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Ben Ayed I, Jallouli O, Murakami Y, Souissi A, Mallouli S, Bouzid A, Kamoun F, Elloumi I, Frikha F, Tlili A, Weckhuysen S, Kinoshita T, Triki CC, Masmoudi S. Case report: Functional analysis of the p.Arg507Trp variant of the PIGT gene supporting the moderate epilepsy phenotype of mutations in the C-terminal region. Front Neurol 2023; 14:1092887. [PMID: 36970549 PMCID: PMC10034188 DOI: 10.3389/fneur.2023.1092887] [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] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 02/01/2023] [Indexed: 03/29/2023] Open
Abstract
Pathogenic germline variants in the PIGT gene are associated with the "multiple congenital anomalies-hypotonia-seizures syndrome 3" (MCAHS3) phenotype. So far, fifty patients have been reported, most of whom suffer from intractable epilepsy. Recently, a comprehensive analysis of a cohort of 26 patients with PIGT variants has broadened the phenotypical spectrum and indicated that both p.Asn527Ser and p.Val528Met are associated with a milder epilepsy phenotype and less severe outcomes. Since all reported patients are of Caucasian/Polish origin and most harbor the same variant (p.Val528Met), the ability to draw definitive conclusions regarding the genotype-phenotype correlation remains limited. We report a new case with a homozygous variant p.Arg507Trp in the PIGT gene, detected on clinical exome sequencing. The North African patient in question displays a predominantly neurological phenotype with global developmental delay, hypotonia, brain abnormalities, and well-controlled epileptic seizures. Homozygous and heterozygous variants in codon 507 have been reported to cause PIGT deficiency without biochemical confirmation. In this study, FACS analysis of knockout HEK293 cells that had been transfected with wild-type or mutant cDNA constructs demonstrated that the p.Arg507Trp variant leads to mildly reduced activity. Our result confirm the pathogenicity of this variant and strengthen recently reported evidence on the genotype-phenotype correlation of the PIGT variant.
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Affiliation(s)
- Ikhlas Ben Ayed
- Laboratory of Molecular and Cellular Screening Processes (LPCMC), Center of Biotechnology of Sfax, University of Sfax, Sfax, Tunisia
- Medical Genetics Department, University Hedi Chaker Hospital of Sfax, Sfax, Tunisia
| | - Olfa Jallouli
- Child Neurology Department, University Hedi Chaker Hospital of Sfax, Sfax, Tunisia
- Research Laboratory “Neuropédiatrie” LR19ES15, Sfax University, Sfax, Tunisia
| | - Yoshiko Murakami
- Laboratory of Immunoglycobiology, Research Institute for Microbial Diseases, Osaka University, Suita, Japan
| | - Amal Souissi
- Laboratory of Molecular and Cellular Screening Processes (LPCMC), Center of Biotechnology of Sfax, University of Sfax, Sfax, Tunisia
| | - Salma Mallouli
- Child Neurology Department, University Hedi Chaker Hospital of Sfax, Sfax, Tunisia
- Research Laboratory “Neuropédiatrie” LR19ES15, Sfax University, Sfax, Tunisia
| | - Amal Bouzid
- Laboratory of Molecular and Cellular Screening Processes (LPCMC), Center of Biotechnology of Sfax, University of Sfax, Sfax, Tunisia
| | - Fatma Kamoun
- Child Neurology Department, University Hedi Chaker Hospital of Sfax, Sfax, Tunisia
- Research Laboratory “Neuropédiatrie” LR19ES15, Sfax University, Sfax, Tunisia
| | - Ines Elloumi
- Laboratory of Molecular and Cellular Screening Processes (LPCMC), Center of Biotechnology of Sfax, University of Sfax, Sfax, Tunisia
| | - Fakher Frikha
- Laboratory of Molecular and Cellular Screening Processes (LPCMC), Center of Biotechnology of Sfax, University of Sfax, Sfax, Tunisia
| | - Abdelaziz Tlili
- Department of Applied Biology, College of Sciences, University of Sharjah, Sharjah, United Arab Emirates
- Human Genetics and Stem Cell Laboratory, Research Institute of Sciences and Engineering, University of Sharjah, Sharjah, United Arab Emirates
| | | | - Taroh Kinoshita
- Laboratory of Immunoglycobiology, Research Institute for Microbial Diseases, Osaka University, Suita, Japan
- Center for Infectious Disease Education and Research, Osaka University, Suita, Japan
| | - Chahnez Charfi Triki
- Child Neurology Department, University Hedi Chaker Hospital of Sfax, Sfax, Tunisia
- Research Laboratory “Neuropédiatrie” LR19ES15, Sfax University, Sfax, Tunisia
| | - Saber Masmoudi
- Laboratory of Molecular and Cellular Screening Processes (LPCMC), Center of Biotechnology of Sfax, University of Sfax, Sfax, Tunisia
- *Correspondence: Saber Masmoudi
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Jezela-Stanek A, Szczepanik E, Mierzewska H, Rydzanicz M, Rutkowska K, Knaus A, Śmigiel R, Stępniak I, Markiewicz MG, Boniel S, Krawitz P, Płoski R. Evidence of the milder phenotypic spectrum of c.1582G>A PIGT variant: Delineation based on seven novel Polish patients. Clin Genet 2021; 98:468-476. [PMID: 32725661 DOI: 10.1111/cge.13822] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [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: 06/18/2020] [Revised: 07/21/2020] [Accepted: 07/23/2020] [Indexed: 11/29/2022]
Abstract
PIGT is one of over 29 glycosylphosphatidylinositol biosynthesis defect genes. Mutations cause genetically determined disorders characterized mainly by epilepsy with fever-sensitivity, central hypotonia, psychomotor delay and congenital malformations. The disease is known as multiple congenital anomalies-hypotonia-seizures syndrome 3 (MCAHS3) or glycosylphosphatidylinositol biosynthesis defect-7. Twenty-eight cases have been reported until today. We present seven novel Polish patients, all harboring 1582G>A variant in a homozygous or compound heterozygous state which seems to cause a milder phenotype of the disease.
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Affiliation(s)
- Aleksandra Jezela-Stanek
- Department of Genetics and Clinical Immunology, National Institute of Tuberculosis and Lung Diseases, Warsaw, Poland
| | - Elżbieta Szczepanik
- Clinic of Pediatric Neurology, Institute of Mother and Child, Warsaw, Poland
| | - Hanna Mierzewska
- Clinic of Pediatric Neurology, Institute of Mother and Child, Warsaw, Poland
| | | | - Karolina Rutkowska
- Department of Medical Genetics, Medical University of Warsaw, Warsaw, Poland
| | - Alexej Knaus
- Institute for Genomic Statistics and Bioinformatics, University Hospital Bonn, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| | - Robert Śmigiel
- Department of Pediatrics, Division Pediatric Propedeutics and Rare Disorders, Wroclaw Medical University, Wroclaw, Poland
| | - Iwona Stępniak
- Department of Genetics, Institute of Psychiatry and Neurology, Warsaw, Poland
| | - Michał G Markiewicz
- First Department of Neurology, Institute of Psychiatry and Neurology, Warsaw, Poland
| | - Snir Boniel
- Department of Medical Genetics, Medical University of Warsaw, Warsaw, Poland
| | - Peter Krawitz
- Institute for Genomic Statistics and Bioinformatics, University Hospital Bonn, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| | - Rafał Płoski
- Department of Medical Genetics, Medical University of Warsaw, Warsaw, Poland
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