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Shanmugasundaram M, Wang A, Morand M, Bixler C, Jain S, Ray J. Expanded prenatal phenotype of ALG12-associated congenital disorder of glycosylation including bilateral multicystic kidneys. Am J Med Genet A 2024; 194:e63660. [PMID: 38717015 DOI: 10.1002/ajmg.a.63660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 04/05/2024] [Accepted: 04/27/2024] [Indexed: 08/10/2024]
Abstract
Congenital disorders of glycosylation (CDG) are a group of rare autosomal recessive genetic disorders caused by pathogenic variants in genes coding for N-glycosylated glycoproteins, which play a role in folding, degrading, and transport of glycoproteins in their pathway. ALG12-CDG specifically is caused by biallelic pathogenic variants in ALG12. Currently reported features of ALG12-CDG include: developmental delay, hypotonia, failure to thrive and/or short stature, brain anomalies, recurrent infections, hypogammaglobulinemia, coagulation abnormalities, and genitourinary abnormalities. In addition, skeletal abnormalities resembling a skeletal dysplasia including shortened long bones and talipes equinovarus have been seen in more severe neonatal presentation of this disorder. We report on a case expanding the phenotype of ALG12-CDG to include bilateral, multicystic kidneys in a neonatal demise identified with homozygous pathogenic variants in the ALG12 gene at c.1001del (p.N334Tfs*15) through clinical trio exome sequencing.
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Affiliation(s)
| | - Amanda Wang
- Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Megan Morand
- Division of Medical Genetics and Metabolism, Department of Pediatrics, University of Texas Medical Branch, Galveston, Texas, USA
| | - Colin Bixler
- Division of Medical Genetics and Metabolism, Department of Pediatrics, University of Texas Medical Branch, Galveston, Texas, USA
| | - Sangeeta Jain
- Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Joseph Ray
- Division of Medical Genetics and Metabolism, Department of Pediatrics, University of Texas Medical Branch, Galveston, Texas, USA
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2
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Li J, Kolin DA, Nallasamy S, Kolin T. Duane syndrome in association with congenital disorder of glycosylation type Ig (ALG12-CDG). J AAPOS 2024; 28:103954. [PMID: 38876156 DOI: 10.1016/j.jaapos.2024.103954] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Revised: 03/13/2024] [Accepted: 03/25/2024] [Indexed: 06/16/2024]
Abstract
Congenital disorders of glycosylation type I (CDG-I) are a group of autosomal recessive genetic multisystem disorders that arise from defective glycoprotein biosynthesis. Although ocular abnormalities have been described in patients with CDG-I, few ocular abnormalities have been associated with ALG12-CDG (CDG-Ig), a rare subtype of CDG-I. We report a case of Duane syndrome, a congenital strabismus syndrome, in a 17-year-old young woman with ALG12-CDG.
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Affiliation(s)
- Joy Li
- Keck School of Medicine, University of Southern California, Los Angeles, California
| | - David A Kolin
- Department of Orthopedic Surgery, Hospital for Special Surgery, New York, New York
| | - Sudha Nallasamy
- The Vision Center at Children's Hospital Los Angeles, Los Angeles, California; USC Roski Eye Institute, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - Talia Kolin
- The Vision Center at Children's Hospital Los Angeles, Los Angeles, California; USC Roski Eye Institute, Keck School of Medicine, University of Southern California, Los Angeles, California; Veterans Affairs Los Angeles Ambulatory Care Center, Los Angeles, California.
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3
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Ballios BG, Mandola A, Tayyib A, Tumber A, Garkaby J, Vong L, Heon E, Roifman CM, Vincent A. Deep phenotypic characterization of the retinal dystrophy in patients with RNU4ATAC-associated Roifman syndrome. Eye (Lond) 2023; 37:3734-3742. [PMID: 37225827 PMCID: PMC10697969 DOI: 10.1038/s41433-023-02581-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 05/01/2023] [Accepted: 05/11/2023] [Indexed: 05/26/2023] Open
Abstract
PURPOSE To characterize the retinal phenotype in RNU4ATAC-associated Roifman syndrome. METHODS Ten patients (including 8 males) with molecularly confirmed Roifman syndrome underwent detailed ophthalmologic evaluation including fundus imaging, fundus autofluorescence (FAF) imaging, spectral-domain optical coherence tomography (SD-OCT), and electroretinography (ERG). Six patients had follow-up eye exams. All patients also underwent comprehensive examination for features of extra-retinal Roifman syndrome. RESULTS All patients had biallelic RNU4ATAC variants. Nyctalopia was common (7/10). Visual acuity at presentation ranged from 20/20 to 20/200 (Age Range: 5-41 years). Retinal exam revealed features of generalized retinopathy with mid-peripheral pigment epithelial changes. A para or peri-foveal ring of hyper-autofluorescence was the commonest FAF abnormality noted (6/8). The SD-OCT demonstrated relative preservation of the foveal ellipsoid zone in six cases; associated features included cystoid changes (5/10) and posterior staphyloma (3/10). The ERG was abnormal in all patients; nine showed generalized rod-cone dystrophy, whilst one patient with sectoral retinal involvement only had isolated rod dystrophy (20 years old). On follow-up examination (Mean duration: 8.16 years), progressive loss of visual acuity (2/6), mid-peripheral retinal atrophy (3/6) or shortening of ellipsoid zone width (1/6) were observed. CONCLUSION This study has characterized the retinal phenotype in RNU4ATAC-associated Roifman syndrome. Retinal involvement is universal, early-onset, and overall, the retinal and FAF features are consistent with rod-cone degeneration that is slowly progressive over time. The sub-foveal retinal ultrastructure is relatively preserved in majority of patients. Phenotypic variability independent of age exists, and more study of allelic- and sex-based determinants of disease severity are necessary.
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Affiliation(s)
- Brian G Ballios
- Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, ON, Canada
| | - Amarilla Mandola
- Division of Immunology and Allergy, The Hospital for Sick Children and the University of Toronto, Toronto, ON, Canada
| | - Alaa Tayyib
- Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, ON, Canada
- Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, ON, Canada
| | - Anupreet Tumber
- Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, ON, Canada
| | - Jenny Garkaby
- Division of Immunology and Allergy, The Hospital for Sick Children and the University of Toronto, Toronto, ON, Canada
| | - Linda Vong
- The Canadian Centre for Primary Immunodeficiency and The Jeffrey Modell Research Laboratory for the Diagnosis of Primary Immunodeficiency, The Hospital for Sick Children, Toronto, ON, Canada
| | - Elise Heon
- Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, ON, Canada
- Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, ON, Canada
| | - Chaim M Roifman
- Division of Immunology and Allergy, The Hospital for Sick Children and the University of Toronto, Toronto, ON, Canada
- The Canadian Centre for Primary Immunodeficiency and The Jeffrey Modell Research Laboratory for the Diagnosis of Primary Immunodeficiency, The Hospital for Sick Children, Toronto, ON, Canada
| | - Ajoy Vincent
- Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, ON, Canada.
- Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, ON, Canada.
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Liew CY, Luo HS, Yang TY, Hung AT, Magoling BJA, Lai CPK, Ni CK. Identification of the High Mannose N-Glycan Isomers Undescribed by Conventional Multicellular Eukaryotic Biosynthetic Pathways. Anal Chem 2023. [PMID: 37235553 DOI: 10.1021/acs.analchem.2c05599] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
N-linked glycosylation is one of the most important post-translational modifications of proteins. Current knowledge of multicellular eukaryote N-glycan biosynthesis suggests high mannose N-glycans are generated in the endoplasmic reticulum and Golgi apparatus through conserved biosynthetic pathways. According to conventional biosynthetic pathways, four Man7GlcNAc2 isomers, three Man6GlcNAc2 isomers, and one Man5GlcNAc2 isomer are generated during this process. In this study, we applied our latest mass spectrometry method, logically derived sequence tandem mass spectrometry (LODES/MSn), to re-examine high mannose N-glycans extracted from various multicellular eukaryotes which are not glycosylation mutants. LODES/MSn identified many high mannose N-glycan isomers previously unreported in plantae, animalia, cancer cells, and fungi. A database consisting of retention time and CID MSn mass spectra was constructed for all possible MannGlcNAc2 (n = 5, 6, 7) isomers that include the isomers by removing arbitrary numbers and positions of mannose from canonical N-glycan, Man9GlcNAc2. Many N-glycans in this database are not found in current N-glycan mass spectrum libraries. The database is useful for rapid high mannose N-glycan isomeric identification.
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Affiliation(s)
- Chia Yen Liew
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
- International Graduate Program of Molecular Science and Technology, National Taiwan University (NTU-MST), Taipei 10617, Taiwan
- Molecular Science and Technology (MST), Taiwan International Graduate Program (TIGP), Academia Sinica, Taipei 10617, Taiwan
| | - Hong-Sheng Luo
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
- Department of Chemistry, National Taiwan Normal University, Taipei 11677, Taiwan
| | - Ting-Yi Yang
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
- Department of Chemistry, National Taiwan Normal University, Taipei 11677, Taiwan
| | - An-Ti Hung
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
- Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Bryan John Abel Magoling
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
- Institute of Biochemical Sciences, College of Life Science, National Taiwan University, Taipei 10617, Taiwan
- Chemical Biology and Molecular Biophysics Program, Taiwan International Graduate Program, Academia Sinica, Taipei 11529, Taiwan
| | - Charles Pin-Kuang Lai
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
- Chemical Biology and Molecular Biophysics Program, Taiwan International Graduate Program, Academia Sinica, Taipei 11529, Taiwan
- Genome and Systems Biology Degree Program, National Taiwan University and Academia Sinica, Taipei 10617, Taiwan
| | - Chi-Kung Ni
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
- Molecular Science and Technology (MST), Taiwan International Graduate Program (TIGP), Academia Sinica, Taipei 10617, Taiwan
- Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan
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Scott TM, Campbell IM, Hernandez-Garcia A, Lalani SR, Liu P, Shaw CA, Rosenfeld JA, Scott DA. Clinical exome sequencing data reveal high diagnostic yields for congenital diaphragmatic hernia plus (CDH+) and new phenotypic expansions involving CDH. J Med Genet 2022; 59:270-278. [PMID: 33461977 PMCID: PMC8286264 DOI: 10.1136/jmedgenet-2020-107317] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Revised: 11/17/2020] [Accepted: 12/26/2020] [Indexed: 01/10/2023]
Abstract
BACKGROUND Congenital diaphragmatic hernia (CDH) is a life-threatening birth defect that often co-occurs with non-hernia-related anomalies (CDH+). While copy number variant (CNV) analysis is often employed as a diagnostic test for CDH+, clinical exome sequencing (ES) has not been universally adopted. METHODS We analysed a clinical database of ~12 000 test results to determine the diagnostic yields of ES in CDH+ and to identify new phenotypic expansions. RESULTS Among the 76 cases with an indication of CDH+, a molecular diagnosis was made in 28 cases for a diagnostic yield of 37% (28/76). A provisional diagnosis was made in seven other cases (9%; 7/76). Four individuals had a diagnosis of Kabuki syndrome caused by frameshift variants in KMT2D. Putatively deleterious variants in ALG12 and EP300 were each found in two individuals, supporting their role in CDH development. We also identified individuals with de novo pathogenic variants in FOXP1 and SMARCA4, and compound heterozygous pathogenic variants in BRCA2. The role of these genes in CDH development is supported by the expression of their mouse homologs in the developing diaphragm, their high CDH-specific pathogenicity scores generated using a previously validated algorithm for genome-scale knowledge synthesis and previously published case reports. CONCLUSION We conclude that ES should be ordered in cases of CDH+ when a specific diagnosis is not suspected and CNV analyses are negative. Our results also provide evidence in favour of phenotypic expansions involving CDH for genes associated with ALG12-congenital disorder of glycosylation, Rubinstein-Taybi syndrome, Fanconi anaemia, Coffin-Siris syndrome and FOXP1-related disorders.
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Affiliation(s)
- Tiana M. Scott
- Department of Microbiology and Molecular Biology, College of Life Sciences, Brigham Young University, Provo, UT, 84602, USA,Texas Children’s Hospital, Houston, TX, 77030, USA
| | - Ian M. Campbell
- Division of Human Genetics, Children’s Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | - Andres Hernandez-Garcia
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Seema R. Lalani
- Texas Children’s Hospital, Houston, TX, 77030, USA,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Pengfei Liu
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA,Baylor Genetics, Houston, TX, 77021, USA
| | - Chad A. Shaw
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Jill A. Rosenfeld
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Daryl A. Scott
- Texas Children’s Hospital, Houston, TX, 77030, USA,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA,Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, 77030, USA,Correspondence Daryl A. Scott, R813, One Baylor Plaza. BCM225, Houston, TX 77030, USA, , Phone: +1 713-203-7242
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6
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Nicotera AG, Spoto G, Calì F, Romeo G, Musumeci A, Vinci M, Fiumara A, Barone R, Di Rosa G, Musumeci SA. A Novel Homozygous ALG12 Mutation in a Patient with CDG Type Ig: New Report of a Case with a Mild Phenotype. Mol Syndromol 2021; 12:327-332. [PMID: 34602961 DOI: 10.1159/000516606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 04/18/2021] [Indexed: 11/19/2022] Open
Abstract
Congenital disorders of glycosylation (CDG) are a group of rare genetic diseases caused by the deficiency of enzymes involved in the biosynthesis or remodeling of the glycan moieties of glycoconjugates. Most of CDG are autosomal recessive; however, few of them show autosomal dominant or X-linked inheritance. ALG12-CDG is an autosomal recessive inherited defect caused by a deficiency in the α-mannosyltransferase, dolichyl-P-mannose: Man7-GlcNAc-2-PP-dolichyl-alpha-6-mannosyltransferase (mannosyltransferase 8), which determines Man7GlcNAc2-PP-dolichol accumulation in tissues including fibroblasts. The clinical features of ALG12-CDG include dysmorphic features, developmental delay, hypotonia, progressive microcephaly, hypogammaglobulinemia, coagulopathies, and failure to thrive. Herein, we describe the case of a Sicilian patient with a milder phenotype bearing an ALG12 homozygous mutation. To date, including this patient, only 16 cases have been described with this form of CDG. Furthermore, our study contributes to understanding the milder ALG12-CDG cases and to further expanding the genotype-phenotype spectrum.
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Affiliation(s)
- Antonio Gennaro Nicotera
- Unit of Child Neurology and Psychiatry, Department of Human Pathology in Adult and Developmental Age "Gaetano Barresi", University of Messina, Messina, Italy
| | - Giulia Spoto
- Unit of Child Neurology and Psychiatry, Department of Human Pathology in Adult and Developmental Age "Gaetano Barresi", University of Messina, Messina, Italy
| | | | - Giusi Romeo
- Oasi Research Institute - IRCCS, Troina, Italy
| | | | | | - Agata Fiumara
- Department of Clinical and Experimental Medicine, Regional Referral Center for Inborn Errors Metabolism, Pediatric Clinic, University of Catania, Catania, Italy
| | - Rita Barone
- Department of Clinical and Experimental Medicine, Regional Referral Center for Inborn Errors Metabolism, Pediatric Clinic, University of Catania, Catania, Italy
| | - Gabriella Di Rosa
- Unit of Child Neurology and Psychiatry, Department of Human Pathology in Adult and Developmental Age "Gaetano Barresi", University of Messina, Messina, Italy
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7
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Liver Involvement in Congenital Disorders of Glycosylation: A Systematic Review. J Pediatr Gastroenterol Nutr 2021; 73:444-454. [PMID: 34173795 PMCID: PMC9255677 DOI: 10.1097/mpg.0000000000003209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
An ever-increasing number of disturbances in glycosylation have been described to underlie certain unexplained liver diseases presenting either almost isolated or in a multi-organ context. We aimed to update previous literature screenings which had identified up to 23 forms of congenital disorders of glycosylation (CDG) with associated liver disease. We conducted a comprehensive literature search of three scientific electronic databases looking at articles published during the last 20 years (January 2000-October 2020). Eligible studies were case reports/series reporting liver involvement in CDG patients. Our systematic review led us to point out 41 forms of CDG where the liver is primarily affected (n = 7) or variably involved in a multisystem disease with mandatory neurological abnormalities (n = 34). Herein we summarize individual clinical and laboratory presentation characteristics of these 41 CDG and outline their main presentation and diagnostic cornerstones with the aid of two synoptic tables. Dietary supplementation strategies have hitherto been investigated only in seven of these CDG types with liver disease, with a wide range of results. In conclusion, the systematic review recognized a liver involvement in a somewhat larger number of CDG variants corresponding to about 30% of the total of CDG so far reported, and it is likely that the number may increase further. This information could assist in an earlier correct diagnosis and a possibly proper management of these disorders.
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8
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Novel ALG12 variants and hydronephrosis in siblings with impaired N-glycosylation. Brain Dev 2021; 43:945-951. [PMID: 34092405 DOI: 10.1016/j.braindev.2021.05.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 05/18/2021] [Accepted: 05/20/2021] [Indexed: 11/22/2022]
Abstract
BACKGROUND ALG12-CDG is a rare autosomal recessive type I congenital disorder of glycosylation (CDG) due to pathogenic variants in ALG12 which encodes the dolichyl-P-mannose:Man-7-GlcNAc-2-PP-dolichyl-alpha-6-mannosyltransferase. Thirteen patients from unrelated 11 families have been reported, most of them result in broad multisystem manifestations with clinical variability. It is important to validate abnormal glycosylation to establish causal relationship. CASE REPORT Here, we report two siblings with novel compound heterozygous variants in ALG12: c.443T>C, p.(Leu148Pro) and c.412_413insCGT, p.(Gln137_Phe138insSer). Both patients showed global developmental delay, microcephaly, hypotonia, failure to thrive, facial dysmorphism, skeletal malformations and coagulation abnormalities, which are common in ALG12-CDG. In addition, one of our patients showed left hydronephrosis, which is a novel clinical feature in ALG12-CDG. Brain MRI showed hypoplasia of cerebrum, brain stem and cerebellar vermis in both patients. N-glycosylation defects of trypsin digested transferrin peptides were revealed by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), and electrospray ionization MS verified the lack of N-glycans in transferrin. CONCLUSIONS The present study can add hydronephrosis to phenotypic spectrum of ALG12-CDG. Since the symptoms of ALG12-CDG are quite diverse, the combination of whole-exome sequencing and transferrin glycopeptide analysis with MS, can help diagnosis of ALG12-CDG.
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9
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Ziburová J, Nemčovič M, Šesták S, Bellová J, Pakanová Z, Siváková B, Šalingová A, Šebová C, Ostrožlíková M, Lekka DE, Brucknerová J, Brucknerová I, Skokňová M, Mc Cullough A, Hrčková G, Hlavatá A, Bzdúch V, Mucha J, Baráth P. A novel homozygous mutation in the human ALG12 gene results in an aberrant profile of oligomannose N-glycans in patient's serum. Am J Med Genet A 2021; 185:3494-3501. [PMID: 34467644 PMCID: PMC9291070 DOI: 10.1002/ajmg.a.62474] [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: 01/28/2021] [Revised: 08/03/2021] [Accepted: 08/11/2021] [Indexed: 12/22/2022]
Abstract
Congenital disorder of glycosylation type Ig (ALG12-CDG) is a rare inherited metabolic disease caused by a defect in alpha-mannosyltransferase 8, encoded by the ALG12 gene (22q13.33). To date, only 15 patients have been diagnosed with ALG12-CDG globally. Due to a newborn Slovak patient's clinical and biochemical abnormalities, the isoelectric focusing of transferrin was performed with observed significant hypoglycosylation typical of CDG I. Furthermore, analysis of neutral serum N-glycans by mass spectrometry revealed the accumulation of GlcNAc2Man5-7 and decreased levels of GlcNAc2Man8-9, which indicated impaired ALG12 enzymatic activity. Genetic analysis of the coding regions of the ALG12 gene of the patient revealed a novel homozygous substitution mutation c.1439T>C p.(Leu480Pro) within Exon 10. Furthermore, both of the patient's parents and his twin sister were asymptomatic heterozygous carriers of the variant. This comprehensive genomic and glycomic approach led to the confirmation of the ALG12 pathogenic variant responsible for the clinical manifestation of the disorder in the patient described.
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Affiliation(s)
- Jana Ziburová
- Department of Glycobiology, Slovak Academy of Sciences, Institute of Chemistry, Bratislava, Slovakia.,Department of Clinical Genetics, St. Elizabeth Cancer Institute, Bratislava, Slovakia
| | - Marek Nemčovič
- Department of Glycobiology, Slovak Academy of Sciences, Institute of Chemistry, Bratislava, Slovakia
| | - Sergej Šesták
- Department of Glycobiology, Slovak Academy of Sciences, Institute of Chemistry, Bratislava, Slovakia
| | - Jana Bellová
- Department of Glycobiology, Slovak Academy of Sciences, Institute of Chemistry, Bratislava, Slovakia
| | - Zuzana Pakanová
- Department of Glycobiology, Slovak Academy of Sciences, Institute of Chemistry, Bratislava, Slovakia
| | - Barbara Siváková
- Department of Glycobiology, Slovak Academy of Sciences, Institute of Chemistry, Bratislava, Slovakia
| | - Anna Šalingová
- Department of Laboratory Medicine, National Institute of Children's Diseases, Bratislava, Slovakia
| | - Claudia Šebová
- Department of Laboratory Medicine, National Institute of Children's Diseases, Bratislava, Slovakia
| | - Mária Ostrožlíková
- Department of Laboratory Medicine, National Institute of Children's Diseases, Bratislava, Slovakia
| | - Dimitra-Evanthia Lekka
- Department of Neonatology and Intensive Medicine, National Institute of Children's Diseases, Bratislava, Slovakia.,Faculty of Medicine, Comenius University, Bratislava, Slovakia
| | - Jana Brucknerová
- Department of Neonatology and Intensive Medicine, National Institute of Children's Diseases, Bratislava, Slovakia.,Faculty of Medicine, Comenius University, Bratislava, Slovakia
| | - Ingrid Brucknerová
- Department of Neonatology and Intensive Medicine, National Institute of Children's Diseases, Bratislava, Slovakia
| | - Martina Skokňová
- Department of Neonatology and Intensive Medicine, National Institute of Children's Diseases, Bratislava, Slovakia
| | - Alexandra Mc Cullough
- Department of Neonatology and Intensive Medicine, National Institute of Children's Diseases, Bratislava, Slovakia
| | - Gabriela Hrčková
- Faculty of Medicine, Department of Paediatrics, National Institute of Children's Diseases, Comenius University, Bratislava, Slovakia
| | - Anna Hlavatá
- Faculty of Medicine, Department of Paediatrics, National Institute of Children's Diseases, Comenius University, Bratislava, Slovakia
| | - Vladimír Bzdúch
- Faculty of Medicine, Department of Paediatrics, National Institute of Children's Diseases, Comenius University, Bratislava, Slovakia
| | - Ján Mucha
- Department of Glycobiology, Slovak Academy of Sciences, Institute of Chemistry, Bratislava, Slovakia
| | - Peter Baráth
- Department of Glycobiology, Slovak Academy of Sciences, Institute of Chemistry, Bratislava, Slovakia
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10
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Messina A, Palmigiano A, Esposito F, Fiumara A, Bordugo A, Barone R, Sturiale L, Jaeken J, Garozzo D. HILIC-UPLC-MS for high throughput and isomeric N-glycan separation and characterization in Congenital Disorders Glycosylation and human diseases. Glycoconj J 2020; 38:201-211. [PMID: 32915358 DOI: 10.1007/s10719-020-09947-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 09/07/2020] [Accepted: 09/08/2020] [Indexed: 12/26/2022]
Abstract
N-glycan analyses may serve uncovering disease-associated biomarkers, as well as for profiling distinctive changes supporting diagnosis of genetic disorders of glycan biosynthesis named congenital disorders of glycosylation (CDG). Strategies based on liquid chromatography (LC) preferentially coupled to electrospray ionization (ESI) - mass spectrometry (MS) have emerged as powerful analytical methods for N-glycan identification and characterization. To enhance detection sensitivity, glycans are commonly labelled with a functional tag prior to LC-MS analysis. Since most derivatization techniques are notoriously time-consuming, some commercial analytical kits have been developed to speed up N-deglycosylation and N-glycan labelling of glycoproteins of pharmaceutical and biological interest such as monoclonal antibodies (mAbs). We exploited the analytical capabilities of RapiFluor-MS (RFMS) to perform, by a slightly modified protocol, a detailed N-glycan characterization of total serum and single serum glycoproteins from specific patients with CDG (MAN1B1-CDG, ALG12-CDG, MOGS-CDG, TMEM199-CDG). This strategy, accomplished by Hydrophilic Interaction Chromatography (HILIC)-UPLC-ESI-MS separation of the RFMS derivatized N-glycans, allowed us to uncover structural details of patients serum released N-glycans, thus extending the current knowledge on glycan profiles in these individual glycosylation diseases. The applied methodology enabled to differentiate in some cases either structural isomers and isomers differing in the linkage type. All the here reported applications demonstrated that RFMS method, coupled to HILIC-UPLC-ESI-MS, represents a sensitive high throughput approach for serum N-glycome analysis and a valuable option for glycan detection and separation particularly for isomeric species.
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Affiliation(s)
- Angela Messina
- CNR, Institute for Polymers, Composites and Biomaterials, IPCB, Catania, Italy
| | - Angelo Palmigiano
- CNR, Institute for Polymers, Composites and Biomaterials, IPCB, Catania, Italy
| | - Francesca Esposito
- CNR, Institute for Polymers, Composites and Biomaterials, IPCB, Catania, Italy
- IOM Ricerca S.r.l, Viagrande, CT, Italy
| | - Agata Fiumara
- Pediatric Clinic- Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Andrea Bordugo
- Department of Mother and Child, Pediatric Clinic, University Hospital of Verona, Verona, Italy
| | - Rita Barone
- CNR, Institute for Polymers, Composites and Biomaterials, IPCB, Catania, Italy
- Child Neurology and Psychiatry, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Luisa Sturiale
- CNR, Institute for Polymers, Composites and Biomaterials, IPCB, Catania, Italy
| | - Jaak Jaeken
- Center for Metabolic Diseases, UZ and KU Leuven, Leuven, Belgium
| | - Domenico Garozzo
- CNR, Institute for Polymers, Composites and Biomaterials, IPCB, Catania, Italy.
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11
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de la Morena-Barrio ME, Sabater M, de la Morena-Barrio B, Ruhaak RL, Miñano A, Padilla J, Toderici M, Roldán V, Gimeno JR, Vicente V, Corral J. ALG12-CDG: An unusual patient without intellectual disability and facial dysmorphism, and with a novel variant. Mol Genet Genomic Med 2020; 8:e1304. [PMID: 32530140 PMCID: PMC7434597 DOI: 10.1002/mgg3.1304] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 04/22/2020] [Accepted: 04/23/2020] [Indexed: 12/23/2022] Open
Abstract
Background Congenital disorder of glycosylation (CDG) type I is a group of rare disorders caused by recessive mutations in up to 25 genes that impair the N‐glycan precursor formation and its transfer to proteins resulting in hypoglycosylation of multiple proteins. Congenital disorder of glycosylation causes multisystem defects usually with psychomotor delay that is diagnosed in the infancy. We aim to supply further evidences supporting that CDG may be underestimated. Methods Antithrombin and factor XI were studied by chromogenic and coagulometric methods. Hypoglycosylation of plasma proteins was evaluated by western blot, HPLC, Q‐TOF, and RP‐LC‐MRM‐MS. Genetic analysis included whole exome, Sanger sequencing, and PCR‐allele specific assay. Results We here present an intriguing patient with an exceptional phenotype: 25‐year‐old women with a ventricular septal defect and severe idiopathic scoliosis but no facial dysmorphism, who dances as a professional, and has a University degree. Congenital disorder of glycosylation diagnosis started through the identification of antithrombin deficiency without SERPINC1 defect and the detection of hypoglycosylated forms. Increased levels of hypoglycosylated forms of F XI (also with significant deficiency) and transferrin were also detected. Whole exome analysis showed a novel homozygous ALG12 variant c.77T>A, p.(Val26Asp) supporting an ALG12‐CDG diagnosis. It also showed three new variants in KMT2D, and a mild, known ALG6 variant. Conclusions This novel ALG12‐CDG patient (the 13th reported) underlines the heterogeneity of this CDG and broadens its phenotypical spectrum, supports that these disorders are underestimated, and suggests that combination of global hypoglycosylation with specific gene defects might determine the clinical manifestations of CDG patients.
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Affiliation(s)
- María Eugenia de la Morena-Barrio
- Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, CIBERER, Universidad de Murcia, IMIB-Arrixaca, Murcia, Spain
| | - María Sabater
- Servicio de Cardiología, Laboratorio de Cardiogenética, CIBERCV, Hospital Clínico Universitario Virgen de la Arrixaca-IMIB, Murcia, Spain
| | - Belén de la Morena-Barrio
- Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, CIBERER, Universidad de Murcia, IMIB-Arrixaca, Murcia, Spain
| | - Renee L Ruhaak
- Department of Clinical Chemistry and Laboratory Medicine, Leiden University Medical Center, Leiden, The Netherlands
| | - Antonia Miñano
- Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, CIBERER, Universidad de Murcia, IMIB-Arrixaca, Murcia, Spain
| | - José Padilla
- Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, CIBERER, Universidad de Murcia, IMIB-Arrixaca, Murcia, Spain
| | - Mara Toderici
- Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, CIBERER, Universidad de Murcia, IMIB-Arrixaca, Murcia, Spain
| | - Vanessa Roldán
- Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, CIBERER, Universidad de Murcia, IMIB-Arrixaca, Murcia, Spain
| | - Juan R Gimeno
- Servicio de Cardiología, Laboratorio de Cardiogenética, CIBERCV, Hospital Clínico Universitario Virgen de la Arrixaca-IMIB, Murcia, Spain
| | - Vicente Vicente
- Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, CIBERER, Universidad de Murcia, IMIB-Arrixaca, Murcia, Spain
| | - Javier Corral
- Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, CIBERER, Universidad de Murcia, IMIB-Arrixaca, Murcia, Spain
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Tahata S, Gunderson L, Lanpher B, Morava E. Complex phenotypes in ALG12-congenital disorder of glycosylation (ALG12-CDG): Case series and review of the literature. Mol Genet Metab 2019; 128:409-414. [PMID: 31481313 DOI: 10.1016/j.ymgme.2019.08.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 08/24/2019] [Accepted: 08/25/2019] [Indexed: 01/20/2023]
Abstract
ALG12-congenital disorder of glycosylation (ALG12-CDG) is a rare disorder caused by a deficiency of dolichol-P-mannose:Man7GlcNAc2-PP-dolichyl-α-6-mannosyltransferase which presents with intellectual disability, hypotonia, dysmorphic features, low IgG levels with recurrent infections, male genital hypoplasia, and coagulation abnormalities. We report a unique family with three affected individuals, including two older brothers with only cognitive and coagulation defects and a younger brother who died from a severe multisystem disease at age 18 months. The two living brothers are the oldest and mildest cases of ALG12-CDG described thus far. Whole exome sequencing of the older brothers revealed a previously described c.1001delA (p.N334TfsX15) pathogenic variant and a c.671C > T (p.T224 M) variant of uncertain significance in ALG12. Our cases broaden the recognized genetic and phenotypic spectrum of this disorder and suggest a role for other genetic and environmental factors in modulating disease phenotype.
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Affiliation(s)
| | | | | | - Eva Morava
- Mayo Clinic, Rochester, MN 55905, United States.
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13
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Esfandiari H, Mets MB, Kim KH, Kurup SP. Ocular abnormalities in a patient with congenital disorder of glycosylation type Ig. Ophthalmic Genet 2019; 40:549-552. [PMID: 31743061 DOI: 10.1080/13816810.2019.1692361] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Background: Congenital disorders of glycosylation (CDG) are a group of hereditary multisystem disorders characterized by hypoglycosylation of glycoproteins. CDG type I results in a defect in the assembly of lipid-linkedoligosaccharides or their transfer onto nascent glycoproteins. Ocular abnormalities are common in CDG, but there is no report of detailed ophthalmologic evaluation in patients with CDG type Ig in the literature.Materials and Methods: Retrospective chart review of a case of CDG type Ig with novel variant in the associated gene: ALG12.Results: In addition to typical systemic findings of CDG, our case was found to have exotropia, bilateralcataracts, and retinitis pigmentosa with extinguished electroretinography in photopic and scotopic conditions.Conclusions: We hope to extend the understanding of ALG12-related CDG type Ig with these ophthalmologic observations.
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Affiliation(s)
- Hamed Esfandiari
- Division of Ophthalmology, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA.,Department of Ophthalmology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Marilyn B Mets
- Division of Ophthalmology, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA.,Department of Ophthalmology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Katherine H Kim
- Division of Genetics, Birth Defects & Metabolism, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA.,Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Sudhi P Kurup
- Division of Ophthalmology, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA.,Department of Ophthalmology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
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14
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ALG12-CDG: novel glycophenotype insights endorse the molecular defect. Glycoconj J 2019; 36:461-472. [DOI: 10.1007/s10719-019-09890-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 07/23/2019] [Accepted: 09/04/2019] [Indexed: 12/15/2022]
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15
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Bacterial Lipid II Analogs: Novel In Vitro Substrates for Mammalian Oligosaccharyl Diphosphodolichol Diphosphatase (DLODP) Activities. Molecules 2019; 24:molecules24112135. [PMID: 31174247 PMCID: PMC6600155 DOI: 10.3390/molecules24112135] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 06/04/2019] [Accepted: 06/05/2019] [Indexed: 11/17/2022] Open
Abstract
Mammalian protein N-glycosylation requires the transfer of an oligosaccharide containing 2 residues of N-acetylglucosamine, 9 residues of mannose and 3 residues of glucose (Glc3Man9 GlcNAc2) from Glc3Man9GlcNAc2-diphospho (PP)-dolichol (DLO) onto proteins in the endoplasmic reticulum (ER). Under some pathophysiological conditions, DLO biosynthesis is perturbed, and truncated DLO is hydrolyzed to yield oligosaccharyl phosphates (OSP) via unidentified mechanisms. DLO diphosphatase activity (DLODP) was described in vitro, but its characterization is hampered by a lack of convenient non-radioactive substrates. Our objective was to develop a fluorescence-based assay for DLO hydrolysis. Using a vancomycin-based solid-phase extraction procedure coupled with thin layer chromatography (TLC) and mass spectrometry, we demonstrate that mouse liver membrane extracts hydrolyze fluorescent bacterial lipid II (LII: GlcNAc-MurNAc(dansyl-pentapeptide)-PP-undecaprenol) to yield GlcNAc-MurNAc(dansyl-pentapeptide)-P (GM5P). GM5P production by solubilized liver microsomal proteins shows similar biochemical characteristics to those reported for human hepatocellular carcinoma HepG2 cell DLODP activity. To conclude, we show, for the first time, hydrolysis of lipid II by a eukaryotic enzyme. As LII and DLO are hydrolyzed by the same, or closely related, enzymes, fluorescent lipid II analogs are convenient non-radioactive substrates for investigating DLODP and DLODP-like activities.
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16
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van den Boogert MAW, Larsen LE, Ali L, Kuil SD, Chong PLW, Loregger A, Kroon J, Schnitzler JG, Schimmel AWM, Peter J, Levels JHM, Steenbergen G, Morava E, Dallinga-Thie GM, Wevers RA, Kuivenhoven JA, Hand NJ, Zelcer N, Rader DJ, Stroes ESG, Lefeber DJ, Holleboom AG. N-Glycosylation Defects in Humans Lower Low-Density Lipoprotein Cholesterol Through Increased Low-Density Lipoprotein Receptor Expression. Circulation 2019; 140:280-292. [PMID: 31117816 DOI: 10.1161/circulationaha.118.036484] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
BACKGROUND The importance of protein glycosylation in regulating lipid metabolism is becoming increasingly apparent. We set out to further investigate this by studying patients with type I congenital disorders of glycosylation (CDGs) with defective N-glycosylation. METHODS We studied 29 patients with the 2 most prevalent types of type I CDG, ALG6 (asparagine-linked glycosylation protein 6)-deficiency CDG and PMM2 (phosphomannomutase 2)-deficiency CDG, and 23 first- and second-degree relatives with a heterozygous mutation and measured plasma cholesterol levels. Low-density lipoprotein (LDL) metabolism was studied in 3 cell models-gene silencing in HepG2 cells, patient fibroblasts, and patient hepatocyte-like cells derived from induced pluripotent stem cells-by measuring apolipoprotein B production and secretion, LDL receptor expression and membrane abundance, and LDL particle uptake. Furthermore, SREBP2 (sterol regulatory element-binding protein 2) protein expression and activation and endoplasmic reticulum stress markers were studied. RESULTS We report hypobetalipoproteinemia (LDL cholesterol [LDL-C] and apolipoprotein B below the fifth percentile) in a large cohort of patients with type I CDG (mean age, 9 years), together with reduced LDL-C and apolipoprotein B in clinically unaffected heterozygous relatives (mean age, 46 years), compared with 2 separate sets of age- and sex-matched control subjects. ALG6 and PMM2 deficiency led to markedly increased LDL uptake as a result of increased cell surface LDL receptor abundance. Mechanistically, this outcome was driven by increased SREBP2 protein expression accompanied by amplified target gene expression, resulting in higher LDL receptor protein levels. Endoplasmic reticulum stress was not found to be a major mediator. CONCLUSIONS Our study establishes N-glycosylation as an important regulator of LDL metabolism. Given that LDL-C was also reduced in a group of clinically unaffected heterozygotes, we propose that increasing LDL receptor-mediated cholesterol clearance by targeting N-glycosylation in the LDL pathway may represent a novel therapeutic strategy to reduce LDL-C and cardiovascular disease.
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Affiliation(s)
- Marjolein A W van den Boogert
- Departments of Vascular Medicine (M.A.W.v.d.B., J.K., G.M.D.-T., E.S.G.S., A.G.H.), Amsterdam University Medical Centers, location AMC, The Netherlands.,Experimental Vascular Medicine (M.A.W.v.d.B., L.E.L., L.A., P.L.W.C., J.K., J.G.S., A.W.M.S., J.P., J.H.M.L., G.M.D.-T.), Amsterdam University Medical Centers, location AMC, The Netherlands
| | - Lars E Larsen
- Experimental Vascular Medicine (M.A.W.v.d.B., L.E.L., L.A., P.L.W.C., J.K., J.G.S., A.W.M.S., J.P., J.H.M.L., G.M.D.-T.), Amsterdam University Medical Centers, location AMC, The Netherlands.,Department of Genetics and Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia (L.E.L., P.L.W.C., N.J.H., D.J.R.)
| | - Lubna Ali
- Experimental Vascular Medicine (M.A.W.v.d.B., L.E.L., L.A., P.L.W.C., J.K., J.G.S., A.W.M.S., J.P., J.H.M.L., G.M.D.-T.), Amsterdam University Medical Centers, location AMC, The Netherlands
| | - Sacha D Kuil
- Department of Laboratory Medicine, Translational Metabolic Laboratory (S.D.K., G.S., R.A.W., D.J.L.), Radboud University Medical Center, Nijmegen, The Netherlands
| | - Patrick L W Chong
- Experimental Vascular Medicine (M.A.W.v.d.B., L.E.L., L.A., P.L.W.C., J.K., J.G.S., A.W.M.S., J.P., J.H.M.L., G.M.D.-T.), Amsterdam University Medical Centers, location AMC, The Netherlands.,Department of Genetics and Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia (L.E.L., P.L.W.C., N.J.H., D.J.R.)
| | - Anke Loregger
- Medical Biochemistry (A.L., N.Z.), Amsterdam University Medical Centers, location AMC, The Netherlands
| | - Jeffrey Kroon
- Departments of Vascular Medicine (M.A.W.v.d.B., J.K., G.M.D.-T., E.S.G.S., A.G.H.), Amsterdam University Medical Centers, location AMC, The Netherlands.,Experimental Vascular Medicine (M.A.W.v.d.B., L.E.L., L.A., P.L.W.C., J.K., J.G.S., A.W.M.S., J.P., J.H.M.L., G.M.D.-T.), Amsterdam University Medical Centers, location AMC, The Netherlands
| | - Johan G Schnitzler
- Experimental Vascular Medicine (M.A.W.v.d.B., L.E.L., L.A., P.L.W.C., J.K., J.G.S., A.W.M.S., J.P., J.H.M.L., G.M.D.-T.), Amsterdam University Medical Centers, location AMC, The Netherlands
| | - Alinda W M Schimmel
- Experimental Vascular Medicine (M.A.W.v.d.B., L.E.L., L.A., P.L.W.C., J.K., J.G.S., A.W.M.S., J.P., J.H.M.L., G.M.D.-T.), Amsterdam University Medical Centers, location AMC, The Netherlands
| | - Jorge Peter
- Experimental Vascular Medicine (M.A.W.v.d.B., L.E.L., L.A., P.L.W.C., J.K., J.G.S., A.W.M.S., J.P., J.H.M.L., G.M.D.-T.), Amsterdam University Medical Centers, location AMC, The Netherlands
| | - Johannes H M Levels
- Experimental Vascular Medicine (M.A.W.v.d.B., L.E.L., L.A., P.L.W.C., J.K., J.G.S., A.W.M.S., J.P., J.H.M.L., G.M.D.-T.), Amsterdam University Medical Centers, location AMC, The Netherlands
| | - Gerry Steenbergen
- Department of Laboratory Medicine, Translational Metabolic Laboratory (S.D.K., G.S., R.A.W., D.J.L.), Radboud University Medical Center, Nijmegen, The Netherlands
| | - Eva Morava
- Department of Clinical Genomics, Mayo Clinic, Rochester, MN (E.M.)
| | - Geesje M Dallinga-Thie
- Departments of Vascular Medicine (M.A.W.v.d.B., J.K., G.M.D.-T., E.S.G.S., A.G.H.), Amsterdam University Medical Centers, location AMC, The Netherlands.,Experimental Vascular Medicine (M.A.W.v.d.B., L.E.L., L.A., P.L.W.C., J.K., J.G.S., A.W.M.S., J.P., J.H.M.L., G.M.D.-T.), Amsterdam University Medical Centers, location AMC, The Netherlands
| | - Ron A Wevers
- Department of Laboratory Medicine, Translational Metabolic Laboratory (S.D.K., G.S., R.A.W., D.J.L.), Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jan Albert Kuivenhoven
- Department of Pediatrics, Section Molecular Genetics, University Medical Center Groningen, University of Groningen, The Netherlands (J.A.K.)
| | - Nicholas J Hand
- Department of Genetics and Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia (L.E.L., P.L.W.C., N.J.H., D.J.R.)
| | - Noam Zelcer
- Medical Biochemistry (A.L., N.Z.), Amsterdam University Medical Centers, location AMC, The Netherlands
| | - Daniel J Rader
- Department of Genetics and Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia (L.E.L., P.L.W.C., N.J.H., D.J.R.)
| | - Erik S G Stroes
- Departments of Vascular Medicine (M.A.W.v.d.B., J.K., G.M.D.-T., E.S.G.S., A.G.H.), Amsterdam University Medical Centers, location AMC, The Netherlands
| | - Dirk J Lefeber
- Department of Laboratory Medicine, Translational Metabolic Laboratory (S.D.K., G.S., R.A.W., D.J.L.), Radboud University Medical Center, Nijmegen, The Netherlands.,Department of Neurology (D.J.L.), Radboud University Medical Center, Nijmegen, The Netherlands
| | - Adriaan G Holleboom
- Departments of Vascular Medicine (M.A.W.v.d.B., J.K., G.M.D.-T., E.S.G.S., A.G.H.), Amsterdam University Medical Centers, location AMC, The Netherlands
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Abstract
Congenital disorders of glycosylation (CDG) is a genetically heterogeneous and clinically polymorphic group of diseases caused by defects in various enzymes, the synthesis and processing of N-linked glycans or oligosaccharides into glycoproteins. Approximately half of all proteins expressed in cells are glycosylated to achieve their full functionality. Basically there are 2 variants of glycosylation: N-glycosylation and O-glycosylation. N-glycans are bound to the amide group of aspartine, whereas O-glycans are bonded to the hydroxyl group of serine or threonine. Synthesis of N-glycans occurs in 3 stages: the formation of nucleotide-linked sugars, assembly (in the cytosol and endoplasmic reticulum) and treatment (in the Golgi apparatus). Synthesis of O-glycans occurs mainly in the Golgi apparatus. The most frequently identified types of CDG are associated with a defect in the N-glycosylation pathway. CDGs are typically multisystem disorders with varying clinical manifestations such as hepatomegaly, cholestasis, liver failure, developmental delay, hypotonia, convulsions, facial dysmorphism and gastrointestinal disorders. Also histological findings showed liver fibrosis, malformation of the ducts, cirrhosis, and steatosis. CDGs typically present in the first months of life, and about 20% of patients do not survive to 5 years. The first line of CDG screening is based on the analysis of N-glycosylation of transf ferin. Exome sequencing or targeted gene panel is used for diagnosis. Several CDG subtypes are amenable to teraphy with mannose and galactose.
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18
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Bastaki F, Bizzari S, Hamici S, Nair P, Mohamed M, Saif F, Malik EM, Al-Ali MT, Hamzeh AR. Single-center experience of N-linked Congenital Disorders of Glycosylation with a Summary of Molecularly Characterized Cases in Arabs. Ann Hum Genet 2017; 82:35-47. [PMID: 28940310 DOI: 10.1111/ahg.12220] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 08/14/2017] [Accepted: 08/16/2017] [Indexed: 12/18/2022]
Abstract
Congenital disorders of glycosylation (CDG) represent an expanding group of conditions that result from defects in protein and lipid glycosylation. Different subgroups of CDG display considerable clinical and genetic heterogeneity due to the highly complex nature of cellular glycosylation. This is further complicated by ethno-geographic differences in the mutational landscape of each of these subgroups. Ten Arab CDG patients from Latifa Hospital in Dubai, United Arab Emirates, were assessed using biochemical (glycosylation status of transferrin) and molecular approaches (next-generation sequencing [NGS] and Sanger sequencing). In silico tools including CADD and PolyPhen-2 were used to predict the functional consequences of uncovered mutations. In our sample of patients, five novel mutations were uncovered in the genes: MPDU1, PMM2, MAN1B1, and RFT1. In total, 9 mutations were harbored by the 10 patients in 7 genes. These are missense and nonsense mutations with deleterious functional consequences. This article integrates a single-center experience within a list of reported CDG mutations in the Arab world, accompanied by full molecular and clinical details pertaining to the studied cases. It also sheds light on potential ethnic differences that were not noted before in regards to CDG in the Arab world.
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Affiliation(s)
- Fatma Bastaki
- Pediatric Department, Latifa Hospital, Dubai Health Authority, Dubai, UAE
| | | | - Sana Hamici
- Pediatric Department, Latifa Hospital, Dubai Health Authority, Dubai, UAE
| | | | - Madiha Mohamed
- Pediatric Department, Latifa Hospital, Dubai Health Authority, Dubai, UAE
| | - Fatima Saif
- Pediatric Department, Latifa Hospital, Dubai Health Authority, Dubai, UAE
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Monticelli M, Ferro T, Jaeken J, Dos Reis Ferreira V, Videira PA. Immunological aspects of congenital disorders of glycosylation (CDG): a review. J Inherit Metab Dis 2016; 39:765-780. [PMID: 27393411 DOI: 10.1007/s10545-016-9954-9] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 05/16/2016] [Accepted: 06/06/2016] [Indexed: 02/06/2023]
Abstract
Congenital disorders of glycosylation (CDG) are a rapidly growing family of genetic diseases comprising more than 85 known distinct disorders. They show a great phenotypic variability ranging from multi-organ/system to mono-organ/system involvement with very mild to extremely severe expression. Immunological dysfunction has a significant impact on the phenotype in a minority of CDG. CDG with major immunological involvement are ALG12-CDG, MAGT1-CDG, MOGS-CDG, SLC35C1-CDG and PGM3-CDG. This review discusses the variety of immunological abnormalities reported in human CDG. Understanding the immunological aspects of CDG may contribute to a better management/treatment of these pathologies and possibly of more common diseases, such as inflammatory diseases.
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Affiliation(s)
- Maria Monticelli
- Centro de Estudos de Doenças Crónicas, CEDOC, NOVA Medical School / Faculdade de Ciências Médicas, Universidade NOVA de Lisboa, Lisbon, Portugal
- Dipartimento di Biologia, Università degli Studi di Napoli "Federico II", Naples, Italy
| | - Tiago Ferro
- Centro de Estudos de Doenças Crónicas, CEDOC, NOVA Medical School / Faculdade de Ciências Médicas, Universidade NOVA de Lisboa, Lisbon, Portugal
- UCIBIO, Departamento Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Caparica, Portugal
| | - Jaak Jaeken
- CDG & Allies - Professionals and Patient Associations International Network (CDG & Allies - PPAIN), Caparica, Portugal
- Center for Metabolic Disease, KU Leuven, Leuven, Belgium
| | - Vanessa Dos Reis Ferreira
- Portuguese Association for Congenital Disorders of Glycosylation (CDG), Lisbon, Portugal.
- CDG & Allies - Professionals and Patient Associations International Network (CDG & Allies - PPAIN), Caparica, Portugal.
| | - Paula A Videira
- Centro de Estudos de Doenças Crónicas, CEDOC, NOVA Medical School / Faculdade de Ciências Médicas, Universidade NOVA de Lisboa, Lisbon, Portugal.
- UCIBIO, Departamento Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Caparica, Portugal.
- CDG & Allies - Professionals and Patient Associations International Network (CDG & Allies - PPAIN), Caparica, Portugal.
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20
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Maratha A, Colhoun HO, Knerr I, Coss KP, Doran P, Treacy EP. Classical Galactosaemia and CDG, the N-Glycosylation Interface. A Review. JIMD Rep 2016; 34:33-42. [PMID: 27502837 PMCID: PMC5509556 DOI: 10.1007/8904_2016_5] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2015] [Revised: 06/21/2016] [Accepted: 06/23/2016] [Indexed: 12/11/2022] Open
Abstract
Classical galactosaemia is a rare disorder of carbohydrate metabolism caused by galactose-1-phosphate uridyltransferase (GALT) deficiency (EC 2.7.7.12). The disease is life threatening if left untreated in neonates and the only available treatment option is a long-term galactose restricted diet. While this is lifesaving in the neonate, complications persist in treated individuals, and the cause of these, despite early initiation of treatment, and shared GALT genotypes remain poorly understood. Systemic abnormal glycosylation has been proposed to contribute substantially to the ongoing pathophysiology. The gross N-glycosylation assembly defects observed in the untreated neonate correct over time with treatment. However, N-glycosylation processing defects persist in treated children and adults.Congenital disorders of glycosylation (CDG) are a large group of over 100 inherited disorders affecting largely N- and O-glycosylation.In this review, we compare the clinical features observed in galactosaemia with a number of predominant CDG conditions.We also summarize the N-glycosylation abnormalities, which we have described in galactosaemia adult and paediatric patients, using an automated high-throughput HILIC-UPLC analysis of galactose incorporation into serum IgG with analysis of the corresponding N-glycan gene expression patterns and the affected pathways.
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Affiliation(s)
- Ashwini Maratha
- National Centre for Inherited Metabolic Disorders, Children's University Hospital, Temple Street, Dublin, Ireland
- University College Dublin Clinical Research Centre, Eccles Street, Dublin, Ireland
| | | | - Ina Knerr
- National Centre for Inherited Metabolic Disorders, Children's University Hospital, Temple Street, Dublin, Ireland
| | - Karen P Coss
- Faculty of Life Sciences and Medicine, Department of Infectious Diseases, King's College London, Guy's Hospital, London, UK
| | - Peter Doran
- University College Dublin Clinical Research Centre, Eccles Street, Dublin, Ireland
| | - Eileen P Treacy
- National Centre for Inherited Metabolic Disorders, Children's University Hospital, Temple Street, Dublin, Ireland.
- University College Dublin Clinical Research Centre, Eccles Street, Dublin, Ireland.
- Trinity College, Dublin, Ireland.
- Mater Misericordiae University Hospital, Eccles Street, Dublin, Ireland.
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21
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Sabry S, Vuillaumier-Barrot S, Mintet E, Fasseu M, Valayannopoulos V, Héron D, Dorison N, Mignot C, Seta N, Chantret I, Dupré T, Moore SEH. A case of fatal Type I congenital disorders of glycosylation (CDG I) associated with low dehydrodolichol diphosphate synthase (DHDDS) activity. Orphanet J Rare Dis 2016; 11:84. [PMID: 27343064 PMCID: PMC4919849 DOI: 10.1186/s13023-016-0468-1] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 06/15/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Type I congenital disorders of glycosylation (CDG-I) are mostly complex multisystemic diseases associated with hypoglycosylated serum glycoproteins. A subgroup harbour mutations in genes necessary for the biosynthesis of the dolichol-linked oligosaccharide (DLO) precursor that is essential for protein N-glycosylation. Here, our objective was to identify the molecular origins of disease in such a CDG-Ix patient presenting with axial hypotonia, peripheral hypertonia, enlarged liver, micropenis, cryptorchidism and sensorineural deafness associated with hypo glycosylated serum glycoproteins. RESULTS Targeted sequencing of DNA revealed a splice site mutation in intron 5 and a non-sense mutation in exon 4 of the dehydrodolichol diphosphate synthase gene (DHDDS). Skin biopsy fibroblasts derived from the patient revealed ~20 % residual DHDDS mRNA, ~35 % residual DHDDS activity, reduced dolichol-phosphate, truncated DLO and N-glycans, and an increased ratio of [2-(3)H]mannose labeled glycoprotein to [2-(3)H]mannose labeled DLO. Predicted truncated DHDDS transcripts did not complement rer2-deficient yeast. SiRNA-mediated down-regulation of DHDDS in human hepatocellular carcinoma HepG2 cells largely mirrored the biochemical phenotype of cells from the patient. The patient also harboured the homozygous ALG6(F304S) variant, which does not cause CDG but has been reported to be more frequent in PMM2-CDG patients with severe/fatal disease than in those with moderate presentations. WES did not reveal other strong candidate causal genes. CONCLUSIONS We describe a patient presenting with severe multisystem disease associated with DHDDS deficiency. As retinitis pigmentosa is the only clinical sign in previously reported cases, this report broadens the spectrum of phenotypes associated with this condition.
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Affiliation(s)
- S Sabry
- INSERM U1149, Faculté de Médecine Xavier Bichat, 16 rue Henri Huchard, Paris, France.,Université Denis Diderot, Paris 7, Paris, France.,Université Pierre et Marie Curie, Paris 6, Paris, France.,Biochemical Genetics Department, Human Genetics Division, National Research Center NRC, Cairo, Egypt
| | - S Vuillaumier-Barrot
- INSERM U1149, Faculté de Médecine Xavier Bichat, 16 rue Henri Huchard, Paris, France.,Université Denis Diderot, Paris 7, Paris, France.,AP-HP, Hôpital Bichat-Claude Bernard, Biochimie, Paris, France
| | - E Mintet
- INSERM U1149, Faculté de Médecine Xavier Bichat, 16 rue Henri Huchard, Paris, France.,Université Denis Diderot, Paris 7, Paris, France
| | - M Fasseu
- INSERM U1149, Faculté de Médecine Xavier Bichat, 16 rue Henri Huchard, Paris, France.,Université Denis Diderot, Paris 7, Paris, France
| | - V Valayannopoulos
- Département de Pédiatrie, AP-HP, Hôpital Necker-Enfants Malades, Paris, France
| | - D Héron
- Département de Génétique & Centre de Référence Déficiences Intellectuelles de Causes Rares, Hôpital Pitié Salpétrière, Paris, France.,Groupe de Recherche Clinique « Déficience Intellectuelle et Autisme » UPMC, Paris, France
| | - N Dorison
- Groupe de Recherche Clinique « Déficience Intellectuelle et Autisme » UPMC, Paris, France
| | - C Mignot
- Département de Génétique & Centre de Référence Déficiences Intellectuelles de Causes Rares, Hôpital Pitié Salpétrière, Paris, France.,Groupe de Recherche Clinique « Déficience Intellectuelle et Autisme » UPMC, Paris, France.,Neuropédiatrie, Hôpital Trousseau, Paris, France
| | - N Seta
- AP-HP, Hôpital Bichat-Claude Bernard, Biochimie, Paris, France.,Université Paris Descartes, Paris, France
| | - I Chantret
- INSERM U1149, Faculté de Médecine Xavier Bichat, 16 rue Henri Huchard, Paris, France.,Université Denis Diderot, Paris 7, Paris, France
| | - T Dupré
- INSERM U1149, Faculté de Médecine Xavier Bichat, 16 rue Henri Huchard, Paris, France.,Université Denis Diderot, Paris 7, Paris, France.,AP-HP, Hôpital Bichat-Claude Bernard, Biochimie, Paris, France
| | - S E H Moore
- INSERM U1149, Faculté de Médecine Xavier Bichat, 16 rue Henri Huchard, Paris, France. .,Université Denis Diderot, Paris 7, Paris, France.
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22
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Massarweh A, Bosco M, Iatmanen-Harbi S, Tessier C, Amana L, Busca P, Chantret I, Gravier-Pelletier C, Moore SEH. Brefeldin A promotes the appearance of oligosaccharyl phosphates derived from Glc3Man9GlcNAc2-PP-dolichol within the endomembrane system of HepG2 cells. J Lipid Res 2016; 57:1477-91. [PMID: 27281477 DOI: 10.1194/jlr.m068551] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Indexed: 01/04/2023] Open
Abstract
We reported an oligosaccharide diphosphodolichol (DLO) diphosphatase (DLODP) that generates dolichyl-phosphate and oligosaccharyl phosphates (OSPs) from DLO in vitro. This enzyme could underlie cytoplasmic OSP generation and promote dolichyl-phosphate recycling from truncated endoplasmic reticulum (ER)-generated DLO intermediates. However, during subcellular fractionation, DLODP distribution is closer to that of a Golgi apparatus (GA) marker than those of ER markers. Here, we examined the effect of brefeldin A (BFA), which fuses the GA with the ER on OSP metabolism. In order to increase the steady state level of truncated DLO while allowing formation of mature DLO (Glc3Man9GlcNAc2-PP-dolichol), dolichyl-P-mannose Man7GlcNAc2-PP-dolichol mannosyltransferase was partially downregulated in HepG2 cells. We show that BFA provokes GA endomannosidase trimming of Glc3Man9GlcNAc2-PP-dolichol to yield a Man8GlcNAc2-PP-dolichol structure that does not give rise to cytoplasmic Man8GlcNAc2-P. BFA also strikingly increased OSP derived from mature DLO within the endomembrane system without affecting levels of Man7GlcNAc2-PP-dolichol or cytoplasmic Man7GlcNAc2-P. The BFA-provoked increase in endomembrane-situated OSP is sensitive to nocodazole, and BFA causes partial redistribution of DLODP activity from GA- to ER-containing regions of density gradients. These findings are consistent with BFA-provoked microtubule-dependent GA-to-ER transport of a previously reported DLODP that acts to generate a novel endomembrane-situated OSP population.
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Affiliation(s)
- Ahmad Massarweh
- INSERM U1149, Paris, France Université Denis Diderot, Paris 7, Paris, France Université Pierre et Marie Curie, Paris 6, Paris, France
| | - Michaël Bosco
- Université Paris Descartes, CICB-Paris, CNRS UMR8601, LCBPT, Paris, France
| | | | - Clarice Tessier
- INSERM U1149, Paris, France Université Denis Diderot, Paris 7, Paris, France
| | - Laura Amana
- INSERM U1149, Paris, France Université Denis Diderot, Paris 7, Paris, France
| | - Patricia Busca
- Université Paris Descartes, CICB-Paris, CNRS UMR8601, LCBPT, Paris, France
| | - Isabelle Chantret
- INSERM U1149, Paris, France Université Denis Diderot, Paris 7, Paris, France
| | | | - Stuart E H Moore
- INSERM U1149, Paris, France Université Denis Diderot, Paris 7, Paris, France
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23
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Merico D, Roifman M, Braunschweig U, Yuen RKC, Alexandrova R, Bates A, Reid B, Nalpathamkalam T, Wang Z, Thiruvahindrapuram B, Gray P, Kakakios A, Peake J, Hogarth S, Manson D, Buncic R, Pereira SL, Herbrick JA, Blencowe BJ, Roifman CM, Scherer SW. Compound heterozygous mutations in the noncoding RNU4ATAC cause Roifman Syndrome by disrupting minor intron splicing. Nat Commun 2015; 6:8718. [PMID: 26522830 PMCID: PMC4667643 DOI: 10.1038/ncomms9718] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 09/25/2015] [Indexed: 11/09/2022] Open
Abstract
Roifman Syndrome is a rare congenital disorder characterized by growth retardation, cognitive delay, spondyloepiphyseal dysplasia and antibody deficiency. Here we utilize whole-genome sequencing of Roifman Syndrome patients to reveal compound heterozygous rare variants that disrupt highly conserved positions of the RNU4ATAC small nuclear RNA gene, a minor spliceosome component that is essential for minor intron splicing. Targeted sequencing confirms allele segregation in six cases from four unrelated families. RNU4ATAC rare variants have been recently reported to cause microcephalic osteodysplastic primordial dwarfism, type I (MOPD1), whose phenotype is distinct from Roifman Syndrome. Strikingly, all six of the Roifman Syndrome cases have one variant that overlaps MOPD1-implicated structural elements, while the other variant overlaps a highly conserved structural element not previously implicated in disease. RNA-seq analysis confirms extensive and specific defects of minor intron splicing. Available allele frequency data suggest that recessive genetic disorders caused by RNU4ATAC rare variants may be more prevalent than previously reported. Roifman Syndrome is a rare disorder whose disease manifestations include growth retardation, spondyloepiphyseal dysplasia and immunodeficiency. Here, the authors use whole-genome sequencing to discover that rare compound heterozygous variants disrupting the small nuclear RNA gene RNU4ATAC cause Roifman Syndrome.
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Affiliation(s)
- Daniele Merico
- The Centre for Applied Genomics (TCAG), Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada M5G 0A4
| | - Maian Roifman
- Division of Clinical and Metabolic Genetics, Department of Paediatrics, The Hospital for Sick Children, Toronto, Ontario, Canada M5G 1X8.,The Prenatal Diagnosis and Medical Genetics Program, Department of Obstetrics and Gynaecology, Mount Sinai Hospital, Toronto, Ontario, Canada M5G 1Z5.,Department of Paediatrics, University of Toronto, Toronto, Ontario, Canada M5G 1X8
| | | | - Ryan K C Yuen
- The Centre for Applied Genomics (TCAG), Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada M5G 0A4
| | - Roumiana Alexandrova
- The Centre for Applied Genomics (TCAG), Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada M5G 0A4
| | - Andrea Bates
- Division for Immunology and Allergy, Canadian Center for Primary Immunodeficiency, The Hospital for Sick Children, Toronto, Ontario, Canada M5G 1X8
| | - Brenda Reid
- Division for Immunology and Allergy, Canadian Center for Primary Immunodeficiency, The Hospital for Sick Children, Toronto, Ontario, Canada M5G 1X8
| | - Thomas Nalpathamkalam
- The Centre for Applied Genomics (TCAG), Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada M5G 0A4
| | - Zhuozhi Wang
- The Centre for Applied Genomics (TCAG), Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada M5G 0A4
| | - Bhooma Thiruvahindrapuram
- The Centre for Applied Genomics (TCAG), Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada M5G 0A4
| | - Paul Gray
- Department of Immunology and Infectious Diseases, Sydney Children's Hospital, Sydney, New South Wales 2031, Australia
| | - Alyson Kakakios
- Department of Allergy and Immunology, The Children's Hospital at Westmead, Westmead, New South Wales 2145, Australia
| | - Jane Peake
- Queensland Paediatric Immunology and Allergy Service, The Lady Cilento Children's Hospital, South Brisbane, Queensland 4101, Australia.,School of Medicine, University of Queensland, Brisbane, Queensland 4006, Australia
| | - Stephanie Hogarth
- Queensland Paediatric Immunology and Allergy Service, The Lady Cilento Children's Hospital, South Brisbane, Queensland 4101, Australia.,School of Medicine, University of Queensland, Brisbane, Queensland 4006, Australia
| | - David Manson
- Department of Diagnostic Imaging, The Hospital for Sick Children, Toronto, Ontario, Canada M5G 1X8
| | - Raymond Buncic
- Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, Ontario, Canada M5G 1X8
| | - Sergio L Pereira
- The Centre for Applied Genomics (TCAG), Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada M5G 0A4
| | - Jo-Anne Herbrick
- The Centre for Applied Genomics (TCAG), Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada M5G 0A4
| | - Benjamin J Blencowe
- Donnelly Centre, University of Toronto, Toronto, Ontario, Canada M5S 3E1.,Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada M5S 1A8
| | - Chaim M Roifman
- Department of Paediatrics, University of Toronto, Toronto, Ontario, Canada M5G 1X8.,Division for Immunology and Allergy, Canadian Center for Primary Immunodeficiency, The Hospital for Sick Children, Toronto, Ontario, Canada M5G 1X8
| | - Stephen W Scherer
- The Centre for Applied Genomics (TCAG), Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada M5G 0A4.,Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada M5S 1A8.,McLaughlin Centre, University of Toronto, Toronto, Ontario, Canada M5G 0A4.,Centre of Excellence in Genomic Medicine Research (CEGMR), King Abdulaziz University, Jeddah 21589, Kingdom of Saudi Arabia
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24
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Harada Y, Hirayama H, Suzuki T. Generation and degradation of free asparagine-linked glycans. Cell Mol Life Sci 2015; 72:2509-33. [PMID: 25772500 PMCID: PMC11113800 DOI: 10.1007/s00018-015-1881-7] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2014] [Revised: 02/19/2015] [Accepted: 03/05/2015] [Indexed: 10/23/2022]
Abstract
Asparagine (N)-linked protein glycosylation, which takes place in the eukaryotic endoplasmic reticulum (ER), is important for protein folding, quality control and the intracellular trafficking of secretory and membrane proteins. It is known that, during N-glycosylation, considerable amounts of lipid-linked oligosaccharides (LLOs), the glycan donor substrates for N-glycosylation, are hydrolyzed to form free N-glycans (FNGs) by unidentified mechanisms. FNGs are also generated in the cytosol by the enzymatic deglycosylation of misfolded glycoproteins during ER-associated degradation. FNGs derived from LLOs and misfolded glycoproteins are eventually merged into one pool in the cytosol and the various glycan structures are processed to a near homogenous glycoform. This article summarizes the current state of our knowledge concerning the formation and catabolism of FNGs.
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Affiliation(s)
- Yoichiro Harada
- Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 Japan
| | - Hiroto Hirayama
- Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 Japan
| | - Tadashi Suzuki
- Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 Japan
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25
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Murali C, Lu JT, Jain M, Liu DS, Lachman R, Gibbs RA, Lee BH, Cohn D, Campeau PM. Diagnosis of ALG12-CDG by exome sequencing in a case of severe skeletal dysplasia. Mol Genet Metab Rep 2014; 1:213-219. [PMID: 25019053 PMCID: PMC4088274 DOI: 10.1016/j.ymgmr.2014.04.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Congenital Disorder of Glycosylation type Ig (ALG12-CDG) is part of a group of autosomal recessive conditions caused by deficiency of proteins involved in the assembly of dolichol-oligosaccharides used for protein N-glycosylation. In ALG12-CDG, the enzyme affected is encoded by the ALG12 gene. Affected individuals present clinically with neurodevelopmental delay, growth retardation, immune deficiency, male genital hypoplasia, and cardiomyopathy. A total of six individuals have been reported in the literature. Here, we present an infant with rhizomelic short stature, talipes equinovarus, platyspondyly, and joint dislocations. The infant had marked under-ossification of the pubic bones. Exome sequencing was performed and two deletions, each resulting in a frameshift, were found in ALG12. A review of the literature revealed two infants with ALG12-CDG and a severe skeletal dysplasia, including under-ossification of cervical vertebrae, pubic bones, and knees; in addition to talipes equinovarus and rhizomelic short stature. The phenotype of the individual we describe resembles pseudodiastrophic dysplasia and we discuss similarities and differences between ALG12-CDG and pseudodiastrophic dysplasia. The differential diagnosis in selected undiagnosed skeletal dysplasias should include CDGs.
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Affiliation(s)
- Chaya Murali
- Department of Molecular and Human Genetics, Baylor College of Medicine; One Baylor Plaza, MS BCM225, Houston, TX, 77030, U.S.A
| | - James T Lu
- Human Genome Sequencing Center, Baylor College of Medicine; One Baylor Plaza, MS BCM225, Houston, TX, 77030, U.S.A. ; Department of Structural and Computational Biology & Molecular Biophysics, Baylor College of Medicine; One Baylor Plaza, MS BCM225, Houston, TX, 77030, U.S.A
| | - Mahim Jain
- Department of Molecular and Human Genetics, Baylor College of Medicine; One Baylor Plaza, MS BCM225, Houston, TX, 77030, U.S.A
| | - David S Liu
- Department of Molecular and Human Genetics, Baylor College of Medicine; One Baylor Plaza, MS BCM225, Houston, TX, 77030, U.S.A
| | - Ralph Lachman
- Radiological Sciences and Pediatrics, University of California-Los Angeles School of Medicine; 550 OHRC, Los Angeles, CA 90095
| | - Richard A Gibbs
- Human Genome Sequencing Center, Baylor College of Medicine; One Baylor Plaza, MS BCM225, Houston, TX, 77030, U.S.A
| | - Brendan H Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine; One Baylor Plaza, MS BCM225, Houston, TX, 77030, U.S.A. ; Howard Hughes Medical Institute; One Baylor Plaza, MS BCM225, Houston, TX, 77030, U.S.A
| | - Daniel Cohn
- Department of Molecular, Cell and Developmental Biology, University of California-Los Angeles; 550 OHRC, Los Angeles, CA 90095 ; Orthopaedic Hospital Research Center, Department of Orthopaedic Surgery, University of California-Los Angeles; 550 OHRC, Los Angeles, CA 90095
| | - Philippe M Campeau
- Medical Genetics Service, Department of Pediatrics, Sainte-Justine Hospital, University of Montreal; Medical genetics service, Room 6727, Sainte-Justine Hospital, 3175, Côte-Sainte-Catherine, Montréal QC Canada H3T 1C5
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26
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Kouwenberg D, Gardeitchik T, Mohamed M, Lefeber DJ, Morava E. Wrinkled skin and fat pads in patients with ALG8-CDG: revisiting skin manifestations in congenital disorders of glycosylation. Pediatr Dermatol 2014; 31:e1-5. [PMID: 24555185 DOI: 10.1111/pde.12233] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Glycosylation is the posttranslational coupling of sugar chains to proteins or lipids. Proper glycosylation is essential for normal protein structure, function, and trafficking. Mutations in the glycosylation pathway lead to a phenotypically heterogeneous group of metabolic disorders, the congenital disorders of glycosylation (CDG). Some of these conditions, including PMM2-CDG, frequently present with recognizable skin abnormalities such as abnormal fat distribution, skin wrinkling, or peau d'orange, whereas others, such as COG7-CDG and ATP6V0A2-CDG, have been described in association with cutis laxa: wrinkled, inelastic, and sagging skin. Ichthyosis is also common in several types of CDG. ALG8-CDG is a severe disorder characterized by dysmorphic features, failure to thrive, protein-losing enteropathy, neurologic and ophthalmologic problems, and developmental delay. We reviewed the clinical features in all nine previously reported patients diagnosed with ALG8-CDG with a special focus on their skin signs. Three of the nine patients had abnormal fat distribution and skin wrinkling. As the spectrum of CDG presenting with skin signs expands further, we suggest screening for CDG in all patients presenting with any type of central nervous involvement and wrinkled skin, cutis laxa, severe ichthyosis, or abnormal fat distribution.
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Affiliation(s)
- Dorus Kouwenberg
- Department of Pediatrics; Radboud University Nijmegen Medical Center; Nijmegen the Netherlands
| | - Thatjana Gardeitchik
- Department of Pediatrics; Radboud University Nijmegen Medical Center; Nijmegen the Netherlands
| | - Miski Mohamed
- Department of Pediatrics; Radboud University Nijmegen Medical Center; Nijmegen the Netherlands
| | - Dirk J. Lefeber
- Laboratory of Genetic, Endocrine and Metabolic Disease; Radboud University Nijmegen Medical Center; Nijmegen the Netherlands
- Department of Neurology; Institute for Genetic and Metabolic Disease; Radboud University Nijmegen Medical Center; Nijmegen the Netherlands
| | - Eva Morava
- Department of Pediatrics; Radboud University Nijmegen Medical Center; Nijmegen the Netherlands
- Department of Pediatrics; Hayward Genetics Center; Tulane University Medical School; New Orleans Louisiana
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27
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Characterization of the 5'-flanking region of the mouse asparagine-linked glycosylation 12 homolog gene. Cell Mol Biol Lett 2013; 18:315-27. [PMID: 23818223 PMCID: PMC6275931 DOI: 10.2478/s11658-013-0091-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Accepted: 05/07/2013] [Indexed: 01/27/2023] Open
Abstract
Recently, we characterized multiple roles of the endoplasmic reticulum stress responsive element (ERSE) in the promotion of a unique headto-head gene pair: mammalian asparagine-linked glycosylation 12 homolog (ALG12) and cysteine-rich with EGF-like domains 2 (CRELD2). This bidirectional promoter, which consists of fewer than 400 base pairs, separates the two genes. It has been demonstrated that the ALG12 promoter shows less transcriptional activity through ERSE, but its basic regulatory mechanism has not been characterized. In this study, we focused on well-conserved binding elements for the transcription factors for ATF6, NF-Y and YY1 and the Sp1 and Ets families in the 5’-flanking region of the mouse ALG12 gene. We characterized their dominant roles in regulating ALG12 promoter activities using several deletion and mutation luciferase reporter constructs. The ALG12 gene is expressed in three distinct cell lines: Neuro2a, C6 glioma and HeLa cells. The reporter activity in each cell line decreased similarly with serial deletions of the mouse ALG12 promoter. Mutations in the ERSE and adjacent NF-Y-binding element slightly affected reporter activity. Each of the mutations in the GC-rich sequence and YY1-binding element reduced ALG12 promoter activity, and the combination of these mutations additively decreased reporter activity. Each mutation in the tandem-arranged Ets-family consensus sequences partially attenuated ALG12 promoter activity, and mutations of all three Ets-binding elements decreased promoter activity by approximately 40%. Mutation of the three conserved regulatory elements (GC-rich, YY1 and Ets) in the ALG12 promoter decreased reporter activity by more than 90%. Our results suggest that the promoter activity of the mouse ALG12 gene is regulated in a similar manner in the three cell lines tested in this study. The well-conserved consensus sequences in the promoter of this gene synergistically contribute to maintaining basal gene expression.
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28
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Matthijs G, Rymen D, Millón MBB, Souche E, Race V. Approaches to homozygosity mapping and exome sequencing for the identification of novel types of CDG. Glycoconj J 2012; 30:67-76. [PMID: 22983704 DOI: 10.1007/s10719-012-9445-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2012] [Revised: 08/21/2012] [Accepted: 08/22/2012] [Indexed: 12/18/2022]
Abstract
In the past decade, the identification of most genes involved in Congenital Disorders of Glycosylation (CDG) (type I) was achieved by a combination of biochemical, cell biological and glycobiological investigations. This has been truly successful for CDG-I, because the candidate genes could be selected on the basis of the homology of the synthetic pathway of the dolichol linked oligosaccharide in human and yeast. On the contrary, only a few CDG-II defects were elucidated, be it that some of the discoveries represent wonderful breakthroughs, like e.g, the identification of the COG defects. In general, many rare genetic defects have been identified by positional cloning. However, only a few types of CDG have effectively been elucidated by linkage analysis and so-called reverse genetics. The reason is that the families were relatively small and could-except for CDG-PMM2-not be pooled for analysis. Hence, a large number of CDG cases has long remained unsolved because the search for the culprit gene was very laborious, due to the heterogeneous phenotype and the myriad of candidate defects. This has changed when homozygosity mapping came of age, because it could be applied to small (consanguineous) families. Many novel CDG genes have been discovered in this way. But the best has yet to come: what we are currently witnessing, is an explosion of novel CDG defects, thanks to exome sequencing: seven novel types were published over a period of only two years. It is expected that exome sequencing will soon become a diagnostic tool, that will continuously uncover new facets of this fascinating group of diseases.
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Affiliation(s)
- Gert Matthijs
- Center for Human Genetics, University of Leuven, Herestraat 49, 3000, Leuven, Belgium.
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29
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Pompach P, Chandler KB, Lan R, Edwards N, Goldman R. Semi-automated identification of N-Glycopeptides by hydrophilic interaction chromatography, nano-reverse-phase LC-MS/MS, and glycan database search. J Proteome Res 2012; 11:1728-40. [PMID: 22239659 DOI: 10.1021/pr201183w] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Glycoproteins fulfill many indispensable biological functions, and changes in protein glycosylation have been observed in various diseases. Improved analytical methods are needed to allow a complete characterization of this complex and common post-translational modification. In this study, we present a workflow for the analysis of the microheterogeneity of N-glycoproteins that couples hydrophilic interaction and nanoreverse-phase C18 chromatography to tandem QTOF mass spectrometric analysis. A glycan database search program, GlycoPeptideSearch, was developed to match N-glycopeptide MS/MS spectra with the glycopeptides comprised of a glycan drawn from the GlycomeDB glycan structure database and a peptide from a user-specified set of potentially glycosylated peptides. Application of the workflow to human haptoglobin and hemopexin, two microheterogeneous N-glycoproteins, identified a total of 57 distinct site-specific glycoforms in the case of haptoglobin and 14 site-specific glycoforms of hemopexin. Using glycan oxonium ions and peptide-characteristic glycopeptide fragment ions and by collapsing topologically redundant glycans, the search software was able to make unique N-glycopeptide assignments for 51% of assigned spectra, with the remaining assignments primarily representing isobaric topological rearrangements. The optimized workflow, coupled with GlycoPeptideSearch, is expected to make high-throughput semiautomated glycopeptide identification feasible for a wide range of users.
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Affiliation(s)
- Petr Pompach
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University , 3970 Reservoir Road NW, Washington, DC 20057-1465, United States
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30
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Lecca MR, Maag C, Berger EG, Hennet T. Fibrotic response in fibroblasts from congenital disorders of glycosylation. J Cell Mol Med 2012; 15:1788-96. [PMID: 21029365 PMCID: PMC4373368 DOI: 10.1111/j.1582-4934.2010.01187.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Congenital disorders of glycosylation (CDG) are characterized by a generalized underglycosylation of proteins. CDG is associated with multiple symptoms such as psychomotor retardation, hypotonia, hormonal disturbances, liver fibrosis and coagulopathies. The molecular basis of these symptoms is poorly understood considering the large extent of affected glycoproteins. To better understand the cellular responses to protein underglycosylation in CDG, we have investigated the differences in gene expression between healthy control and CDG fibroblasts by transcriptome comparison. This analysis revealed a strong induction of several genes encoding components of the extracellular matrix, such as collagens, COMP, IGFBP5 and biglycan. The extent of this response was confirmed at the protein level by showing increased production of collagen type-I for example. This fibrotic response of CDG fibroblasts was not paralleled by a differentiation to myofibroblasts and by increased TGF-β signalling. We could show that the addition of recombinant IGFBP5, one of the induced proteins in CDG, to healthy control fibroblasts increased the production of collagen type-I to levels similar to those found in CDG fibroblasts. The fibrotic response identified in CDG fibroblasts may account for the elevated tissue fibrosis, which is often encountered in CDG patients.
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Affiliation(s)
- M Rita Lecca
- Institute of Physiology and Zürich Center for Integrative Human Physiology, University of Zürich, Zürich, Switzerland
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31
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Abstract
Glycosylation is an essential process by which sugars are attached to proteins and lipids. Complete lack of glycosylation is not compatible with life. Because of the widespread function of glycosylation, inherited disorders of glycosylation are multisystemic. Since the identification of the first defect on N-linked glycosylation in the 1980s, there are over 40 different congenital protein hypoglycosylation diseases. This review will include defects of N-linked glycosylation, O-linked glycosylation and disorders of combined N- and O-linked glycosylation.
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Affiliation(s)
- Susan E Sparks
- Department of Pediatrics, Levine Children's Hospital at Carolinas Medical Center, Charlotte, NC, USA; Department of Pediatrics, University of North Carolina School of Medicine, Chapel Hill, NC, USA
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Huybrechts S, De Laet C, Bontems P, Rooze S, Souayah H, Sznajer Y, Sturiale L, Garozzo D, Matthijs G, Ferster A, Jaeken J, Goyens P. Deficiency of Subunit 6 of the Conserved Oligomeric Golgi Complex (COG6-CDG): Second Patient, Different Phenotype. JIMD Rep 2011; 4:103-8. [PMID: 23430903 DOI: 10.1007/8904_2011_79] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Revised: 06/28/2011] [Accepted: 07/14/2011] [Indexed: 02/07/2023] Open
Abstract
We describe a 27-month-old girl with COG6 deficiency. She is the first child of healthy consanguineous Moroccan parents. She presented at birth with dysmorphic features including microcephaly, post-axial polydactyly, broad palpebral fissures, retrognathia, and anal anteposition. The clinical phenotype was further characterised by multiorgan involvement including mild psychomotor retardation, and microcephaly, chronic inflammatory bowel disease, micronodular liver cirrhosis, associated with life-threatening and recurrent infections due to combined T- and B-cell dysfunction and neutrophil dysfunction.Mutation analysis showed the patient to be homozygous for the c.G1646T mutation in the COG6 gene. She is the second reported patient with a deficiency of subunit 6 of the COG complex. Although both patients are homozygous for the same mutation, they present a markedly different clinical picture. Indeed immunodeficiency as well as inflammatory bowel disease has not been described previously in patients with any COG-CDG.
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Affiliation(s)
- S Huybrechts
- Department of Hematology-Oncology, Hôpital Universitaire des Enfants Reine Fabiola (HUDERF), Brussels, Belgium,
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Vleugels W, Duvet S, Peanne R, Mir AM, Cacan R, Michalski JC, Matthijs G, Foulquier F. Identification of phosphorylated oligosaccharides in cells of patients with a congenital disorders of glycosylation (CDG-I). Biochimie 2011; 93:823-33. [PMID: 21315133 DOI: 10.1016/j.biochi.2011.01.016] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2010] [Accepted: 01/29/2011] [Indexed: 11/24/2022]
Abstract
Protein N-glycosylation is initiated by the dolichol cycle in which the oligosaccharide precursor Glc(3)Man(9)GlcNAc(2)-PP-dolichol is assembled in the endoplasmic reticulum (ER). One critical step in the dolichol cycle concerns the availability of Dol-P at the cytosolic face of the ER membrane. In RFT1 cells, the lipid-linked oligosaccharide (LLO) intermediate Man(5)GlcNAc(2)-PP-Dol accumulates at the cytosolic face of the ER membrane. Since Dol-P is a rate-limiting intermediate during protein N-glycosylation, continuous accumulation of Man(5)GlcNAc(2)-PP-Dol would block the dolichol cycle. Hence, we investigated the molecular mechanisms by which accumulating Man(5)GlcNAc(2)-PP-Dol could be catabolized in RFT1 cells. On the basis of metabolic labeling experiments and in comparison to human control cells, we identified phosphorylated oligosaccharides (POS), not found in human control cells and present evidence that they originate from the accumulating LLO intermediates. In addition, POS were also detected in other CDG patients' cells accumulating specific LLO intermediates at different cellular locations. Moreover, the enzymatic activity that hydrolyses oligosaccharide-PP-Dol into POS was identified in human microsomal membranes and required Mn(2+) for optimal activity. In CDG patients' cells, we thus identified and characterized POS that could result from the catabolism of accumulating LLO intermediates.
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Affiliation(s)
- Wendy Vleugels
- Laboratory for Molecular Diagnosis, Center for Human Genetics, University of Leuven, B-3000 Leuven, Belgium
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Oh-Hashi K, Koga H, Ikeda S, Shimada K, Hirata Y, Kiuchi K. Role of an ER stress response element in regulating the bidirectional promoter of the mouse CRELD2 - ALG12 gene pair. BMC Genomics 2010; 11:664. [PMID: 21106106 PMCID: PMC3091781 DOI: 10.1186/1471-2164-11-664] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2010] [Accepted: 11/25/2010] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Recently, we identified cysteine-rich with EGF-like domains 2 (CRELD2) as a novel endoplasmic reticulum (ER) stress-inducible gene and characterized its transcriptional regulation by ATF6 under ER stress conditions. Interestingly, the CRELD2 and asparagine-linked glycosylation 12 homolog (ALG12) genes are arranged as a bidirectional (head-to-head) gene pair and are separated by less than 400 bp. In this study, we characterized the transcriptional regulation of the mouse CRELD2 and ALG12 genes that is mediated by a common bidirectional promoter. RESULTS This short intergenic region contains an ER stress response element (ERSE) sequence and is well conserved among the human, rat and mouse genomes. Microarray analysis revealed that CRELD2 and ALG12 mRNAs were induced in Neuro2a cells by treatment with thapsigargin (Tg), an ER stress inducer, in a time-dependent manner. Other ER stress inducers, tunicamycin and brefeldin A, also increased the expression of these two mRNAs in Neuro2a cells. We then tested for the possible involvement of the ERSE motif and other regulatory sites of the intergenic region in the transcriptional regulation of the mouse CRELD2 and ALG12 genes by using variants of the bidirectional reporter construct. With regards to the promoter activities of the CRELD2-ALG12 gene pair, the entire intergenic region hardly responded to Tg, whereas the CRELD2 promoter constructs of the proximal region containing the ERSE motif showed a marked responsiveness to Tg. The same ERSE motif of ALG12 gene in the opposite direction was less responsive to Tg. The direction and the distance of this motif from each transcriptional start site, however, has no impact on the responsiveness of either gene to Tg treatment. Additionally, we found three putative sequences in the intergenic region that antagonize the ERSE-mediated transcriptional activation. CONCLUSIONS These results show that the mouse CRELD2 and ALG12 genes are arranged as a unique bidirectional gene pair and that they may be regulated by the combined interactions between ATF6 and multiple other transcriptional factors. Our studies provide new insights into the complex transcriptional regulation of bidirectional gene pairs under pathophysiological conditions.
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Affiliation(s)
- Kentaro Oh-Hashi
- Department of Biomolecular Science, Faculty of Engineering, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan.
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35
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Peric D, Durrant-Arico C, Delenda C, Dupré T, De Lonlay P, de Baulny HO, Pelatan C, Bader-Meunier B, Danos O, Chantret I, Moore SEH. The compartmentalisation of phosphorylated free oligosaccharides in cells from a CDG Ig patient reveals a novel ER-to-cytosol translocation process. PLoS One 2010; 5:e11675. [PMID: 20652024 PMCID: PMC2907391 DOI: 10.1371/journal.pone.0011675] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2010] [Accepted: 06/14/2010] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Biosynthesis of the dolichol linked oligosaccharide (DLO) required for protein N-glycosylation starts on the cytoplasmic face of the ER to give Man(5)GlcNAc(2)-PP-dolichol, which then flips into the ER for further glycosylation yielding mature DLO (Glc(3)Man(9)GlcNAc(2)-PP-dolichol). After transfer of Glc(3)Man(9)GlcNAc(2) onto protein, dolichol-PP is recycled to dolichol-P and reused for DLO biosynthesis. Because de novo dolichol synthesis is slow, dolichol recycling is rate limiting for protein glycosylation. Immature DLO intermediates may also be recycled by pyrophosphatase-mediated cleavage to yield dolichol-P and phosphorylated oligosaccharides (fOSGN2-P). Here, we examine fOSGN2-P generation in cells from patients with type I Congenital Disorders of Glycosylation (CDG I) in which defects in the dolichol cycle cause accumulation of immature DLO intermediates and protein hypoglycosylation. METHODS AND PRINCIPAL FINDINGS In EBV-transformed lymphoblastoid cells from CDG I patients and normal subjects a correlation exists between the quantities of metabolically radiolabeled fOSGN2-P and truncated DLO intermediates only when these two classes of compounds possess 7 or less hexose residues. Larger fOSGN2-P were difficult to detect despite an abundance of more fully mannosylated and glucosylated DLO. When CDG Ig cells, which accumulate Man(7)GlcNAc(2)-PP-dolichol, are permeabilised so that vesicular transport and protein synthesis are abolished, the DLO pool required for Man(7)GlcNAc(2)-P generation could be depleted by adding exogenous glycosylation acceptor peptide. Under conditions where a glycotripeptide and neutral free oligosaccharides remain predominantly in the lumen of the ER, Man(7)GlcNAc(2)-P appears in the cytosol without detectable generation of ER luminal Man(7)GlcNAc(2)-P. CONCLUSIONS AND SIGNIFICANCE The DLO pools required for N-glycosylation and fOSGN2-P generation are functionally linked and this substantiates the hypothesis that pyrophosphatase-mediated cleavage of DLO intermediates yields recyclable dolichol-P. The kinetics of cytosolic fOSGN2-P generation from a luminally-generated DLO intermediate demonstrate the presence of a previously undetected ER-to-cytosol translocation process for either fOSGN2-P or DLO.
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Affiliation(s)
- Delphine Peric
- INSERM U773 CRB3, Paris, France
- Université Denis Diderot, Paris 7, Paris, France
| | | | | | - Thierry Dupré
- INSERM U773 CRB3, Paris, France
- Université Denis Diderot, Paris 7, Paris, France
- AP-HP, Hôpital Bichat-Claude Bernard, Biochimie Métabolique et Cellulaire, Paris, France
| | - Pascale De Lonlay
- Département de Pédiatrie, Hôpital Necker-Enfants Malades, Paris, France
| | | | - Cécile Pelatan
- Centre Hospitalier, Service de Pédiatrie, Le Mans, France
| | | | - Olivier Danos
- Généthon: Evry, France
- INSERM U781, Hôpital Necker-Enfants Malades, Paris, France
| | - Isabelle Chantret
- INSERM U773 CRB3, Paris, France
- Université Denis Diderot, Paris 7, Paris, France
| | - Stuart E. H. Moore
- INSERM U773 CRB3, Paris, France
- Université Denis Diderot, Paris 7, Paris, France
- * E-mail:
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36
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Haeuptle MA, Hennet T. Congenital disorders of glycosylation: an update on defects affecting the biosynthesis of dolichol-linked oligosaccharides. Hum Mutat 2010; 30:1628-41. [PMID: 19862844 DOI: 10.1002/humu.21126] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Defects in the biosynthesis of the oligosaccharide precursor for N-glycosylation lead to decreased occupancy of glycosylation sites and thereby to diseases known as congenital disorders of glycosylation (CDG). In the last 20 years, approximately 1,000 CDG patients have been identified presenting with multiple organ dysfunctions. This review sets the state of the art by listing all mutations identified in the 15 genes (PMM2, MPI, DPAGT1, ALG1, ALG2, ALG3, ALG9, ALG12, ALG6, ALG8, DOLK, DPM1, DPM3, MPDU1, and RFT1) that yield a deficiency of dolichol-linked oligosaccharide biosynthesis. The present analysis shows that most mutations lead to substitutions of strongly conserved amino acid residues across eukaryotes. Furthermore, the comparison between the different forms of CDG affecting dolichol-linked oligosaccharide biosynthesis shows that the severity of the disease does not relate to the position of the mutated gene along this biosynthetic pathway.
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Affiliation(s)
- Micha A Haeuptle
- Institute of Physiology, University of Zürich, Zürich, Switzerland
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37
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Footitt EJ, Karimova A, Burch M, Yayeh T, Dupré T, Vuillaumier-Barrot S, Chantret I, Moore SEH, Seta N, Grunewald S. Cardiomyopathy in the congenital disorders of glycosylation (CDG): a case of late presentation and literature review. J Inherit Metab Dis 2009; 32 Suppl 1:S313-9. [PMID: 19757145 DOI: 10.1007/s10545-009-1262-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Revised: 07/28/2009] [Accepted: 07/30/2009] [Indexed: 11/25/2022]
Abstract
The congenital disorders of glycosylation (CDG) are a recently described group of inherited multisystem disorders characterized by defects predominantly of N- and O-glycosylation of proteins. Cardiomyopathy in CDG has previously been described in several subtypes; it is usually associated with high morbidity and mortality and the majority of cases present in the first 2 years of life. This is the first case with presentation in late childhood and the article reviews current literature. An 11-year-old female with a background of learning difficulties presented in cardiac failure secondary to severe dilated cardiomyopathy. Prior to the diagnosis of CDG, her condition deteriorated; she required mechanical support (Excor Berlin Heart) and was listed for cardiac transplant. Investigations included screening for glycosylation disorders, and isoelectric focusing of transferrin revealed an abnormal type 1 pattern. Analysis of phosphomannomutase and phosphomannose isomerase showed normal enzyme activity, excluding PMM2 (CDG Ia) and MPI (CDG Ib). Lipid-linked oligosaccharide and mutational studies have not yet defined the defect. Despite aggressive therapy there were persistent difficulties achieving adequate anticoagulation and she developed multiple life-threatening thrombotic complications. She was removed from the transplant list and died from overwhelming sepsis 5 weeks following admission. This case emphasizes the need to screen all children with an undiagnosed cardiomyopathy for CDG, regardless of age, and where possible to exclude CDG before the use of cardiac bridging devices. It highlights the many practical and ethical challenges that may be encountered where clinical knowledge and experience are still evolving.
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Affiliation(s)
- E J Footitt
- Metabolic Medicine Unit, Great Ormond Street Hospital for Children with UCL Institute of Child Health, London, UK.
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38
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Vleugels W, Keldermans L, Jaeken J, Butters TD, Michalski JC, Matthijs G, Foulquier F. Quality control of glycoproteins bearing truncated glycans in an ALG9-defective (CDG-IL) patient. Glycobiology 2009; 19:910-7. [PMID: 19451548 DOI: 10.1093/glycob/cwp067] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
We describe an ALG9-defective (congenital disorders of glycosylation type IL) patient who is homozygous for the p.Y286C (c.860A>G) mutation. This patient presented with psychomotor retardation, axial hypotonia, epilepsy, failure to thrive, inverted nipples, hepatomegaly, and pericardial effusion. Due to the ALG9 deficiency, the cells of this patient accumulated the lipid-linked oligosaccharides Man(6)GlcNAc(2)-PP-dolichol and Man(8)GlcNAc(2)-PP-dolichol. It is known that the oligosaccharide structure has a profound effect on protein glycosylation. Therefore, we investigated the influence of these truncated oligosaccharide structures on the protein transfer efficiency, the quality control of newly synthesized glycoproteins, and the eventual degradation of the truncated glycoproteins formed in this patient. We demonstrated that lipid-linked Man(6)GlcNAc(2) and Man(8)GlcNAc(2) are transferred onto proteins with the same efficiency. In addition, glycoproteins bearing these Man(6)GlcNAc(2) and Man(8)GlcNAc(2) structures efficiently entered in the glucosylation/deglucosylation cycle of the quality control system to assist in protein folding. We also showed that in comparison with control cells, patient's cells degraded misfolded glycoproteins at an increasing rate. The Man(8)GlcNAc(2) isomer C on the patient's glycoproteins was found to promote the degradation of misfolded glycoproteins.
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Affiliation(s)
- Wendy Vleugels
- Laboratory for Molecular Diagnosis, Center for Human Genetics, University of Leuven, Leuven, Belgium
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39
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Ming JE, Stiehm ER. Genetic syndromic immunodeficiencies with antibody defects. Immunol Allergy Clin North Am 2009; 28:715-36, vii. [PMID: 18940571 DOI: 10.1016/j.iac.2008.06.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
This article reviews the major syndromic immunodeficiencies with significant antibody defects, many of which may require intravenous immunogammaglobulin therapy. The authors define syndromic immunodeficiency as an illness associated with a characteristic group of phenotypic abnormalities or laboratory features that comprise a recognizable syndrome. Many are familial with a defined inheritance pattern. Immunodeficiency may not be a major part of the illness and may not be present in all patients; thus, these conditions differ from primary immunodeficiency syndromes, in which immune abnormalities are a consistent and prominent feature of their disease.
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Affiliation(s)
- Jeffrey E Ming
- Division of Human Genetics, Department of Pediatrics, The Children's Hospital of Philadelphia, The University of Pennsylvania School of Medicine, 3615 Civic Center Boulevard, Philadelphia, PA 19104, USA
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40
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Kranz C, Basinger AA, Güçsavaş-Calikoğlu M, Sun L, Powell CM, Henderson FW, Aylsworth AS, Freeze HH. Expanding spectrum of congenital disorder of glycosylation Ig (CDG-Ig): sibs with a unique skeletal dysplasia, hypogammaglobulinemia, cardiomyopathy, genital malformations, and early lethality. Am J Med Genet A 2008; 143A:1371-8. [PMID: 17506107 DOI: 10.1002/ajmg.a.31791] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
In this report, we describe a brother and sister who presented at birth with short-limb skeletal dysplasia, polyhydramnios, prematurity, and generalized edema. Dysmorphic features included broad nose, thick ears, thin lips, micrognathia, inverted nipples, ulnar deviation at the wrists, spatulate fingers, fifth finger camptodactyly, nail hypoplasia, and talipes equinovarus. Other features included short stature, microcephaly, psychomotor retardation, B-cell lymphopenic hypogammaglobulinemia, sensorineural deafness, retinal detachment and blindness, intestinal malrotation with poor gastrointestinal motility, persistent hyponatremia, intermittent hypoglycemia, and thrombocytopenia. Cardiac anomalies included PDA, VSD, hypertrophic cardiomyopathy, and arrhythmias. The brother had a small penis with hypospadias, hypoplastic scrotum, and non-palpable testes. Skeletal findings included absent ossification of cervical vertebral bodies, pubic bones, knee epiphyses, and tali. Both sibs died before age 2 years, one of overwhelming sepsis and the other of cardiorespiratory failure associated with her cardiomyopathy. Metabolic studies showed a type 1 pattern of abnormal serum transferrin glycosylation. Fibroblasts synthesized truncated LLOs, primarily Man(7)GlcNAc(2), suggestive of CDG-Ig. Both sibs were compound heterozygotes for a novel 301 G > A (G101R) mutation and a previously described 437 G > A (R146Q) mutation in ALG12. Congenital disorders of glycosylation should be considered for children with undiagnosed multi-system disease including neurodevelopmental delay, skeletal dysplasia, immune deficiency, male genital hypoplasia, and cardiomyopathy.
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Affiliation(s)
- Christian Kranz
- Burnham Institute for Medical Research, La Jolla, California, USA
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41
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Chantret I, Moore SEH. Free oligosaccharide regulation during mammalian protein N-glycosylation. Glycobiology 2007; 18:210-24. [DOI: 10.1093/glycob/cwn003] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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42
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Abstract
Congenital disorders of glycosylation (CDG) are a large family of genetic diseases resulting from defects in the synthesis of glycans and in the attachment of glycans to other compounds. These disorders cause a wide range of human diseases, with examples emanating from all medical subspecialties. Since our 2001 review on CDG ( 36 ), this field has seen substantial growth: The number of N-glycosylation defects has doubled (from 6 to 12), five new O-glycosylation defects have been added to the two previously known ones, three combined N- and O-glycosylation defects have been identified, the first lipid glycosylation defects have been discovered, and a new domain, that of the hyperglycosylation defects, has been introduced. A number of CDG are due to defects in enzymes with a putative glycosyltransferase function. There is also a growing group of patients with unidentified defects (CDG-x), some with typical clinical presentations and others with presentations not seen before in CDG. This review focuses on the clinical, biochemical, and genetic characteristics of CDG and on advances expected in their future study and clinical management.
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Affiliation(s)
- Jaak Jaeken
- Department of Pediatrics, Center for Metabolic Disease, University of Leuven, Leuven, Belgium.
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43
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Hardré R, Khaled A, Willemetz A, Dupré T, Moore S, Gravier-Pelletier C, Le Merrer Y. Mono, di and tri-mannopyranosyl phosphates as mannose-1-phosphate prodrugs for potential CDG-Ia therapy. Bioorg Med Chem Lett 2007; 17:152-5. [PMID: 17049852 DOI: 10.1016/j.bmcl.2006.09.074] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2006] [Revised: 09/21/2006] [Accepted: 09/22/2006] [Indexed: 11/23/2022]
Abstract
An efficient and convergent method for the synthesis of mannose-1-phosphate prodrugs is described as a potential therapy for congenital disorders of glycosylation-Ia (CDG-Ia). The key feature of the proposed approach is the silver assisted nucleophilic substitution of 2,3,4,6-tetra-O-protected-alpha-d-mannopyranosyl bromides with various silver phosphate salts to afford mono, di, and tri-mannopyranosyl phosphates. A preliminary biological evaluation of the synthesized phosphate prodrugs has been carried out.
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Affiliation(s)
- Renaud Hardré
- Université René Descartes, UMR 8601 CNRS, Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, 45 rue des Saints-Pères, 75006 Paris, France
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44
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Kranz C, Sun L, Eklund EA, Krasnewich D, Casey JR, Freeze HH. CDG-Id in two siblings with partially different phenotypes. Am J Med Genet A 2007; 143A:1414-20. [PMID: 17551933 DOI: 10.1002/ajmg.a.31796] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
We present two sibs with congenital disorder of glycosylation (CDG) type Id. Each shows severe global delay, failure to thrive, seizures, microcephaly, axial hypotonia, and disaccharidase deficiency. One sib has more severe digestive issues, while the other is more neurologically impaired. Each is compound heterozygous for a novel point mutation and an already known mutation in the ALG3 gene that leads to the synthesis of a severely truncated oligosaccharide precursor for N-glycans. The defect is corrected by introduction of a normal ALG3 cDNA. CDG should be ruled out in all patients with severe seizures and failure to thrive. (c) 2007 Wiley-Liss, Inc.
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Affiliation(s)
- Christian Kranz
- Glycobiology and Carbohydrate Chemistry Program, The Burnham Institute for Medical Research, 10901 N. Torrey Pines Road, La Jolla, CA 92037, USA
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45
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Abstract
The congenital disorders of N-glycosylation (CDG), a steadily increasing group of multi-systemic disorders, have severe clinical implications in infancy and early childhood. The various inborn errors responsible adversely affect N-glycosylation of lysosomal proteins because of either failing assembly of lipid-linked (LL) oligosaccharides (OS) in the endoplasmic reticulum, CDG Type I, or faulty processing of the asparagines (N)-linked OS in the ER and in the Golgi, CDG Type II. The overlap of phenotypes precludes specific clinical delineation. Isoelectric focusing (IEF) of plasma transferrin remains a valuable, albeit imperfect, screening tool. IEF of plasma ApoC-III protein, introduced O-glycosylation defects that delineated some new CDGs due to mutations of both N- and O-glycosylation. Only CDG-Ib is amenable to treatment with free mannose supplementation. Hence, early specific diagnosis of any one entity is crucial for genetic counseling and elective preventive measures.
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Affiliation(s)
- Jules G Leroy
- Department of Pediatrics, Ghent University School of Medicine and University, B-9000 Ghent, Belgium.
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46
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Cohn RD, Eklund E, Bergner AL, Casella JF, Woods SL, Althaus J, Blakemore KJ, Fox HE, Hoover-Fong JE, Hamosh A, Braverman NE, Freeze HH, Boyadjiev SA. Intracranial hemorrhage as the initial manifestation of a congenital disorder of glycosylation. Pediatrics 2006; 118:e514-21. [PMID: 16816004 DOI: 10.1542/peds.2005-1307] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Intracranial hemorrhage in a term neonate is a rare event in the absence of an identifiable precipitating factor such as severe thrombocytopenia, mechanical trauma, asphyxia, infections, or congenital vascular malformations. Congenital disorders of glycosylation are a genetically and clinically heterogeneous group of multisystem disorders characterized by the abnormal glycosylation of a number of glycoproteins. Although bleeding caused by abnormal glycosylation of various coagulation factors is a well-known clinical complication of several types of congenital disorders of glycosylation, intracranial hemorrhage has not been reported as an initial manifestation of this entity. Here we report the detailed history of a family with 2 consecutive male infants, both born at term with intracranial hemorrhage diagnosed within the first 24 hours of life. The diagnosis of a congenital disorder of glycosylation was established in the second infant by an abnormal glycosylation of serum transferrin detected by electrospray-ionization mass spectrometry. Both infants showed significant neurologic deterioration during the first month of life, and both died at 5 months of age. Intracranial hemorrhage in a term neonate without a potential precipitating factor represents yet another clinical feature that should raise the suspicion for a congenital disorder of glycosylation.
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Affiliation(s)
- Ronald D Cohn
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins Hospital, Children's Center, Johns Hopkins University School of Medicine, 600 N Wolfe St, Blalock 1008, Baltimore, Maryland 21205, USA.
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47
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Dancourt J, Vuillaumier-Barrot S, de Baulny HO, Sfaello I, Barnier A, le Bizec C, Dupre T, Durand G, Seta N, Moore SEH. A new intronic mutation in the DPM1 gene is associated with a milder form of CDG Ie in two French siblings. Pediatr Res 2006; 59:835-9. [PMID: 16641202 DOI: 10.1203/01.pdr.0000219430.52532.8e] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Congenital disorders of glycosylation (CDG) type I (CDG I) are rare autosomal recessive diseases caused by deficiencies in the assembly of the dolichol-linked oligosaccharide (DLO) that is required for N-glycoprotein biosynthesis. CDG Ie is due to a defect in the synthesis of dolichyl-phosphoryl-mannose (Dol-P-Man), which is needed for DLO biosynthesis as well as for other glycosylation pathways. Human Dol-P-Man synthase is a heterotrimeric complex composed of DPM1p, DPM2p, and DPM3p, with DPM1p being the catalytic subunit. Here, we report two new CDG Ie patients who present milder symptoms than the five other CDG Ie patients described to date. The clinical pictures of the patients MS and his sister MT are dominated by major ataxia, with no notable hepatic involvement. MS cells accumulate the immature DLO species Dol-PP-GlcNAc2Man5 and possess only residual Dol-P-Man synthase activity. One homozygous intronic mutation, g.IVS4-5T>A, was found in the DPM1 gene, leading to exon skipping and transcription of a shortened transcript. Moreover, DPM1 expression was reduced by more than 90% in MS cells, in a nonsense-mediated mRNA decay (NMD)-independent manner. Full analysis of the DPM2 and DPM3 genes revealed a decrease in DPM2 expression and normal expression of DPM3. This description emphasizes the large spectrum of symptoms characterizing CDG I patients.
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48
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Abstract
The congenital disorders of glycosylation (CDG) are a rapidly expanding group of metabolic syndromes with a wide symptomatology and severity. They all stem from deficient N-glycosylation of proteins. To date the group contains 18 different subtypes: 12 of Type I (disrupted synthesis of the lipid-linked oligosaccharide precursor) and 6 of Type II (malfunctioning trimming/processing of the protein-bound oligosaccharide). Main features of CDG involve psychomotor retardation; ataxia; seizures; retinopathy; liver fibrosis; coagulopathies; failure to thrive; dysmorphic features, including inverted nipples and subcutaneous fat pads; and strabismus. No treatment currently is available for the vast majority of these syndromes (CDG-Ib and CDG-IIc are exceptions), even though attempts to synthesize drugs for the most common subtype, CDG-Ia, have been made. In this review we will discuss the individual syndromes, with focus on their neuronal involvement, available and possible treatments, and future directions.
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Affiliation(s)
- Erik A. Eklund
- />Department of Cell and Molecular Biology, Lund University, Lund, Sweden
- />Program for Glycobiology and Carbohydrate Chemistry, Burnham Institute for Medical Research, 92037 La Jolla, California
| | - Hudson H. Freeze
- />Program for Glycobiology and Carbohydrate Chemistry, Burnham Institute for Medical Research, 92037 La Jolla, California
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49
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Kelleher DJ, Gilmore R. An evolving view of the eukaryotic oligosaccharyltransferase. Glycobiology 2005; 16:47R-62R. [PMID: 16317064 DOI: 10.1093/glycob/cwj066] [Citation(s) in RCA: 403] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Asparagine-linked glycosylation (ALG) is one of the most common protein modification reactions in eukaryotic cells, as many proteins that are translocated across or integrated into the rough endoplasmic reticulum (RER) carry N-linked oligosaccharides. Although the primary focus of this review will be the structure and function of the eukaryotic oligosaccharyltransferase (OST), key findings provided by the analysis of the archaebacterial and eubacterial OST homologues will be reviewed, particularly those that provide insight into the recognition of donor and acceptor substrates. Selection of the fully assembled donor substrate will be considered in the context of the family of human diseases known as congenital disorders of glycosylation (CDG). The yeast and vertebrate OST are surprisingly complex hetero-oligomeric proteins consisting of seven or eight subunits (Ost1p, Ost2p, Ost3p/Ost6p, Ost4p, Ost5p, Stt3p, Wbp1p, and Swp1p in yeast; ribophorin I, DAD1, N33/IAP, OST4, STT3A/STT3B, Ost48, and ribophorin II in mammals). Recent findings from several laboratories have provided overwhelming evidence that the STT3 subunit is critical for catalytic activity. Here, we will consider the evolution and assembly of the eukaryotic OST in light of recent genomic evidence concerning the subunit composition of the enzyme in diverse eukaryotes.
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Affiliation(s)
- Daniel J Kelleher
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605-2324, USA
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50
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Abstract
N-linked glycosylation is essential for normal cellular function. Defects have now been described in eighteen genes that participate in the process. All give rise to complex multisystem diseases which, with a few exceptions, primarily involve the nervous system. Frequent features of these disorders include developmental delay, ataxia, seizures, stroke-like episodes, recurrent infections, coagulopathy and dysmorphism. Most cases can be detected by screening carbohydrate-deficient transferrin, but definitive diagnosis requires enzymatic and molecular confirmation, frequently in collaboration with a research glycobiologist.
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Affiliation(s)
- Marc C Patterson
- Division of Pediatric Neurology, Columbia University Medical Center, Harkness Pavilion, HP-540, 180 Fort Washington Avenue, New York, NY 10032, USA
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