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Yoldas Celik M, Yazici H, Erdem F, Yuksel Yanbolu A, Aykut A, Durmaz A, Zeybek S, Canda E, Kalkan Ucar S, Coker M. Unique clinical presentations and follow-up outcomes from experience with congenital disorders of glycosylation: PMM2-PGM1-DPAGT1-MPI- POMT2-B3GALNT2-DPM1-SRD5A3-CDG. J Pediatr Endocrinol Metab 2023:jpem-2022-0641. [PMID: 37042760 DOI: 10.1515/jpem-2022-0641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/25/2022] [Accepted: 03/26/2023] [Indexed: 04/13/2023]
Abstract
OBJECTIVES Congenital Glycosylation Disorders (CDG) are a large group of inherited metabolic diseases with multi-organ involvement. Herein, we aimed to expand the clinical characteristics of patients with CDG based on our experience with diagnoses and follow-up of CDG patients from different subtypes. METHODS The clinical and laboratory findings from the last 15 years were reviewed retrospectively in Ege University Child Metabolism and Nutrition Department. RESULTS There were 8 (57.2 %) females and 6 (42.8 %) males. Diagnoses of the patients were PMM2-CDG (n=4), PGM1-CDG (n=2), DPAGT1-CDG (n=2), SRD5A3-CDG (n=2), MPI-CDG (n=1), POMT2-CDG (n=1), B3GALNT2-CDG (n=1), DPM1-CDG (n=1). The clinical findings of the patients were dysmorphia (85.7 %), developmental delay (85.7 %), intellectual disability (85.7 %), ocular abnormalities (64.2 %), skeletal malformations (64.2 %), failure to thrive (57.1 %), microcephaly (57.1 %), hepatomegaly (35.7 %), hearing loss (35.7 %), seizures (28.5 %), gastrointestinal symptoms (21.4 %), endocrine abnormalities (21.4 %), and cardiac abnormalities (7.1 %). Laboratory findings were abnormal TIEF (92.8 %), abnormal liver enzymes (64.2 %), decreased protein C (64.2 %), decreased antithrombin III (64.2 %), decreased protein S (42.8 %), hypogammaglobulinemia (35.7 %), cerebellar hypoplasia (28.5 %), CK elevation (7.1 %), and hypoglycemia (7.1 %). CONCLUSIONS This study contributes to the literature by sharing our ultra-rare DPM1-CDG case with less than 20 cases in the literature and expanding the clinical and molecular characteristics of other CDG patients. Hyperinsulinemic hypoglycemia, short stature, hypothyroidism, growth hormone deficiency, hypogammaglobulinemia, pericardial effusion, elevated CK, congenital myasthenia, and anorectal malformation were unique findings that were observed. Cerebello-ocular findings accompanying multi-organ involvement were an essential clue for a possible CDG.
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Affiliation(s)
- Merve Yoldas Celik
- Department of Pediatrics, Division of Pediatric Metabolism and Nutrition, Ege University Faculty of Medicine, Izmir, Türkiye
| | - Havva Yazici
- Department of Pediatrics, Division of Pediatric Metabolism and Nutrition, Ege University Faculty of Medicine, Izmir, Türkiye
| | - Fehime Erdem
- Department of Pediatrics, Division of Pediatric Metabolism and Nutrition, Ege University Faculty of Medicine, Izmir, Türkiye
| | - Ayse Yuksel Yanbolu
- Department of Pediatrics, Division of Pediatric Metabolism and Nutrition, Ege University Faculty of Medicine, Izmir, Türkiye
| | - Ayca Aykut
- Department of Genetics, Ege University Faculty of Medicine, Izmir, Türkiye
| | - Asude Durmaz
- Department of Genetics, Ege University Faculty of Medicine, Izmir, Türkiye
| | - Selcan Zeybek
- Department of Genetics, Tinaztepe University Faculty of Medicine, Izmir, Türkiye
| | - Ebru Canda
- Department of Pediatrics, Division of Pediatric Metabolism and Nutrition, Ege University Faculty of Medicine, Izmir, Türkiye
| | - Sema Kalkan Ucar
- Department of Pediatrics, Division of Pediatric Metabolism and Nutrition, Ege University Faculty of Medicine, Izmir, Türkiye
| | - Mahmut Coker
- Department of Pediatrics, Division of Pediatric Metabolism and Nutrition, Ege University Faculty of Medicine, Izmir, Türkiye
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Zhao X, Gao C, Li L, Jiang L, Wei Y, Che F, Liu Q. Clinical exome sequencing identifies novel compound heterozygous mutations of the POMT2 gene in patients with limb-girdle muscular dystrophy. Int J Dev Neurosci 2023; 83:23-30. [PMID: 36217604 DOI: 10.1002/jdn.10233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 09/21/2022] [Accepted: 09/26/2022] [Indexed: 02/04/2023] Open
Abstract
OBJECTIVE Mutations in protein O-mannosyltransferase 2 (POMT2) (MIM#607439) have been identified in severe congenital muscular dystrophy such as Walker-Warburg syndrome (WWS) and milder limb-girdle muscular dystrophy type 2N (LGMD2N). The aim of this study is to investigate the genetic causes in patients with LGMD2N. METHODS Three patients diagnosed with mild limb-girdle muscular dystrophy were recruited. The genetically pathogenic variant was identified by clinical exome sequencing, and healthy controls were verified by Sanger sequencing. RESULTS Novel compound heterozygous mutations c.800A > G and c.1074_1075delinsAT of POMT2 were revealed in one affected individual by clinical exome sequencing. There was no report of these two variants and predicted to be highly damaging to the function of the POMT2. CONCLUSION The novel variants extend the spectrum of POMT2 mutations, which promotes the prognostic value of testing for POMT2 mutations in patients with LGMD2N.
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Affiliation(s)
- Xiangyu Zhao
- Department of Clinical Laboratory, Linyi People's Hospital, Shandong University, Linyi, China
| | - Chunhai Gao
- Department of Clinical Laboratory, Linyi People's Hospital, Shandong University, Linyi, China
| | - Lin Li
- Department of Clinical Laboratory, Linyi People's Hospital, Shandong University, Linyi, China
| | - Liangqian Jiang
- Department of Clinical Laboratory, Linyi People's Hospital, Shandong University, Linyi, China
| | - Yuda Wei
- Department of Clinical Laboratory, Linyi People's Hospital, Shandong University, Linyi, China
| | - Fengyuan Che
- Department of Central Laboratory, Linyi People's Hospital, Shandong University, Linyi, China.,Department of Neurology, Linyi People's Hospital, Shandong University, Linyi, China
| | - Qiji Liu
- Key Laboratory for Experimental Teratology of the Ministry of Education, Department of Medical Genetics, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, China
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Chen XY, Song DY, Jiang L, Tan DD, Liu YD, Liu JY, Chang XZ, Xing GG, Toda T, Xiong H. Phenotype and Genotype Study of Chinese POMT2-Related α-Dystroglycanopathy. Front Genet 2021; 12:692479. [PMID: 34413876 PMCID: PMC8370027 DOI: 10.3389/fgene.2021.692479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 07/09/2021] [Indexed: 11/25/2022] Open
Abstract
Objective Alpha-dystroglycanopathy (α-DGP) is a subtype of muscular dystrophy caused by defects in the posttranslational glycosylation of α-dystroglycan (α-DG). Our study aimed to summarize the clinical and genetic features of POMT2-related α-DGP in a cohort of patients in China. Methods Pedigrees, clinical data, and laboratory tests of patients diagnosed with POMT2-related α-DGP were analyzed retrospectively. The pathogenicity of variants in POMT2 were predicted by bioinformatics software. The variants with uncertain significance were verified by further analysis. Results The 11 patients, comprising eight males and three females, were from nine non-consanguineous families. They exhibited different degrees of muscle weakness, ambulation, and intellectual impairment. Among them, three had a muscle-eye-brain disease (MEB)-like phenotype, five presented congenital muscular dystrophy with intellectual disability (CMD-ID), and three presented limb-girdle muscular dystrophy (LGMD). Overall, nine novel variants of POMT2, including two non-sense, one frameshift and six missense variants, were identified. The pathogenicity of two missense variants, c.1891G > C and c.874G > C, was uncertain based on bioinformatics software prediction. In vitro minigene analysis showed that c.1891G > C affects the splicing of POMT2. Immunofluorescence staining with the IIH6C4 antibody of muscle biopsy from the patient carrying the c.874G > C variant showed an apparent lack of expression. Conclusion This study summarizes the clinical and genetic characteristics of a cohort of POMT2-related α-DGP patients in China for the first time, expanding the mutational spectrum of the disease. Further study of the pathogenicity of some missense variants based on enzyme activity detection is needed.
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Affiliation(s)
- Xiao-Yu Chen
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Dan-Yu Song
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Li Jiang
- Department of Neurology, Children's Hospital of Chongqing Medical University, Chongqing, China
| | - Dan-Dan Tan
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Yi-Dan Liu
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Jie-Yu Liu
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Xing-Zhi Chang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Guo-Gang Xing
- Department of Neurobiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, China
| | - Tatsushi Toda
- Department of Neurology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Hui Xiong
- Department of Pediatrics, Peking University First Hospital, Beijing, China
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Abstract
Dystroglycan (DG) is a major cell membrane glycoprotein, which is encoded by the DAG1 gene. α-DG is one of DG subunits, belongs to O-mannosylated protein of mammals and was identified in brain, peripheral nerves and muscle. Dystroglycanopathies are a group of heterogeneous congenital muscular dystrophies, which can result from defective α-DG mannosylation. First line of α-DG glycosylation is catalyzed by protein O-mannosyltransferase family (PMT). In this study, the mutation was identified in the POMT2 gene, which encodes O-mannosyltransferase 2 protein and its mutations can be contributed to dystroglycanopathies. A very rare missense mutation in the POMT2 gene (NM_013382: exon9: c. 1106G>A) was identified by next generation sequencing (NGS) and was subsequently confirmed using Sanger sequencing in both affected siblings. There was no report of this mutation in the literature, therefore, the significance was uncertain. Our findings confirmed the pathogenicity of mutation and expanded the mutation spectrum of POMT2, which will be helpful in further molecular evaluations of muscular diseases.
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Affiliation(s)
- Ghazale Mahjoub
- Persian BayanGene Research and Training Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Mohammad Ali Faghihi
- Persian BayanGene Research and Training Center, Shiraz University of Medical Sciences, Shiraz, Iran
- Center for Therapeutic Innovation, Department of Psychiatry and Behavioral Sciences, University of Miami Miller School of Medicine, Miami, USA
| | - Maryam Taghdiri
- Genetic Counseling Center, Shiraz Welfare Organization, Shiraz, Iran
- Comprehensive Medical Genetic Center, Shiraz University of Medical Sciences, Shiraz, Iran
- Address correspondence to:Maryam Taghdiri, Genetic Counseling Center, Shiraz Welfare Organization, Shiraz, Iran and Comprehensive Medical Genetic Center, Shiraz University of Medical Sciences, Shiraz, Iran. E-mail:
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Brun BN, Willer T, Darbro BW, Gonorazky HD, Naumenko S, Dowling JJ, Campbell KP, Moore SA, Mathews KD. Uniparental disomy unveils a novel recessive mutation in POMT2. Neuromuscul Disord 2018; 28:592-6. [PMID: 29759639 DOI: 10.1016/j.nmd.2018.04.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2018] [Revised: 03/24/2018] [Accepted: 04/04/2018] [Indexed: 01/05/2023]
Abstract
Mutations in POMT2 are most commonly associated with Walker-Warburg syndrome and Muscle-Eye-Brain disease, but can also cause limb girdle muscular dystrophy (LGMD2N). We report a case of LGMD due to a novel mutation in POMT2 unmasked by uniparental isodisomy. The patient experienced proximal muscle weakness from three years of age with minimal progression. She developed progressive contractures and underwent unilateral Achilles tenotomy. By age 11, she had borderline low left ventricular ejection fraction and mild restrictive lung disease. Muscle biopsy showed mild dystrophic changes with selective reduction in α-dystroglycan immunostaining. Sequencing of POMT2 showed a novel homozygous c.1502A>C variant that was predicted to be probably pathogenic. Fibroblast complementation studies showed lack of functional glycosylation rescued by wild-type POMT2 expression. Chromosomal microarray showed a single 15 Mb copy number neutral loss of heterozygosity on chromosome 14 encompassing POMT2. RNAseq verified homozygosity at this locus. Together, our findings indicate maternal uniparental isodisomy causing LGMD2N.
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Saredi S, Gibertini S, Ardissone A, Fusco I, Zanotti S, Blasevich F, Morandi L, Moroni I, Mora M. A fourth case of POMT2-related limb girdle muscle dystrophy with mild reduction of α-dystroglycan glycosylation. Eur J Paediatr Neurol 2014; 18:404-8. [PMID: 24183756 DOI: 10.1016/j.ejpn.2013.10.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 10/17/2013] [Accepted: 10/17/2013] [Indexed: 02/07/2023]
Abstract
BACKGROUND POMT2 mutations have been identified in Walker-Warburg syndrome or muscle-eye-brain-like, but rarely in limb girdle muscular dystrophy (LGMD). RESULTS Two POMT2 mutations, one null and one missense, were found in a patient with LGMD and mild mental impairment, no brain or ocular involvement, minor histopathological features, and slight reduction of α-dystroglycan (α-DG) glycosylation and α-DG laminin binding. CONCLUSIONS Our case, the fourth LGMD POMT2-mutated reported to date, provides further evidence of correlation between level of α-DG glycosylation and phenotype severity.
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Hafner P, Bonati U, Fischmann A, Schneider J, Frank S, Morris-Rosendahl DJ, Dumea A, Heinimann K, Fischer D. Skeletal muscle MRI of the lower limbs in congenital muscular dystrophy patients with novel POMT1 and POMT2 mutations. Neuromuscul Disord 2014; 24:321-4. [PMID: 24556424 DOI: 10.1016/j.nmd.2014.01.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Revised: 01/06/2014] [Accepted: 01/20/2014] [Indexed: 12/20/2022]
Abstract
Alpha-dystroglycanopathies form a genetically heterogeneous group of congenital muscular dystrophies with a large variety of clinical phenotypes. Within this group mutations in the protein O-mannosyltransferase genes (POMT1 and POMT2) are known to cause a spectrum of CMD disorders including the Walker-Warburg Syndrome with severe brain and ocular malformations, and the limb girdle muscular dystrophy with and without mental retardation. In this case report the clinical phenotype and brain and muscle MRI findings of two siblings of 10 and 7years (male/female) homozygous for a novel mutation in the POMT1 gene (c.2220G>C, p.Trp740Cys) and a 10year old boy with two novel mutations in the POMT2 gene ((c.215G>A, p.Arg72His) and (c.713G>T, p.Gly238Val) are presented. Mutation detection was performed by direct sequencing of the FKRP, FKTN, POMT1 and POMT2 genes. T1-weighted axial muscle MRI of the lower limbs revealed diffuse fatty degeneration of thigh and calf muscles with predominance of gluteus maximus, adductor magnus, posterior thigh, medial gastrocnemius, and peroneus muscles, but no edematous changes. As a similar pattern of muscle involvement had been described in FKRP related α-dystroglycanopathy LGMD2I, we conclude that α-dystroglycanopathies may present with distinctive muscle MRI changes.
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Affiliation(s)
- Patricia Hafner
- Division of Neuropaediatrics, University of Basel Children's Hospital, Switzerland; Department of Neurology, University of Basel Hospital, Switzerland
| | - Ulrike Bonati
- Division of Neuropaediatrics, University of Basel Children's Hospital, Switzerland; Department of Neurology, University of Basel Hospital, Switzerland.
| | - Arne Fischmann
- Department of Radiology, Division of Neuroradiology, University of Basel Hospital, Switzerland
| | - Jacques Schneider
- Department of Radiology, University of Basel Children's Hospital, Switzerland
| | - Stephan Frank
- Division of Neuropathology, Institute of Pathology, University of Basel Hospital, Switzerland
| | | | - Anamaria Dumea
- Institute for Medical Genetics, University of Basel Children's Hospital, Switzerland
| | - Karl Heinimann
- Institute for Medical Genetics, University of Basel Children's Hospital, Switzerland
| | - Dirk Fischer
- Division of Neuropaediatrics, University of Basel Children's Hospital, Switzerland; Department of Neurology, University of Basel Hospital, Switzerland.
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Lommel M, Winterhalter PR, Willer T, Dahlhoff M, Schneider MR, Bartels MF, Renner-Müller I, Ruppert T, Wolf E, Strahl S. Protein O-mannosylation is crucial for E-cadherin-mediated cell adhesion. Proc Natl Acad Sci U S A 2013; 110:21024-9. [PMID: 24297939 DOI: 10.1073/pnas.1316753110] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In recent years protein O-mannosylation has become a focus of attention as a pathomechanism underlying severe congenital muscular dystrophies associated with neuronal migration defects. A key feature of these disorders is the lack of O-mannosyl glycans on α-dystroglycan, resulting in abnormal basement membrane formation. Additional functions of O-mannosylation are still largely unknown. Here, we identify the essential cell-cell adhesion glycoprotein epithelial (E)-cadherin as an O-mannosylated protein and establish a functional link between O-mannosyl glycans and cadherin-mediated cell-cell adhesion. By genetically and pharmacologically blocking protein O-mannosyltransferases, we found that this posttranslational modification is essential for preimplantation development of the mouse embryo. O-mannosylation-deficient embryos failed to proceed from the morula to the blastocyst stage because of defects in the molecular architecture of cell-cell contact sites, including the adherens and tight junctions. Using mass spectrometry, we demonstrate that O-mannosyl glycans are present on E-cadherin, the major cell-adhesion molecule of blastomeres, and present evidence that this modification is generally conserved in cadherins. Further, the use of newly raised antibodies specific for an O-mannosyl-conjugated epitope revealed that these glycans are present on early mouse embryos. Finally, our cell-aggregation assays demonstrated that O-mannosyl glycans are crucial for cadherin-based cell adhesion. Our results redefine the significance of O-mannosylation in humans and other mammals, showing the immense impact of cadherins on normal as well as pathogenic cell behavior.
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Rosenthal SL, Wang X, Demirci FY, Barmada MM, Ganguli M, Lopez OL, Kamboh MI. Beta-amyloid toxicity modifier genes and the risk of Alzheimer's disease. Am J Neurodegener Dis 2012; 1:191-198. [PMID: 22984654 PMCID: PMC3560458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Accepted: 08/10/2012] [Indexed: 06/01/2023]
Abstract
Late-onset Alzheimer's disease (LOAD) is a complex and multifactorial disease. So far ten loci have been identified for LOAD, including APOE, PICALM, CLU, BIN1, CD2AP, CR1, CD33, EPHA1, ABCA7, and MS4A4A/MS4A6E, but they explain about 50% of the genetic risk and thus additional risk genes need to be identified. Amyloid beta (Aβ) plaques develop in the brains of LOAD patients and are considered to be a pathological hallmark of this disease. Recently 12 new Aβ toxicity modifier genes (ADSSL1, PICALM, SH3KBP1, XRN1, SNX8, PPP2R5C, FBXL2, MAP2K4, SYNJ1, RABGEF1, POMT2, and XPO1) have been identified that potentially play a role in LOAD risk. In this study, we have examined the association of 222 SNPs in these 12 candidate genes with LOAD risk in 1291 LOAD cases and 958 cognitively normal controls. Single site and haplotype analyses were performed using PLINK. Following adjustment for APOE genotype, age, sex, and principal components, we found single nucleotide polymorphisms (SNPs) in PPP2R5C, PICALM, SH3KBP1, XRN1, and SNX8 that showed significant association with risk of LOAD. The top SNP was located in intron 3 of PPP2R5C (P=0.009017), followed by an intron 19 SNP in PICALM (P=0.0102). Haplotype analysis revealed significant associations in ADSSL1, PICALM, PPP2R5C, SNX8, and SH3KBP1 genes. Our data indicate that genetic variation in these new candidate genes affects the risk of LOAD. Further investigation of these genes, including additional replication in other case-control samples and functional studies to elucidate the pathways by which they affect Aβ, are necessary to determine the degree of involvement these genes have for LOAD risk.
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