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Ren Y, Luo X, Tong H, Wang S, Yan J, Lin L, Chen Y. Preliminary Study on Clinical Characteristics and Pathogenesis of IQSEC2 Mutations Patients. Pharmgenomics Pers Med 2024; 17:289-318. [PMID: 38827181 PMCID: PMC11144418 DOI: 10.2147/pgpm.s455840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Accepted: 05/18/2024] [Indexed: 06/04/2024] Open
Abstract
Background The IQ motif and Sec7 domain ArfGEF 2 (IQSEC2), an X-linked gene that encodes the BRAG1 protein, is a guanine nucleotide exchange factor for the ADP ribosylation factor (ARF) protein family in the small guanosine triphosphate (GTP) binding protein. Mutations in this gene result in disorders such as intellectual disability (ID) and epilepsy. In this study, we analyze the clinical features of two patients with IQSEC2-mutation-related disease and discuss their possible pathogenesis. Methods The two patients were diagnosed with ID and epilepsy. Genetic testing was performed using whole-exome sequencing, and the three-dimensional protein structure was analyzed. UCSC Genome Browser was used to analyze the conservation of IQSEC2 in different species. We compared IQSEC2 expression in the proband families with that in a control group, as well as the expression of the postsynaptic identity protein 95 (PSD-95), synapse-associated protein 97 (SAP97), ADP ribosylation factor 6 (ARF-6), and insulin receptor substrate 53kDa (IRSP53) genes interacting with IQSEC2. Results We identified two semi-zygote mutations located in conserved positions in different species: an unreported de novo mutation, C.3576C>A (p. Tyr1192*), and a known mutation, c.2983C>T (p. Arg995Trp). IQSEC2 mutations resulted in significant changes in the predicted three-dimensional protein structure, while its expression in the two probands was significantly lower than that in the age-matched control group, and IQSEC2 expression in proband 1 was lower than that in his family members. The expression levels of PSD-95, ARF-6, and SAP97, IRSP 53, which interact with IQSEC2, were also significantly different from those in the family members and age-matched healthy children. Conclusion The clinical phenotype resulting from IQSEC2 mutations can be explained by the significant decrease in its expression, loss of function of the mutant protein, and change in the expression of related genes. Our results provide novel insights into the molecular phenotype conferred by the IQSEC2 variants.
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Affiliation(s)
- Yun Ren
- Department of Neurology, Shanghai Children’s Hospital, School of Medicine, Shanghai JiaoTong University, Shanghai, People’s Republic of China
| | - Xiaona Luo
- Department of Neurology, Shanghai Children’s Hospital, School of Medicine, Shanghai JiaoTong University, Shanghai, People’s Republic of China
| | - Haiyan Tong
- Department of Neurology, Shanghai Children’s Hospital, School of Medicine, Shanghai JiaoTong University, Shanghai, People’s Republic of China
| | - Simei Wang
- Department of Neurology, Shanghai Children’s Hospital, School of Medicine, Shanghai JiaoTong University, Shanghai, People’s Republic of China
| | - Jinbin Yan
- Department of Neurology, Shanghai Children’s Hospital, School of Medicine, Shanghai JiaoTong University, Shanghai, People’s Republic of China
| | - Longlong Lin
- Department of Neurology, Shanghai Children’s Hospital, School of Medicine, Shanghai JiaoTong University, Shanghai, People’s Republic of China
| | - Yucai Chen
- Department of Neurology, Shanghai Children’s Hospital, School of Medicine, Shanghai JiaoTong University, Shanghai, People’s Republic of China
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Nakashima M, Shiroshima T, Fukaya M, Sugawara T, Sakagami H, Yamazawa K. C-terminal truncations in IQSEC2: implications for synaptic localization, guanine nucleotide exchange factor activity, and neurological manifestations. J Hum Genet 2024; 69:119-123. [PMID: 38200111 DOI: 10.1038/s10038-023-01210-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Revised: 11/29/2023] [Accepted: 11/30/2023] [Indexed: 01/12/2024]
Abstract
IQSEC2 gene on chromosome Xq11.22 encodes a member of guanine nucleotide exchange factor (GEF) protein that is implicated in the activation of ADP-ribosylation factors (Arfs) at the postsynaptic density (PSD), and plays a crucial role in synaptic transmission and dendritic spine formation. Alterations in IQSEC2 have been linked to X-linked intellectual developmental disorders including epilepsy and behavioral abnormalities. Of interest, truncating variants at the C-terminus of IQSEC2 can cause severe phenotypes, akin to truncating variants located in other regions. Here, we present a 5-year-old boy with severe intellectual disability and progressive epilepsy. The individual carried a nonsense variant p.Q1227* in the last exon of the IQSEC2 gene that was supposed to escape nonsense-mediated mRNA decay, thereby leading to a translation of C-terminus truncated IQSEC2 protein with residual activity. The functional analyses showed that the GEF activity of IQSEC2 Q1227* was compromised, and that the IQSEC2 Q1227* lacked preferential synaptic localization due to the absence of functional domains for binding to scaffolding proteins in the PSD. The impaired GEF activity and disrupted synaptic localization of the mutant IQSEC2 protein could impact dendritic and spine development in neurons, potentially explaining the patient's severe neurological manifestations. Our findings indicate that C-terminal truncations in IQSEC2, previously not well-characterized, may have significant pathogenic implications.
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Affiliation(s)
- Moeko Nakashima
- Department of Medical Genetics, NHO Tokyo Medical Center, Tokyo, 152-8902, Japan
| | - Tomoko Shiroshima
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, 252-0374, Japan
| | - Masahiro Fukaya
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, 252-0374, Japan
| | - Takeyuki Sugawara
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, 252-0374, Japan
| | - Hiroyuki Sakagami
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, 252-0374, Japan.
| | - Kazuki Yamazawa
- Department of Medical Genetics, NHO Tokyo Medical Center, Tokyo, 152-8902, Japan.
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Shokhen M, Walikonis R, Uversky VN, Allbeck A, Zezelic C, Feldman D, Levy NS, Levy AP. Molecular modeling of ARF6 dysregulation caused by mutations in IQSEC2. J Biomol Struct Dyn 2024; 42:1268-1279. [PMID: 37078745 DOI: 10.1080/07391102.2023.2199085] [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: 12/10/2022] [Accepted: 03/29/2023] [Indexed: 04/21/2023]
Abstract
IQSEC2 gene mutations are associated with epilepsy, autism, and intellectual disability. The primary function IQSEC2, mediated via its Sec 7 domain, is to act as a guanine nucleotide exchange factor for ARF6. We sought to develop a molecular model, which may explain the aberrant Sec 7 activity on ARF6 of different human IQSEC2 mutations. We integrated experimental data of IQSEC2 mutants with protein structure prediction by the RaptorX server combined with molecular modeling and molecular dynamics simulations. Normally, apocalmodulin (apoCM) binds to IQSEC2 resulting in its N-terminal fragment inhibiting access of its Sec 7 domain to ARF6. An increase in Ca2+ concentration destabilizes the interaction of IQSEC2 with apoCM and removes steric hindrance of Sec 7 binding with ARF6. Mutations at amino acid residue 350 of IQSEC2 result in loss of steric hindrance of Sec 7 binding with ARF6 leading to constitutive activation of ARF6 by Sec 7. On the other hand, a mutation at amino acid residue 359 of IQSEC2 results in constitutive hindrance of Sec 7 binding to ARF6 leading to the loss of the ability of IQSEC2 to activate ARF6. These studies provide a model for dysregulation of IQSEC2 Sec 7 activity by mutant IQSEC2 proteins.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Michael Shokhen
- Department of Chemistry, Bar Ilan University, Ramat Gan, Israel
| | - Randall Walikonis
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, USA
| | - Vladimir N Uversky
- Department of Molecular Medicine and Byrd Alzheimer's Center and Research Institute, University of South Florida, Tampa, Florida, USA
| | - Amnon Allbeck
- Department of Chemistry, Bar Ilan University, Ramat Gan, Israel
| | - Camryn Zezelic
- Technion Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Danielle Feldman
- Technion Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Nina S Levy
- Technion Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Andrew P Levy
- Technion Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
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Bai G, Li H, Qin P, Guo Y, Yang W, Lian Y, Ye F, Chen J, Wu M, Huang R, Li J, Lu Y, Zhang M. Ca2+-induced release of IQSEC2/BRAG1 autoinhibition under physiological and pathological conditions. J Cell Biol 2023; 222:e202307117. [PMID: 37787765 PMCID: PMC10548395 DOI: 10.1083/jcb.202307117] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 08/31/2023] [Accepted: 09/14/2023] [Indexed: 10/04/2023] Open
Abstract
IQSEC2 (aka BRAG1) is a guanine nucleotide exchange factor (GEF) highly enriched in synapses. As a top neurodevelopmental disorder risk gene, numerous mutations are identified in Iqsec2 in patients with intellectual disabilities accompanied by other developmental, neurological, and psychiatric symptoms, though with poorly understood underlying molecular mechanisms. The atomic structures of IQSECs, together with biochemical analysis, presented in this study reveal an autoinhibition and Ca2+-dependent allosteric activation mechanism for all IQSECs and rationalize how each identified Iqsec2 mutation can alter the structure and function of the enzyme. Transgenic mice modeling two pathogenic variants of Iqsec2 (R359C and Q801P), with one activating and the other inhibiting the GEF activity of the enzyme, recapitulate distinct clinical phenotypes in patients. Our study demonstrates that different mutations on one gene such as Iqsec2 can have distinct neurological phenotypes and accordingly will require different therapeutic strategies.
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Affiliation(s)
- Guanhua Bai
- School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Kowloon, China
| | - Hao Li
- Department of Pathophysiology, School of Basic Medicine and Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- The Institute for Brain Research, Collaborative Innovation Center for Brain Science, Huazhong University of Science and Technology, Wuhan, China
| | - Pengwei Qin
- Department of Pathophysiology, School of Basic Medicine and Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- The Institute for Brain Research, Collaborative Innovation Center for Brain Science, Huazhong University of Science and Technology, Wuhan, China
| | - Yiqing Guo
- Department of Pathophysiology, School of Basic Medicine and Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- The Institute for Brain Research, Collaborative Innovation Center for Brain Science, Huazhong University of Science and Technology, Wuhan, China
| | - Wanfa Yang
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Kowloon, China
| | - Yinmiao Lian
- Department of Pathophysiology, School of Basic Medicine and Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- The Institute for Brain Research, Collaborative Innovation Center for Brain Science, Huazhong University of Science and Technology, Wuhan, China
| | - Fei Ye
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Kowloon, China
| | - Jianxin Chen
- State Key Laboratory of Cell Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China
- School of Life Science and Technology, Shanghai Tech University, Shanghai, China
| | - Meiling Wu
- School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
| | - Ruifeng Huang
- School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
| | - Jinsong Li
- State Key Laboratory of Cell Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China
- School of Life Science and Technology, Shanghai Tech University, Shanghai, China
| | - Youming Lu
- Department of Pathophysiology, School of Basic Medicine and Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- The Institute for Brain Research, Collaborative Innovation Center for Brain Science, Huazhong University of Science and Technology, Wuhan, China
| | - Mingjie Zhang
- School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Kowloon, China
- Greater Bay Biomedical Innocenter, Shenzhen Bay Laboratory, Shenzhen, China
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Leoncini S, Boasiako L, Lopergolo D, Altamura M, Fazzi C, Canitano R, Grosso S, Meloni I, Baldassarri M, Croci S, Renieri A, Mastrangelo M, De Felice C. Natural Course of IQSEC2-Related Encephalopathy: An Italian National Structured Survey. CHILDREN (BASEL, SWITZERLAND) 2023; 10:1442. [PMID: 37761403 PMCID: PMC10528631 DOI: 10.3390/children10091442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 08/16/2023] [Accepted: 08/22/2023] [Indexed: 09/29/2023]
Abstract
Pathogenic loss-of-function variants in the IQ motif and SEC7 domain containing protein 2 (IQSEC2) gene cause intellectual disability with Rett syndrome (RTT)-like features. The aim of this study was to obtain systematic information on the natural history and extra-central nervous system (CNS) manifestations for the Italian IQSEC2 population (>90%) by using structured family interviews and semi-quantitative questionnaires. IQSEC2 encephalopathy prevalence estimate was 7.0 to 7.9 × 10-7. Criteria for typical RTT were met in 42.1% of the cases, although psychomotor regression was occasionally evidenced. Genetic diagnosis was occasionally achieved in infancy despite a clinical onset before the first 24 months of life. High severity in both the CNS and extra-CNS manifestations for the IQSEC2 patients was documented and related to a consistently adverse quality of life. Neurodevelopmental delay was diagnosed before the onset of epilepsy by 1.8 to 2.4 years. An earlier age at menarche in IQSEC2 female patients was reported. Sleep disturbance was highly prevalent (60 to 77.8%), with mandatory co-sleeping behavior (50% of the female patients) being related to de novo variant origin, younger age, taller height with underweight, better social interaction, and lower life quality impact for the family and friends area. In conclusion, the IQSEC2 encephalopathy is a rare and likely underdiagnosed developmental encephalopathy leading to an adverse life quality impact.
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Affiliation(s)
- Silvia Leoncini
- Neonatal Intensive Care Unit, Department of Women’s and Children’s Health, University Hospital Azienda Ospedaliera Universitaria Senese, 53100 Siena, Italy; (S.L.); (L.B.); (M.A.); (C.F.)
- Rett Syndrome Trial Center, University Hospital Azienda Ospedaliera Universitaria Senese, 53100 Siena, Italy
| | - Lidia Boasiako
- Neonatal Intensive Care Unit, Department of Women’s and Children’s Health, University Hospital Azienda Ospedaliera Universitaria Senese, 53100 Siena, Italy; (S.L.); (L.B.); (M.A.); (C.F.)
- Rett Syndrome Trial Center, University Hospital Azienda Ospedaliera Universitaria Senese, 53100 Siena, Italy
| | - Diego Lopergolo
- Department of Medicine, Surgery and Neurosciences, University of Siena, 53100 Siena, Italy;
- UOC Neurologia e Malattie Neurometaboliche, Azienda Ospedaliero Universitaria Senese, Policlinico Le Scotte, 53100 Siena, Italy
- IRCCS Stella Maris Foundation, Molecular Medicine for Neurodegenerative and Neuromuscular Diseases Unit, 56018 Pisa, Italy
| | - Maria Altamura
- Neonatal Intensive Care Unit, Department of Women’s and Children’s Health, University Hospital Azienda Ospedaliera Universitaria Senese, 53100 Siena, Italy; (S.L.); (L.B.); (M.A.); (C.F.)
- Rett Syndrome Trial Center, University Hospital Azienda Ospedaliera Universitaria Senese, 53100 Siena, Italy
| | - Caterina Fazzi
- Neonatal Intensive Care Unit, Department of Women’s and Children’s Health, University Hospital Azienda Ospedaliera Universitaria Senese, 53100 Siena, Italy; (S.L.); (L.B.); (M.A.); (C.F.)
- Rett Syndrome Trial Center, University Hospital Azienda Ospedaliera Universitaria Senese, 53100 Siena, Italy
| | - Roberto Canitano
- Child Neuropsychiatry Unit, Department of Mental Health, University Hospital Azienda Ospedaliera Universitaria Senese, 53100 Siena, Italy;
| | - Salvatore Grosso
- Department of Molecular and Developmental Medicine, University of Siena, 53100 Siena, Italy;
- Pediatric Unit, Department of Women’s and Children’s Health, University Hospital Azienda Ospedaliera Universitaria Senese, 53100 Siena, Italy
| | - Ilaria Meloni
- Medical Genetics, University of Siena, 53100 Siena, Italy; (I.M.); (M.B.); (S.C.); (A.R.)
- Med Biotech Hub and Competence Center, Department of Medical Biotechnologies, University of Siena, 53100 Siena, Italy
| | - Margherita Baldassarri
- Medical Genetics, University of Siena, 53100 Siena, Italy; (I.M.); (M.B.); (S.C.); (A.R.)
- Med Biotech Hub and Competence Center, Department of Medical Biotechnologies, University of Siena, 53100 Siena, Italy
- Genetica Medica, Azienda Ospedaliera Universitaria Senese, 53100 Siena, Italy
| | - Susanna Croci
- Medical Genetics, University of Siena, 53100 Siena, Italy; (I.M.); (M.B.); (S.C.); (A.R.)
- Med Biotech Hub and Competence Center, Department of Medical Biotechnologies, University of Siena, 53100 Siena, Italy
| | - Alessandra Renieri
- Medical Genetics, University of Siena, 53100 Siena, Italy; (I.M.); (M.B.); (S.C.); (A.R.)
- Med Biotech Hub and Competence Center, Department of Medical Biotechnologies, University of Siena, 53100 Siena, Italy
- Genetica Medica, Azienda Ospedaliera Universitaria Senese, 53100 Siena, Italy
| | - Mario Mastrangelo
- Maternal Infantile and Urological Sciences Department, Sapienza University of Rome, 00185 Rome, Italy;
- Child Neurology and Psychiatry Unit, Department of Neurosciences and Mental Health, Azienda Ospedaliero-Universitaria Policlinico Umberto I, 00161 Rome, Italy
| | - Claudio De Felice
- Neonatal Intensive Care Unit, Department of Women’s and Children’s Health, University Hospital Azienda Ospedaliera Universitaria Senese, 53100 Siena, Italy; (S.L.); (L.B.); (M.A.); (C.F.)
- Rett Syndrome Trial Center, University Hospital Azienda Ospedaliera Universitaria Senese, 53100 Siena, Italy
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Shafique A, Sultan T, Alzahrani F, Hun Seo G, Alkuraya FS, Naz S. Genomic Analysis of Multiplex Consanguineous Families Reveals Causes of Neurodevelopmental Disorders with Epilepsy. Gene 2023:147599. [PMID: 37393059 DOI: 10.1016/j.gene.2023.147599] [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: 03/27/2023] [Revised: 06/12/2023] [Accepted: 06/28/2023] [Indexed: 07/03/2023]
Abstract
INTRODUCTION Neurodevelopmental disorders (NDD) are a diverse group of disorders that affect the development of the nervous system. Epilepsy is a common phenotypic aspect of NDD. METHODS We recruited eight consanguineous families from Pakistan which segregated recessively inherited NDD with epilepsy. Magnetic Resonance imaging (MRI) and Electroencephalogram (EEG) were completed. Exome sequencing was carried out for selected participants from each family. The exome data were analyzed for exonic and splice-site variants that had allele frequencies of less than 0.01 in public databases. RESULTS Clinical investigations determined that developmental delay, intellectual disability and seizures were manifested by most patients in early childhood. EEG findings were abnormal in the participants of four families. MRI revealed demyelination orcerebral atrophic changes in multiple participants. We identified four novel homozygous variants including nonsense andmissense variants in OCLN, ALDH7A1, IQSEC2 and COL3A1, segregating with the phenotypes in the participants of four families. Previously reported homozygous variants of CNTNAP2, TRIT1 and NARS1 were found in individuals from three families. Clinical utility was observed in directing treatment in case of patients with an ALDH7A1 variant which included pyridoxine administration and enabling accurate counseling about the natural history and recurrence risk. CONCLUSION Our results add to the clinical and molecular delineation of very rare NDD with epilepsy. The high success rate of exome sequencing is likely attributable to the expectation of homozygous variants in patients of consanguineous families, and in one case, the availability of positional mapping data that greatly aided the variant prioritization.
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Affiliation(s)
- Anum Shafique
- School of Biological Sciences, University of the Punjab, Lahore, Pakistan.
| | - Tipu Sultan
- Children's Hospital & the Institute of Child Health, Lahore, Pakistan.
| | - Fatema Alzahrani
- Center for Genomic Medicine, Department of Translational Genomics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia.
| | | | - Fowzan S Alkuraya
- Center for Genomic Medicine, Department of Translational Genomics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia.
| | - Sadaf Naz
- School of Biological Sciences, University of the Punjab, Lahore, Pakistan.
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Al Sammarraie SHA, Aprile D, Meloni I, Alessio N, Mari F, Manata M, Lo Rizzo C, Di Bernardo G, Peluso G, Renieri A, Galderisi U. An Example of Neuro-Glial Commitment and Differentiation of Muse Stem Cells Obtained from Patients with IQSEC2-Related Neural Disorder: A Possible New Cell-Based Disease Model. Cells 2023; 12:cells12070977. [PMID: 37048050 PMCID: PMC10093355 DOI: 10.3390/cells12070977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 03/13/2023] [Accepted: 03/21/2023] [Indexed: 04/14/2023] Open
Abstract
Although adult stem cells may be useful for studying tissue-specific diseases, they cannot be used as a general model for investigating human illnesses given their limited differentiation potential. Multilineage-differentiating stress-enduring (Muse) stem cells, a SSEA3(+) cell population isolated from mesenchymal stromal cells, fat, and skin fibroblasts, may be able to overcome that restriction. The Muse cells present in fibroblast cultures obtained from biopsies of patients' skin may be differentiated into cells of interest for analyzing diseases. We isolated Muse stem cells from patients with an intellectual disability (ID) and mutations in the IQSEC2 gene (i.e., BRAG1 gene) and induced in vitro neuroglial differentiation to study cell commitment and the differentiation of neural lineages. The neuroglial differentiation of Muse cells revealed that IQSEC2 mutations may alter the self-renewal and lineage specification of stem cells. We observed a decrease in the percentage of SOX2 (+) neural stem cells and neural progenitors (i.e., SOX2+ and NESTIN+) in cultures obtained from Muse cells with the mutated IQSEC2 gene. The alteration in the number of stem cells and progenitors produced a bias toward the astrocytes' differentiation. Our research demonstrates that Muse stem cells may represent a new cell-based disease model.
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Affiliation(s)
| | - Domenico Aprile
- Department of Experimental Medicine, Luigi Vanvitelli Campania University, 80138 Naples, Italy
| | - Ilaria Meloni
- Department of Medical Biotechnology, University of Siena, 53100 Siena, Italy
| | - Nicola Alessio
- Department of Experimental Medicine, Luigi Vanvitelli Campania University, 80138 Naples, Italy
| | - Francesca Mari
- Department of Medical Biotechnology, University of Siena, 53100 Siena, Italy
| | - Marianna Manata
- Department of Medical Biotechnology, University of Siena, 53100 Siena, Italy
| | - Caterina Lo Rizzo
- Department of Medical Biotechnology, University of Siena, 53100 Siena, Italy
| | - Giovanni Di Bernardo
- Department of Experimental Medicine, Luigi Vanvitelli Campania University, 80138 Naples, Italy
- Sbarro Institute for Cancer Research and Molecular Medicine, Center for Biotechnology, Temple University, Philadelphia, PA 19122, USA
| | | | - Alessandra Renieri
- Department of Medical Biotechnology, University of Siena, 53100 Siena, Italy
| | - Umberto Galderisi
- Department of Experimental Medicine, Luigi Vanvitelli Campania University, 80138 Naples, Italy
- Sbarro Institute for Cancer Research and Molecular Medicine, Center for Biotechnology, Temple University, Philadelphia, PA 19122, USA
- Genome and Stem Cell Center (GENKÖK), Erciyes University, 38280 Kayseri, Turkey
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8
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Molecular Insights into IQSEC2 Disease. Int J Mol Sci 2023; 24:ijms24054984. [PMID: 36902414 PMCID: PMC10003148 DOI: 10.3390/ijms24054984] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 03/02/2023] [Accepted: 03/02/2023] [Indexed: 03/08/2023] Open
Abstract
Recent insights into IQSEC2 disease are summarized in this review as follows: (1) Exome sequencing of IQSEC2 patient DNA has led to the identification of numerous missense mutations that delineate at least six and possibly seven essential functional domains present in the IQSEC2 gene. (2) Experiments using IQSEC2 transgenic and knockout (KO) mouse models have recapitulated the presence of autistic-like behavior and epileptic seizures in affected animals; however, seizure severity and etiology appear to vary considerably between models. (3) Studies in IQSEC2 KO mice reveal that IQSEC2 is involved in inhibitory as well as stimulatory neurotransmission. The overall picture appears to be that mutated or absent IQSEC2 arrests neuronal development, resulting in immature neuronal networks. Subsequent maturation is aberrant, leading to increased inhibition and reduced neuronal transmission. (4) The levels of Arf6-GTP remain constitutively high in IQSEC2 knockout mice despite the absence of IQSEC2 protein, indicating impaired regulation of the Arf6 guanine nucleotide exchange cycle. (5) A new therapy that has been shown to reduce the seizure burden for the IQSEC2 A350V mutation is heat treatment. Induction of the heat shock response may be responsible for this therapeutic effect.
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Daily Brief Heat Therapy Reduces Seizures in A350V IQSEC2 Mice and Is Associated with Correction of AMPA Receptor-Mediated Synaptic Dysfunction. Int J Mol Sci 2023; 24:ijms24043924. [PMID: 36835332 PMCID: PMC9965438 DOI: 10.3390/ijms24043924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 02/12/2023] [Accepted: 02/13/2023] [Indexed: 02/17/2023] Open
Abstract
Purposeful induction of fever for healing, including the treatment of epilepsy, was used over 2000 years ago by Hippocrates. More recently, fever has been demonstrated to rescue behavioral abnormalities in children with autism. However, the mechanism of fever benefit has remained elusive due in large part to the lack of appropriate human disease models recapitulating the fever effect. Pathological mutations in the IQSEC2 gene are frequently seen in children presenting with intellectual disability, autism and epilepsy. We recently described a murine A350V IQSEC2 disease model, which recapitulates important aspects of the human A350V IQSEC2 disease phenotype and the favorable response to a prolonged and sustained rise in body core temperature in a child with the mutation. Our goal has been to use this system to understand the mechanism of fever benefit and then develop drugs that can mimic this effect and reduce IQSEC2-associated morbidity. In this study, we first demonstrate a reduction in seizures in the mouse model following brief periods of heat therapy, similar to what was observed in a child with the mutation. We then show that brief heat therapy is associated with the correction of synaptic dysfunction in neuronal cultures of A350V mice, likely mediated by Arf6-GTP.
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10
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Liu X, Zhang S, Wan L, Zhang X, Wang H, Zhang H, Zhu G, Liang Y, Yan H, Zhang B, Yang G. IQSEC2-related encephalopathy in male children: Novel mutations and phenotypes. Front Mol Neurosci 2022; 15:984776. [PMID: 36267700 PMCID: PMC9577604 DOI: 10.3389/fnmol.2022.984776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Accepted: 08/30/2022] [Indexed: 11/13/2022] Open
Abstract
The isoleucine–glutamine (IQ) motif and Sec7 domain-containing protein 2 (IQSEC2) gene, located at Xp11. 2, are associated with nervous system diseases, such as epilepsy, autism, and intellectual disabilities. Gender-related differences in the severity of phenotype severity have been described previously. Here, we report the details of seven male children with IQSEC2 mutations from different families. During this investigation, we explored the relationship between the genotype and phenotype of IQSEC2 mutations; to do so, we recruited seven children with pathogenic/likely pathogenic IQSEC2 mutations who were diagnosed with global developmental delay and/or epilepsy. Their clinical features were assessed, and Trio-based whole-exome sequencing (trio WES) was conducted in seven pedigrees. A variety of algorithms and computational tools were used to calculate the pathogenicity, protein stability, conservation, side chain properties, and protein-protein interactions of mutated proteins. The seven patients ranged in age from 18 months to 5 years. Among them, six children were found to have both developmental delay and epilepsy, and one child only exhibited developmental delay. Four novel mutations (c.316C > T, c.443_4 44dup, c.3235T > C, and c.1417G > T) were newly reported. Two patients did not have truncated aberrant proteins caused by missense mutations. Still, they did have severe phenotypes, such as early-onset epilepsy in infancy, because the mutations were located in domains like the pleckstrin homology and IQ calmodulin-binding motif domains. The bioinformatics analysis also proved that missense mutations may be located in the functional region, which affects protein stability and is harmful. In summary, severe phenotypes, such as early-onset epilepsy in infancy, occur in male patients with a missense mutation in specific domains (e.g., pleckstrin homology and IQ calmodulin-binding motif domains). Some female individuals with IQSEC2 mutations may be asymptomatic because of the skewed inactivation of the X chromosome.
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Affiliation(s)
- Xinting Liu
- Department of Pediatrics, The First Medical Center, Chinese PLA General Hospital, Beijing, China
- Senior Department of Pediatrics, The Seventh Medical Center of PLA General Hospital, Beijing, China
- Medical School of Chinese PLA, Beijing, China
| | - Shan Zhang
- Medical School of Chinese PLA, Beijing, China
- Fuxing Road Clinic, Jingnan Medical District, Chinese PLA General Hospital, Beijing, China
| | - Lin Wan
- Department of Pediatrics, The First Medical Center, Chinese PLA General Hospital, Beijing, China
- Senior Department of Pediatrics, The Seventh Medical Center of PLA General Hospital, Beijing, China
- Medical School of Chinese PLA, Beijing, China
| | - Xiaoli Zhang
- Department of Pediatrics, The Third Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Haiping Wang
- Department of Pediatric Neurology, Hangzhou Children's Hospital, Hangzhou, China
| | - Hongwei Zhang
- Department of Neurology, Jinan Children's Hospital, Jinan, China
| | - Gang Zhu
- Department of Pediatrics, The First Medical Center, Chinese PLA General Hospital, Beijing, China
- Senior Department of Pediatrics, The Seventh Medical Center of PLA General Hospital, Beijing, China
- Medical School of Chinese PLA, Beijing, China
| | - Yan Liang
- Department of Pediatrics, The First Medical Center, Chinese PLA General Hospital, Beijing, China
- Senior Department of Pediatrics, The Seventh Medical Center of PLA General Hospital, Beijing, China
- Medical School of Chinese PLA, Beijing, China
| | - Huimin Yan
- Department of Pediatrics, The First Medical Center, Chinese PLA General Hospital, Beijing, China
- Senior Department of Pediatrics, The Seventh Medical Center of PLA General Hospital, Beijing, China
- Medical School of Chinese PLA, Beijing, China
| | - Bo Zhang
- Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, United States
- Biostatistics and Research Design Center, Institutional Centers for Clinical and Translational Research, Boston Children's Hospital, Harvard Medical School, Boston, MA, United States
- Bo Zhang
| | - Guang Yang
- Department of Pediatrics, The First Medical Center, Chinese PLA General Hospital, Beijing, China
- Senior Department of Pediatrics, The Seventh Medical Center of PLA General Hospital, Beijing, China
- The Second School of Clinical Medicine, Southern Medical University, Guangzhou, China
- *Correspondence: Guang Yang
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Baladron B, Mielu LM, López-Martín E, Barrero MJ, Lopez L, Alvarado JI, Monzón S, Varona S, Cuesta I, Cazorla R, Lara J, Iglesias G, Román E, Ros P, Gomez-Mariano G, Cubillo I, Miguel EHS, Rivera D, Alonso J, Bermejo-Sánchez E, Posada M, Martínez-Delgado B. Differences in Expression of IQSEC2 Transcript Isoforms in Male and Female Cases with Loss of Function Variants and Neurodevelopmental Disorder. Int J Mol Sci 2022; 23:ijms23169480. [PMID: 36012761 PMCID: PMC9409358 DOI: 10.3390/ijms23169480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 08/18/2022] [Accepted: 08/20/2022] [Indexed: 11/16/2022] Open
Abstract
Pathogenic hemizygous or heterozygous mutations in the IQSEC2 gene cause X-linked intellectual developmental disorder-1 (XLID1), characterized by a variable phenotype including developmental delay, intellectual disability, epilepsy, hypotonia, autism, microcephaly and stereotypies. It affects both males and females typically through loss of function in males and haploinsufficiency in heterozygous females. Females are generally less affected than males. Two novel unrelated cases, one male and one female, with de novo IQSEC2 variants were detected by trio-based whole exome sequencing. The female case had a previously undescribed frameshift mutation (NM_001111125:c.3300dup; p.Met1101Tyrfs*5), and the male showed an intronic variant in intron 6, with a previously unknown effect (NM_001111125:c.2459+21C>T). IQSEC2 gene expression study revealed that this intronic variant created an alternative donor splicing site and an aberrant product, with the inclusion of 19bp, confirming the pathogenic effect of the intron variant. Moreover, a strong reduction in the expression of the long, but also the short IQSEC2 isoforms, was detected in the male correlating with a more severe phenotype, while the female case showed no decreased expression of the short isoform, and milder effects of the disease. This suggests that the abnormal expression levels of the different IQSEC2 transcripts could be implicated in the severity of disease manifestations.
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Affiliation(s)
- Beatriz Baladron
- Instituto de Investigación de Enfermedades Raras (IIER), Instituto de Salud Carlos III (ISCIII), 28220 Madrid, Spain
| | - Lidia M. Mielu
- Instituto de Investigación de Enfermedades Raras (IIER), Instituto de Salud Carlos III (ISCIII), 28220 Madrid, Spain
| | - Estrella López-Martín
- Instituto de Investigación de Enfermedades Raras (IIER), Instituto de Salud Carlos III (ISCIII), 28220 Madrid, Spain
| | - Maria J. Barrero
- Instituto de Investigación de Enfermedades Raras (IIER), Instituto de Salud Carlos III (ISCIII), 28220 Madrid, Spain
| | - Lidia Lopez
- Instituto de Investigación de Enfermedades Raras (IIER), Instituto de Salud Carlos III (ISCIII), 28220 Madrid, Spain
| | - Jose I. Alvarado
- Instituto de Investigación de Enfermedades Raras (IIER), Instituto de Salud Carlos III (ISCIII), 28220 Madrid, Spain
| | - Sara Monzón
- Bioinformatics Unit, Instituto de Salud Carlos III (ISCIII), 28220 Madrid, Spain
| | - Sarai Varona
- Bioinformatics Unit, Instituto de Salud Carlos III (ISCIII), 28220 Madrid, Spain
| | - Isabel Cuesta
- Bioinformatics Unit, Instituto de Salud Carlos III (ISCIII), 28220 Madrid, Spain
| | - Rosario Cazorla
- Neuropediatrics Service, Hospital Puerta de Hierro, 28222 Madrid, Spain
| | - Julián Lara
- Neuropediatrics Service, Hospital Puerta de Hierro, 28222 Madrid, Spain
| | - Gemma Iglesias
- Neuropediatrics Service, Hospital Puerta de Hierro, 28222 Madrid, Spain
| | - Enriqueta Román
- Neuropediatrics Service, Hospital Puerta de Hierro, 28222 Madrid, Spain
| | - Purificación Ros
- Neuropediatrics Service, Hospital Puerta de Hierro, 28222 Madrid, Spain
| | - Gema Gomez-Mariano
- Instituto de Investigación de Enfermedades Raras (IIER), Instituto de Salud Carlos III (ISCIII), 28220 Madrid, Spain
| | - Isabel Cubillo
- Instituto de Investigación de Enfermedades Raras (IIER), Instituto de Salud Carlos III (ISCIII), 28220 Madrid, Spain
| | - Esther Hernandez-San Miguel
- Instituto de Investigación de Enfermedades Raras (IIER), Instituto de Salud Carlos III (ISCIII), 28220 Madrid, Spain
| | - Daniel Rivera
- Instituto de Investigación de Enfermedades Raras (IIER), Instituto de Salud Carlos III (ISCIII), 28220 Madrid, Spain
| | - Javier Alonso
- Instituto de Investigación de Enfermedades Raras (IIER), Instituto de Salud Carlos III (ISCIII), 28220 Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), U758, 28029 Madrid, Spain
| | - Eva Bermejo-Sánchez
- Instituto de Investigación de Enfermedades Raras (IIER), Instituto de Salud Carlos III (ISCIII), 28220 Madrid, Spain
| | - Manuel Posada
- Instituto de Investigación de Enfermedades Raras (IIER), Instituto de Salud Carlos III (ISCIII), 28220 Madrid, Spain
| | - Beatriz Martínez-Delgado
- Instituto de Investigación de Enfermedades Raras (IIER), Instituto de Salud Carlos III (ISCIII), 28220 Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), U758, 28029 Madrid, Spain
- Correspondence:
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12
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Shoubridge C, Dudding-Byth T, Pasquier L, Goel H, Yap P, Mcconnell V. IQSEC2-related encephalopathy in males due to missense variants in the PH domain. Clin Genet 2022; 102:72-77. [PMID: 35347702 PMCID: PMC9325495 DOI: 10.1111/cge.14136] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 03/25/2022] [Accepted: 03/25/2022] [Indexed: 11/29/2022]
Abstract
Pathogenic variants in IQ motif and SEC7 domain containing protein 2 (IQSEC2) gene cause a variety of neurodevelopmental disorders, with intellectual disability as a uniform feature. We report five cases, each with a novel missense variant in the pleckstrin homology (PH) domain of the IQSEC2 protein. Male patients all present with moderate to profound intellectual disability, significant delays or absent language and speech and variable seizures. We describe the phenotypic spectrum associated with missense variants in PH domain of IQSEC2, further delineating the genotype–phenotype correlation for this X‐linked gene.
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Affiliation(s)
- Cheryl Shoubridge
- Robinson Research Institute, and Adelaide Medical School, University of Adelaide, South Australia, Australia
| | | | - Laurent Pasquier
- CHU Rennes, Service de Génétique Clinique, Centre de Référence Déficiences Intellectuelles Hôpital Sud, Rennes, France
| | - Himanshu Goel
- Hunter Genetics, Waratah, New South Wales, Australia
| | - Patrick Yap
- Genetic Health Service New Zealand (Northern Hub), Auckland, New Zealand
| | - Vivienne Mcconnell
- Northern Ireland Regional Genetics Service, Belfast City Hospital, Belfast Health & Social Care Trust, Belfast, UK
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13
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Kane O, McCoy A, Jada R, Borisov V, Zag L, Zag A, Schragenheim-Rozales K, Shalgi R, Levy NS, Levy AP, Marsh ED. Characterization of spontaneous seizures and EEG abnormalities in a mouse model of the human A350V IQSEC2 mutation and identification of a possible target for precision medicine based therapy. Epilepsy Res 2022; 182:106907. [DOI: 10.1016/j.eplepsyres.2022.106907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 02/01/2022] [Accepted: 03/11/2022] [Indexed: 11/16/2022]
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14
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Jada R, Zag L, Borisov V, Levy NS, Netser S, Jabarin R, Wagner S, Schragenheim-Rozales K, Shalgi R, Levy AP. Housing of A350V IQSEC2 pups at 37 °C ambient temperature prevents seizures and permits the development of social vocalizations in adulthood. Int J Hyperthermia 2021; 38:1495-1501. [PMID: 34666607 DOI: 10.1080/02656736.2021.1988730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
OBJECTIVES Mutations in the human IQSEC2 gene are associated with drug-resistant epilepsy and severe behavioral dysfunction. We have focused on understanding one human IQSEC2 missense mutation (A350V) for which we have created a corresponding A350V IQSEC2 mouse model by CRISPR which demonstrates seizures when the mice are 15-20 days old and impaired social vocalizations in adulthood. We observed that a child with the A350V mutation stops having seizures when experiencing a fever of greater than 38 °C. In this study, we first sought to determine if we could recapitulate this phenomenon in A350V 15-20 day old mice using a previously established protocol to raise body temperature to 39 °C achieved by housing the mice at 37 °C. We then sought to determine if mice in whom seizure activity had been prevented as pups would develop social vocalization activity in adulthood. METHODS 15-20 day old A350V male mice were housed either at 37 °C or 22 °C. Ultrasonic vocalizations of these mice were assessed at 8-10 weeks in response to a female stimulus. RESULTS Housing of 15-20 day old A350V mice at 37 °C resulted in a reduction in lethal seizures to 2% (1/41) compared to 45% (48/108) in mice housed at 22 °C, p = 0.0001. Adult A350V mice who had been housed at 37 °C as pups displayed a significant improvement in the production of social vocalizations. CONCLUSION Raising the body temperature by raising the ambient temperature might provide a means to reduce seizures associated with the A350V IQSEC2 mutation and thereby allow for an improved neurodevelopmental trajectory.
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Affiliation(s)
- Reem Jada
- Technion Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Liron Zag
- Technion Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Veronika Borisov
- Technion Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Nina S Levy
- Technion Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Shai Netser
- Faculty of Natural Sciences, Sagol Department of Neurobiology, University of Haifa, Haifa, Israel
| | - Renad Jabarin
- Faculty of Natural Sciences, Sagol Department of Neurobiology, University of Haifa, Haifa, Israel
| | - Shlomo Wagner
- Faculty of Natural Sciences, Sagol Department of Neurobiology, University of Haifa, Haifa, Israel
| | | | - Reut Shalgi
- Technion Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Andrew P Levy
- Technion Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
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15
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Levy AP, Levy NS, Heyman E, Schertz M, Genizi J. Reduction in seizure burden in a child with a A350V IQSEC2 mutation using heat therapy with a Jacuzzi. Clin Case Rep 2021; 9:e04734. [PMID: 34484768 PMCID: PMC8405536 DOI: 10.1002/ccr3.4734] [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: 04/18/2021] [Revised: 07/15/2021] [Accepted: 08/09/2021] [Indexed: 12/14/2022] Open
Abstract
A child with a A350V IQSEC2 missense mutation resulting in drug-resistant epilepsy stops having seizures when he has a fever. We demonstrate that raising the body temperature of the child using a commercial Jacuzzi dramatically reduces his seizures and appears to improve his social behavioral interactions.
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Affiliation(s)
- Andrew P Levy
- Technion Israel Institute of TechnologyTechnion Faculty of MedicineDepartment of BiochemistryHaifaIsrael
| | - Nina S Levy
- Technion Israel Institute of TechnologyTechnion Faculty of MedicineDepartment of BiochemistryHaifaIsrael
| | - Eli Heyman
- Department of Pediatric NeurologyAssaf Harofeh Medical Center and Tel Aviv UniversityTel AvivIsrael
| | - Mitchell Schertz
- Child Development and Pediatric Neurology ServiceMehudet North and Technion Israel Institute of TechnologyHaifaIsrael
| | - Jacob Genizi
- Bnai Zion Medical Center and Technion Israel Institute of TechnologyPediatric Neurology UnitHaifaIsrael
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16
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Karaman Mercan T, Altiok Clark O, Erkal O, Nur B, Mihci E, Karaman B, Senol AU, Berker Karauzum S. Coexistence of a Homozygous Chromosome 4q35.2 Deletion and Hidden IQSEC2 Pathogenic Variant in a Child with Intellectual Disability. Cytogenet Genome Res 2021; 161:153-159. [PMID: 34229322 DOI: 10.1159/000515368] [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: 09/24/2019] [Accepted: 02/22/2021] [Indexed: 11/19/2022] Open
Abstract
Terminal deletions in the long arm of chromosome 4 are an uncommon event, with a worldwide incidence of approximately 0.001%. The majority of these deletions occur de novo. Terminal deletion cases are usually accompanied by clinical findings that include facial and cardiac anomalies, as well as intellectual disability. In this study, we describe the case of a 2-year-old girl, the fourth child born to consanguineous parents. While her karyotype was normal, a homozygous deletion was identified in the chromosome 4q35.2 region by subtelomeric FISH. A heterozygous deletion of the chromosome 4q35.2 region was observed in both parents. According to the literature, this is the first report of a case that has inherited a homozygous deletion of chromosome 4qter from carrier parents. Subsequent array-CGH analyses were performed on both the case and her parents. Whole-exome sequencing was also carried out to determine potential variants. We detected a NM_001111125.3:c.2329G>T (p.Glu777Ter) nonsense variant of the IQSEC2 gene in the girl, a variant that is related to X-linked intellectual disability.
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Affiliation(s)
- Tuğba Karaman Mercan
- Department of Medical Biology and Genetics, Faculty of Medicine, Akdeniz University, Antalya, Turkey
| | - Ozden Altiok Clark
- Department of Medical Genetics, Faculty of Medicine, Akdeniz University, Antalya, Turkey
| | - Ozgur Erkal
- Department of Medical Genetics, Antalya Training and Research Hospital, Antalya, Turkey
| | - Banu Nur
- Department of Pediatric Genetics, Faculty of Medicine, Akdeniz University, Antalya, Turkey
| | - Ercan Mihci
- Department of Pediatric Genetics, Faculty of Medicine, Akdeniz University, Antalya, Turkey
| | - Birsen Karaman
- Department of Medical Genetics, Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | - Abdullah Utku Senol
- Department of Radiodiagnostics, Faculty of Medicine, Akdeniz University, Antalya, Turkey
| | - Sibel Berker Karauzum
- Department of Medical Biology and Genetics, Faculty of Medicine, Akdeniz University, Antalya, Turkey
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Jabarin R, Levy N, Abergel Y, Berman JH, Zag A, Netser S, Levy AP, Wagner S. Pharmacological modulation of AMPA receptors rescues specific impairments in social behavior associated with the A350V Iqsec2 mutation. Transl Psychiatry 2021; 11:234. [PMID: 33888678 PMCID: PMC8062516 DOI: 10.1038/s41398-021-01347-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 03/19/2021] [Accepted: 03/30/2021] [Indexed: 12/18/2022] Open
Abstract
In this study we tested the hypothesis that pharmacological modulation of glutamatergic neurotransmission could rescue behavioral deficits exhibited by mice carrying a specific mutation in the Iqsec2 gene. The IQSEC2 protein plays a key role in glutamatergic synapses and mutations in the IQSEC2 gene are a frequent cause of neurodevelopmental disorders. We have recently reported on the molecular pathophysiology of one such mutation A350V and demonstrated that this mutation downregulates AMPA type glutamatergic receptors (AMPAR) in A350V mice. Here we sought to identify behavioral deficits in A350V mice and hypothesized that we could rescue these deficits by PF-4778574, a positive AMPAR modulator. Using a battery of social behavioral tasks, we found that A350V Iqsec2 mice exhibit specific deficits in sex preference and emotional state preference behaviors as well as in vocalizations when encountering a female mouse. The social discrimination deficits, but not the impaired vocalization, were rescued with a single dose of PF-4778574. We conclude that social behavior deficits associated with the A350V Iqsec2 mutation may be rescued by enhancing AMPAR mediated synaptic transmission.
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Affiliation(s)
- Renad Jabarin
- Sagol Department of Neurobiology, Faculty of Natural Sciences, University of Haifa, Haifa, Israel
| | - Nina Levy
- Technion Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Yasmin Abergel
- Sagol Department of Neurobiology, Faculty of Natural Sciences, University of Haifa, Haifa, Israel
| | - Joshua H Berman
- Sagol Department of Neurobiology, Faculty of Natural Sciences, University of Haifa, Haifa, Israel
| | - Amir Zag
- Technion Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Shai Netser
- Sagol Department of Neurobiology, Faculty of Natural Sciences, University of Haifa, Haifa, Israel
| | - Andrew P Levy
- Technion Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.
| | - Shlomo Wagner
- Sagol Department of Neurobiology, Faculty of Natural Sciences, University of Haifa, Haifa, Israel.
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Ferreira SS, Mesquita M, Nunes J, Alonso I, Leão M, Santos F, Real MV. Rett-like Syndrome in a Pediatric Patient—A Challenging Diagnosis. JOURNAL OF PEDIATRIC NEUROLOGY 2021. [DOI: 10.1055/s-0040-1714105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
AbstractNeurodevelopmental disorders with features overlapping Rett's syndrome frequently remain unexplained in patients without disease-causing variants in MECP2. Variants in IQSEC2 frequently cause nonsyndromic X-linked intellectual disability (XLID), although de novo variants may cause a severe syndrome that resembles Rett and Angelman's syndrome. We report a 7-year-old girl presenting severe neurodevelopmental delay, stereotypic hand movements, hypotonia, autistic-like features, inappropriate laughing/screaming spells, and symmetrical hypomyelination. A whole exome sequencing detected a novel de novo heterozygous truncating variant within the IQSEC2 gene. Variants of IQSEC2 should be considered in patients with Rett–Angelman phenotype spectrum and autistic features when those causes were excluded.
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Affiliation(s)
- Sofia Simões Ferreira
- Department of Pediatrics, Centro Hospitalar de Vila Nova de Gaia/Espinho, EPE, Vila Nova de Gaia, Portugal
| | - Marta Mesquita
- Department of Paediatrics, Centro Hospitalar Baixo Vouga, Aveiro, Portugal
| | - Joana Nunes
- Division of Neuroradiology, Department of Imaging, Centro Hospitalar de Vila Nova de Gaia/Espinho, Vila Nova de Gaia, Portugal
| | - Isabel Alonso
- UnIGENe and CGPP, IBMC - Institute for Molecular and Cell Biology, i3S - Instituto de Investigação e Inovação em Saúde, University of Porto, Genetyca-ICM, Porto, Portugal
| | - Miguel Leão
- Pediatric Neurology Unit, Department of Paediatrics, Centro Hospitalar Universitário São João, Porto, Portugal
- Neurogenetics Unit, Department of Medical Genetics, Centro Hospitalar Universitário São João, Porto, Portugal
| | - Fátima Santos
- Neuroscience Unit for Children and Adolescents, Department of Paediatrics, Centro Hospitalar de Vila Nova de Gaia/Espinho, Vila Nova de Gaia, Portugal
| | - Marta Vila Real
- Neuroscience Unit for Children and Adolescents, Department of Paediatrics, Centro Hospitalar de Vila Nova de Gaia/Espinho, Vila Nova de Gaia, Portugal
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Liu J, Wang K, Li B, Yang X. A novel Xp11.22-22.33 deletion suggesting a possible mechanism of congenital cervical spinal muscular atrophy. Mol Genet Genomic Med 2021; 9:e1606. [PMID: 33513289 PMCID: PMC8104167 DOI: 10.1002/mgg3.1606] [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: 10/31/2020] [Revised: 01/01/2021] [Accepted: 01/05/2021] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND Congenital cervical spinal muscular atrophy (CCSMA) is a rare, nonprogressive, neurogenic disorder characterized by symmetric arthrogryposis and motor deficits mainly confined to upper extremities. Since its first proposal by Darwish et al. 39 years ago, only few cases have ever been reported. Vascular insult to the anterior horn of cervical spinal cord during fetal development was speculated to be the cause, however, the exact pathogenesis is still not well understood. METHODS In this study, whole-exome sequencing (WES) and copy number variation (CNV) analysis were conducted on a definitive CCSMA patient, confirmed by the clinical manifestations and other supplementary examinations. RESULTS On physical examination, the patient was mainly characterized by symmetric, congenital, nonprogressive contractures, hypotonia, and muscle weakness mainly confined to the upper limbs, which were further supported by MRI and electromyography. Neuromuscular biopsy of the deltoid muscle demonstrated the type 1 myofiber predominance without any infiltration of inflammatory cells. The WES and CNV analysis unveiled a de novo Xp11.22-22.33 deletion. On further examination of the genes contained within this segment, we recognize UBA1 gene as the most likely pathogenic gene. Ubiquitin-like modifier activating enzyme 1 is encoded by UBA1 gene (MIM 314370) located in Xp11.3 and is a critical protein that plays a vital role in ubiquitin-proteasome system and autophagy. It is well documented that UBA1 gene mutation causes X-linked infantile spinal muscular atrophy (XL-SMA), which manifests phenotypes of arthrogryposis, hypotonia, and myopathic face. Type 2 XL-SMA, which follows a nonprogressive and nonlethal course is very similar to the presentations of CCSMA. CONCLUSION The phenotypic similarities between this CCSMA case and XL-SMA prompt us to hypothesize a possible connection between UBA1 gene deficit and the pathogenesis of CCSMA. Our study is the first to demonstrate that CCSMA might have a genetic etiology, thus, expanding our insights into the underlying cause of CCSMA.
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Affiliation(s)
- Jingwei Liu
- Department of Pediatric Surgery, Qilu Hospital of Shandong University, Jinan, Shandong, China
| | - Kelai Wang
- Department of Pediatric Surgery, Qilu Hospital of Shandong University, Jinan, Shandong, China
| | - Baomin Li
- Department of Pediatric, Qilu Hospital of Shandong University, Jinan, Shandong, China
| | - Xiaofan Yang
- Department of Pediatric, Qilu Hospital of Shandong University, Jinan, Shandong, China.,Department of Genetics, School of Basic Medical Sciences, Shandong University, Jinan, Shandong, China
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20
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Lopergolo D, Privitera F, Castello G, Lo Rizzo C, Mencarelli MA, Pinto AM, Ariani F, Currò A, Lamacchia V, Canitano R, Vaghi E, Ferrarini A, Baltodano GM, Lederer D, Van Maldergem L, Serrano M, Pineda M, Fons-Estupina MDC, Van Esch H, Breckpot J, Kumps C, Callewaert B, Mueller S, Ramelli GP, Armstrong J, Renieri A, Mari F. IQSEC2 disorder: A new disease entity or a Rett spectrum continuum? Clin Genet 2021; 99:462-474. [PMID: 33368194 DOI: 10.1111/cge.13908] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Revised: 12/12/2020] [Accepted: 12/22/2020] [Indexed: 12/27/2022]
Abstract
IQSEC2 mutations are associated with IQSEC2-related intellectual disability (ID). Phenotypic spectrum has been better defined in the last few years by the increasing number of reported cases although the genotype-phenotype relationship for IQSEC2 remains overall complex. As for IQSEC2-related ID a wide phenotypic diversity has been described in Rett syndrome (RTT). Several patients harboring IQSEC2 mutations present with clinical symptoms similar to RTT and some cases meet most of the criteria for classic RTT. With the aim of establishing a genotype-phenotype correlation, we collected data of 16 patients harboring IQSEC2 point mutations (15 of them previously unreported) and of five novel patients carrying CNVs encompassing IQSEC2. Most of our patients surprisingly shared a moderate-to-mild phenotype. The similarities in the clinical course between our mild cases and patients with milder forms of atypical RTT reinforce the hypothesis that also IQSEC2 mutated patients may lay under the wide clinical spectrum of RTT and thus IQSEC2 should be considered in the differential diagnosis. Our data confirm that position, type of variant and gender are crucial for IQSEC2-associated phenotype delineation.
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Affiliation(s)
- Diego Lopergolo
- Medical Genetics, University of Siena, Siena, Italy.,Genetica Medica, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | | | | | - Caterina Lo Rizzo
- Genetica Medica, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | | | - Anna Maria Pinto
- Genetica Medica, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Francesca Ariani
- Medical Genetics, University of Siena, Siena, Italy.,Genetica Medica, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Aurora Currò
- Medical Genetics, University of Siena, Siena, Italy.,Genetica Medica, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Vittoria Lamacchia
- Medical Genetics, University of Siena, Siena, Italy.,Genetica Medica, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Roberto Canitano
- Division of Child and Adolescent Neuropsychiatry, University Hospital of Siena, Siena, Italy
| | - Elisabetta Vaghi
- MAS Clinica Generale, Istituto Oncologico della Svizzera Italiana, Ospedale Regionale di Lugano, Italiano, Lugano, Switzerland
| | - Alessandra Ferrarini
- Chief Medical Genetics EOC, CSSI- Ospedale Regionale di Lugano, Italiano, Lugano, Switzerland
| | | | - Damien Lederer
- Department of Clinical Genetics, Centre for Human Genetics, Gosselies, Belgium
| | | | - Mercedes Serrano
- Pediatric Neurology Department, Hospital Sant Joan de Déu, Institut de Recerca, Barcelona, Spain.,U-703 CIBERER, Instituto de Salud Carlos III, Barcelona, Spain
| | - Mercè Pineda
- Department of Neuropediatria, Fundación Sant Joan de Déu, Barcelona, Spain
| | - Maria Del Carmen Fons-Estupina
- U-703 CIBERER, Instituto de Salud Carlos III, Barcelona, Spain.,Pediatric Neurology Department, Fetal-Neonatal Neurology Unit and Early Onset Epilepsy, Hospital Sant Joan de Déu, Institut de Recerca, Barcelona, Spain
| | - Hilde Van Esch
- Center for Human Genetics, University Hospitals Leuven, Leuven, Belgium
| | - Jeroen Breckpot
- Center for Human Genetics, University Hospitals Leuven, Leuven, Belgium
| | - Candy Kumps
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium
| | - Bert Callewaert
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium
| | - Sabrina Mueller
- Pediatric Institute of Southern Switzerland, Ente Ospedaliero Cantonale, Bellinzona, Switzerland
| | - Gian Paolo Ramelli
- Pediatric Institute of Southern Switzerland, Ente Ospedaliero Cantonale, Bellinzona, Switzerland
| | - Judith Armstrong
- Genetics Department, Hospital Sant Joan de Deu, Institut Pediàtric de Recerca and CIBERER, Barcelona, Spain
| | - Alessandra Renieri
- Medical Genetics, University of Siena, Siena, Italy.,Genetica Medica, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Francesca Mari
- Medical Genetics, University of Siena, Siena, Italy.,Genetica Medica, Azienda Ospedaliera Universitaria Senese, Siena, Italy
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21
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IQSEC2 mutation associated with epilepsy, intellectual disability, and autism results in hyperexcitability of patient-derived neurons and deficient synaptic transmission. Mol Psychiatry 2021; 26:7498-7508. [PMID: 34535765 PMCID: PMC8873005 DOI: 10.1038/s41380-021-01281-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2020] [Revised: 07/09/2021] [Accepted: 08/24/2021] [Indexed: 12/03/2022]
Abstract
Mutations in the IQSEC2 gene are associated with drug-resistant, multifocal infantile and childhood epilepsy; autism; and severe intellectual disability (ID). We used induced pluripotent stem cell (iPSC) technology to obtain hippocampal neurons to investigate the neuropathology of IQSEC2-mediated disease. The neurons were characterized at three-time points during differentiation to assess developmental progression. We showed that immature IQSEC2 mutant dentate gyrus (DG) granule neurons were extremely hyperexcitable, exhibiting increased sodium and potassium currents compared to those of CRISPR-Cas9-corrected isogenic controls, and displayed dysregulation of genes involved in differentiation and development. Immature IQSEC2 mutant cultured neurons exhibited a marked reduction in the number of inhibitory neurons, which contributed further to hyperexcitability. As the mutant neurons aged, they became hypoexcitable, exhibiting reduced sodium and potassium currents and a reduction in the rate of synaptic and network activity, and showed dysregulation of genes involved in synaptic transmission and neuronal differentiation. Mature IQSEC2 mutant neurons were less viable than wild-type mature neurons and had reduced expression of surface AMPA receptors. Our studies provide mechanistic insights into severe infantile epilepsy and neurodevelopmental delay associated with this mutation and present a human model for studying IQSEC2 mutations in vitro.
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22
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Briševac D, Scholz R, Du D, Elagabani MN, Köhr G, Kornau HC. The small GTPase Arf6 is dysregulated in a mouse model for fragile X syndrome. J Neurochem 2020; 157:666-683. [PMID: 33125726 DOI: 10.1111/jnc.15230] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 10/09/2020] [Accepted: 10/27/2020] [Indexed: 11/29/2022]
Abstract
Fragile X syndrome (FXS), the most common inherited cause of intellectual disability, results from silencing of the fragile X mental retardation gene 1 (FMR1). The analyses of FXS patients' brain autopsies revealed an increased density of immature dendritic spines in cortical areas. We hypothesize that the small GTPase Arf6, an actin regulator critical for the development of glutamatergic synapses and dendritic spines, is implicated in FXS. Here, we determined the fraction of active, GTP-bound Arf6 in cortical neuron cultures and synaptoneurosomes from Fmr1 knockout mice, measured actin polymerization in neurons expressing Arf6 mutants with variant GTP- or GDP-binding properties, and recorded hippocampal long-term depression induced by metabotropic glutamate receptors (mGluR-LTD) in acute brain slices. We detected a persistently elevated Arf6 activity, a loss of Arf6 sensitivity to synaptic stimulation and an increased Arf6-dependent dendritic actin polymerization in mature Fmr1 knockout neurons. Similar imbalances in Arf6-GTP levels and actin filament assembly were caused in wild-type neurons by RNAi-mediated depletion of the postsynaptic Arf6 guanylate exchange factors IQSEC1 (BRAG2) or IQSEC2 (BRAG1). Targeted deletion of Iqsec1 in hippocampal neurons of 3-week-old mice interfered with mGluR-LTD in wild-type, but not in Fmr1 knockout mice. Collectively, these data suggest an aberrant Arf6 regulation in Fmr1 knockout neurons with consequences for the actin cytoskeleton, spine morphology, and synaptic plasticity. Moreover, FXS and syndromes caused by genetic variants in IQSEC1 and IQSEC2 share intellectual disabilities and developmental delay as main symptoms. Therefore, dysregulation of Arf6 may contribute to the cognitive impairment in FXS.
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Affiliation(s)
- Dušica Briševac
- Neuroscience Research Center (NWFZ), Charité - Universitätsmedizin Berlin, Berlin, Germany.,Department of Biology, Chemistry, and Pharmacy, Freie Universität Berlin, Berlin, Germany
| | - Ralf Scholz
- Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Dan Du
- Central Institute of Mental Health, Mannheim Center for Translational Neuroscience, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | | | - Georg Köhr
- Central Institute of Mental Health, Mannheim Center for Translational Neuroscience, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany.,Department of Neurophysiology, Mannheim Center for Translational Neuroscience, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Hans-Christian Kornau
- Neuroscience Research Center (NWFZ), Charité - Universitätsmedizin Berlin, Berlin, Germany.,Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany.,German Center for Neurodegenerative Diseases (DZNE) Berlin, Berlin, Germany
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23
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Nagabushana D, Chatterjee A, Kenchaiah R, Asranna A, Arunachal G, Mundlamuri RC. Response to Steroids in IQSEC2-Related Encephalopathy Presenting with Rett-Like Phenotype and Infantile Spasms. J Pediatr Genet 2020; 12:76-80. [PMID: 36684544 PMCID: PMC9848762 DOI: 10.1055/s-0040-1721371] [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: 08/29/2020] [Accepted: 10/14/2020] [Indexed: 01/25/2023]
Abstract
Introduction IQSEC2-related encephalopathy is an X-linked childhood neurodevelopmental disorder with intellectual disability, epilepsy, and autism. This disorder is caused by a mutation in the IQSEC2 gene, the product of which plays an important role in the development of the central nervous system. Case Report We describe the symptomatology, clinical course, and management of a 17-month-old male child with a novel IQSEC2 mutation. He presented with an atypical Rett syndrome phenotype with developmental delay, autistic features, midline stereotypies, microcephaly, hypotonia and epilepsy with multiple seizure types including late-onset infantile spasms. Spasms were followed by worsening of behavior and cognition, and regression of acquired milestones. Treatment with steroids led to control of spasms and improved attention, behavior and recovery of lost motor milestone. In the past 10 months following steroid therapy, child lags in development, remains autistic with no further seizure recurrence. Conclusion IQSEC2-related encephalopathy may present with Rett atypical phenotypes and childhood spasms. In resource-limited settings, steroids may be considered for spasm remission in IQSEC2-related epileptic encephalopathy.
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Affiliation(s)
- Divya Nagabushana
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bengaluru, India
| | - Aparajita Chatterjee
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bengaluru, India
| | - Raghavendra Kenchaiah
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bengaluru, India
| | - Ajay Asranna
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bengaluru, India
| | - Gautham Arunachal
- Department of Human Genetics, National Institute of Mental Health and Neurosciences, Bengaluru, India
| | - Ravindranadh Chowdary Mundlamuri
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bengaluru, India,Address for correspondence Ravindranadh Chowdary Mundlamuri, DM Department of Neurology, National Institute of Mental Health and NeurosciencesBengaluru 560029India
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24
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Wayhelova M, Ryzí M, Oppelt J, Hladilkova E, Vallova V, Krskova L, Vilemova M, Polackova H, Gaillyova R, Kuglik P. Novel familial IQSEC2 pathogenic sequence variant associated with neurodevelopmental disorders and epilepsy. Neurogenetics 2020; 21:269-278. [PMID: 32564198 DOI: 10.1007/s10048-020-00616-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 05/11/2020] [Indexed: 01/22/2023]
Abstract
Pathogenic sequence variants in the IQ motif- and Sec7 domain-containing protein 2 (IQSEC2) gene have been confirmed as causative in the aetiopathogenesis of neurodevelopmental disorders (intellectual disability, autism) and epilepsy. We report on a case of a family with three sons; two of them manifest delayed psychomotor development and epilepsy. Initially proband A was examined using a multistep molecular diagnostics algorithm, including karyotype and array-comparative genomic hybridization analysis, both with negative results. Therefore, probands A and B and their unaffected parents were enrolled for an analysis using targeted "next-generation" sequencing (NGS) with a gene panel ClearSeq Inherited DiseaseXT (Agilent Technologies) and verification analysis by Sanger sequencing. A novel frameshift variant in the X-linked IQSEC2 gene NM_001111125.2:c.1813_1814del, p.(Asp605Profs*3) on protein level, was identified in both affected probands and their asymptomatic mother, having skewed X chromosome inactivation (XCI) (100:0). As the IQSEC2 gene is a known gene escaping from XCI in humans, we expect the existence of mechanisms maintaining the normal or enough level of the IQSEC2 protein in the asymptomatic mother. Further analyses may help to the characterization of the presented novel frameshift variant in the IQSEC2 gene as well as to elucidate the mechanisms leading to the rare asymptomatic phenotypes in females.
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Affiliation(s)
- Marketa Wayhelova
- Department of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czech Republic.,Department of Medical Genetics, University Hospital Brno, Brno, Czech Republic
| | - Michal Ryzí
- Clinic of Children's Neurology, University Hospital Brno, Brno, Czech Republic
| | - Jan Oppelt
- CEITEC-Central European Institute of Technology, Masaryk University, Brno, Czech Republic
| | - Eva Hladilkova
- Department of Medical Genetics, University Hospital Brno, Brno, Czech Republic
| | - Vladimira Vallova
- Department of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czech Republic.,Department of Medical Genetics, University Hospital Brno, Brno, Czech Republic
| | - Lenka Krskova
- Department of Pathology and Molecular Medicine, 2nd Faculty of Medicine, Charles University in Prague and Motol University Hospital, Prague, Czech Republic
| | - Marcela Vilemova
- Department of Medical Genetics, University Hospital Brno, Brno, Czech Republic
| | - Hana Polackova
- Department of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Renata Gaillyova
- Department of Medical Genetics, University Hospital Brno, Brno, Czech Republic
| | - Petr Kuglik
- Department of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czech Republic. .,Department of Medical Genetics, University Hospital Brno, Brno, Czech Republic.
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25
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Psychiatric features and variable neurodevelopment outcome in four females with IQSEC2 spectrum disorder. J Genet 2020. [DOI: 10.1007/s12041-020-01204-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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26
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Barrie ES, Cottrell CE, Gastier-Foster J, Hickey SE, Patel AD, Santoro SL, Alfaro MP. Genotype-phenotype correlation: Inheritance and variant-type infer pathogenicity in IQSEC2 gene. Eur J Med Genet 2020; 63:103735. [DOI: 10.1016/j.ejmg.2019.103735] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 07/15/2019] [Accepted: 08/11/2019] [Indexed: 10/26/2022]
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27
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Altered excitatory transmission onto hippocampal interneurons in the IQSEC2 mouse model of X-linked neurodevelopmental disease. Neurobiol Dis 2020; 137:104758. [PMID: 31978606 DOI: 10.1016/j.nbd.2020.104758] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2019] [Revised: 12/16/2019] [Accepted: 01/20/2020] [Indexed: 02/01/2023] Open
Abstract
Mutations in the X-linked gene IQSEC2 are associated with multiple cases of epilepsy, epileptic encephalopathy, intellectual disability and autism spectrum disorder, the mechanistic understanding and successful treatment of which remain a significant challenge in IQSEC2 and related neurodevelopmental genetic diseases. To investigate disease etiology, we studied behaviors and synaptic function in IQSEC2 deficient mice. Hemizygous Iqsec2 null males exhibit growth deficits, hyperambulation and hyperanxiety phenotypes. Adult hemizygotes experience lethal spontaneous seizures, but paradoxically have a significantly increased threshold to electrically induced limbic seizures and relative resistance to chemically induced seizures. Although there are no gross defects in brain morphology, hemizygotes exhibit stark hippocampal reactive astrogliosis. Electrophysiological recordings of hippocampal neurons reveal increased excitatory drive specifically onto interneurons, and significant alterations in intrinsic electrical properties specific to the interneuron population. As they age, hemizygotes also develop an increased abundance of parvalbumin-positive interneurons in the hippocampus, neurons in which IQSEC2 is expressed in addition to the excitatory neurons. These findings point to a novel role of IQSEC2 in hippocampal interneuron synaptic function and development with implications for a class of intractable neurodevelopmental diseases.
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28
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Johnson BV, Kumar R, Oishi S, Alexander S, Kasherman M, Vega MS, Ivancevic A, Gardner A, Domingo D, Corbett M, Parnell E, Yoon S, Oh T, Lines M, Lefroy H, Kini U, Van Allen M, Grønborg S, Mercier S, Küry S, Bézieau S, Pasquier L, Raynaud M, Afenjar A, Billette de Villemeur T, Keren B, Désir J, Van Maldergem L, Marangoni M, Dikow N, Koolen DA, VanHasselt PM, Weiss M, Zwijnenburg P, Sa J, Reis CF, López-Otín C, Santiago-Fernández O, Fernández-Jaén A, Rauch A, Steindl K, Joset P, Goldstein A, Madan-Khetarpal S, Infante E, Zackai E, Mcdougall C, Narayanan V, Ramsey K, Mercimek-Andrews S, Pena L, Shashi V, Schoch K, Sullivan JA, Pinto E Vairo F, Pichurin PN, Ewing SA, Barnett SS, Klee EW, Perry MS, Koenig MK, Keegan CE, Schuette JL, Asher S, Perilla-Young Y, Smith LD, Rosenfeld JA, Bhoj E, Kaplan P, Li D, Oegema R, van Binsbergen E, van der Zwaag B, Smeland MF, Cutcutache I, Page M, Armstrong M, Lin AE, Steeves MA, Hollander ND, Hoffer MJV, Reijnders MRF, Demirdas S, Koboldt DC, Bartholomew D, Mosher TM, Hickey SE, Shieh C, Sanchez-Lara PA, Graham JM, Tezcan K, Schaefer GB, Danylchuk NR, Asamoah A, Jackson KE, Yachelevich N, Au M, Pérez-Jurado LA, Kleefstra T, Penzes P, Wood SA, Burne T, Pierson TM, Piper M, Gécz J, Jolly LA. Partial Loss of USP9X Function Leads to a Male Neurodevelopmental and Behavioral Disorder Converging on Transforming Growth Factor β Signaling. Biol Psychiatry 2020; 87:100-112. [PMID: 31443933 PMCID: PMC6925349 DOI: 10.1016/j.biopsych.2019.05.028] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 05/23/2019] [Accepted: 05/30/2019] [Indexed: 12/29/2022]
Abstract
BACKGROUND The X-chromosome gene USP9X encodes a deubiquitylating enzyme that has been associated with neurodevelopmental disorders primarily in female subjects. USP9X escapes X inactivation, and in female subjects de novo heterozygous copy number loss or truncating mutations cause haploinsufficiency culminating in a recognizable syndrome with intellectual disability and signature brain and congenital abnormalities. In contrast, the involvement of USP9X in male neurodevelopmental disorders remains tentative. METHODS We used clinically recommended guidelines to collect and interrogate the pathogenicity of 44 USP9X variants associated with neurodevelopmental disorders in males. Functional studies in patient-derived cell lines and mice were used to determine mechanisms of pathology. RESULTS Twelve missense variants showed strong evidence of pathogenicity. We define a characteristic phenotype of the central nervous system (white matter disturbances, thin corpus callosum, and widened ventricles); global delay with significant alteration of speech, language, and behavior; hypotonia; joint hypermobility; visual system defects; and other common congenital and dysmorphic features. Comparison of in silico and phenotypical features align additional variants of unknown significance with likely pathogenicity. In support of partial loss-of-function mechanisms, using patient-derived cell lines, we show loss of only specific USP9X substrates that regulate neurodevelopmental signaling pathways and a united defect in transforming growth factor β signaling. In addition, we find correlates of the male phenotype in Usp9x brain-specific knockout mice, and further resolve loss of hippocampal-dependent learning and memory. CONCLUSIONS Our data demonstrate the involvement of USP9X variants in a distinctive neurodevelopmental and behavioral syndrome in male subjects and identify plausible mechanisms of pathogenesis centered on disrupted transforming growth factor β signaling and hippocampal function.
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Affiliation(s)
- Brett V Johnson
- University of Adelaide and Robinson Research Institute, Adelaide, Australia
| | - Raman Kumar
- University of Adelaide and Robinson Research Institute, Adelaide, Australia
| | - Sabrina Oishi
- School of Biomedical Sciences, The University of Queensland, Brisbane, Australia
| | - Suzy Alexander
- Queensland Brain Institute, The University of Queensland, Brisbane, Australia; Queensland Centre for Mental Health Research, Wacol, Queensland, Australia
| | - Maria Kasherman
- School of Biomedical Sciences, The University of Queensland, Brisbane, Australia; Griffith Institute for Drug Discovery, Griffith University, Brisbane, Australia
| | | | - Atma Ivancevic
- University of Adelaide and Robinson Research Institute, Adelaide, Australia; BioFrontiers Institute, University of Colorado Boulder, Boulder, Colorado
| | - Alison Gardner
- University of Adelaide and Robinson Research Institute, Adelaide, Australia
| | - Deepti Domingo
- University of Adelaide and Robinson Research Institute, Adelaide, Australia
| | - Mark Corbett
- University of Adelaide and Robinson Research Institute, Adelaide, Australia
| | - Euan Parnell
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Sehyoun Yoon
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Tracey Oh
- Department of Medical Genetics, British Columbia Women's Hospital and University of British Columbia, Vancouver, British Columbia, Canada
| | - Matthew Lines
- Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
| | - Henrietta Lefroy
- Oxford Centre for Genomic Medicine, Oxford University Hospitals National Health Services Foundation Trust, Oxford, United Kingdom
| | - Usha Kini
- Oxford Centre for Genomic Medicine, Oxford University Hospitals National Health Services Foundation Trust, Oxford, United Kingdom
| | - Margot Van Allen
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Sabine Grønborg
- Center for Rare Diseases, Department of Pediatrics and Department of Clinical Genetics, University Hospital Copenhagen, Copenhagen, Denmark
| | - Sandra Mercier
- Service de Génétique Médicale, Centre Hospitalier Universitaire Nantes and l'Institut du Thorax, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Université de Nantes, Nantes, France
| | - Sébastien Küry
- Service de Génétique Médicale, Centre Hospitalier Universitaire Nantes and l'Institut du Thorax, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Université de Nantes, Nantes, France
| | - Stéphane Bézieau
- Service de Génétique Médicale, Centre Hospitalier Universitaire Nantes and l'Institut du Thorax, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Université de Nantes, Nantes, France
| | - Laurent Pasquier
- Service de Génétique Clinique, Centre de Référence Déficiences Intellectuelles de Causes Rares, Centre Hospitalier Universitaire Hôpital Sud, Rennes, France
| | - Martine Raynaud
- Centre Hospitalier Régional Universitaire de Tours, Service de Génétique, Unité Nixte de Recherche 1253, iBrain, Université de Tours, Institut National de la Santé et de la Recherche Médicale, Tours, France
| | - Alexandra Afenjar
- Groupe de Recherche Clinique No. 19, ConCer-LD, Département de Génétique, Assistance Publique-Hôpitaux de Paris, Hôpital Armand Trousseau, Centres de Référence Maladies Rares des Déficits Intellectuels de Causes Rares, Paris, France
| | - Thierry Billette de Villemeur
- Sorbonne Université, Groupe de Recherche Clinique No. 19, ConCer-LD, Neuropédiatrie, Centres de Référence Maladies Rares Neurogénétique, Institut National de la Santé et de la Recherche Médicale, Assistance Publique-Hôpitaux de Paris, Hôpital Armand Trousseau, Paris, France
| | - Boris Keren
- Hôpital de la Pitié-Salpêtrière, Département de Génétique, Paris, France
| | - Julie Désir
- Erasme University Hospital, Université Libre de Bruxelles, Brussels, Belgium
| | | | - Martina Marangoni
- Erasme University Hospital, Université Libre de Bruxelles, Brussels, Belgium
| | - Nicola Dikow
- Institute of Human Genetics, Heidelberg University, Heidelberg, Germany
| | - David A Koolen
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Peter M VanHasselt
- Department of Metabolic Diseases, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Marjan Weiss
- Department of Clinical Genetics, Vrije Universiteit University Medical Center, Amsterdam, The Netherlands
| | - Petra Zwijnenburg
- Medical Genetics Unit, Hospital Pediátrico, Centro Hospitalar e Universitário de Coimbra, Coimbra, Portugal
| | - Joaquim Sa
- Medical Genetics Unit, Hospital Pediátrico, Centro Hospitalar e Universitário de Coimbra, Coimbra, Portugal
| | - Claudia Falcao Reis
- Medical Genetics Unit, Hospital Pediátrico, Centro Hospitalar e Universitário de Coimbra, Coimbra, Portugal
| | - Carlos López-Otín
- Departamento de Bioquímica y Biología Molecular, Instituto Universitário de Oncología del Principado de Asturias, Universidad de Oviedo, Oviedo, Spain; Centro de Investigación Biomédica en Red de Cáncer, Spain
| | - Olaya Santiago-Fernández
- Departamento de Bioquímica y Biología Molecular, Instituto Universitário de Oncología del Principado de Asturias, Universidad de Oviedo, Oviedo, Spain
| | | | - Anita Rauch
- Institute of Medical Genetics, University of Zurich, Schlieren, Switzerland
| | - Katharina Steindl
- Institute of Medical Genetics, University of Zurich, Schlieren, Switzerland
| | - Pascal Joset
- Institute of Medical Genetics, University of Zurich, Schlieren, Switzerland
| | - Amy Goldstein
- Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | | | - Elena Infante
- Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania
| | - Elaine Zackai
- Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Carey Mcdougall
- Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Vinodh Narayanan
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, Arizona
| | - Keri Ramsey
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, Arizona
| | - Saadet Mercimek-Andrews
- Division of Clinical and Metabolic Genetics, Department of Pediatrics, University of Toronto, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Loren Pena
- Division of Human Genetics, Cincinnati Children's Hospital; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - Vandana Shashi
- Department of Pediatrics, Division of Medical Genetics, Duke University Medical Center, Durham, North Carolina
| | - Kelly Schoch
- Department of Pediatrics, Division of Medical Genetics, Duke University Medical Center, Durham, North Carolina
| | - Jennifer A Sullivan
- Department of Pediatrics, Division of Medical Genetics, Duke University Medical Center, Durham, North Carolina
| | - Filippo Pinto E Vairo
- Department of Clinical Genomics, Mayo Clinic, Rochester, Minnesota; Center for Individualized Medicine, Mayo Clinic, Rochester, Minnesota
| | - Pavel N Pichurin
- Department of Clinical Genomics, Mayo Clinic, Rochester, Minnesota
| | - Sarah A Ewing
- Department of Clinical Genomics, Mayo Clinic, Rochester, Minnesota
| | - Sarah S Barnett
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Eric W Klee
- Department of Clinical Genomics, Mayo Clinic, Rochester, Minnesota
| | - M Scott Perry
- Jane and John Justin Neuroscience Center, Cook Children's Medical Center, Fort Worth, Texas
| | - Mary Kay Koenig
- Department of Pediatrics, University of Texas Medical School at Houston, Houston, Texas
| | - Catherine E Keegan
- Division of Genetics, Department of Pediatrics, University of Michigan, Ann Arbor, Michigan
| | - Jane L Schuette
- Division of Genetics, Department of Pediatrics, University of Michigan, Ann Arbor, Michigan
| | - Stephanie Asher
- Translational Medicine & Human Genetics, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Yezmin Perilla-Young
- Division of Pediatric Genetics and Metabolism, University of North Carolina, Chapel Hill, North Carolina
| | - Laurie D Smith
- Division of Pediatric Genetics and Metabolism, University of North Carolina, Chapel Hill, North Carolina
| | | | - Elizabeth Bhoj
- Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Paige Kaplan
- Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Dong Li
- Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Renske Oegema
- Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Ellen van Binsbergen
- Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Bert van der Zwaag
- Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | | | | | - Matthew Page
- Translational Medicine, UCB Pharma, Braine-l'Alleud, Belgium
| | | | - Angela E Lin
- Medical Genetics Unit, Mass General Hospital for Children, Boston, Massachusetts
| | - Marcie A Steeves
- Medical Genetics Unit, Mass General Hospital for Children, Boston, Massachusetts
| | | | - Mariëtte J V Hoffer
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Margot R F Reijnders
- Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Serwet Demirdas
- Department of Clinical Genetics, Erasmus University Medical Center, Rotterdam, The Netherlands
| | | | | | | | - Scott E Hickey
- Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio
| | - Christine Shieh
- David Geffen School of Medicine, University of California-Los Angeles, California
| | | | - John M Graham
- Department of Pediatrics, Cedars-Sinai Medical Center, Los Angeles, California
| | - Kamer Tezcan
- Department of Genetics, Kaiser Permanente, Sacramento, California
| | - G B Schaefer
- Section of Genetics and Metabolism, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Noelle R Danylchuk
- Department of Genetic Counseling, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Alexander Asamoah
- Department of Pediatrics, University of Louisville School of Medicine, Louisville, Kentucky
| | - Kelly E Jackson
- Department of Pediatrics, University of Louisville School of Medicine, Louisville, Kentucky
| | - Naomi Yachelevich
- Clinical Genetics Services, Department of Pediatrics, New York University School of Medicine, New York, New York
| | - Margaret Au
- Department of Pediatrics, Cedars-Sinai Medical Center, Los Angeles, California
| | - Luis A Pérez-Jurado
- University of Adelaide and Robinson Research Institute, Adelaide, Australia; Women's and Children's Hospital, Adelaide, Australia; South Australian Health and Medical Research Institute, Adelaide, South Australia; Hospital del Mar Research Institute, Network Research Centre for Rare Diseases and Universitat Pompeu Fabra, Barcelona, Spain
| | - Tjitske Kleefstra
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Peter Penzes
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Stephen A Wood
- Griffith Institute for Drug Discovery, Griffith University, Brisbane, Australia
| | - Thomas Burne
- Queensland Brain Institute, The University of Queensland, Brisbane, Australia; Queensland Centre for Mental Health Research, Wacol, Queensland, Australia
| | - Tyler Mark Pierson
- Department of Pediatrics, Cedars-Sinai Medical Center, Los Angeles, California; Department of Neurology and the Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California
| | - Michael Piper
- School of Biomedical Sciences, The University of Queensland, Brisbane, Australia; Queensland Brain Institute, The University of Queensland, Brisbane, Australia
| | - Jozef Gécz
- University of Adelaide and Robinson Research Institute, Adelaide, Australia; South Australian Health and Medical Research Institute, Adelaide, South Australia.
| | - Lachlan A Jolly
- University of Adelaide and Robinson Research Institute, Adelaide, Australia.
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29
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Tejada MI, Ibarluzea N. Non-syndromic X linked intellectual disability: Current knowledge in light of the recent advances in molecular and functional studies. Clin Genet 2020; 97:677-687. [PMID: 31898314 DOI: 10.1111/cge.13698] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 12/09/2019] [Accepted: 12/24/2019] [Indexed: 12/23/2022]
Abstract
Since the discovery of the FMR1 gene and the clinical and molecular characterization of Fragile X Syndrome in 1991, more than 141 genes have been identified in the X-chromosome in these 28 years thanks to applying continuously evolving molecular techniques to X-linked intellectual disability (XLID) families. In the past decade, array comparative genomic hybridization and next generation sequencing technologies have accelerated gene discovery exponentially. Classically, XLID has been subdivided in syndromic intellectual disability (S-XLID)-where intellectual disability (ID) is always associated with other recognizable physical and/or neurological features-and non-specific or non-syndromic intellectual disability (NS-XLID) where the only common feature is ID. Nevertheless, new advances on the study of these entities have showed that this classification is not always clear-cut because distinct variants in several of these XLID genes can result in S-XLID as well as in NS-XLID. This review focuses on the current knowledge on the XLID genes involved in non-syndromic forms, with the emphasis on their pathogenic mechanism, thus allowing the possibility to elucidate why some of them can give both syndromic and non-syndromic phenotypes.
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Affiliation(s)
- María Isabel Tejada
- Genetics Service, Cruces University Hospital, Osakidetza Basque Health Service, Barakaldo, Spain.,Biocruces-Bizkaia Health Research Institute, Barakaldo, Spain.,Clinical Group, Centre for Biomedical Research on Rare Diseases (CIBERER), Valencia, Spain
| | - Nekane Ibarluzea
- Biocruces-Bizkaia Health Research Institute, Barakaldo, Spain.,Clinical Group, Centre for Biomedical Research on Rare Diseases (CIBERER), Valencia, Spain
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30
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Ibarluzea N, de la Hoz AB, Villate O, Llano I, Ocio I, Martí I, Guitart M, Gabau E, Andrade F, Gener B, Tejada MI. Targeted Next-Generation Sequencing in Patients with Suggestive X-Linked Intellectual Disability. Genes (Basel) 2020; 11:genes11010051. [PMID: 31906484 PMCID: PMC7017351 DOI: 10.3390/genes11010051] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 12/19/2019] [Accepted: 12/30/2019] [Indexed: 12/28/2022] Open
Abstract
X-linked intellectual disability (XLID) is known to contribute up to 10% of intellectual disability (ID) in males and could explain the increased ratio of affected males observed in patients with ID. Over the past decade, next-generation sequencing has clearly stimulated the gene discovery process and has become part of the diagnostic procedure. We have performed targeted next-generation sequencing of 82 XLID genes on 61 non-related male patients with suggestive non-syndromic XLID. These patients were initially referred to the molecular genetics laboratory to exclude Fragile X Syndrome. The cohort includes 47 male patients with suggestive X-linked family history of ID meaning that they had half-brothers or maternal cousins or uncles affected; and 14 male patients with ID and affected brothers whose mothers show skewed X-inactivation. Sequencing data analysis identified 17 candidate variants in 16 patients. Seven families could be re-contacted and variant segregation analysis of the respective eight candidate variants was performed: HUWE1, IQSEC2, MAOA, MED12, PHF8, SLC6A8, SLC9A6, and SYN1. Our results show the utility of targeted next-generation sequencing in unravelling the genetic origin of XLID, especially in retrospective cases. Variant segregation and additional studies like RNA sequencing and biochemical assays also helped in re-evaluating and further classifying the genetic variants found.
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Affiliation(s)
- Nekane Ibarluzea
- Biocruces Bizkaia Health Research Institute, 48903 Barakaldo, Spain
- Spanish Consortium for Research on Rare Diseases (CIBERER), 28029 Madrid, Spain
| | - Ana Belén de la Hoz
- Biocruces Bizkaia Health Research Institute, 48903 Barakaldo, Spain
- Spanish Consortium for Research on Rare Diseases (CIBERER), 28029 Madrid, Spain
| | - Olatz Villate
- Biocruces Bizkaia Health Research Institute, 48903 Barakaldo, Spain
- Spanish Consortium for Research on Rare Diseases (CIBERER), 28029 Madrid, Spain
- Genetics Service, Cruces University Hospital, Osakidetza Basque Health Service, 48903 Barakaldo, Spain
| | - Isabel Llano
- Biocruces Bizkaia Health Research Institute, 48903 Barakaldo, Spain
- Spanish Consortium for Research on Rare Diseases (CIBERER), 28029 Madrid, Spain
- Genetics Service, Cruces University Hospital, Osakidetza Basque Health Service, 48903 Barakaldo, Spain
| | - Intzane Ocio
- Department of Paediatric Neurology, Araba University Hospital, Osakidetza Basque Health Service, 01009 Gasteiz, Spain
| | - Itxaso Martí
- Department of Paediatric Neurology, Donostia University Hospital, Osakidetza Basque Health Service, 20014 Donostia, Spain
| | - Miriam Guitart
- Genetics Laboratory, Paediatric Unit, Parc Taulí Hospital Universitari, Institut d’Investigació i Innovació Parc Taulí I3PT, Universitat Autònoma de Barcelona, 08208 Sabadell, Spain
| | - Elisabeth Gabau
- Genetics Laboratory, Paediatric Unit, Parc Taulí Hospital Universitari, Institut d’Investigació i Innovació Parc Taulí I3PT, Universitat Autònoma de Barcelona, 08208 Sabadell, Spain
| | - Fernando Andrade
- Biocruces Bizkaia Health Research Institute, 48903 Barakaldo, Spain
- Spanish Consortium for Research on Rare Diseases (CIBERER), 28029 Madrid, Spain
| | - Blanca Gener
- Biocruces Bizkaia Health Research Institute, 48903 Barakaldo, Spain
- Spanish Consortium for Research on Rare Diseases (CIBERER), 28029 Madrid, Spain
- Genetics Service, Cruces University Hospital, Osakidetza Basque Health Service, 48903 Barakaldo, Spain
| | - María-Isabel Tejada
- Biocruces Bizkaia Health Research Institute, 48903 Barakaldo, Spain
- Spanish Consortium for Research on Rare Diseases (CIBERER), 28029 Madrid, Spain
- Genetics Service, Cruces University Hospital, Osakidetza Basque Health Service, 48903 Barakaldo, Spain
- Correspondence:
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31
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Ansar M, Chung HL, Al-Otaibi A, Elagabani MN, Ravenscroft TA, Paracha SA, Scholz R, Abdel Magid T, Sarwar MT, Shah SF, Qaisar AA, Makrythanasis P, Marcogliese PC, Kamsteeg EJ, Falconnet E, Ranza E, Santoni FA, Aldhalaan H, Al-Asmari A, Faqeih EA, Ahmed J, Kornau HC, Bellen HJ, Antonarakis SE. Bi-allelic Variants in IQSEC1 Cause Intellectual Disability, Developmental Delay, and Short Stature. Am J Hum Genet 2019; 105:907-920. [PMID: 31607425 DOI: 10.1016/j.ajhg.2019.09.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 09/11/2019] [Indexed: 12/30/2022] Open
Abstract
We report two consanguineous families with probands that exhibit intellectual disability, developmental delay, short stature, aphasia, and hypotonia in which homozygous non-synonymous variants were identified in IQSEC1 (GenBank: NM_001134382.3). In a Pakistani family, the IQSEC1 segregating variant is c.1028C>T (p.Thr343Met), while in a Saudi Arabian family the variant is c.962G>A (p.Arg321Gln). IQSEC1-3 encode guanine nucleotide exchange factors for the small GTPase ARF6 and their loss affects a variety of actin-dependent cellular processes, including AMPA receptor trafficking at synapses. The ortholog of IQSECs in the fly is schizo and its loss affects growth cone guidance at the midline in the CNS, also an actin-dependent process. Overexpression of the reference IQSEC1 cDNA in wild-type flies is lethal, but overexpression of the two variant IQSEC1 cDNAs did not affect viability. Loss of schizo caused embryonic lethality that could be rescued to 2nd instar larvae by moderate expression of the human reference cDNA. However, the p.Arg321Gln and p.Thr343Met variants failed to rescue embryonic lethality. These data indicate that the variants behave as loss-of-function mutations. We also show that schizo in photoreceptors is required for phototransduction. Finally, mice with a conditional Iqsec1 deletion in cortical neurons exhibited an increased density of dendritic spines with an immature morphology. The phenotypic similarity of the affecteds and the functional experiments in flies and mice indicate that IQSEC1 variants are the cause of a recessive disease with intellectual disability, developmental delay, and short stature, and that axonal guidance and dendritic projection defects as well as dendritic spine dysgenesis may underlie disease pathogenesis.
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32
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Fang H, Disteche CM, Berletch JB. X Inactivation and Escape: Epigenetic and Structural Features. Front Cell Dev Biol 2019; 7:219. [PMID: 31632970 PMCID: PMC6779695 DOI: 10.3389/fcell.2019.00219] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 09/18/2019] [Indexed: 12/27/2022] Open
Abstract
X inactivation represents a complex multi-layer epigenetic mechanism that profoundly modifies chromatin composition and structure of one X chromosome in females. The heterochromatic inactive X chromosome adopts a unique 3D bipartite structure and a location close to the nuclear periphery or the nucleolus. X-linked lncRNA loci and their transcripts play important roles in the recruitment of proteins that catalyze chromatin and DNA modifications for silencing, as well as in the control of chromatin condensation and location of the inactive X chromosome. A subset of genes escapes X inactivation, raising questions about mechanisms that preserve their expression despite being embedded within heterochromatin. Escape gene expression differs between males and females, which can lead to physiological sex differences. We review recent studies that emphasize challenges in understanding the role of lncRNAs in the control of epigenetic modifications, structural features and nuclear positioning of the inactive X chromosome. Second, we highlight new findings about the distribution of genes that escape X inactivation based on single cell studies, and discuss the roles of escape genes in eliciting sex differences in health and disease.
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Affiliation(s)
- He Fang
- Department of Pathology, University of Washington, Seattle, WA, United States
| | - Christine M. Disteche
- Department of Pathology, University of Washington, Seattle, WA, United States
- Department of Medicine, University of Washington, Seattle, WA, United States
| | - Joel B. Berletch
- Department of Pathology, University of Washington, Seattle, WA, United States
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33
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Jackson MR, Loring KE, Homan CC, Thai MH, Määttänen L, Arvio M, Jarvela I, Shaw M, Gardner A, Gecz J, Shoubridge C. Heterozygous loss of function of IQSEC2/ Iqsec2 leads to increased activated Arf6 and severe neurocognitive seizure phenotype in females. Life Sci Alliance 2019; 2:2/4/e201900386. [PMID: 31439632 PMCID: PMC6706959 DOI: 10.26508/lsa.201900386] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 07/25/2019] [Accepted: 08/15/2019] [Indexed: 12/30/2022] Open
Abstract
Clinical presentations of mutations in the IQSEC2 gene on the X-chromosome initially implicated to cause non-syndromic intellectual disability (ID) in males have expanded to include early onset seizures in males as well as in females. The molecular pathogenesis is not well understood, nor the mechanisms driving disease expression in heterozygous females. Using a CRISPR/Cas9-edited Iqsec2 KO mouse model, we confirm the loss of Iqsec2 mRNA expression and lack of Iqsec2 protein within the brain of both founder and progeny mice. Both male (52%) and female (46%) Iqsec2 KO mice present with frequent and recurrent seizures. Focusing on Iqsec2 KO heterozygous female mice, we demonstrate increased hyperactivity, altered anxiety and fear responses, decreased social interactions, delayed learning capacity and decreased memory retention/novel recognition, recapitulating psychiatric issues, autistic-like features, and cognitive deficits present in female patients with loss-of-function IQSEC2 variants. Despite Iqsec2 normally acting to activate Arf6 substrate, we demonstrate that mice modelling the loss of Iqsec2 function present with increased levels of activated Arf6. We contend that loss of Iqsec2 function leads to altered regulation of activated Arf6-mediated responses to synaptic signalling and immature synaptic networks. We highlight the importance of IQSEC2 function for females by reporting a novel nonsense variant c.566C > A, p.(S189*) in an elderly female patient with profound intellectual disability, generalised seizures, and behavioural disturbances. Our human and mouse data reaffirm IQSEC2 as another disease gene with an unexpected X-chromosome heterozygous female phenotype. Our Iqsec2 mouse model recapitulates the phenotypes observed in human patients despite the differences in the IQSEC2/Iqsec2 gene X-chromosome inactivation between the species.
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Affiliation(s)
- Matilda R Jackson
- Intellectual Disability Research, Adelaide Medical School, The University of Adelaide, Adelaide, Australia.,Department of Paediatrics, Robinson Research Institute, University of Adelaide, Adelaide, Australia
| | - Karagh E Loring
- Intellectual Disability Research, Adelaide Medical School, The University of Adelaide, Adelaide, Australia.,Department of Paediatrics, Robinson Research Institute, University of Adelaide, Adelaide, Australia
| | - Claire C Homan
- Department of Paediatrics, Robinson Research Institute, University of Adelaide, Adelaide, Australia
| | - Monica Hn Thai
- Intellectual Disability Research, Adelaide Medical School, The University of Adelaide, Adelaide, Australia
| | - Laura Määttänen
- Department of Child Neurology, Turku University Hospital, Turku, Finland
| | - Maria Arvio
- Department of Child Neurology, Turku University Hospital, Turku, Finland.,Joint Authority for Päijät-Häme Social and Health Care, Lahti, Finland.,PEDEGO, Oulu University Hospital, Oulu, Finland
| | - Irma Jarvela
- Department of Medical Genetics, University of Helsinki, Helsinki, Finland
| | - Marie Shaw
- Department of Paediatrics, Robinson Research Institute, University of Adelaide, Adelaide, Australia
| | - Alison Gardner
- Department of Paediatrics, Robinson Research Institute, University of Adelaide, Adelaide, Australia
| | - Jozef Gecz
- Department of Paediatrics, Robinson Research Institute, University of Adelaide, Adelaide, Australia.,South Australian Health and Medical Research Institute, Adelaide, Australia
| | - Cheryl Shoubridge
- Intellectual Disability Research, Adelaide Medical School, The University of Adelaide, Adelaide, Australia .,Department of Paediatrics, Robinson Research Institute, University of Adelaide, Adelaide, Australia
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34
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Levy NS, Umanah GKE, Rogers EJ, Jada R, Lache O, Levy AP. IQSEC2-Associated Intellectual Disability and Autism. Int J Mol Sci 2019; 20:ijms20123038. [PMID: 31234416 PMCID: PMC6628259 DOI: 10.3390/ijms20123038] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 06/19/2019] [Indexed: 01/02/2023] Open
Abstract
Mutations in IQSEC2 cause intellectual disability (ID), which is often accompanied by seizures and autism. A number of studies have shown that IQSEC2 is an abundant protein in excitatory synapses and plays an important role in neuronal development as well as synaptic plasticity. Here, we review neuronal IQSEC2 signaling with emphasis on those aspects likely to be involved in autism. IQSEC2 is normally bound to N-methyl-D-aspartate (NMDA)-type glutamate receptors via post synaptic density protein 95 (PSD-95). Activation of NMDA receptors results in calcium ion influx and binding to calmodulin present on the IQSEC2 IQ domain. Calcium/calmodulin induces a conformational change in IQSEC2 leading to activation of the SEC7 catalytic domain. GTP is exchanged for GDP on ADP ribosylation factor 6 (ARF6). Activated ARF6 promotes downregulation of surface α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type glutamate receptors through a c-jun N terminal kinase (JNK)-mediated pathway. NMDA receptors, AMPA receptors, and PSD-95 are all known to be adversely affected in autism. An IQSEC2 transgenic mouse carrying a constitutively active mutation (A350V) shows autistic features and reduced levels of surface AMPA receptor subunit GluA2. Sec7 activity and AMPA receptor recycling are presented as two targets, which may respond to drug treatment in IQSEC2-associated ID and autism.
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Affiliation(s)
- Nina S Levy
- Technion Israel Institute of Technology, 1 Efron St., Haifa, 3525422, Israel.
| | - George K E Umanah
- Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, USA.
| | - Eli J Rogers
- Technion Israel Institute of Technology, 1 Efron St., Haifa, 3525422, Israel.
| | - Reem Jada
- Technion Israel Institute of Technology, 1 Efron St., Haifa, 3525422, Israel.
| | - Orit Lache
- Technion Israel Institute of Technology, 1 Efron St., Haifa, 3525422, Israel.
| | - Andrew P Levy
- Technion Israel Institute of Technology, 1 Efron St., Haifa, 3525422, Israel.
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35
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Radley JA, O'Sullivan RB, Turton SE, Cox H, Vogt J, Morton J, Jones E, Smithson S, Lachlan K, Rankin J, Clayton-Smith J, Willoughby J, Elmslie FF, Sansbury FH, Cooper N, Balasubramanian M. Deep phenotyping of 14 new patients with IQSEC2
variants, including monozygotic twins of discordant phenotype. Clin Genet 2019; 95:496-506. [PMID: 30666632 DOI: 10.1111/cge.13507] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 01/09/2019] [Accepted: 01/11/2019] [Indexed: 01/22/2023]
Affiliation(s)
- Jessica A. Radley
- West Midlands Regional Clinical Genetics Service and Birmingham Health Partners; Birmingham Women's and Children's Hospitals NHS Foundation Trust; Birmingham UK
| | | | - Sarah E. Turton
- West Midlands Regional Genetics Laboratory Birmingham Women's and Children's Hospitals NHS Foundation Trust; Birmingham UK
| | - Helen Cox
- West Midlands Regional Clinical Genetics Service and Birmingham Health Partners; Birmingham Women's and Children's Hospitals NHS Foundation Trust; Birmingham UK
| | - Julie Vogt
- West Midlands Regional Clinical Genetics Service and Birmingham Health Partners; Birmingham Women's and Children's Hospitals NHS Foundation Trust; Birmingham UK
| | - Jenny Morton
- West Midlands Regional Clinical Genetics Service and Birmingham Health Partners; Birmingham Women's and Children's Hospitals NHS Foundation Trust; Birmingham UK
| | - Elizabeth Jones
- Manchester Centre for Genomic Medicine, Manchester University Hospitals NHS Foundation Trust; Manchester UK
- Division of Evolution and Genomic Sciences, School of Biological Sciences; University of Manchester; Manchester UK
| | - Sarah Smithson
- University Hospitals Bristol NHS Foundation Trust; Clinical Genetics, St. Michael's Hospital; Bristol UK
| | - Katherine Lachlan
- Wessex Clinical Genetics Service; University Hospitals of Southampton NHS Trust; Southampton UK
| | - Julia Rankin
- Peninsula Clinical Genetics; Royal Devon and Exeter NHS Trust; Exeter UK
| | - Jill Clayton-Smith
- Manchester Centre for Genomic Medicine, Manchester University Hospitals NHS Foundation Trust; Manchester UK
- Division of Evolution and Genomic Sciences, School of Biological Sciences; University of Manchester; Manchester UK
| | - Josh Willoughby
- Sheffield Diagnostic Genetics Service; Sheffield Children's NHS Foundation Trust; Sheffield UK
| | - Frances F. Elmslie
- South West Thames Regional Genetics Service; St George's University Hospitals NHS Foundation Trust; London UK
| | - Francis H. Sansbury
- University Hospitals Bristol NHS Foundation Trust; Clinical Genetics, St. Michael's Hospital; Bristol UK
- All Wales Medical Genetics Service, Cardiff and Vale University Health Board, Institute of Medical Genetics; University Hospital of Wales; Cardiff UK
| | - Nicola Cooper
- West Midlands Regional Clinical Genetics Service and Birmingham Health Partners; Birmingham Women's and Children's Hospitals NHS Foundation Trust; Birmingham UK
| | - Meena Balasubramanian
- Sheffield Clinical Genetics Service; Sheffield Children's NHS Foundation Trust; Sheffield UK
- Academic Unit of Child Health, Department of Oncology and Metabolism; University of Sheffield; Sheffield UK
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36
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Rogers EJ, Jada R, Schragenheim-Rozales K, Sah M, Cortes M, Florence M, Levy NS, Moss R, Walikonis RS, Palty R, Shalgi R, Lichtman D, Kavushansky A, Gerges NZ, Kahn I, Umanah GKE, Levy AP. An IQSEC2 Mutation Associated With Intellectual Disability and Autism Results in Decreased Surface AMPA Receptors. Front Mol Neurosci 2019; 12:43. [PMID: 30842726 PMCID: PMC6391579 DOI: 10.3389/fnmol.2019.00043] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Accepted: 02/01/2019] [Indexed: 12/30/2022] Open
Abstract
We have recently described an A350V mutation in IQSEC2 associated with intellectual disability, autism and epilepsy. We sought to understand the molecular pathophysiology of this mutation with the goal of developing targets for drug intervention. We demonstrate here that the A350V mutation results in interference with the binding of apocalmodulin to the IQ domain of IQSEC2. We further demonstrate that this mutation results in constitutive activation of the guanine nucleotide exchange factor (GEF) activity of IQSEC2 resulting in increased production of the active form of Arf6. In a CRISPR generated mouse model of the A350V IQSEC2 mutation, we demonstrate that the surface expression of GluA2 AMPA receptors in mouse hippocampal tissue was significantly reduced in A350V IQSEC2 mutant mice compared to wild type IQSEC2 mice and that there is a significant reduction in basal synaptic transmission in the hippocampus of A350V IQSEC2 mice compared to wild type IQSEC2 mice. Finally, the A350V IQSEC2 mice demonstrated increased activity, abnormal social behavior and learning as compared to wild type IQSEC2 mice. These findings suggest a model of how the A350V mutation in IQSEC2 may mediate disease with implications for targets for drug therapy. These studies provide a paradigm for a personalized approach to precision therapy for a disease that heretofore has no therapy.
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Affiliation(s)
- Eli J Rogers
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | - Reem Jada
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | | | - Megha Sah
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, United States
| | - Marisol Cortes
- Department of Neurology, Johns Hopkins University, Baltimore, MD, United States
| | - Matthew Florence
- Department of Biopharmaceutical Sciences and Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Nina S Levy
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | - Rachel Moss
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | - Randall S Walikonis
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, United States
| | - Raz Palty
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | - Reut Shalgi
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | - Daniela Lichtman
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | - Alexandra Kavushansky
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | - Nashaat Z Gerges
- Department of Biopharmaceutical Sciences and Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Itamar Kahn
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | - George K E Umanah
- Department of Neurology, Johns Hopkins University, Baltimore, MD, United States
| | - Andrew P Levy
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
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