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Naruse H, Ishiura H, Esaki K, Mitsui J, Satake W, Greimel P, Shingai N, Machino Y, Kokubo Y, Hamaguchi H, Oda T, Ikkaku T, Yokota I, Takahashi Y, Suzuki Y, Matsukawa T, Goto J, Koh K, Takiyama Y, Morishita S, Yoshikawa T, Tsuji S, Toda T. SPTLC2 variants are associated with early-onset ALS and FTD due to aberrant sphingolipid synthesis. Ann Clin Transl Neurol 2024; 11:946-957. [PMID: 38316966 PMCID: PMC11021611 DOI: 10.1002/acn3.52013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2023] [Revised: 01/02/2024] [Accepted: 01/20/2024] [Indexed: 02/07/2024] Open
Abstract
OBJECTIVE Amyotrophic lateral sclerosis (ALS) is a devastating, incurable neurodegenerative disease. A subset of ALS patients manifests with early-onset and complex clinical phenotypes. We aimed to elucidate the genetic basis of these cases to enhance our understanding of disease etiology and facilitate the development of targeted therapies. METHODS Our research commenced with an in-depth genetic and biochemical investigation of two specific families, each with a member diagnosed with early-onset ALS (onset age of <40 years). This involved whole-exome sequencing, trio analysis, protein structure analysis, and sphingolipid measurements. Subsequently, we expanded our analysis to 62 probands with early-onset ALS and further included 440 patients with adult-onset ALS and 1163 healthy controls to assess the prevalence of identified genetic variants. RESULTS We identified heterozygous variants in the serine palmitoyltransferase long chain base subunit 2 (SPTLC2) gene in patients with early-onset ALS. These variants, located in a region closely adjacent to ORMDL3, bear similarities to SPTLC1 variants previously implicated in early-onset ALS. Patients with ALS carrying these SPTLC2 variants displayed elevated plasma ceramide levels, indicative of increased serine palmitoyltransferase (SPT) activity leading to sphingolipid overproduction. INTERPRETATION Our study revealed novel SPTLC2 variants in patients with early-onset ALS exhibiting frontotemporal dementia. The combination of genetic evidence and the observed elevation in plasma ceramide levels establishes a crucial link between dysregulated sphingolipid metabolism and ALS pathogenesis. These findings expand our understanding of ALS's genetic diversity and highlight the distinct roles of gene defects within SPT subunits in its development.
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Affiliation(s)
- Hiroya Naruse
- Department of Neurology, Graduate School of MedicineThe University of TokyoTokyoJapan
- Department of Precision Medicine Neurology, Graduate School of MedicineThe University of TokyoTokyoJapan
| | - Hiroyuki Ishiura
- Department of Neurology, Graduate School of MedicineThe University of TokyoTokyoJapan
- Department of NeurologyOkayama University Graduate School of Medicine, Dentistry and Pharmaceutical SciencesOkayamaJapan
| | - Kayoko Esaki
- Department of Biotechnology and Life Sciences, Faculty of Biotechnology and Life SciencesSojo UniversityKumamotoJapan
| | - Jun Mitsui
- Department of Neurology, Graduate School of MedicineThe University of TokyoTokyoJapan
- Department of Precision Medicine Neurology, Graduate School of MedicineThe University of TokyoTokyoJapan
| | - Wataru Satake
- Department of Neurology, Graduate School of MedicineThe University of TokyoTokyoJapan
| | - Peter Greimel
- Laboratory for Cell Function Dynamics, RIKEN Centre for Brain SciencesWakoSaitamaJapan
| | - Nanoka Shingai
- Division of Applied Life Science, Graduate School of EngineeringSojo UniversityKumamotoJapan
| | - Yuka Machino
- Department of NeurologyNational Hospital Organization Mie National HospitalTsuMieJapan
| | - Yasumasa Kokubo
- Kii ALS/PDC Research Center, Graduate School of Regional Innovation StudiesMie UniversityTsuMieJapan
| | | | - Tetsuya Oda
- Department of NeurologyKita‐Harima Medical CenterOnoHyogoJapan
| | - Tomoko Ikkaku
- Division of NeurologyKobe University Graduate School of MedicineKobeHyogoJapan
- Department of NeurologyHyogo Prefectural Rehabilitation Central HospitalKobeHyogoJapan
| | - Ichiro Yokota
- Division of NeurologyKobe University Graduate School of MedicineKobeHyogoJapan
- Department of NeurologyNational Hospital Organization Hyogo‐Chuo National HospitalSandaHyogoJapan
| | - Yuji Takahashi
- Department of NeurologyNational Center Hospital, National Center of Neurology and PsychiatryTokyoJapan
| | - Yuta Suzuki
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier SciencesThe University of TokyoChibaJapan
| | - Takashi Matsukawa
- Department of Neurology, Graduate School of MedicineThe University of TokyoTokyoJapan
| | - Jun Goto
- Department of NeurologyInternational University of Health and Welfare Ichikawa HospitalChibaJapan
| | - Kishin Koh
- Department of Neurology, Graduate School of Medical SciencesUniversity of YamanashiYamanashiJapan
- Department of NeurologyYumura Onsen HospitalYamanashiJapan
| | - Yoshihisa Takiyama
- Department of Neurology, Graduate School of Medical SciencesUniversity of YamanashiYamanashiJapan
- Department of NeurologyFuefuki Central HospitalYamanashiJapan
| | - Shinichi Morishita
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier SciencesThe University of TokyoChibaJapan
| | - Takeo Yoshikawa
- Laboratory of Molecular Psychiatry, RIKEN Center for Brain ScienceWakoSaitamaJapan
| | - Shoji Tsuji
- Department of Neurology, Graduate School of MedicineThe University of TokyoTokyoJapan
- Institute of Medical GenomicsInternational University of Health and WelfareChibaJapan
| | - Tatsushi Toda
- Department of Neurology, Graduate School of MedicineThe University of TokyoTokyoJapan
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Syeda SB, Lone MA, Mohassel P, Donkervoort S, Munot P, França MC, Galarza-Brito JE, Eckenweiler M, Asamoah A, Gable K, Majumdar A, Schumann A, Gupta SD, Lakhotia A, Shieh PB, Foley AR, Jackson KE, Chao KR, Winder TL, Catapano F, Feng L, Kirschner J, Muntoni F, Dunn TM, Hornemann T, Bönnemann CG. Recurrent de novo SPTLC2 variant causes childhood-onset amyotrophic lateral sclerosis (ALS) by excess sphingolipid synthesis. J Neurol Neurosurg Psychiatry 2024; 95:103-113. [PMID: 38041679 PMCID: PMC10850718 DOI: 10.1136/jnnp-2023-332132] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Accepted: 09/27/2023] [Indexed: 12/03/2023]
Abstract
BACKGROUND Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease of the upper and lower motor neurons with varying ages of onset, progression and pathomechanisms. Monogenic childhood-onset ALS, although rare, forms an important subgroup of ALS. We recently reported specific SPTLC1 variants resulting in sphingolipid overproduction as a cause for juvenile ALS. Here, we report six patients from six independent families with a recurrent, de novo, heterozygous variant in SPTLC2 c.778G>A [p.Glu260Lys] manifesting with juvenile ALS. METHODS Clinical examination of the patients along with ancillary and genetic testing, followed by biochemical investigation of patients' blood and fibroblasts, was performed. RESULTS All patients presented with early-childhood-onset progressive weakness, with signs and symptoms of upper and lower motor neuron degeneration in multiple myotomes, without sensory neuropathy. These findings were supported on ancillary testing including nerve conduction studies and electromyography, muscle biopsies and muscle ultrasound studies. Biochemical investigations in plasma and fibroblasts showed elevated levels of ceramides and unrestrained de novo sphingolipid synthesis. Our studies indicate that SPTLC2 variant [c.778G>A, p.Glu260Lys] acts distinctly from hereditary sensory and autonomic neuropathy (HSAN)-causing SPTLC2 variants by causing excess canonical sphingolipid biosynthesis, similar to the recently reported SPTLC1 ALS associated pathogenic variants. Our studies also indicate that serine supplementation, which is a therapeutic in SPTLC1 and SPTCL2-associated HSAN, is expected to exacerbate the excess sphingolipid synthesis in serine palmitoyltransferase (SPT)-associated ALS. CONCLUSIONS SPTLC2 is the second SPT-associated gene that underlies monogenic, juvenile ALS and further establishes alterations of sphingolipid metabolism in motor neuron disease pathogenesis. Our findings also have important therapeutic implications: serine supplementation must be avoided in SPT-associated ALS, as it is expected to drive pathogenesis further.
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Affiliation(s)
- Safoora B Syeda
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Museer A Lone
- Institute of Clinical Chemistry, University Hospital Zürich, Zürich, Switzerland
| | - Payam Mohassel
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Sandra Donkervoort
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Pinki Munot
- NIHR Great Ormond Street Hospital Biomedical Research Centre, London, UK
| | - Marcondes C França
- Department of Neurology, University of Campinas, Campinas, Sao Paulo, Brazil
| | | | - Matthias Eckenweiler
- Department of Neuropediatrics and Muscle Disorders, Faculty of Medicine, Medical Center, University of Freiburg, Freiburg, Germany
| | - Alexander Asamoah
- Norton Children's Medical Group, University of Louisville School of Medicine, Louisville, KY, USA
| | - Kenneth Gable
- Department of Biochemistry and Molecular Biology, Uniformed Services University, Bethesda, Maryland, USA
| | - Anirban Majumdar
- Department of Paediatric Neurology, Bristol Children's Hospital, Bristol, UK
| | - Anke Schumann
- Department of Paediatrics and Adolescent Medicine, Faculty of Medicine, Medical Centre, University of Freiburg, Baden-Württemberg, Germany
| | - Sita D Gupta
- Department of Biochemistry and Molecular Biology, Uniformed Services University, Bethesda, Maryland, USA
| | - Arpita Lakhotia
- Norton Children's Medical Group, University of Louisville School of Medicine, Louisville, KY, USA
- University of Louisville, Louisville, Kentucky, USA
| | - Perry B Shieh
- Department of Neurology and Pediatrics, University of California Los Angeles, Los Angeles, CA, USA
| | - A Reghan Foley
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Kelly E Jackson
- Norton Children's Medical Group, University of Louisville School of Medicine, Louisville, KY, USA
| | - Katherine R Chao
- Center for Mendelian Genomics, Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | | | - Francesco Catapano
- Dubowitz Neuromuscular Centre, CL Great Ormond Street Institute of Child Health and Great Ormond Street Hospital, London, UK
| | - Lucy Feng
- Dubowitz Neuromuscular Centre, CL Great Ormond Street Institute of Child Health and Great Ormond Street Hospital, London, UK
| | - Janbernd Kirschner
- Department of Neuropediatrics and Muscle Disorders, Faculty of Medicine, Medical Center, University of Freiburg, Freiburg, Germany
| | - Francesco Muntoni
- NIHR Great Ormond Street Hospital Biomedical Research Centre, London, UK
- Dubowitz Neuromuscular Centre, CL Great Ormond Street Institute of Child Health and Great Ormond Street Hospital, London, UK
| | - Teresa M Dunn
- Department of Biochemistry and Molecular Biology, Uniformed Services University of Health Sciences, Bethesda, MD, USA
| | - Thorsten Hornemann
- Institute of Clinical Chemistry, University Hospital Zürich, Zürich, Switzerland
| | - Carsten G Bönnemann
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
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Wilson LMQ, Saba S, Li J, Prasov L, Miller JML. Specific Deoxyceramide Species Correlate with Expression of Macular Telangiectasia Type 2 (MacTel2) in a SPTLC2 Carrier HSAN1 Family. Genes (Basel) 2023; 14:931. [PMID: 37107689 PMCID: PMC10137565 DOI: 10.3390/genes14040931] [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: 02/11/2023] [Revised: 04/07/2023] [Accepted: 04/12/2023] [Indexed: 04/29/2023] Open
Abstract
Hereditary sensory and autonomic neuropathy type 1 (HSAN1/HSN1) is a peripheral neuropathy most commonly associated with pathogenic variants in the serine palmitoyltransferase complex (SPTLC1, SPTLC2) genes, which are responsible for sphingolipid biosynthesis. Recent reports have shown that some HSAN1 patients also develop macular telangiectasia type 2 (MacTel2), a retinal neurodegeneration with an enigmatic pathogenesis and complex heritability. Here, we report a novel association of a SPTLC2 c.529A>G p.(Asn177Asp) variant with MacTel2 in a single member of a family that otherwise has multiple members afflicted with HSAN1. We provide correlative data to suggest that the variable penetrance of the HSAN1/MacTel2-overlap phenotype in the proband may be explained by levels of certain deoxyceramide species, which are aberrant intermediates of sphingolipid metabolism. We provide detailed retinal imaging of the proband and his HSAN1+/MacTel2- brothers and suggest mechanisms by which deoxyceramide levels may induce retinal degeneration. This is the first report of HSAN1 vs. HSAN1/MacTel2 overlap patients to comprehensively profile sphingolipid intermediates. The biochemical data here may help shed light on the pathoetiology and molecular mechanisms of MacTel2.
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Affiliation(s)
- Lindsey M. Q. Wilson
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Sadaf Saba
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Jun Li
- Department of Neurology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Lev Prasov
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI 48109, USA
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan Medical School, Ann Arbor, MI 48105, USA
- Cellular and Molecular Biology Program, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Jason M. L. Miller
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan Medical School, Ann Arbor, MI 48105, USA
- Cellular and Molecular Biology Program, University of Michigan Medical School, Ann Arbor, MI 48109, USA
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