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Zhong D, Huang X, Feng T, Zeng J, Gu S, Ning F, Yang Y, Zhu J, Wang Y, Chen R, Ma G. Congenital disorder of glycosylation type Ia in a Chinese family: Function analysis of a novel PMM2 complex heterozygosis mutation. Mol Genet Metab Rep 2024; 39:101067. [PMID: 38433930 PMCID: PMC10905039 DOI: 10.1016/j.ymgmr.2024.101067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 01/24/2024] [Accepted: 02/19/2024] [Indexed: 03/05/2024] Open
Abstract
Congenital disorder of glycosylation type Ia (CDG-Ia) is an autosomal recessive genetic disease caused by a mutation in the phosphomannomutase 2 (PMM2) gene. We have identified a 13-month-old boy who has been diagnosed with CDG-Ia. He displays several characteristic symptoms, including cerebellar hypoplasia, severe developmental retardation, hypothyroidism, impaired liver function, and abnormal serum ferritin levels. Through whole-exome sequencing, we discovered novel complex heterozygous mutations in the PMM2 gene, specifically the c.663C > G (p.F221L) mutation and loss of exon 2. Further analysis revealed that the enzymatic activity of the mutant PMM2 protein was significantly reduced by 44.97% (p < 0.05) compared to the wild-type protein.
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Affiliation(s)
- Dan Zhong
- Maternal and Children's Health Research Institute, Shunde Women and Children's Hospital, Guangdong Medical University, Foshan 528300, China
| | - Xiujuan Huang
- Department of Child Healthcare, Shunde Women and Children's Hospital, Guangdong Medical University, Foshan 528300, China
| | - Taoshan Feng
- Maternal and Children's Health Research Institute, Shunde Women and Children's Hospital, Guangdong Medical University, Foshan 528300, China
| | - Jieqing Zeng
- Maternal and Children's Health Research Institute, Shunde Women and Children's Hospital, Guangdong Medical University, Foshan 528300, China
| | - Shanshan Gu
- Maternal and Children's Health Research Institute, Shunde Women and Children's Hospital, Guangdong Medical University, Foshan 528300, China
| | - Fan Ning
- Maternal and Children's Health Research Institute, Shunde Women and Children's Hospital, Guangdong Medical University, Foshan 528300, China
| | - Yue Yang
- Department of Child Healthcare, Shunde Women and Children's Hospital, Guangdong Medical University, Foshan 528300, China
| | - Jinyuan Zhu
- Department of Child Healthcare, Shunde Women and Children's Hospital, Guangdong Medical University, Foshan 528300, China
| | - Yajun Wang
- Institute of Respiratory, Shunde Women and Children's Hospital, Guangdong Medical University, Foshan 528300, China
| | - Riling Chen
- Maternal and Children's Health Research Institute, Shunde Women and Children's Hospital, Guangdong Medical University, Foshan 528300, China
- Department of Pediatrics, Shunde Women and Children's Hospital, Guangdong Medical University, Foshan 528300, China
| | - Guoda Ma
- Maternal and Children's Health Research Institute, Shunde Women and Children's Hospital, Guangdong Medical University, Foshan 528300, China
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Quelhas D, Carneiro J, Lopes-Marques M, Jaeken J, Martins E, Rocha JF, Teixeira Carla SS, Ferreira CR, Sousa SF, Azevedo L. Assessing the effects of PMM2 variants on protein stability. Mol Genet Metab 2021; 134:344-352. [PMID: 34863624 DOI: 10.1016/j.ymgme.2021.11.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 10/30/2021] [Accepted: 11/02/2021] [Indexed: 11/16/2022]
Abstract
Phosphomannomutase 2 deficiency, PMM2-CDG, is the most frequent disorder of protein N-glycosylation. It is an autosomal recessive disease with a broad clinical and biochemical phenotype. Trying to predict the impact of novel variants is often a challenge due to the high number of variants and the difficulty to establish solid genotype-phenotype correlations. A potential useful strategy is to use computational chemistry calculations as a tool from which relevant information on the structural impact of novel variants may be deduced. Here we present our analyses based on four well-known PMM2 deleterious variants (p.(Leu32Arg), p.(Asp65Tyr), p.(Phe119Leu), p.(Arg141His)) and the polymorphic p.(Glu197Ala) for which we have predicted the effect on protein stability. Our work predicts the effect of different amino acid residues on the conformation and stability of PMM2. These computational simulations are, therefore, an extremely useful methodology which, in combination with routinely used in silico methods of pathogenicity prediction, may help to reveal the structural impact of novel variants at the protein level, potentially leading to a better understanding of target biological molecules.
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Affiliation(s)
- D Quelhas
- Unidade de Bioquímica Genética, Centro de Genética Médica, Centro Hospitalar Universitário do Porto, Porto, Portugal; Unit for Multidisciplinary Research in Biomedicine, ICBAS, UP, Porto, Portugal; Centro Referência Doenças Hereditárias do Metabolismo, Centro Hospitalar Universitário do Porto, Porto, Portugal.
| | - J Carneiro
- CIIMAR, Interdisciplinary Centre of Marine and Environmental Research, Matosinhos, Portugal
| | - M Lopes-Marques
- i3S- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; IPATIMUP-Institute of Molecular Pathology and Immunology, University of Porto, Porto, Portugal; FCUP-Department of Biology, Faculty of Sciences, University of Porto, Porto, Portugal
| | - J Jaeken
- Center for Metabolic Diseases, KU Leuven, Leuven, Belgium
| | - E Martins
- Unit for Multidisciplinary Research in Biomedicine, ICBAS, UP, Porto, Portugal; Centro Referência Doenças Hereditárias do Metabolismo, Centro Hospitalar Universitário do Porto, Porto, Portugal
| | - J F Rocha
- Associate Laboratory i4HB - Institute for Health and Bioeconomy, Faculty of Medicine, University of Porto, 4200-319 Porto, Portugal; UCIBIO - Applied Molecular Biosciences Unit, BioSIM - Department of Biomedicine, Faculty of Medicine, University of Porto, 4200-319 Porto, Portugal
| | - S S Teixeira Carla
- Associate Laboratory i4HB - Institute for Health and Bioeconomy, Faculty of Medicine, University of Porto, 4200-319 Porto, Portugal; UCIBIO - Applied Molecular Biosciences Unit, BioSIM - Department of Biomedicine, Faculty of Medicine, University of Porto, 4200-319 Porto, Portugal
| | - C R Ferreira
- Skeletal Genomics Unit, Medical Genomics and Metabolic Genetics Branch, National Human Genome Research Institute, Bethesda, MD 20892, USA
| | - S F Sousa
- Associate Laboratory i4HB - Institute for Health and Bioeconomy, Faculty of Medicine, University of Porto, 4200-319 Porto, Portugal; UCIBIO - Applied Molecular Biosciences Unit, BioSIM - Department of Biomedicine, Faculty of Medicine, University of Porto, 4200-319 Porto, Portugal
| | - L Azevedo
- i3S- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; IPATIMUP-Institute of Molecular Pathology and Immunology, University of Porto, Porto, Portugal; FCUP-Department of Biology, Faculty of Sciences, University of Porto, Porto, Portugal
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Masunaga Y, Mochizuki M, Kadoya M, Wada Y, Okamoto N, Fukami M, Kato F, Saitsu H, Ogata T. Primary ovarian insufficiency in a female with phosphomannomutase-2 gene (PMM2) mutations for congenital disorder of glycosylation. Endocr J 2021; 68:605-611. [PMID: 33583911 DOI: 10.1507/endocrj.ej20-0706] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Primary ovarian insufficiency (POI) is a highly heterogeneous condition, and its underlying causes remain to be clarified in a large fraction of patients. Congenital disorders of glycosylation (CDG) are multisystem diseases caused by mutations of a number of genes involved in N-glycosylation or O-glycosylation, and the most frequent form is PMM2-CDG (alias, CDG-Ia) resulting from biallelic mutations in PMM2 encoding phosphomannomutase-2 involved in N-glycosylation. Here, we examined a 46,XX Japanese female with syndromic POI accompanied by an undetectable level of serum anti-Müllerian hormone (AMH). Whole exome sequencing identified biallelic pathogenic mutations of PMM2 (a novel c.34G>C:p.(Asp12His) of maternal origin and a recurrent c.310C>G:p.(Leu104Val) of paternal origin) (NM_000303.3), and N-glycosylation studies detected asialotransferrin and disialotransferrin characteristic of PMM2-CDG, in addition to normally glycosylated tetrasialotransferrin. Clinical assessment showed cerebellar hypotrophy, which is a fairly characteristic and highly prevalent feature in PMM2-CDG, together with multiple non-specific features reported in PMM2-CDG such as characteristic face, intellectual disability, skeletal abnormalities, and low blood antithrombin III value. These results including the undetectable level of serum AMH, in conjunction with previously reported findings suggestive of the critical role of glycosylation in oocyte development and function, imply that PMM2-CDG almost invariably leads to POI primarily because of the defective oogenesis and/or oocyte-dependent early folliculogenesis rather than the compromised bioactivity of FSH/LH with defective glycosylation. Thus, it is recommended to examine PMM2 in patients with syndromic POI, especially in those with cerebellar ataxia/hypotrophy.
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Affiliation(s)
- Yohei Masunaga
- Department of Pediatrics, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan
| | - Mie Mochizuki
- Department of Pediatrics, University of Yamanashi, Faculty of Medicine, Chuou 409-3898, Japan
| | - Machiko Kadoya
- Department of Molecular Medicine, Osaka Women's and Children's Hospital, Izumi 594-1101, Japan
| | - Yoshinao Wada
- Department of Molecular Medicine, Osaka Women's and Children's Hospital, Izumi 594-1101, Japan
| | - Nobuhiko Okamoto
- Department of Molecular Medicine, Osaka Women's and Children's Hospital, Izumi 594-1101, Japan
| | - Maki Fukami
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo 157-8535, Japan
| | - Fumiko Kato
- Department of Pediatrics, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan
| | - Hirotomo Saitsu
- Department of Biochemistry, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan
| | - Tsutomu Ogata
- Department of Pediatrics, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan
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Farmania R, Jain P, Sharma S, Aneja S. Unusual Presentation of PMM2-Congenital Disorder of Glycosylation With Isolated Strokelike Episodes in a Young Girl. J Child Neurol 2019; 34:410-414. [PMID: 30857461 DOI: 10.1177/0883073819833543] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Congenital disorders of glycosylation (CDG) are multisystemic inherited metabolic disorders with marked phenotypic variability. The most frequent described type is PMM2-CDG (earlier known as CDG Type Ia) which presents either with pure neurologic features or with combined neurologic and systemic features. The classical presentation is characterized by varied combinations of developmental delay, hypotonia, ataxia, dysmorphism, inverted nipples, and abnormal fat distribution. Strokelike episodes and seizures are known acute complications that usually occur on a background of developmental delay, ataxia, or dysmorphism. We report here a developmentally normal young girl who presented with isolated strokelike episodes and was diagnosed to have CDG Type Ia. This condition should be kept in the differentials of unexplained strokelike episodes in children. The diagnosis has important therapeutic and prognostic implications.
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Affiliation(s)
- Rajni Farmania
- 1 Division of Pediatric Neurology, Department of Pediatrics, BL Kapur (BLK) Super Speciality Hospital, Pusa Road, New Delhi, India
| | - Puneet Jain
- 1 Division of Pediatric Neurology, Department of Pediatrics, BL Kapur (BLK) Super Speciality Hospital, Pusa Road, New Delhi, India.,2 Division of Neurology, Department of Pediatrics, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Suvasini Sharma
- 3 Neurology Division, Department of Pediatrics, Lady Hardinge Medical College (LHMC) and associated Kalawati Saran Children Hospital, New Delhi, India
| | - Satinder Aneja
- 3 Neurology Division, Department of Pediatrics, Lady Hardinge Medical College (LHMC) and associated Kalawati Saran Children Hospital, New Delhi, India.,4 Department of Pediatrics, School of Medical Sciences & Research, Sharda University, Greater Noida, UP, India
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Application of whole exome sequencing to a rare inherited metabolic disease with neurological and gastrointestinal manifestations: a congenital disorder of glycosylation mimicking glycogen storage disease. Clin Chim Acta 2015; 444:50-3. [PMID: 25681648 DOI: 10.1016/j.cca.2015.02.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 02/03/2015] [Indexed: 01/31/2023]
Abstract
BACKGROUND Rare inherited metabolic diseases with neurological and gastrointestinal manifestations can be misdiagnosed as other diseases or remain as disorders with indeterminate etiologies. This study aims to provide evidence to recommend the utility of whole exome sequencing in clinical diagnosis of a rare inherited metabolic disease. METHODS AND RESULTS A 4-month-old female baby visited an outpatient clinic due to poor weight gain, repeated seizure-like episodes, developmental delay, and unexplained hepatomegaly with abnormal liver function test results. Although liver biopsy revealed moderate fibrosis with a suggested diagnosis of glycogen storage disease (GSD), no mutations were identified either by single gene approach for GSD (G6PC and GAA) or by next generation sequencing panels for GSD (including 21 genes). Whole exome sequencing of the patient revealed compound heterozygous mutations of PMM2: c.580C>T (p.Arg194*) and c.713G>C (p.Arg238Pro) which mutations were associated with congenital disorder of glycosylation Ia (CDG-Ia: PMM2-CDG). CONCLUSIONS We successfully applied exome sequencing to diagnose the first reported Korean patient with CDG-Ia, which was misdiagnosed as GSD. Whole exome sequencing may prove to be the preferred strategy for analysis of clinical features that do not readily suggest a specific diagnosis, such as those observed in inherited metabolic diseases, including CDG.
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Linssen M, Mohamed M, Wevers RA, Lefeber DJ, Morava E. Thrombotic complications in patients with PMM2-CDG. Mol Genet Metab 2013; 109:107-11. [PMID: 23499581 DOI: 10.1016/j.ymgme.2013.02.006] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Accepted: 02/08/2013] [Indexed: 11/22/2022]
Abstract
Many proteins regulating coagulation, including factor IX, factor XI, Antithrombin-III, Protein C and Protein S are deficient or decreased in activity in congenital disorders of glycosylation (CDG). Because of the imbalance of coagulation and anticoagulation factors, some patients develop acute vascular events, such as thrombosis. Identifying patients with increased risk for thrombotic events could prevent serious complications and even mortality. We performed a systematic review on patients diagnosed with the most common CDG form; PMM2-CDG, reported between 1990 and 2012 in medical literature. We also evaluated our PMM2-CDG patient-cohort of 15 patients. In total, based on the availability of comprehensive clinical descriptions, 100 patients were included in the study. Patients with and without thrombotic events were compared based on the alterations of the following glycosylated coagulation and anticoagulation factors: Antithrombin-III, Protein C, Protein S, factors IX and XI. We also assessed the global hemostasis, family history and provoking events. In the group of 100 PMM2-CDG patients 14 had suffered a venous or arterial thrombotic event. Low activity of several anticoagulation factors correlated with thrombotic events. Relatively high factor IX and XI activities were not associated with thrombosis. Prolonged PT and aPTT did not seem to protect against thrombosis in patients. Surgical procedures were frequently associated with thrombotic events. Based on the association of thrombosis and surgery in PMM2-CDG we advise to avoid elective surgical procedures in PMM2-CDG patients. Easily preventable risk factors like immobility should be treated with regular physiotherapy. We suggest a yearly follow-up for Antithrombin-III and Protein C levels and parent education for early thrombotic signs in CDG.
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Affiliation(s)
- M Linssen
- Department of Pediatrics, Radboud University Nijmegen Medical Centre, the Netherlands
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DFT investigation on the reaction mechanism catalyzed by α-phosphomannomutase1 in protonated/deprotonated states. J Mol Model 2011; 17:577-85. [DOI: 10.1007/s00894-010-0743-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2009] [Accepted: 05/04/2010] [Indexed: 10/19/2022]
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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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Thong MK, Fietz M, Nicholls C, Lee MH, Asma O. Congenital disorder of glycosylation type Ia in a Malaysian family: clinical outcome and description of a novel PMM2 mutation. J Inherit Metab Dis 2009; 32 Suppl 1:S41-4. [PMID: 19165618 DOI: 10.1007/s10545-009-1031-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2008] [Revised: 12/09/2008] [Accepted: 12/16/2008] [Indexed: 10/21/2022]
Abstract
There are few reports of congenital disorders of glycosylation (CDGs) in the Asian population, although they have been reported worldwide. We identified a Malaysian infant female at 2 days of life with CDG type Ia. The diagnosis was suspected on the basis of inverted nipples and abnormal fat distribution. She had cerebellar hypoplasia and developed coagulopathy, hypothyroidism and severe pericardial effusion and died at 7 months of life. The diagnosis was supported by abnormal serum transferrin isoform pattern that showed elevated levels of the disialotransferrin isoform and trace levels of the asialotransferrin isoform. Enzyme testing of peripheral leukocytes showed decreased level of phosphomannomutase (PMM) activity (0.6 nmol/min per mg protein, normal range 1.6-6.2) and a normal level of phosphomannose isomerase activity (19 nmol/min per mg protein, normal range 12-25), indicating a diagnosis of CDG type Ia. Mutation study of the PMM2 gene showed the patient was heterozygous for both the common p.R141H (c.422T>A) mutation and a novel sequence change in exon 7, c.618C>A. The latter change is predicted to result in the replacement of the highly conserved phenylalanine residue at position 206 with a leucine residue (p.F206L) and occurs in the same codon as the previously reported p.F206S mutation. Analysis of 100 control chromosomes has shown that the p.F206L sequence change is not present, making it highly likely that this change is functionally important. To the best of our knowledge, this is the first report of CDG in the Malay population. Prenatal diagnosis was successfully performed in a subsequent pregnancy for this family.
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Affiliation(s)
- M K Thong
- Department of Paediatrics, Faculty of Medicine, University of Malaya, 50603, Kuala Lumpur, Malaysia.
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Coman D, Bostock D, Hunter M, Kannu P, Irving M, Mayne V, Fietz M, Jaeken J, Savarirayan R. Primary skeletal dysplasia as a major manifesting feature in an infant with congenital disorder of glycosylation type Ia. Am J Med Genet A 2008; 146A:389-92. [DOI: 10.1002/ajmg.a.32119] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Coman D, McGill J, MacDonald R, Morris D, Klingberg S, Jaeken J, Appleton D. Congenital disorder of glycosylation type 1a: Three siblings with a mild neurological phenotype. J Clin Neurosci 2007; 14:668-72. [PMID: 17451957 DOI: 10.1016/j.jocn.2006.04.008] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2005] [Revised: 04/11/2006] [Accepted: 04/12/2006] [Indexed: 11/16/2022]
Abstract
We report 3 siblings (1 male and 2 female) recently diagnosed with congenital disorder of glycosylation type Ia (CDG-Ia) in their mid-20s. They experience mild mental retardation but manage to function independently in society. Their professions are library assistant, professional artistic painter and secretarial work. All three siblings have cerebellar hypoplasia and ataxia, but are able to ambulate easily. Two of the siblings have required strabismus surgical repairs. All have antithrombin III deficiency, osteoporosis, and mild dysmorphic features. Hypergonadotrophic hypogonadism was a feature of the two female siblings. A type 1 sialotransferrin pattern and phosphomannomutase (PMM) deficiency have been demonstrated. They are compound heterozygotes for R141H and L32R mutations in the PMM2 gene. While there is clinical heterogeneity in CDG-Ia, we believe that our patients are among the mildest of intellectually affected CDG-Ia patients reported to date.
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Affiliation(s)
- D Coman
- Department of Metabolic Medicine, The Royal Children's Hospital, Brisbane, Queensland, Australia
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Mandato C, Brive L, Miura Y, Davis JA, Di Cosmo N, Lucariello S, Pagliardini S, Seo NS, Parenti G, Vecchione R, Freeze HH, Vajro P. Cryptogenic liver disease in four children: a novel congenital disorder of glycosylation. Pediatr Res 2006; 59:293-8. [PMID: 16439595 DOI: 10.1203/01.pdr.0000196378.30165.26] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
We investigated the metabolic defect(s) of four children who presented with isolated cryptogenic chronic liver disease, coagulopathy, and abnormalities of several unrelated serum glycoproteins. Analysis of the patients' serum glycoproteins and fibroblasts suggest they have a novel congenital disorder of glycosylation (CDG). All had abnormal transferrin (Tf) isoelectric focusing (IEF) profiles. More detailed analysis of Tf by electrospray ionization mass spectrometry (ESI-MS) showed a plethora of abnormal glycosylations that included loss of 1-2 sialic acids and 1-2 galactose units, typical of Group II defects. Tf from two patients also lacked 1-2 entire oligosaccharide chains, typical of Group One disorders. Total serum N-glycans were analyzed by HPLC and matrix-assisted laser desorption/ionization mass spectrometry and also showed increased proportion of neutral glycan chains lacking sialic acids and galactose units. Analysis of patient fibroblasts eliminated CDG-Ia, through CDG-Ih, -IL and CDG-IId. Our results suggest that a subset of children with clinically asymptomatic, cryptogenic hypertransaminasemia and/or liver steato-fibrosis may represent a novel type of CDG-X with an unknown defect(s). Clinicians are encouraged to test such patients for abnormal Tf glycosylation by ESI-MS.
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Affiliation(s)
- Claudia Mandato
- Department of Pediatrics, University of Naples Federico II, Italy
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Enns GM, Steiner RD, Buist N, Cowan C, Leppig KA, McCracken MF, Westphal V, Freeze HH, O'brien JF, Jaeken J, Matthijs G, Behera S, Hudgins L. Clinical and molecular features of congenital disorder of glycosylation in patients with type 1 sialotransferrin pattern and diverse ethnic origins. J Pediatr 2002; 141:695-700. [PMID: 12410200 DOI: 10.1067/mpd.2002.128658] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE To increase awareness of congenital disorders of glycosylation (CDG), we report the features of patients with a variety of clinical presentations ranging from mild hypotonia and strabismus to severe neurologic impairment. STUDY DESIGN Nine North American patients with CDG type I and different ethnic origins were studied. RESULTS All patients had transferrin isoelectric focusing studies with a type 1 sialotransferrin pattern. Molecular analysis showed the previously described R141H, V231M, and T237M PMM2 mutations in four patients as well as 3 rare mutations (DeltaC389, L104V, and IVS1 -1 G-->A) in the PMM2 gene in two Asian patients. CONCLUSIONS The clinical features of these patients with diverse ethnic backgrounds confirm the variable course of CDG type I. Screening for CDG should be considered in children with relatively mild neurologic impairment, especially if they have suggestive findings such as cerebellar hypoplasia and abnormal fat distribution.
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Affiliation(s)
- Gregory M Enns
- Division of Medical Genetics, Department of Pediatrics, Stanford University, Palo Alto, California 94305, USA
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Westphal V, Peterson S, Patterson M, Tournay A, Blumenthal A, Treacy EP, Freeze HH. Functional significance of PMM2 mutations in mildly affected patients with congenital disorders of glycosylation Ia. Genet Med 2001; 3:393-8. [PMID: 11715002 DOI: 10.1097/00125817-200111000-00003] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
PURPOSE Congenital disorders of glycosylation (CDG) result from mutations in N-glycan biosynthesis. Mutations in phosphomannomutase (PMM2) cause CDG-Ia. Here, we report four clinically mild patients and their mutations in PMM2. METHODS Analysis of the PMM2 cDNA and gene revealed the mutations affecting the glycosylation efficiency. RESULTS The patients have 30% to 50% normal PMM activity in fibroblasts due to different mutations in PMM2, and we studied the effect of each mutation on the PMM activity in a Saccharomyces cerevisiae expression system. CONCLUSIONS Each patient carried a severe mutation that decreased the PMM activity to less than 10% as well as a relatively mild mutation. A new mutation, deletion of base 24, changed the reading frame. The C9Y, C241S, and L32R mutations showed 27% to 45% activity when expressed in the eukaryotic expression system, and the more severe D148N was shown to be thermolabile.
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Affiliation(s)
- V Westphal
- The Burnham Institute, Glycobiology Program, La Jolla, California 92037, USA
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