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Gyening YK, Boris K, Cyril M, Brush RS, Nassogne MC, Agbaga MP. A novel ELOVL4 variant, L168S, causes early childhood-onset Spinocerebellar ataxia-34 and retinal dysfunction: a case report. Acta Neuropathol Commun 2023; 11:131. [PMID: 37568198 PMCID: PMC10416515 DOI: 10.1186/s40478-023-01628-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 07/22/2023] [Indexed: 08/13/2023] Open
Abstract
Spinocerebellar ataxia 34 (SCA34) is an autosomal dominant inherited disease characterized by age-related cerebellar degeneration and ataxia caused by mutations in the Elongation of Very Long Chain Fatty Acid-4 (ELOVL4) gene. The ELOVL4 enzyme catalyzes the biosynthesis of both very long chain saturated fatty acids (VLC-SFA) and very long chain polyunsaturated fatty acids (VLC-PUFA) that are important for neuronal, reproductive, and skin function. Several variants in ELOVL4 have been shown to cause different tissue-specific disorders including SCA34 with or without Erythrokeratodermia Variabilis (EKV), a skin condition characterized by dry, scaly skin, Autosomal Dominant Stargardt-Like Macular Dystrophy (STGD3), and seizures associated with neuro-ichthyotic disorders. What is puzzling is how different mutations in the same gene seem to cause different tissue-specific disorders. To date, no SCA34 patients have presented with both SCA34 and STGD3 pathology that is caused by ELOVL4 variants that cause truncation of ELOVL4. Here, we report a novel case of an early childhood onset and rapidly progressive cerebellar degeneration and retinal dysfunction in a Belgian-Italian girl who developed severe dysarthria and gait problems starting at about 3.5 years of age and progressed to immobility by 4.5 years of age. Brain magnetic resonance imaging (MRI) revealed progressive vermian, cerebellar, cortical atrophy, progressive corpus callosum slimming, and hot cross bun sign visible on the MRI. Ophthalmological examinations also revealed progressive macular dysfunction as measured by electroretinography. Using exome sequencing, we identified a novel heterozygous ELOVL4 variant, c.503 T > C (p. L168S) in the patient. To understand the enzymatic function of this novel ELOVL4 variant and how it alters the levels of VLC-PUFA and VLC-SFA biosynthesis to contribute to cerebellar and retinal dysfunction, we expressed wild-type ELOVL4 or the L168S ELOVL4 variant in cell culture and supplemented the cultures with VLC-PUFA or VLC-SFA precursors. We showed that the L168S ELOVL4 variant is deficient in the biosynthesis of VLC-SFA and VLC-PUFA. Our work suggests that differential depletion of these fatty acids may be a contributing factor to the pathogenic mechanism of SCA34 with or without EKV. Further studies will help further define how the different ELOVL4 variants cause different tissue-specific disorders with variable ages of onset.
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Affiliation(s)
- Yeboah Kofi Gyening
- Department of Cell Biology, University of Oklahoma Health Sciences Center, DMEI 423 Parke Pavilion, 608 Stanton L. Young Boulevard, Oklahoma City, OK, 73104, USA
- Department of Ophthalmology and Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, USA
- Unité Déficiences Intellectuelles/Troubles du, Développement, Service de Génétique Clinique et Médicale, AP-HP. Sorbonne Université -Hôpital de La Pitié-Salpêtrière, Paris, France
| | - Keren Boris
- UF de Génomique du Développement, Centre de Génétique Moléculaire et Chromosomique, AP-HP.Sorbonne Université - Hôpital de La Pitié-Salpêtrière, Paris, France
- Unité Déficiences Intellectuelles/Troubles du, Développement, Service de Génétique Clinique et Médicale, AP-HP. Sorbonne Université -Hôpital de La Pitié-Salpêtrière, Paris, France
| | - Mignot Cyril
- Unité Déficiences Intellectuelles/Troubles du, Développement, Service de Génétique Clinique et Médicale, AP-HP. Sorbonne Université -Hôpital de La Pitié-Salpêtrière, Paris, France
- Centre de Référence des Maladies Héréditaires du Métabolisme - Service de NeurologiePédiatrique, Cliniques Universitaires Saint-Luc -UCLouvain, Avenue Hippocrate, 10, 1200, Brussels, Belgium
| | - Richard S Brush
- Department of Cell Biology, University of Oklahoma Health Sciences Center, DMEI 423 Parke Pavilion, 608 Stanton L. Young Boulevard, Oklahoma City, OK, 73104, USA
- Department of Ophthalmology and Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, USA
- Unité Déficiences Intellectuelles/Troubles du, Développement, Service de Génétique Clinique et Médicale, AP-HP. Sorbonne Université -Hôpital de La Pitié-Salpêtrière, Paris, France
| | - Marie-Cécile Nassogne
- Centre de Référence des Maladies Héréditaires du Métabolisme - Service de NeurologiePédiatrique, Cliniques Universitaires Saint-Luc -UCLouvain, Avenue Hippocrate, 10, 1200, Brussels, Belgium.
| | - Martin-Paul Agbaga
- Department of Cell Biology, University of Oklahoma Health Sciences Center, DMEI 423 Parke Pavilion, 608 Stanton L. Young Boulevard, Oklahoma City, OK, 73104, USA.
- Department of Ophthalmology and Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, USA.
- Unité Déficiences Intellectuelles/Troubles du, Développement, Service de Génétique Clinique et Médicale, AP-HP. Sorbonne Université -Hôpital de La Pitié-Salpêtrière, Paris, France.
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Agbaga MP. Different Mutations in ELOVL4 Affect Very Long Chain Fatty Acid Biosynthesis to Cause Variable Neurological Disorders in Humans. Adv Exp Med Biol 2016; 854:129-35. [PMID: 26427403 DOI: 10.1007/978-3-319-17121-0_18] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
All mammalian cell membranes are characterized by amphipathic lipid molecules that interact with proteins to confer structural and functional properties on the cell. The predominant lipid species are phospholipids, glycolipids, sphingolipids and cholesterol. These lipids contain fatty acids with variable hydrocarbon chain lengths between C14-C40, either saturated or unsaturated, that are derived from diet, synthesized de novo, or elongated from shorter chain fatty acids by fatty acid elongase enzymes. One member of the family of elongases, ELOngation of Very Long chain fatty acids-4 (ELOVL4), mediates the biosynthesis of both saturated and unsaturated very long chain fatty acids (VLC-FA; > C26) in the retina, meibomian gland, brain, skin, and testis. Different mutations in ELOVL4 cause tissue-specific maculopathy and/or neuro-ichthyotic disorders. The goal of this mini-review is to highlight how different mutations in ELOVL4 can cause variable phenotypic disorder, and propose a possible mechanism, based on the role of fatty acids in membranes, which could explain the different phenotypes.
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Affiliation(s)
- Martin-Paul Agbaga
- Department of Ophthalmology, Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd., DMEI 429PB, 73104, Oklahoma City, OK, USA.
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