Istanbul University Cerrahpasa, Medicine School, Istanbul, Turkey
| | - Beyhan Tüysüz
- Department of Pediatric Genetics, Istanbul University Cerrahpasa, Medicine School, Istanbul, Turkey
| | - Karen L Tylee
- Willink Biochemical Genetics Unit, Manchester Centre for Genomic Medicine, Manchester University NHS Foundation Trust, Saint Mary's Hospital, Manchester, UK
| | - Kathryn L Brammeier
- Willink Biochemical Genetics Unit, Manchester Centre for Genomic Medicine, Manchester University NHS Foundation Trust, Saint Mary's Hospital, Manchester, UK
| | - Lesley Heptinstall
- Genomic Diagnostics Laboratory, Manchester Centre for Genomic Medicine, Manchester University NHS Foundation Trust, Saint Mary's Hospital, Manchester, UK
| | - Esmee Oussoren
- Department of Pediatrics, Center for LyMannose phosphorylation in health and diseasesosomal and Metabolic Diseases, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Ans T van der Ploeg
- Department of Pediatrics, Center for LyMannose phosphorylation in health and diseasesosomal and Metabolic Diseases, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Christine Petersen
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Sandra Alves
- Department of Human Genetics, INSA, National Health Institute Doutor Ricardo Jorge, Porto, Portugal
| | - Gloria Durán Saavedra
- División de Pediatría, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Ida V Schwartz
- Department of Genetics, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.,Post-Graduation Program in Genetics and Molecular Biology, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | - Nicole Muschol
- International Center for Lysosomal Disorders, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Kerstin Kutsche
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Sandra Pohl
- Section Cell Biology of Rare Diseases, Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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9
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Does the clinical phenotype of mucolipidosis-IIIγ differ from its αβ counterpart?: supporting facts in a cohort of 18 patients. Clin Dysmorphol 2019; 28:7-16. [PMID: 30507725 DOI: 10.1097/mcd.0000000000000249] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Mucolipidosis-IIIγ (ML-IIIγ) is a recessively inherited slowly progressive skeletal dysplasia caused by mutations in GNPTG. We report the genetic and clinical findings in the largest cohort with ML-IIIγ so far: 18 affected individuals from 12 families including 12 patients from India, five from Turkey, and one from the USA. With consanguinity confirmed in eight of 12 families, molecular characterization showed that all affected patients had homozygous pathogenic GNPTG genotypes, underscoring the rarity of the disorder. Unlike ML-IIIαβ, which present with a broader spectrum of severity, the ML-III γ phenotype is milder, with onset in early school age, but nonetheless thus far considered phenotypically not differentiable from ML-IIIαβ. Evaluation of this cohort has yielded phenotypic findings including hypertrophy of the forearms and restricted supination as clues for ML-IIIγ, facilitating an earlier correct choice of genotype screening. Early identification of this disorder may help in offering a timely intervention for the relief of carpal tunnel syndrome, monitoring and surgery for cardiac valve involvement, and evaluation of the need for joint replacement. As this condition may be confused with rheumatoid arthritis, confirmation of diagnosis will prevent inappropriate use of immunosuppressants and disease-modifying agents.
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10
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Rare Diseases with Periodontal Manifestations. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2019; 16:ijerph16050867. [PMID: 30857312 PMCID: PMC6427617 DOI: 10.3390/ijerph16050867] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/10/2019] [Revised: 03/04/2019] [Accepted: 03/05/2019] [Indexed: 12/13/2022]
Abstract
Background: The object of this paper was to provide an overview of rare diseases (RDs) with periodontal manifestations and allocate them to relevant categories. Methods: In ROMSE, a database for “Rare Diseases with Orofacial Involvement”, all 541 entities were analyzed with respect to manifestations of periodontal relevance. Inclusion criteria were periodontally relevant changes to the oral cavity, in accordance with the 2018 version of the Classification of Periodontal and Peri-Implant Diseases and Conditions. Rare diseases were recorded, using the methodology described, and subsequently compared with the Orphanet Classification of Rare Diseases. Results: A total of 76 RDs with periodontal involvement were recorded and allocated in accordance with the Classification of Periodontal and Peri-Implant Diseases and Conditions. Of the 541 RDs analyzed as having known orofacial manifestations, almost 14 percent indicated a periodontally compromised dentition. Conclusions: Around 14 percent of RDs with an orofacial involvement showed periodontally relevant manifestations, which present not only as a result of gingivitis and periodontitis, but also gingival hyperplasia in connection with an underlying disease. Thus, dentists play an important role in therapy and early diagnoses of underlying diseases based on periodontally relevant manifestations.
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11
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Wang Y, Ye J, Qiu WJ, Han LS, Gao XL, Liang LL, Gu XF, Zhang HW. Identification of predominant GNPTAB gene mutations in Eastern Chinese patients with mucolipidosis II/III and a prenatal diagnosis of mucolipidosis II. Acta Pharmacol Sin 2019; 40:279-287. [PMID: 29872134 DOI: 10.1038/s41401-018-0023-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 03/28/2018] [Indexed: 11/09/2022] Open
Abstract
Mucolipidosis II α/β, mucolipidosis III α/β, and mucolipidosis III γ are autosomal recessive disorders belonging to the family of lysosomal storage disorders caused by deficiency of the UDP-N-acetylglucosamine, a lysosomal enzyme N-acetylglucosamine-1-phosphotransferase (GlcNAc-phosphotransferase) localized in the Golgi apparatus, which is essential for normal processing and packaging of soluble lysosomal enzymes with initiating the first step of tagging lysosomal enzymes with mannose-6-phosphate (M6P). Mucolipidosis II and III are caused by mutations in the GNPTAB and GNPTG genes, and patients with these diseases are characterized by short stature, skeletal abnormalities, and developmental delay. In this study we report 38 patients with mucolipidosis II and III enrolled in Eastern China during the past 8 years. The diagnosis was made based on clinical characteristics and measurement of plasma lysosomal enzyme activity. Sanger sequencing of GNPTAB and/or GNPTG for all patients and real-time quantitative PCR were performed to confirm the diagnosis. In addition, 11 cases of prenatal mucolipidosis II were diagnosed based on measurement of the enzyme activity in amniotic fluid supernatant and genetic testing of cultured amniotic cells. Based on molecular genetic tests, 30 patients were diagnosed with mucolipidosis II α/β, 6 were diagnosed with III α/β and 2 were diagnosed with III γ. Thirty-seven different GNPTAB gene mutations were identified in 29 patients with mucolipidosis II α/β and six patients with III α/β. These mutations included 22 new mutations (p.W44X, p.E279X, p.W416X, p.W463X, p.Q802X, p.Q882X, p.A34P, p.R334P, p.D408N, p.D534N, p.Y997C, p.D1018V, p.L1025S, p.L1033P, c.88_89delAC, c.890_891insT, c.1150_1151insTTA, c.1523delG, c.2473_2474insA, c.2980_2983delGCCT, c.3094delA, and deletion of exon 9). Four new GNPTG gene mutations were identified (c.13delC, p.Y81X, p.G126R and c.609+1delG) in two mucolipidosis III γ patients. Among the 11 cases of prenatal diagnosis, four were mucolipidosis II fetuses, three were heterozygous, and the remaining four were normal fetuses. This study expands the mutation spectrum of the GNPTAB and GNPTG genes and contributes to specific knowledge of mucolipidosis II/III in a population from Eastern China.
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12
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Wang P, Mazrier H, Caverly Rae J, Raj K, Giger U. A GNPTAB nonsense variant is associated with feline mucolipidosis II (I-cell disease). BMC Vet Res 2018; 14:416. [PMID: 30591066 PMCID: PMC6307278 DOI: 10.1186/s12917-018-1728-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 11/30/2018] [Indexed: 11/15/2022] Open
Abstract
Background Mucolipidosis II (ML II; I-cell disease) is caused by a deficiency of N-acetylglucosamine-1-phosphotransferase (GNPTAB; EC 2.7.8.17), which leads to a failure to internalize acid hydrolases into lysosomes for proper catabolism of various substances. This is an autosomal recessive lysosomal storage disease and causes severe progressive neuropathy and oculoskeletal dysfunction in humans (OMIM 252500). A naturally occurring disease model has been reported in juvenile domestic cats (OMIA 001248–9685) with clinical signs similar to human patients. We investigated the molecular genetic basis of ML II in a colony of affected cats by sequencing the coding and regulatory regions of GNPTAB from affected and clinically healthy related and unrelated domestic cats and compared the sequences to the published feline genome sequence (NCBI-RefSeq accession no. XM_003989173.4, Gene ID: 101100231). Results All affected cats were homozygous for a single base substitution (c.2644C > T) in exon 13 of GNPTAB. This variant results in a premature stop codon (p.Gln882*) which predicts severe truncation and complete dysfunction of the GNPTAB enzyme. About 140 GNPTAB variants have been described in human ML II patients, with 41.3% nonsense/missense mutations, nine occurring in the same gene region as in this feline model. Restriction fragment length polymorphism and allelic discrimination real-time polymerase chain reaction assays accurately differentiated between clear, asymptomatic carriers and homozygous affected cats. Conclusion Molecular genetic characterization advances this large animal model of ML II for use to further define the pathophysiology of the disease and evaluate novel therapeutic approaches for this fatal lysosomal storage disease in humans. Electronic supplementary material The online version of this article (10.1186/s12917-018-1728-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ping Wang
- Section of Medical Genetics, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA.
| | - Hamutal Mazrier
- Section of Medical Genetics, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Jessica Caverly Rae
- Section of Medical Genetics, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Karthik Raj
- Section of Medical Genetics, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Urs Giger
- Section of Medical Genetics, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
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13
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Oussoren E, van Eerd D, Murphy E, Lachmann R, van der Meijden JC, Hoefsloot LH, Verdijk R, Ruijter GJG, Maas M, Hollak CEM, Langendonk JG, van der Ploeg AT, Langeveld M. Mucolipidosis type III, a series of adult patients. J Inherit Metab Dis 2018; 41:839-848. [PMID: 29704188 PMCID: PMC6133174 DOI: 10.1007/s10545-018-0186-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Revised: 04/04/2018] [Accepted: 04/10/2018] [Indexed: 01/29/2023]
Abstract
BACKGROUND Mucolipidosis type III α/β or γ (MLIII) are rare autosomal recessive diseases, in which reduced activity of the enzyme UDP-N-acetyl glucosamine-1-phosphotransferase (GlcNAc-PTase) leads to intra-lysosomal accumulation of different substrates. Publications on the natural history of MLIII, especially the milder forms, are scarce. This study provides a detailed description of the disease characteristics and its natural course in adult patients with MLIII. METHODS In this retrospective chart study, the clinical, biochemical and molecular findings in adult patients with a confirmed diagnosis of MLIII from three treatment centres were collected. RESULTS Thirteen patients with MLIII were included in this study. Four patients (31%) were initially misdiagnosed with a type of mucopolysaccharidosis (MPS). Four patients (31%) had mild cognitive impairment. Six patients (46%) needed help with activities of daily living (ADL) or were wheelchair-dependent. All patients had dysostosis multiplex and progressive secondary osteoarthritis, characterised by cartilage destruction and bone lesions in multiple joints. All patients underwent multiple orthopaedic surgical interventions as early as the second or third decades of life, of which total hip replacement (THR) was the most common procedure (61% of patients). Carpal tunnel syndrome (CTS) was found in 12 patients (92%) and in eight patients (61%), CTS release was performed. CONCLUSIONS Severe skeletal abnormalities, resulting from abnormal bone development and severe progressive osteoarthritis, are the hallmark of MLIII, necessitating surgical orthopaedic interventions early in life. Future therapies for this disease should focus on improving cartilage and bone quality, preventing skeletal complications and improving mobility.
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Affiliation(s)
- Esmee Oussoren
- Department of Pediatrics, Center for Lysosomal and Metabolic Diseases, Erasmus MC—Sophia Children’s Hospital, P.O. Box 2060, 3000 CB Rotterdam, The Netherlands
| | - David van Eerd
- Department of Internal Medicine, Center for Lysosomal and Metabolic Diseases, Erasmus MC, Rotterdam, The Netherlands
| | - Elaine Murphy
- Charles Dent Metabolic Unit, National Hospital for Neurology and Neurosurgery, Queen Square, London, UK
| | - Robin Lachmann
- Charles Dent Metabolic Unit, National Hospital for Neurology and Neurosurgery, Queen Square, London, UK
| | - Jan C. van der Meijden
- Department of Pediatrics, Center for Lysosomal and Metabolic Diseases, Erasmus MC—Sophia Children’s Hospital, P.O. Box 2060, 3000 CB Rotterdam, The Netherlands
| | - Lies H. Hoefsloot
- Department of Clinical Genetics, Center for Lysosomal and Metabolic Diseases, Erasmus MC, Rotterdam, The Netherlands
| | - Rob Verdijk
- Department of Pathology, Erasmus MC, Rotterdam, The Netherlands
| | - George J. G. Ruijter
- Department of Clinical Genetics, Center for Lysosomal and Metabolic Diseases, Erasmus MC, Rotterdam, The Netherlands
| | - Mario Maas
- Department of Radiology and Nuclear Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Carla E. M. Hollak
- Department of Endocrinology and Metabolism, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Janneke G. Langendonk
- Department of Internal Medicine, Center for Lysosomal and Metabolic Diseases, Erasmus MC, Rotterdam, The Netherlands
| | - Ans T. van der Ploeg
- Department of Pediatrics, Center for Lysosomal and Metabolic Diseases, Erasmus MC—Sophia Children’s Hospital, P.O. Box 2060, 3000 CB Rotterdam, The Netherlands
| | - Mirjam Langeveld
- Department of Endocrinology and Metabolism, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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14
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Di Lorenzo G, Velho RV, Winter D, Thelen M, Ahmadi S, Schweizer M, De Pace R, Cornils K, Yorgan TA, Grüb S, Hermans-Borgmeyer I, Schinke T, Müller-Loennies S, Braulke T, Pohl S. Lysosomal Proteome and Secretome Analysis Identifies Missorted Enzymes and Their Nondegraded Substrates in Mucolipidosis III Mouse Cells. Mol Cell Proteomics 2018; 17:1612-1626. [PMID: 29773673 DOI: 10.1074/mcp.ra118.000720] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 04/27/2018] [Indexed: 11/06/2022] Open
Abstract
Targeting of soluble lysosomal enzymes requires mannose 6-phosphate (M6P) signals whose formation is initiated by the hexameric N-acetylglucosamine (GlcNAc)-1-phosphotransferase complex (α2β2γ2). Upon proteolytic cleavage by site-1 protease, the α/β-subunit precursor is catalytically activated but the functions of γ-subunits (Gnptg) in M6P modification of lysosomal enzymes are unknown. To investigate this, we analyzed the Gnptg expression in mouse tissues, primary cultured cells, and in Gnptg reporter mice in vivo, and found high amounts in the brain, eye, kidney, femur, vertebra and fibroblasts. Consecutively we performed comprehensive quantitative lysosomal proteome and M6P secretome analysis in fibroblasts of wild-type and Gnptgko mice mimicking the lysosomal storage disorder mucolipidosis III. Although the cleavage of the α/β-precursor was not affected by Gnptg deficiency, the GlcNAc-1-phosphotransferase activity was significantly reduced. We purified lysosomes and identified 29 soluble lysosomal proteins by SILAC-based mass spectrometry exhibiting differential abundance in Gnptgko fibroblasts which was confirmed by Western blotting and enzymatic activity analysis for selected proteins. A subset of these lysosomal enzymes show also reduced M6P modifications, fail to reach lysosomes and are secreted, among them α-l-fucosidase and arylsulfatase B. Low levels of these enzymes correlate with the accumulation of non-degraded fucose-containing glycostructures and sulfated glycosaminoglycans in Gnptgko lysosomes. Incubation of Gnptgko fibroblasts with arylsulfatase B partially rescued glycosaminoglycan storage. Combinatorial treatments with other here identified missorted enzymes of this degradation pathway might further correct glycosaminoglycan accumulation and will provide a useful basis to reveal mechanisms of selective, Gnptg-dependent formation of M6P residues on lysosomal proteins.
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Affiliation(s)
- Giorgia Di Lorenzo
- From the ‡Section Biochemistry, Children's Hospital, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Renata Voltolini Velho
- From the ‡Section Biochemistry, Children's Hospital, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Dominic Winter
- §Institute of Biochemistry and Molecular Biology, University of Bonn, Bonn, Germany
| | - Melanie Thelen
- §Institute of Biochemistry and Molecular Biology, University of Bonn, Bonn, Germany
| | - Shiva Ahmadi
- §Institute of Biochemistry and Molecular Biology, University of Bonn, Bonn, Germany
| | - Michaela Schweizer
- ¶Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Raffaella De Pace
- From the ‡Section Biochemistry, Children's Hospital, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Kerstin Cornils
- ‖Research Department Cell and Gene Therapy, Department of Stem Cell Transplantation, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Timur Alexander Yorgan
- **Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Saskia Grüb
- From the ‡Section Biochemistry, Children's Hospital, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Irm Hermans-Borgmeyer
- ¶Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Thorsten Schinke
- **Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Sven Müller-Loennies
- ‡‡Division Biophysics, Research Center Borstel, Leibniz Lung Center, 23845 Borstel, Germany
| | - Thomas Braulke
- From the ‡Section Biochemistry, Children's Hospital, University Medical Center Hamburg-Eppendorf, Hamburg, Germany;
| | - Sandra Pohl
- From the ‡Section Biochemistry, Children's Hospital, University Medical Center Hamburg-Eppendorf, Hamburg, Germany;
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15
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Tüysüz B, Kasapçopur Ö, Alkaya DU, Şahin S, Sözeri B, Yeşil G. Mucolipidosis type III gamma: Three novel mutation and genotype-phenotype study in eleven patients. Gene 2017; 642:398-407. [PMID: 29170090 DOI: 10.1016/j.gene.2017.11.052] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Revised: 11/07/2017] [Accepted: 11/17/2017] [Indexed: 11/18/2022]
Abstract
Mucolipidosis type III gamma (MLIII gamma) is a lysosomal storage disease characterized by joint stiffness, mild coarse face and corneal clouding, which becomes recognizable usually in childhood. Biallelic mutations in the GNPTG gene, which encode the γ subunit of the N-acetylglucosamine-1-phosphotransferase enzyme, are the underlying cause of MLIII gamma. The aim of this study is to evaluate the longitudinal findings and genotype of eleven patients from eight families with MLIII gamma and to establish a genotype-phenotype correlation. The most frequently observed initial finding was stiffness of finger joints, which detected in patients between 18month-olds and five year-olds. However, in four patients presented here, initial finding was knee pain or waddling gait, which started between six-16years of age. All patients also had variable degrees of stiffness on large joints. The longest follow up period was 16years while the shortest was three years and six months. We observed that the patients who had an early onset disease and severe joint stiffness had also rapidly progressive joint involvement mostly localized in hands, shoulders, and hip. However; the patients with late onset and/or mild joint stiffness experienced slowly progressive symptoms. Most patients dropped in their growth curve in time and the ones who were severely affected reached the final height below the third centile. Seven disease-causing mutations, three of them novel, were detected in GNPTG gene. According to our clinical observations c.493_494insC and c.283_284insC mutations lead to a severe phenotype and c.196C>T, c.347_349del, c.652_655delTACT and c.445delG/c.367A>G mutations seemed to generate a milder phenotype.
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Affiliation(s)
- Beyhan Tüysüz
- Department of Pediatric Genetics, Cerrahpasa Medical School, Istanbul University, Istanbul, Turkey.
| | - Özgür Kasapçopur
- Department of Pediatric Rheumatology, Cerrahpasa Medical School, Istanbul University, Istanbul, Turkey
| | - Dilek Uludağ Alkaya
- Department of Pediatric Genetics, Cerrahpasa Medical School, Istanbul University, Istanbul, Turkey
| | - Sezgin Şahin
- Department of Pediatric Rheumatology, Cerrahpasa Medical School, Istanbul University, Istanbul, Turkey
| | - Betül Sözeri
- Department of Pediatric Rheumatology, Ege University Medical School, Izmir, Turkey
| | - Gözde Yeşil
- Department of Medical Genetics, BezmialemVakif University, Istanbul, Turkey
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16
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I Cell Disease (Mucolipidosis II Alpha/Beta): From Screening to Molecular Diagnosis. Indian J Pediatr 2017; 84:144-146. [PMID: 27785713 DOI: 10.1007/s12098-016-2243-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 10/07/2016] [Indexed: 10/20/2022]
Abstract
Mucopolysaccharidosis (MPS) and Mucolipidosis (ML) share common phenotypes (coarse facial features, organomegaly, dysostosis multiplex) despite having different molecular basis. Thus, they pose great diagnostic challenge to treating clinicians. Differentiating between the two conditions requires a battery of tests from screening to molecular diagnosis. Besides discussing differential diagnosis of MPS like features with negative urinary Glycosaminoglycans (GAG), the authors also discuss the utility of p-nitrocatechol sulphate based chemical test as an important screening tool, besides establishing molecular basis in index case.
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17
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Wagner MW, Poretti A, Benson JE, Huisman TAGM. Neuroimaging Findings in Pediatric Genetic Skeletal Disorders: A Review. J Neuroimaging 2016; 27:162-209. [PMID: 28000960 DOI: 10.1111/jon.12413] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Accepted: 11/01/2016] [Indexed: 12/15/2022] Open
Abstract
Genetic skeletal disorders (GSDs) are a heterogeneous group characterized by an intrinsic abnormality in growth and (re-)modeling of cartilage and bone. A large subgroup of GSDs has additional involvement of other structures/organs beside the skeleton, such as the central nervous system (CNS). CNS abnormalities have an important role in long-term prognosis of children with GSDs and should consequently not be missed. Sensitive and specific identification of CNS lesions while evaluating a child with a GSD requires a detailed knowledge of the possible associated CNS abnormalities. Here, we provide a pattern-recognition approach for neuroimaging findings in GSDs guided by the obvious skeletal manifestations of GSD. In particular, we summarize which CNS findings should be ruled out with each GSD. The diseases (n = 180) are classified based on the skeletal involvement (1. abnormal metaphysis or epiphysis, 2. abnormal size/number of bones, 3. abnormal shape of bones and joints, and 4. abnormal dynamic or structural changes). For each disease, skeletal involvement was defined in accordance with Online Mendelian Inheritance in Man. Morphological CNS involvement has been described based on extensive literature search. Selected examples will be shown based on prevalence of the diseases and significance of the CNS involvement. CNS involvement is common in GSDs. A wide spectrum of morphological abnormalities is associated with GSDs. Early diagnosis of CNS involvement is important in the management of children with GSDs. This pattern-recognition approach aims to assist and guide physicians in the diagnostic work-up of CNS involvement in children with GSDs and their management.
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Affiliation(s)
- Matthias W Wagner
- Section of Pediatric Neuroradiology, Division of Pediatric Radiology, Russell H. Morgan Department of Radiology, The Johns Hopkins University School of Medicine, Baltimore, MD.,Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Zurich, Switzerland
| | - Andrea Poretti
- Section of Pediatric Neuroradiology, Division of Pediatric Radiology, Russell H. Morgan Department of Radiology, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Jane E Benson
- Section of Pediatric Neuroradiology, Division of Pediatric Radiology, Russell H. Morgan Department of Radiology, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Thierry A G M Huisman
- Section of Pediatric Neuroradiology, Division of Pediatric Radiology, Russell H. Morgan Department of Radiology, The Johns Hopkins University School of Medicine, Baltimore, MD
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18
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Coutinho MF, Encarnação M, Laranjeira F, Lacerda L, Prata MJ, Alves S. Solving a case of allelic dropout in the GNPTAB gene: implications in the molecular diagnosis of mucolipidosis type III alpha/beta. J Pediatr Endocrinol Metab 2016; 29:1225-1228. [PMID: 27710913 DOI: 10.1515/jpem-2016-0173] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 08/29/2016] [Indexed: 11/15/2022]
Abstract
While being well known that the diagnosis of many genetic disorders relies on a combination of clinical suspicion and confirmatory genetic testing, not rarely, however, genetic testing needs much perseverance and cunning strategies to identify the causative mutation(s). Here we present a case of a thorny molecular diagnosis of mucolipidosis type III alpha/beta, which is an autosomal recessive lysosomal storage disorder, caused by a defect in the GNPTAB gene that codes for the α/β-subunits of the GlcNAc-1-phosphotransferase. We used both cDNA and gDNA analyses to characterize a mucolipidosis type III alpha/beta patient whose clinical diagnosis was already confirmed biochemically. In a first stage only one causal mutation was identified in heterozygosity, the already described missense mutation c.1196C>T(p.S399F), both at cDNA and gDNA levels. Only after conducting inhibition of nonsense-mediated mRNA decay (NMD) assays and after the utilization of another pair of primers the second mutation, the c.3503_3504delTC deletion, was identified. Our findings illustrate that allelic dropout due to the presence of polymorphisms and/or of mutations that trigger the NMD pathway can cause difficulties in current molecular diagnosis tests.
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19
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Hashemi-Gorji F, Ghafouri-Fard S, Salehpour S, Yassaee VR, Miryounesi M. A novel splice site mutation in the GNPTAB gene in an Iranian patient with mucolipidosis II α/β. J Pediatr Endocrinol Metab 2016; 29:991-3. [PMID: 27180337 DOI: 10.1515/jpem-2016-0032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 03/29/2016] [Indexed: 12/19/2022]
Abstract
Mucolipidosis type II α/β (ML II α/β) and mucolipidosis type III α/β (ML III α/β) have been shown to be caused by an absence or reduced level of uridine diphosphate (UDP)-N-acetylglucosamine-1-phosphotransferase enzyme (EC 2.7.8.17) activity, respectively. Both disorders are caused by mutations in the GNPTAB gene and are inherited in an autosomal recessive manner. Here we report a 2-year-old female patient being diagnosed as a case of ML II α/β due to coarse face, severe developmental delay, multiple dysostosis, noticeable increase of multiple lysosomal enzymes activity in plasma and normal acid mucopolysaccharides in urine. Mutational analysis of the GNPTAB gene has revealed a novel homozygous mutation in the patient (c.3250-2A>G) with both parents being heterozygote. Transcript analyses showed that this novel splice site mutation leads to exon 17 skipping and a frameshift afterwards (p.P1084_R1112del F1113Vfs*1). Consequently, we confirmed the association of this mutation with ML II α/β. Our finding expands the number of reported cases of this rare metabolic disorder and adds to the GNPTAB mutation database.
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20
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Flanagan-Steet H, Matheny C, Petrey A, Parker J, Steet R. Enzyme-specific differences in mannose phosphorylation between GlcNAc-1-phosphotransferase αβ and γ subunit deficient zebrafish support cathepsin proteases as early mediators of mucolipidosis pathology. Biochim Biophys Acta Gen Subj 2016; 1860:1845-53. [PMID: 27241848 DOI: 10.1016/j.bbagen.2016.05.029] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 04/28/2016] [Accepted: 05/20/2016] [Indexed: 11/25/2022]
Abstract
Targeting soluble acid hydrolases to lysosomes requires the addition of mannose 6-phosphate residues on their N-glycans. This process is initiated by GlcNAc-1-phosphotransferase, a multi-subunit enzyme encoded by the GNPTAB and GNPTG genes. The GNPTAB gene products (the α and ß subunits) are responsible for recognition and catalysis of hydrolases whereas the GNPTG gene product (the γ subunit) enhances mannose phosphorylation of a subset of hydrolases. Here we identify and characterize a zebrafish gnptg insertional mutant and show that loss of the gamma subunit reduces mannose phosphorylation on a subset glycosidases but does not affect modification of several cathepsin proteases. We further show that glycosidases, but not cathepsins, are hypersecreted from gnptg(-/-) embryonic cells, as evidenced by reduced intracellular activity and increased circulating serum activity. The gnptg(-/-) embryos lack the gross morphological or craniofacial phenotypes shown in gnptab-deficient morphant embryos to result from altered cathepsin activity. Despite the lack of overt phenotypes, decreased fertilization and embryo survival were noted in mutants, suggesting that gnptg associated deposition of mannose 6-phosphate modified hydrolases into oocytes is important for early embryonic development. Collectively, these findings demonstrate that loss of the zebrafish GlcNAc-1-phosphotransferase γ subunit causes enzyme-specific effects on mannose phosphorylation. The finding that cathepsins are normally modified in gnptg(-/-) embryos is consistent with data from gnptab-deficient zebrafish suggesting these proteases are the key mediators of acute pathogenesis. This work also establishes a valuable new model that can be used to probe the functional relevance of GNPTG mutations in the context of a whole animal.
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Affiliation(s)
- Heather Flanagan-Steet
- Complex Carbohydrate Research Center, 315 Riverbend Road, University of Georgia, Athens, GA 30602, United States
| | - Courtney Matheny
- Complex Carbohydrate Research Center, 315 Riverbend Road, University of Georgia, Athens, GA 30602, United States
| | - Aaron Petrey
- Complex Carbohydrate Research Center, 315 Riverbend Road, University of Georgia, Athens, GA 30602, United States
| | - Joshua Parker
- Complex Carbohydrate Research Center, 315 Riverbend Road, University of Georgia, Athens, GA 30602, United States
| | - Richard Steet
- Complex Carbohydrate Research Center, 315 Riverbend Road, University of Georgia, Athens, GA 30602, United States.
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21
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Koehne T, Markmann S, Schweizer M, Muschol N, Friedrich RE, Hagel C, Glatzel M, Kahl-Nieke B, Amling M, Schinke T, Braulke T. Mannose 6-phosphate-dependent targeting of lysosomal enzymes is required for normal craniofacial and dental development. Biochim Biophys Acta Mol Basis Dis 2016; 1862:1570-80. [PMID: 27239697 DOI: 10.1016/j.bbadis.2016.05.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 05/04/2016] [Accepted: 05/26/2016] [Indexed: 02/06/2023]
Abstract
Mucolipidosis II (MLII) is a severe systemic genetic disorder caused by defects in mannose 6-phosphate-dependent targeting of multiple lysosomal hydrolases and subsequent lysosomal accumulation of non-degraded material. MLII patients exhibit marked facial coarseness and gingival overgrowth soon after birth, accompanied with delayed tooth eruption and dental infections. To examine the pathomechanisms of early craniofacial and dental abnormalities, we analyzed mice with an MLII patient mutation that mimic the clinical and biochemical symptoms of MLII patients. The mouse data were compared with clinical and histological data of gingiva and teeth from MLII patients. Here, we report that progressive thickening and porosity of calvarial and mandibular bones, accompanied by elevated bone loss due to 2-fold higher number of osteoclasts cause the characteristic craniofacial phenotype in MLII. The analysis of postnatal tooth development by microcomputed tomography imaging and histology revealed normal dentin and enamel formation, and increased cementum thickness accompanied with accumulation of storage material in cementoblasts of MLII mice. Massive accumulation of storage material in subepithelial cells as well as disorganization of collagen fibrils led to gingival hypertrophy. Electron and immunofluorescence microscopy, together with (35)S-sulfate incorporation experiments revealed the accumulation of non-degraded material, non-esterified cholesterol and glycosaminoglycans in gingival fibroblasts, which was accompanied by missorting of various lysosomal proteins (α-fucosidase 1, cathepsin L and Z, Npc2, α-l-iduronidase). Our study shows that MLII mice closely mimic the craniofacial and dental phenotype of MLII patients and reveals the critical role of mannose 6-phosphate-dependent targeting of lysosomal proteins for alveolar bone, cementum and gingiva homeostasis.
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Affiliation(s)
- Till Koehne
- Department of Orthodontics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany; Department of Osteology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Sandra Markmann
- Department of Biochemistry, Children's Hospital, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Michaela Schweizer
- ZMNH, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Nicole Muschol
- Department of Biochemistry, Children's Hospital, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Reinhard E Friedrich
- Department of Oral and Maxillofacial Surgery, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Christian Hagel
- Institute of Neuropathology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Markus Glatzel
- Institute of Neuropathology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Bärbel Kahl-Nieke
- Department of Orthodontics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Michael Amling
- Department of Osteology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Thorsten Schinke
- Department of Osteology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Thomas Braulke
- Department of Biochemistry, Children's Hospital, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany.
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22
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Enigmatic in vivo GlcNAc-1-phosphotransferase (GNPTG) transcript correction to wild type in two mucolipidosis III gamma siblings homozygous for nonsense mutations. J Hum Genet 2016; 61:555-60. [PMID: 26935170 DOI: 10.1038/jhg.2016.13] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 01/20/2016] [Accepted: 01/21/2016] [Indexed: 12/25/2022]
Abstract
Mucolipidosis (ML) III gamma is a rare autosomal-recessive disorder caused by pathogenic mutations in the GNPTG gene. GNPTG encodes the γ-subunit of GlcNAc-1-phosphotransferase that catalyzes mannose 6-phosphate targeting signal synthesis on soluble lysosomal enzymes. ML III gamma patients are characterized by missorting of lysosomal enzymes. In this report, we describe the probable occurrence of mRNA editing in two ML III gamma patients. Patients A and B (siblings) presented at the adult age with a typical clinical picture of ML III gamma, mainly compromising bone and joints, and high levels of lysosomal enzymes in plasma and low levels in fibroblasts. Both were found to be homozygous for c.-112C>G and c.328G>T (p.Glu110Ter) mutations in genomic DNA (gDNA) analysis of GNPTG. Analysis of complementary DNA (cDNA), however, showed normal genotypes for both patients. Low GNPTG mRNA expression was observed in both patients. The mRNA editing can explain the differences found in patients A and B regarding gDNA and cDNA analysis, and the mild clinical phenotype associated with homozygosity for a nonsense mutation. Our results suggest that mRNA editing can be more frequent than expected in monogenic disorders and that GNPTG analysis should be performed on gDNA.
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Tüysüz B, Ercan-Sencicek AG, Canpolat N, Koparır A, Yılmaz S, Kılıçaslan I, Gülez B, Bilguvar K, Günel M. Renal involvement in patients with mucolipidosis IIIalpha/beta: Causal relation or co-occurrence? Am J Med Genet A 2016; 170A:1187-95. [PMID: 26749367 DOI: 10.1002/ajmg.a.37543] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 12/21/2015] [Indexed: 11/07/2022]
Abstract
Mucolipidosis IIIalpha/beta (MLIIIalpha/beta) is a rare lysosomal storage disorder characterized by childhood onset of flexion contractures of fingers, joint stiffness in the shoulders, hips, and knees, and mild short stature. Recessive mutations in the GNPTAB gene have been associated with MLIIIalpha/beta. We present five children aged 9-16 years from a large kindred family whose serum activities of several lysosomal enzymes were significantly elevated. Whole exome sequencing followed by confirmation by Sanger sequencing identified a novel homozygous missense mutation (c.22 A > G; p.R8G) in the GNPTAB gene in all affected subjects. The five patients initially presented with flexion contractures of fingers followed by stiffnes of large joints. Only two affected boys also had a nephrotic-range proteinuria. Renal biopsy showed focal segmental glomerulosclerosis and foamy appearance of glomerular visceral epithelial cells which were compatible with storage disease. No other known causes of proteinuria could be detected by both laboratory and biopsy findings. There was no known family history of hereditary kidney disease, and healthy siblings and parents had normal renal function and urinalysis. These findings suggest that the renal involvement probably due to MLIIIalpha/beta, although it can still be present by coincidence in the two affected patients.
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Affiliation(s)
- Beyhan Tüysüz
- Department of Pediatric Genetics, Cerrahpasa Medical School, Istanbul University, Istanbul, Turkey
| | | | - Nur Canpolat
- Department of Pediatric Nephrology, Cerrahpasa Medical School, Istanbul University, Istanbul, Turkey
| | - Asuman Koparır
- Department of Pediatric Genetics, Cerrahpasa Medical School, Istanbul University, Istanbul, Turkey
| | - Saliha Yılmaz
- Department of Neurosurgery, Program on Neurogenetics, Yale School of Medicine, New Haven, Connecticut
| | - Işın Kılıçaslan
- Department of Pathology, Istanbul Medical School, Istanbul University, Istanbul, Turkey
| | - Burcu Gülez
- Department of Neurosurgery, Program on Neurogenetics, Yale School of Medicine, New Haven, Connecticut
| | - Kaya Bilguvar
- Department of Neurosurgery, Program on Neurogenetics, Yale School of Medicine, New Haven, Connecticut
| | - Murat Günel
- Department of Neurosurgery, Program on Neurogenetics, Yale School of Medicine, New Haven, Connecticut
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Qian Y, van Meel E, Flanagan-Steet H, Yox A, Steet R, Kornfeld S. Analysis of mucolipidosis II/III GNPTAB missense mutations identifies domains of UDP-GlcNAc:lysosomal enzyme GlcNAc-1-phosphotransferase involved in catalytic function and lysosomal enzyme recognition. J Biol Chem 2014; 290:3045-56. [PMID: 25505245 DOI: 10.1074/jbc.m114.612507] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
UDP-GlcNAc:lysosomal enzyme GlcNAc-1-phosphotransferase tags newly synthesized lysosomal enzymes with mannose 6-phosphate recognition markers, which are required for their targeting to the endolysosomal system. GNPTAB encodes the α and β subunits of GlcNAc-1-phosphotransferase, and mutations in this gene cause the lysosomal storage disorders mucolipidosis II and III αβ. Prior investigation of missense mutations in GNPTAB uncovered amino acids in the N-terminal region and within the DMAP domain involved in Golgi retention of GlcNAc-1-phosphotransferase and its ability to specifically recognize lysosomal hydrolases, respectively. Here, we undertook a comprehensive analysis of the remaining missense mutations in GNPTAB reported in mucolipidosis II and III αβ patients using cell- and zebrafish-based approaches. We show that the Stealth domain harbors the catalytic site, as some mutations in these regions greatly impaired the activity of the enzyme without affecting its Golgi localization and proteolytic processing. We also demonstrate a role for the Notch repeat 1 in lysosomal hydrolase recognition, as missense mutations in conserved cysteine residues in this domain do not affect the catalytic activity but impair mannose phosphorylation of certain lysosomal hydrolases. Rescue experiments using mRNA bearing Notch repeat 1 mutations in GNPTAB-deficient zebrafish revealed selective effects on hydrolase recognition that differ from the DMAP mutation. Finally, the mutant R587P, located in the spacer between Notch 2 and DMAP, was partially rescued by overexpression of the γ subunit, suggesting a role for this region in γ subunit binding. These studies provide new insight into the functions of the different domains of the α and β subunits.
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Affiliation(s)
- Yi Qian
- From the Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110 and
| | - Eline van Meel
- From the Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110 and
| | | | - Alex Yox
- Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602
| | - Richard Steet
- Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602
| | - Stuart Kornfeld
- From the Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110 and
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Sperb-Ludwig F, Alegra T, Velho RV, Ludwig N, Kim CA, Kok F, Kitajima JP, van Meel E, Kornfeld S, Burin MG, Schwartz IVD. Exome sequencing for mucolipidosis III: Detection of a novel GNPTAB gene mutation in a patient with a very mild phenotype. Mol Genet Metab Rep 2014. [PMID: 28649523 PMCID: PMC5471150 DOI: 10.1016/j.ymgmr.2014.12.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Mucolipidosis II and III alpha/beta (ML II/III alpha/beta) are rare autosomal recessive lysosomal storage diseases that are caused by a deficiency of UDP-GlcNAc:lysosomal enzyme N-acetylglucosamine-1-phosphotransferase, the enzyme responsible for the synthesis of the mannose 6-phosphate targeting signal on lysosomal hydrolases. A Brazilian patient suspected of having a very mild ML III was investigated using whole next-generation sequencing (NGS). Two mutations in the GNPTAB gene were detected and confirmed to be in trans status by parental analysis: c.1208T>C (p.Ile403Thr), previously reported as being pathogenic, and the novel mutation c.1723G>A (p.Gly575Arg). This study demonstrates the effectiveness of using whole NGS for the molecular diagnosis of very mild ML III alpha/beta patients.
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Affiliation(s)
- F Sperb-Ludwig
- BRAIN (Basic Research and Advanced Investigations in Neurosciences) Laboratory, Hospital de Clínicas de Porto Alegre (HCPA), Brazil.,Postgraduate Program in Medical Sciences: Medical Sciences, Universidade Federal do Rio Grande do Sul (UFRGS), Brazil
| | - T Alegra
- Postgraduate Program in Genetics and Molecular Biology, UFRGS, Brazil
| | - R V Velho
- Postgraduate Program in Genetics and Molecular Biology, UFRGS, Brazil
| | - N Ludwig
- BRAIN (Basic Research and Advanced Investigations in Neurosciences) Laboratory, Hospital de Clínicas de Porto Alegre (HCPA), Brazil
| | - C A Kim
- Genetics Unit, Instituto da Criança da Faculdade de Medicina, Universidade de São Paulo, Brazil
| | - F Kok
- Mendelics Genomic Analysis, São Paulo, Brazil
| | | | - E van Meel
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, USA
| | - S Kornfeld
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, USA
| | - M G Burin
- Medical Genetics Service, HCPA, Brazil
| | - I V D Schwartz
- BRAIN (Basic Research and Advanced Investigations in Neurosciences) Laboratory, Hospital de Clínicas de Porto Alegre (HCPA), Brazil.,Postgraduate Program in Medical Sciences: Medical Sciences, Universidade Federal do Rio Grande do Sul (UFRGS), Brazil.,Postgraduate Program in Genetics and Molecular Biology, UFRGS, Brazil.,Medical Genetics Service, HCPA, Brazil.,Genetics Department, UFRGS, Brazil
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26
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Aggarwal S, Coutinho MF, Dalal AB, Mohamed Nurul Jain S, Prata MJ, Alves S. Prenatal skeletal dysplasia phenotype in severe MLII alpha/beta with novel GNPTAB mutation. Gene 2014; 542:266-8. [DOI: 10.1016/j.gene.2014.03.053] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Revised: 03/24/2014] [Accepted: 03/27/2014] [Indexed: 01/29/2023]
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Velho RV, Alegra T, Sperb F, Ludwig NF, Saraiva-Pereira ML, Matte U, Schwartz IVD. A de novo or germline mutation in a family with Mucolipidosis III gamma: Implications for molecular diagnosis and genetic counseling. Mol Genet Metab Rep 2014; 1:98-102. [PMID: 27896079 PMCID: PMC5121289 DOI: 10.1016/j.ymgmr.2014.01.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Revised: 01/26/2014] [Accepted: 01/26/2014] [Indexed: 11/23/2022] Open
Abstract
Mucolipidosis III (ML III) gamma is a very rare autosomal-recessive disorder characterized by the abnormal trafficking and subcellular localization of lysosomal enzymes due to mutations in the GNPTG gene. The present study consists of a report of a Brazilian compound heterozygote patient with ML III gamma resulting from one mutant paternal allele and one allele that had most likely undergone a de novo or maternal germline mutation. This is the first report of a de novo mutation in ML III gamma. This finding has significant implications for genetic counseling.
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Affiliation(s)
- Renata Voltolini Velho
- Gene Therapy Center, Experimental Research Center, Hospital de Clínicas de Porto Alegre, RS, Brazil; Genetics and Molecular Biology Postgraduate Program, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Taciane Alegra
- Genetics and Molecular Biology Postgraduate Program, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Fernanda Sperb
- Gene Therapy Center, Experimental Research Center, Hospital de Clínicas de Porto Alegre, RS, Brazil; Postgraduation Program in Medical Sciences, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Nataniel Floriano Ludwig
- Gene Therapy Center, Experimental Research Center, Hospital de Clínicas de Porto Alegre, RS, Brazil
| | - Maria Luiza Saraiva-Pereira
- Genetics and Molecular Biology Postgraduate Program, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil; Medical Genetics Service, Hospital de Clínicas de Porto Alegre, RS, Brazil
| | - Ursula Matte
- Gene Therapy Center, Experimental Research Center, Hospital de Clínicas de Porto Alegre, RS, Brazil; Genetics and Molecular Biology Postgraduate Program, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Ida V D Schwartz
- Genetics and Molecular Biology Postgraduate Program, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil; Department of Genetics and Molecular Biology, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil; Postgraduation Program in Medical Sciences, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil; Brain Laboratory, Experimental Research Center, Hospital de Clínicas de Porto Alegre, RS, Brazil; Medical Genetics Service, Hospital de Clínicas de Porto Alegre, RS, Brazil
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De Pace R, Coutinho MF, Koch-Nolte F, Haag F, Prata MJ, Alves S, Braulke T, Pohl S. Mucolipidosis II-related mutations inhibit the exit from the endoplasmic reticulum and proteolytic cleavage of GlcNAc-1-phosphotransferase precursor protein (GNPTAB). Hum Mutat 2014; 35:368-76. [PMID: 24375680 DOI: 10.1002/humu.22502] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Accepted: 12/13/2013] [Indexed: 01/12/2023]
Abstract
Mucolipidosis (ML) II and MLIII alpha/beta are two pediatric lysosomal storage disorders caused by mutations in the GNPTAB gene, which encodes an α/β-subunit precursor protein of GlcNAc-1-phosphotransferase. Considerable variations in the onset and severity of the clinical phenotype in these diseases are observed. We report here on expression studies of two missense mutations c.242G>T (p.Trp81Leu) and c.2956C>T (p.Arg986Cys) and two frameshift mutations c.3503_3504delTC (p.Leu1168GlnfsX5) and c.3145insC (p.Gly1049ArgfsX16) present in severely affected MLII patients, as well as two missense mutations c.1196C>T (p.Ser399Phe) and c.3707A>T (p.Lys1236Met) reported in more mild affected individuals. We generated a novel α-subunit-specific monoclonal antibody, allowing the analysis of the expression, subcellular localization, and proteolytic activation of wild-type and mutant α/β-subunit precursor proteins by Western blotting and immunofluorescence microscopy. In general, we found that both missense and frameshift mutations that are associated with a severe clinical phenotype cause retention of the encoded protein in the endoplasmic reticulum and failure to cleave the α/β-subunit precursor protein are associated with a severe clinical phenotype with the exception of p.Ser399Phe found in MLIII alpha/beta. Our data provide new insights into structural requirements for localization and activity of GlcNAc-1-phosphotransferase that may help to explain the clinical phenotype of MLII patients.
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Affiliation(s)
- Raffaella De Pace
- Section Biochemistry, Children's Hospital, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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Liu S, Zhang W, Shi H, Meng Y, Qiu Z. Three novel homozygous mutations in the GNPTG gene that cause mucolipidosis type III gamma. Gene 2013; 535:294-8. [PMID: 24316125 DOI: 10.1016/j.gene.2013.11.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Revised: 10/30/2013] [Accepted: 11/04/2013] [Indexed: 11/27/2022]
Abstract
BACKGROUND Mucolipidosis type III gamma (MLIII gamma) is an autosomal recessive disease caused by a mutation in the GNPTG gene, which encodes the γ subunit of the N-acetylglucosamine-1-phosphotransferase (GlcNAc-1-phosphotransferase). This protein plays a key role in the transport of lysosomal hydrolases to the lysosome. METHODS Three Chinese children with typical skeletal abnormalities of MLIII were identified, who were from unrelated consanguineous families. After obtaining informed consent, genomic DNA was isolated from the patients and their parents. Direct sequencing of the GNPTG and GNPTAB genes was performed using standard PCR reactions. RESULTS The three probands showed clinical features typical of MLIII gamma, such as joint stiffness and vertebral scoliosis without coarsened facial features. Mutation analysis of the GNPTG gene showed that three novel mutations were identified, two in exon seven [c.425G>A (p.Cys142Val)] and [c.515dupC (p.His172Profs27X)], and one in exon eight [c.609+1G>C]. Their parents were determined to be heterozygous carriers when compared to the reference sequence in GenBank on NCBI. CONCLUSIONS Mutation of the GNPTG gene is the cause of MLIII gamma in our patients. Our findings expand the mutation spectrum of the GNPTG gene and extend the knowledge of the phenotype-genotype correlation of the disease.
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Affiliation(s)
- Shuang Liu
- Department of Pediatrics, PUMC Hospital, CAMS&PUMC, Beijing 100730, PR China
| | - Weimin Zhang
- Clinical Research Laboratory, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, PR China
| | - Huiping Shi
- Department of Medical Genetics, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, PR China
| | - Yan Meng
- Department of Medical Genetics, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, PR China
| | - Zhengqing Qiu
- Department of Pediatrics, PUMC Hospital, CAMS&PUMC, Beijing 100730, PR China.
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Yang Y, Wu J, Liu H, Chen X, Wang Y, Zhao M, He X. Two homozygous nonsense mutations of GNPTAB gene in two Chinese families with mucolipidosis II alpha/beta using targeted next-generation sequencing. Genomics 2013; 102:169-73. [PMID: 23773965 DOI: 10.1016/j.ygeno.2013.06.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 06/05/2013] [Accepted: 06/08/2013] [Indexed: 12/16/2022]
Abstract
Mucolipidosis II alpha/beta (ML II alpha/beta; I-cell disease) is a rare, inherited, metabolic disease and has often been clinically misdiagnosed. ML II alpha/beta results from a deficiency of the enzyme N-acetylglucosamine-1-phosphotransferase (GlcNAc-PT), which causes the lysosomal enzymes to accumulate in plasma. We identified two new Chinese patients with ML II alpha/beta by lysosomal enzyme assay. Using targeted next-generation sequencing genetic analysis, we located two homozygous nonsense mutations in the GNPTAB gene, c.1071G>A (p.W357X) and c.1090C>T (p.R364X). These results were confirmed by Sanger sequencing. To our knowledge, the c.1071G>A mutation has not been previously reported. Our findings add to the number of reported cases of this rare illness and to the GNPTAB pathogenic mutation database. This work also demonstrates the application of lysosomal enzyme assay and targeted next-generation sequencing for the genetic screening analysis and diagnosis of ML II alpha/beta.
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Affiliation(s)
- Yao Yang
- Department of Clinical Genetics, Bayi Children's Hospital Affiliated to General Hospital of Beijing Military Region, China
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Mucolipidosis II and III alpha/beta in Brazil: analysis of the GNPTAB gene. Gene 2013; 524:59-64. [PMID: 23566849 DOI: 10.1016/j.gene.2013.03.105] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 03/03/2013] [Accepted: 03/26/2013] [Indexed: 11/20/2022]
Abstract
UNLABELLED Mucolipidosis II and III (MLII and MLIII) alpha/beta are rare autosomal recessive lysosomal storage diseases (LSDs) caused by pathogenic variations in the GNPTAB gene. GNPTAB gene codes for the α and β subunits of phosphotransferase, the enzyme responsible for synthesis of the mannose-6-phosphate (M6P) marker that directs lysosomal enzymes to the lysosome. OBJECTIVES The objective of this study is to identify sequence variations of the GNPTAB gene in Brazilian patients with MLII and MLIII alpha/beta. METHOD Sequencing of the GNPTAB gene was performed in samples of gDNA extracted from the peripheral blood of patients with MLII/III diagnosed at a national reference center for LSDs. RESULTS Twelve unrelated patients, from several regions of Brazil, were included in this study. Only one was born of consanguineous parents. All patients were found to carry at least one nonpathogenic variation. Nine causal sequence variations were found: c.242G>T (p.W81L); c.1123C>T (p.R375X); c.1196C>T (p.S399F); c.1208T>C (p.I403T); c.1514G>A (p.C505Y); c.1759C>T (p.R587X); c.2808A>G (p.Y937_M972del, novel mutation); c. 2269_2273delGAAAC (p.E757KfsX2, novel mutation); and c.3503_3504delTC (p.L1168QfsX5). Both pathogenic variations were identified in 8 of 12 patients; in four patients, only one pathogenic variation was identified. Mutation c.3503_3504delTC, located in exon 19, was the most frequent pathogenic variation found (n=11/24 alleles). The deleterious effect of the c.2808A>C mutation on splicing was confirmed by cDNA analysis. DISCUSSION/CONCLUSIONS Our findings confirm that the GNPTAB gene presents broad allelic heterogeneity and suggests that, in Brazilian ML II and III patients, screening for mutations should begin at exon 19 of the GNPTAB gene. Further analyses will be conducted on patients in whom both pathogenic mutations have not been found in this study.
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Coutinho MF, Prata MJ, Alves S. Mannose-6-phosphate pathway: a review on its role in lysosomal function and dysfunction. Mol Genet Metab 2012; 105:542-50. [PMID: 22266136 DOI: 10.1016/j.ymgme.2011.12.012] [Citation(s) in RCA: 169] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Revised: 12/15/2011] [Accepted: 12/15/2011] [Indexed: 12/20/2022]
Abstract
Lysosomal hydrolases are synthesized in the rough endoplasmic reticulum and specifically transported through the Golgi apparatus to the trans-Golgi network, from which transport vesicles bud to deliver them to the endosomal/lysosomal compartment. The explanation of how are the lysosomal enzymes accurately recognized and selected over many other proteins in the trans-Golgi network relies on being tagged with a unique marker: the mannose-6-phosphate (M6P) group, which is added exclusively to the N-linked oligosaccharides of lysosomal soluble hydrolases, as they pass through the cis-Golgi network. Generation of the M6P recognition marker depends on a reaction involving two different enzymes: UDP-N-acetylglucosamine 1-phosphotransferase and α-N-acetylglucosamine-1-phosphodiester α-N-acetylglucosaminidase. The M6P groups are then recognized by two independent transmembrane M6P receptors, present in the trans-Golgi network: the cation-independent M6P receptor and/or the cation-dependent M6P receptor. These proteins bind to lysosomal hydrolases on the lumenal side of the membrane and to adaptins in assembling clathrin coats on the cytosolic side. In this way, the M6P receptors help package the hydrolases into vesicles that bud from the trans-Golgi network to deliver their contents to endosomes that ultimately will develop into mature lysosomes, where recently-delivered hydrolases may start digesting the endocyted material. The above described process is known as the M6P-dependent pathway and is responsible for transporting most lysosomal enzymes. This review synthesizes the current knowledge on each of the major proteins involved in the M6P-dependent pathway. Impairments in this pathway will also be addressed, highlighting the lysosomal storage disorders associated to GlcNAc-1-phosphotransferase loss of function: mucolipidosis type II and III.
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Coutinho MF, da Silva Santos L, Lacerda L, Quental S, Wibrand F, Lund AM, Johansen KB, Prata MJ, Alves S. Alu-Alu Recombination Underlying the First Large Genomic Deletion in GlcNAc-Phosphotransferase Alpha/Beta (GNPTAB) Gene in a MLII Alpha/Beta Patient. JIMD Rep 2011; 4:117-24. [PMID: 23430906 PMCID: PMC3509902 DOI: 10.1007/8904_2011_83] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Revised: 07/26/2011] [Accepted: 07/27/2011] [Indexed: 02/01/2023] Open
Abstract
Mucolipidosis type II α/β is a severe, autosomal recessive lysosomal storage disorder, caused by a defect in the GNPTAB gene that codes for the α/β subunits of the GlcNAc-phosphotransferase. To date, over 100 different mutations have been identified in MLII α/β patients, but no large deletions have been reported. Here we present the first case of a large homozygous intragenic GNPTAB gene deletion (c.3435-386_3602 + 343del897) encompassing exon 19, identified in a ML II α/β patient. Long-range PCR and sequencing methodologies were used to refine the characterization of this rearrangement, leading to the identification of a 21 bp repetitive motif in introns 18 and 19. Further analysis revealed that both the 5' and 3' breakpoints were located within highly homologous Alu elements (Alu-Sz in intron 18 and Alu-Sq2, in intron 19), suggesting that this deletion has probably resulted from Alu-Alu unequal homologous recombination. RT-PCR methods were used to further evaluate the consequences of the alteration for the processing of the mutant pre mRNA GNPTAB, revealing the production of three abnormal transcripts: one without exon 19 (p.Lys1146_Trp1201del); another with an additional loss of exon 20 (p.Arg1145Serfs*2), and a third in which exon 19 was substituted by a pseudoexon inclusion consisting of a 62 bp fragment from intron 18 (p.Arg1145Serfs*16). Interestingly, this 62 bp fragment corresponds to the Alu-Sz element integrated in intron 18.This represents the first description of a large deletion identified in the GNPTAB gene and contributes to enrich the knowledge on the molecular mechanisms underlying causative mutations in ML II.
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Affiliation(s)
| | | | - Lúcia Lacerda
- Biochemical Genetics Unit, Department of Genetics, CGMJM, INSA, Porto, Portugal
| | | | - Flemming Wibrand
- Department of Clinical Genetics, Rigshospitalet, Copenhagen, Denmark
| | - Allan M. Lund
- Department of Clinical Genetics, Rigshospitalet, Copenhagen, Denmark
| | | | - Maria João Prata
- IPATIMUP/ Department of Biology, Faculty of Sciences, Porto, Portugal
| | - Sandra Alves
- Research and Development Unit, Department of Genetics, CGMJM, INSA, Porto, Portugal
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Using next-generation sequencing for the diagnosis of rare disorders: a family with retinitis pigmentosa and skeletal abnormalities. J Pathol 2011; 225:12-8. [DOI: 10.1002/path.2941] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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35
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Coutinho MF, Lacerda L, Macedo-Ribeiro S, Baptista E, Ribeiro H, Prata MJ, Alves S. Lysosomal multienzymatic complex-related diseases: a genetic study among Portuguese patients. Clin Genet 2011; 81:379-93. [PMID: 21214877 DOI: 10.1111/j.1399-0004.2011.01625.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The functional activity of lysosomal enzymes sialidase, β-galactosidase and N-acetylaminogalacto-6-sulfate-sulfatase in the cell depends on their association in a multienzyme complex with cathepsin A. Mutations in any of the components of this complex result in functional deficiency thereby causing severe lysosomal storage disorders. Here, we report the molecular defects underlying sialidosis (mutations in sialidase; gene NEU1), galactosialidosis (mutations in cathepsin A; gene PPGB) and GM1 gangliosidosis (mutations in β-galactosidase; gene GLB1) in Portuguese patients. We performed molecular studies of the PPGB, NEU1 and GLB1 genes in biochemically diagnosed Portuguese patients. Gene expression was determined and the effect of each mutation predicted at protein levels. In the NEU1 gene, we found three novel missense mutations (p.P200L, p.D234N and p.Q282H) and one nonsense mutation (p.R341X). In the PPGB gene, we identified two missense mutations, one novel (p.G86V) and one already described (p.V104M), as well as two new deletions (c.230delC and c.991-992delT) that give rise to non-functional proteins. We also present the first molecular evidence of a causal missense mutation localized to the cathepsin A active site. Finally, in the GLB1 gene, we found six different mutations, all of them previously described (p.R59H, p.R201H, p.H281Y, p.W527X, c.1572-1577InsG and c.845-846delC). Seven novel mutations are reported here, contributing to our knowledge of the mutational spectrum of these diseases and to a better understanding of the genetics of the lysosomal multienzymatic complex. The results of this study will allow carrier detection in affected families and prenatal molecular diagnosis, leading to the improvement of genetic counseling.
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Affiliation(s)
- M F Coutinho
- Centro de Genética Médica Doutor Jacinto de Magalhães, INSA, I.P., Praça Pedro Nunes 88, Porto, Portugal.
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36
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Gao Y, Yang K, Xu S, Wang C, Liu J, Zhang Z, Yuan M, Luo X, Liu M, Wang QK, Liu JY. Identification of compound heterozygous mutations in GNPTG in three siblings of a Chinese family with mucolipidosis type III gamma. Mol Genet Metab 2011; 102:107-9. [PMID: 20951619 DOI: 10.1016/j.ymgme.2010.09.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2010] [Accepted: 09/18/2010] [Indexed: 10/19/2022]
Abstract
Mucolipidosis III gamma is an autosomal recessive disorder with defective phosphorylation and trafficking of lysosomal enzymes. In a Chinese family with three siblings, linkage analysis revealed positive linkage of the family to GNPTG. Direct DNA sequence analysis identified two novel compound heterozygous mutations, c.471delC in exon 7 and IVS4-1G>C, in three patients. The two mutations cause frameshift and abnormal splicing, respectively, and represent the first series of GNPTG mutations in the Chinese population.
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Affiliation(s)
- Yong Gao
- Key Laboratory of Molecular Biophysics of the Ministry of Education, Center for Human Genome Research, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China
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37
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Coutinho MF, Encarnação M, Gomes R, da Silva Santos L, Martins S, Sirois-Gagnon D, Bargal R, Filocamo M, Raas-Rothschild A, Tappino B, Laprise C, Cury GK, Schwartz IV, Artigalás O, Prata MJ, Alves S. Origin and spread of a common deletion causing mucolipidosis type II: insights from patterns of haplotypic diversity. Clin Genet 2010; 80:273-80. [PMID: 20880125 DOI: 10.1111/j.1399-0004.2010.01539.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Mucolipidosis II (ML II alpha/beta), or I-cell disease, is a rare genetic disease in which activity of the uridine diphosphate (UDP)-N-acetylglucosamine:lysosomal enzyme N-acetylglucosamine-1-phosphotransferase (GlcNAc-phosphotransferase) is absent. GlcNAc-phosphotransferase is a multimeric enzyme encoded by two genes, GNPTAB and GNPTG. A spectrum of mutations in GNPTAB has been recently reported to cause ML II alpha/beta. Most of these mutations were found to be private or rare. However, the mutation c.3503_3504delTC has been detected among Israeli and Palestinian Arab-Muslim, Turkish, Canadian, Italian, Portuguese, Irish traveller and US patients. We analysed 44 patients who were either homozygous or compound heterozygous for this deletion (22 Italians, 8 Arab-Muslims, 1 Turk, 3 Argentineans, 3 Brazilians, 2 Irish travellers and 5 Portuguese) and 16 carriers (15 Canadians and 1 Italian) for three intragenic polymorphisms: c.-41_-39delGGC, c.18G>A and c.1932A>G as well as two microsatellite markers flanking the GNPTAB gene (D12S1607 and D12S1727). We identified a common haplotype in all chromosomes bearing the c.3503_3504delTC mutation. In summary, we showed that patients carrying the c.3503_3504delTC deletion presented with a common haplotype, which implies a common origin of this mutation. Additionally, the level of diversity observed at the most distant locus indicates that the mutation is relatively ancient (around 2063 years old), and the geographical distribution further suggests that it probably arose in a peri-Mediterranean region.
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Affiliation(s)
- M F Coutinho
- Medical Genetics Center Jacinto Magalhães, Research and Development Unit, Department of Genetics, INSA, Portugal
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Pohl S, Encarnacão M, Castrichini M, Müller-Loennies S, Muschol N, Braulke T. Loss of N-acetylglucosamine-1-phosphotransferase gamma subunit due to intronic mutation in GNPTG causes mucolipidosis type III gamma: Implications for molecular and cellular diagnostics. Am J Med Genet A 2009; 152A:124-32. [DOI: 10.1002/ajmg.a.33170] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Kollmann K, Pohl S, Marschner K, Encarnação M, Sakwa I, Tiede S, Poorthuis BJ, Lübke T, Müller-Loennies S, Storch S, Braulke T. Mannose phosphorylation in health and disease. Eur J Cell Biol 2009; 89:117-23. [PMID: 19945768 DOI: 10.1016/j.ejcb.2009.10.008] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Lysosomal hydrolases catalyze the degradation of a variety of macromolecules including proteins, carbohydrates, nucleic acids and lipids. The biogenesis of lysosomes or lysosome-related organelles requires a continuous substitution of soluble acid hydrolases and lysosomal membrane proteins. The targeting of lysosomal hydrolases depends on mannose 6-phosphate residues (M6P) that are recognized by specific receptors mediating their transport to an endosomal/prelysosomal compartment. The key role in the formation of M6P residues plays the GlcNAc-1-phosphotransferase localized in the Golgi apparatus. Two genes have been identified recently encoding the type III alpha/beta-subunit precursor membrane protein and the soluble gamma-subunit of GlcNAc-1-phosphotransferase. Mutations in these genes result in two severe diseases, mucolipidosis type II (MLII) and III (MLIII), biochemically characterized by the missorting of multiple lysosomal hydrolases due to impaired formation of the M6P recognition marker, and general lysosomal dysfunction. This review gives an update on structural properties, localization and functions of the GlcNAc-1-phosphotransferase subunits and improvements of pre- and postnatal diagnosis of ML patients. Further, the generation of recombinant single-chain antibody fragments against M6P residues and of new mouse models of MLII and MLIII will have considerable impact to provide deeper insight into the cell biology of lysosomal dysfunctions and the pathomechanisms underlying these lysosomal disorders.
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Affiliation(s)
- Katrin Kollmann
- Department of Biochemistry, Children's Hospital, University Medical Center Hamburg-Eppendorf, Research Campus, Martinistrasse 52, 20246 Hamburg, Germany
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