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Markus F, Kannengießer A, Näder P, Atigbire P, Scholten A, Vössing C, Bültmann E, Korenke GC, Owczarek-Lipska M, Neidhardt J. A novel missense variant in the EML1 gene associated with bilateral ribbon-like subcortical heterotopia leads to ciliary defects. J Hum Genet 2021; 66:1159-1167. [PMID: 34211111 PMCID: PMC8612930 DOI: 10.1038/s10038-021-00947-5] [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: 03/08/2021] [Revised: 06/01/2021] [Accepted: 06/02/2021] [Indexed: 02/06/2023]
Abstract
Heterotopia is a brain malformation caused by a failed migration of cortical neurons during development. Clinical symptoms of heterotopia vary in severity of intellectual disability and may be associated with epileptic disorders. Abnormal neuronal migration is known to be associated with mutations in the doublecortin gene (DCX), the platelet-activating factor acetylhydrolase gene (PAFAH1B1), or tubulin alpha-1A gene (TUBA1A). Recently, a new gene encoding echinoderm microtubule-associated protein-like 1 (EML1) was reported to cause a particular form of subcortical heterotopia, the ribbon-like subcortical heterotopia (RSH). EML1 mutations are inherited in an autosomal recessive manner. Only six unrelated EML1-associated heterotopia-affected families were reported so far. The EML1 protein is a member of the microtubule-associated proteins family, playing an important role in microtubule assembly and stabilization as well as in mitotic spindle formation in interphase. Herein, we present a novel homozygous missense variant in EML1 (NM_004434.2: c.692G>A, NP_004425.2: p.Gly231Asp) identified in a male RSH-affected patient. Our clinical and molecular findings confirm the genotype-phenotype associations of EML1 mutations and RSH. Analyses of patient-derived fibroblasts showed the significantly reduced length of primary cilia. In addition, our results presented, that the mutated EML1 protein did not change binding capacities with tubulin. The data described herein will expand the mutation spectrum of the EML1 gene and provide further insight into molecular and cellular bases of the pathogenic mechanisms underlying RSH.
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Affiliation(s)
- Fenja Markus
- grid.5560.60000 0001 1009 3608Junior Research Group, Genetics of Childhood Brain Malformations, Faculty VI-School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany ,grid.5560.60000 0001 1009 3608Human Genetics, Faculty VI-School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany
| | - Annika Kannengießer
- grid.5560.60000 0001 1009 3608Junior Research Group, Genetics of Childhood Brain Malformations, Faculty VI-School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany ,grid.5560.60000 0001 1009 3608Human Genetics, Faculty VI-School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany
| | - Patricia Näder
- grid.5560.60000 0001 1009 3608Human Genetics, Faculty VI-School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany
| | - Paul Atigbire
- grid.5560.60000 0001 1009 3608Human Genetics, Faculty VI-School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany
| | - Alexander Scholten
- grid.5560.60000 0001 1009 3608Division of Biochemistry, Biochemistry of signal transduction/neurosensory processes, Faculty VI-School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany
| | - Christine Vössing
- grid.5560.60000 0001 1009 3608Human Genetics, Faculty VI-School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany
| | - Eva Bültmann
- grid.10423.340000 0000 9529 9877Institute of Diagnostic and Interventional Neuroradiology, Hannover Medical School, Hannover, Germany
| | - G. Christoph Korenke
- grid.419838.f0000 0000 9806 6518Department of Neuropediatrics, University Children’s Hospital, Klinikum Oldenburg, Oldenburg, Germany
| | - Marta Owczarek-Lipska
- grid.5560.60000 0001 1009 3608Junior Research Group, Genetics of Childhood Brain Malformations, Faculty VI-School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany ,grid.5560.60000 0001 1009 3608Human Genetics, Faculty VI-School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany ,grid.5560.60000 0001 1009 3608Research Center Neurosensory Science, University of Oldenburg, Oldenburg, Germany
| | - John Neidhardt
- grid.5560.60000 0001 1009 3608Human Genetics, Faculty VI-School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany ,grid.5560.60000 0001 1009 3608Research Center Neurosensory Science, University of Oldenburg, Oldenburg, Germany
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Oegema R, McGillivray G, Leventer R, Le Moing AG, Bahi-Buisson N, Barnicoat A, Mandelstam S, Francis D, Francis F, Mancini GMS, Savelberg S, van Haaften G, Mankad K, Lequin MH. EML1-associated brain overgrowth syndrome with ribbon-like heterotopia. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2019; 181:627-637. [PMID: 31710781 PMCID: PMC6916563 DOI: 10.1002/ajmg.c.31751] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/21/2019] [Revised: 09/23/2019] [Accepted: 10/09/2019] [Indexed: 01/17/2023]
Abstract
EML1 encodes the protein Echinoderm microtubule-associated protein-like 1 or EMAP-1 that binds to the microtubule complex. Mutations in this gene resulting in complex brain malformations have only recently been published with limited clinical descriptions. We provide further clinical and imaging details on three previously published families, and describe two novel unrelated individuals with a homozygous partial EML1 deletion and a homozygous missense variant c.760G>A, p.(Val254Met), respectively. From review of the clinical and imaging data of eight individuals from five families with biallelic EML1 variants, a very consistent imaging phenotype emerges. The clinical syndrome is characterized by mainly neurological features including severe developmental delay, drug-resistant seizures and visual impairment. On brain imaging there is megalencephaly with a characteristic ribbon-like subcortical heterotopia combined with partial or complete callosal agenesis and an overlying polymicrogyria-like cortical malformation. Several of its features can be recognized on prenatal imaging especially the abnormaly formed lateral ventricles, hydrocephalus (in half of the cases) and suspicion of a neuronal migration disorder. In conclusion, biallelic EML1 disease-causing variants cause a highly specific pattern of congenital brain malformations, severe developmental delay, seizures and visual impairment.
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Affiliation(s)
- Renske Oegema
- Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - George McGillivray
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Australia
| | - Richard Leventer
- Department of Neurology, Royal Children's Hospital, Murdoch Children's Research Institute and, University of Melbourne Department of Pediatrics, Melbourne, Australia.,Department of Pediatrics, University of Melbourne, Melbourne, Australia
| | | | - Nadia Bahi-Buisson
- Université Paris Descartes, Sorbonne Paris Cités, Paris, France.,Embryology and genetics of congenital malformations, Institut Imagine-INSERM, Paris, France.,Pediatric Neurology, Necker Enfants Malades Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Angela Barnicoat
- Department of Clinical Genetics, Great Ormond Street Hospital, London, UK
| | - Simone Mandelstam
- Royal Children's Hospital, Department of Pediatrics, University of Melbourne, Murdoch Children's Research Institute, Melbourne, Australia.,Royal Children's Hospital, Department of Radiology, University of Melbourne, Murdoch Children's Research Institute, Melbourne, Australia
| | - David Francis
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Australia
| | - Fiona Francis
- INSERM U 1270, Paris, France.,Sorbonne Université, UMR-S 1270, Paris, France.,Institut du Fer à Moulin, Paris, France
| | - Grazia M S Mancini
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Sanne Savelberg
- Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Gijs van Haaften
- Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Kshitij Mankad
- Department of Radiology, Great Ormond Street Hospital, London, UK
| | - Maarten H Lequin
- Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands
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Abstract
Mutations causing dysfunction of the tubulins and microtubule-associated proteins, otherwise known as tubulinopathies, are a group of recently described entities, that lead to complex brain malformations. An understanding of the fundamental principles of operation of the cytoskeleton and compounds in particular microtubules, actin, and microtubule-associated proteins, can assist in the interpretation of the imaging findings of tubulinopathies. Somewhat consistent morphological imaging patterns have been described in tubulinopathies such as dysmorphic basal ganglia-the hallmark (found in 75% of cases), callosal dysgenesis, cerebellar hypoplasia/dysplasia, and cortical malformations, most notably lissencephaly. Recognizing the common imaging phenotypes present in tubulinopathies can prove invaluable in directing the genetic workup for a patient with brain malformations.
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