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Lee HF, Chi CS. Congenital disorders of glycosylation and infantile epilepsy. Epilepsy Behav 2023; 142:109214. [PMID: 37086590 DOI: 10.1016/j.yebeh.2023.109214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Revised: 04/01/2023] [Accepted: 04/04/2023] [Indexed: 04/24/2023]
Abstract
Congenital disorders of glycosylation (CDG) are a group of rare inherited metabolic disorders caused by defects in various defects of protein or lipid glycosylation pathways. The symptoms and signs of CDG usually develop in infancy. Epilepsy is commonly observed in CDG individuals and is often a presenting symptom. These epilepsies can present across the lifespan, share features of refractoriness to antiseizure medications, and are often associated with comorbid developmental delay, psychomotor regression, intellectual disability, and behavioral problems. In this review, we discuss CDG and infantile epilepsy, focusing on an overview of clinical manifestations and electroencephalographic features. Finally, we propose a tiered approach that will permit a clinician to systematically investigate and identify CDG earlier, and furthermore, to provide genetic counseling for the family.
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Affiliation(s)
- Hsiu-Fen Lee
- Department of Post-Baccalaureate Medicine, College of Medicine, National Chung Hsing University, 145, Xingda Rd., Taichung 402, Taiwan; Division of Pediatric Neurology, Children's Medical Center, Taichung Veterans General Hospital, 1650, Taiwan Boulevard Sec. 4, Taichung 407, Taiwan.
| | - Ching-Shiang Chi
- Division of Pediatric Neurology, Children's Medical Center, Taichung Veterans General Hospital, 1650, Taiwan Boulevard Sec. 4, Taichung 407, Taiwan.
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Elsharkawi I, Wongkittichote P, James Paul Daniel E, Starosta RT, Ueda K, Ng BG, Freeze HH, He M, Shinawi M. DDOST-CDG: Clinical and molecular characterization of a third patient with a milder and a predominantly movement disorder phenotype. J Inherit Metab Dis 2023; 46:92-100. [PMID: 36214423 PMCID: PMC9852036 DOI: 10.1002/jimd.12565] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 09/02/2022] [Accepted: 09/30/2022] [Indexed: 01/22/2023]
Abstract
Congenital disorders of glycosylation (CDG) are a group of heterogeneous inherited metabolic disorders affecting posttranslational protein modification. DDOST-CDG, caused by biallelic pathogenic variants in DDOST which encodes dolichyl-diphospho-oligosaccharide-protein glycosyltransferase, a subunit of N-glycosylation oligosaccharyltransferase (OST) complex, is an ultra-rare condition that has been described in two patients only. The main clinical features in the two reported patients include profound developmental delay, failure to thrive, and hypotonia. In addition, both patients had abnormal transferrin glycosylation. Here, we report an 18-year-old male who presented with moderate developmental delay, progressive opsoclonus, myoclonus, ataxia, tremor, and dystonia. Biochemical studies by carbohydrate deficient transferrin analysis showed a type I CDG pattern. Exome sequencing identified compound heterozygous variants in DDOST: a maternally inherited variant, c.1142dupT (p.Leu381Phefs*11), and a paternally inherited variant, c.661 T > C (p.Ser221Pro). Plasma N-glycan profiling showed mildly increased small high mannose glycans including Man0-5 GlcNAc2, a pattern consistent with what was previously reported in DDOST-CDG or defects in other subunits of OST complex. Western blot analysis on patient's fibroblasts revealed decreased expression of DDOST and reduced intracellular N-glycosylation, as evident by the biomarkers ICAM-1 and LAMP2. Our study highlights the clinical variability, expands the clinical and biochemical phenotypes, and describes new genotype, which all are essential for diagnosing and managing patients with DDOST-CDG.
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Affiliation(s)
- Ibrahim Elsharkawi
- Division of Genetics and Genomic Medicine, Department of Pediatrics, St. Louis Children’s Hospital, Washington University School of Medicine, St. Louis, MO, USA
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, Children’s Hospital of Philadelphia, Philadelphia, PA, USA
| | - Parith Wongkittichote
- Division of Genetics and Genomic Medicine, Department of Pediatrics, St. Louis Children’s Hospital, Washington University School of Medicine, St. Louis, MO, USA
| | | | - Rodrigo Tzovenos Starosta
- Division of Genetics and Genomic Medicine, Department of Pediatrics, St. Louis Children’s Hospital, Washington University School of Medicine, St. Louis, MO, USA
| | - Keisuke Ueda
- Division of Pediatric Neurology, Department of Neurology, St. Louis Children’s Hospital, Washington University School of Medicine, St. Louis, MO, USA
| | - Bobby G. Ng
- Human Genetics Program, Sanford Children’s Health Research Center, La Jolla, CA, USA
| | - Hudson H. Freeze
- Human Genetics Program, Sanford Children’s Health Research Center, La Jolla, CA, USA
| | - Miao He
- Palmieri Metabolic Disease Laboratory, Children’s Hospital of Philadelphia, Philadelphia, PA, USA
| | - Marwan Shinawi
- Division of Genetics and Genomic Medicine, Department of Pediatrics, St. Louis Children’s Hospital, Washington University School of Medicine, St. Louis, MO, USA
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The second DDOST-CDG patient with lactose intolerance, developmental delay, and situs inversus totalis. J Hum Genet 2021; 67:103-106. [PMID: 34462534 DOI: 10.1038/s10038-021-00974-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 08/08/2021] [Accepted: 08/17/2021] [Indexed: 11/08/2022]
Abstract
Congenital disorders of glycosylation (CDGs) are inherited metabolic diseases affecting protein and lipid glycosylation. DDOST-CDG is a rare, newly identified type of CDGs, with only one case reported so far. In this study, we report a Chinese patient with a homozygous pathogenic variant in DDOST (c.1187G>A) and who presented with feeding difficulty, lactose intolerance, facial dysmorphism, failure to thrive, strabismus, high myopia, astigmatism, hypotonia, developmental delay and situs inversus totalis. Serum transferrin isoelectrofocusing demonstrated defective glycosylation in our patient. This finding further identifies DDOST as a genetic cause of CDGs and expands the clinical phenotype of DDOST-CDG.
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The evolving genetic landscape of congenital disorders of glycosylation. Biochim Biophys Acta Gen Subj 2021; 1865:129976. [PMID: 34358634 DOI: 10.1016/j.bbagen.2021.129976] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 07/30/2021] [Indexed: 01/01/2023]
Abstract
Congenital Disorders of Glycosylation (CDG) are an expanding and complex group of rare genetic disorders caused by defects in the glycosylation of proteins and lipids. The genetic spectrum of CDG is extremely broad with mutations in over 140 genes leading to a wide variety of symptoms ranging from mild to severe and life-threatening. There has been an expansion in the genetic complexity of CDG in recent years. More specifically several examples of alternate phenotypes in recessive forms of CDG and new types of CDG following an autosomal dominant inheritance pattern have been identified. In addition, novel genetic mechanisms such as expansion repeats have been reported and several already known disorders have been classified as CDG as their pathophysiology was better elucidated. Furthermore, we consider the future and outlook of CDG genetics, with a focus on exploration of the non-coding genome using whole genome sequencing, RNA-seq and multi-omics technology.
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Paprocka J, Jezela-Stanek A, Tylki-Szymańska A, Grunewald S. Congenital Disorders of Glycosylation from a Neurological Perspective. Brain Sci 2021; 11:brainsci11010088. [PMID: 33440761 PMCID: PMC7827962 DOI: 10.3390/brainsci11010088] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 01/01/2021] [Accepted: 01/04/2021] [Indexed: 12/11/2022] Open
Abstract
Most plasma proteins, cell membrane proteins and other proteins are glycoproteins with sugar chains attached to the polypeptide-glycans. Glycosylation is the main element of the post-translational transformation of most human proteins. Since glycosylation processes are necessary for many different biological processes, patients present a diverse spectrum of phenotypes and severity of symptoms. The most frequently observed neurological symptoms in congenital disorders of glycosylation (CDG) are: epilepsy, intellectual disability, myopathies, neuropathies and stroke-like episodes. Epilepsy is seen in many CDG subtypes and particularly present in the case of mutations in the following genes: ALG13, DOLK, DPAGT1, SLC35A2, ST3GAL3, PIGA, PIGW, ST3GAL5. On brain neuroimaging, atrophic changes of the cerebellum and cerebrum are frequently seen. Brain malformations particularly in the group of dystroglycanopathies are reported. Despite the growing number of CDG patients in the world and often neurological symptoms dominating in the clinical picture, the number of performed screening tests eg transferrin isoforms is systematically decreasing as broadened genetic testing is recently more favored. The aim of the review is the summary of selected neurological symptoms in CDG described in the literature in one paper. It is especially important for pediatric neurologists not experienced in the field of metabolic medicine. It may help to facilitate the diagnosis of this expanding group of disorders. Biochemically, this paper focuses on protein glycosylation abnormalities.
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Affiliation(s)
- Justyna Paprocka
- Department of Pediatric Neurology, Faculty of Medical Science in Katowice, Medical University of Silesia, 40-752 Katowice, Poland
- Correspondence: ; Tel.: +48-606-415-888
| | - Aleksandra Jezela-Stanek
- Department of Genetics and Clinical Immunology, National Institute of Tuberculosis and Lung Diseases, 01-138 Warsaw, Poland;
| | - Anna Tylki-Szymańska
- Department of Pediatrics, Nutrition and Metabolic Diseases, The Children’s Memorial Health Institute, W 04-730 Warsaw, Poland;
| | - Stephanie Grunewald
- NIHR Biomedical Research Center (BRC), Metabolic Unit, Great Ormond Street Hospital and Institute of Child Health, University College London, London SE1 9RT, UK;
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Regulation of organic anion transporters: Role in physiology, pathophysiology, and drug elimination. Pharmacol Ther 2020; 217:107647. [PMID: 32758646 DOI: 10.1016/j.pharmthera.2020.107647] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 07/27/2020] [Indexed: 12/24/2022]
Abstract
The members of the organic anion transporter (OAT) family are mainly expressed in kidney, liver, placenta, intestine, and brain. These transporters play important roles in the disposition of clinical drugs, pesticides, signaling molecules, heavy metal conjugates, components of phytomedicines, and toxins, and therefore critical for maintaining systemic homeostasis. Alterations in the expression and function of OATs contribute to the intra- and inter-individual variability of the therapeutic efficacy and the toxicity of many drugs, and to many pathophysiological conditions. Consequently, the activity of these transporters must be highly regulated to carry out their normal functions. This review will present an update on the recent advance in understanding the cellular and molecular mechanisms underlying the regulation of renal OATs, emphasizing on the post-translational modification (PTM), the crosstalk among these PTMs, and the remote sensing and signaling network of OATs. Such knowledge will provide significant insights into the roles of these transporters in health and disease.
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