title: Reduced ceramide synthase 2 activity causes progressive myoclonic epilepsy.
abstract: OBJECTIVE
  Ceramides are precursors of complex sphingolipids (SLs), which are important for normal functioning of both the developing and mature brain. Altered SL levels have been associated with many neurodegenerative disorders, including epilepsy, although few direct links have been identified between genes involved in SL metabolism and epilepsy.
  
  
  METHODS
  We used quantitative real-time PCR, Western blotting, and enzymatic assays to determine the mRNA, protein, and activity levels of ceramide synthase 2 (CERS2) in fiibroblasts isolated from parental control subjects and from a patient diagnosed with progressive myoclonic epilepsy (PME). Mass spectrometry and fluorescence microscopy were used to examine the effects of reduced CERS2 activity on cellular lipid composition and plasma membrane functions.
  
  
  RESULTS
  We identify a novel 27 kb heterozygous deletion including the CERS2 gene in a proband diagnosed with PME. Compared to parental controls, levels of CERS2 mRNA, protein, and activity were reduced by ˜50% in fibroblasts isolated from this proband, resulting in significantly reduced levels of ceramides and sphingomyelins containing the very long-chain fatty acids C24:0 and C26:0. The change in SL composition was also reflected in a reduction in cholera toxin B immunofluorescence, indicating that membrane composition and function are altered.
  
  
  CONCLUSIONS
  We propose that reduced levels of CERS2, and consequently diminished levels of ceramides and SLs containing very long-chain fatty acids, lead to development of PME.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Southern Denmark Odense M, DK-5230, Denmark.
authors.forename: Mai-Britt
authors.initials: MB
authors.lastname: Mosbech
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Southern Denmark Odense M, DK-5230, Denmark.
authors.forename: Anne S B
authors.initials: AS
authors.lastname: Olsen
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Southern Denmark Odense M, DK-5230, Denmark.
authors.forename: Ditte
authors.initials: D
authors.lastname: Neess
authors.affiliation: Department of Biological Chemistry, Weizmann Institute of Science Rehovot, 76100, Israel.
authors.forename: Oshrit
authors.initials: O
authors.lastname: Ben-David
authors.affiliation: The Danish Epilepsy Centre, Filadelfia Dianalund, DK-4293, Denmark.
authors.forename: Laura L
authors.initials: LL
authors.lastname: Klitten
authors.affiliation: The Danish Epilepsy Centre, Filadelfia Dianalund, DK-4293, Denmark ; Department of Cellular and Molecular Medicine, The Panum Institute, University of Copenhagen Copenhagen, DK-2100, Denmark.
authors.forename: Jan
authors.initials: J
authors.lastname: Larsen
authors.affiliation: Department of Neurology, Rigshospitalet, University of Copenhagen Copenhagen, DK-2100, Denmark.
authors.forename: Anne
authors.initials: A
authors.lastname: Sabers
authors.affiliation: Department of Neurology, Rigshospitalet, University of Copenhagen Copenhagen, DK-2100, Denmark.
authors.forename: John
authors.initials: J
authors.lastname: Vissing
authors.affiliation: Neurogenetics Clinic, Danish Dementia Research Centre, Department of Neurology, Rigshospitalet, Copenhagen University Hospital Copenhagen, DK-2100, Denmark.
authors.forename: Jørgen E
authors.initials: JE
authors.lastname: Nielsen
authors.affiliation: Department of Cellular and Molecular Medicine, The Panum Institute, University of Copenhagen Copenhagen, DK-2100, Denmark.
authors.forename: Lis
authors.initials: L
authors.lastname: Hasholt
authors.affiliation: Department of Biological Chemistry, Weizmann Institute of Science Rehovot, 76100, Israel.
authors.forename: Andres D
authors.initials: AD
authors.lastname: Klein
authors.affiliation: Behavioral and Physiological Phenotyping Unit, Department of Veterinary Resources, Weizmann Institute of Science Rehovot, 76100, Israel.
authors.forename: Michael M
authors.initials: MM
authors.lastname: Tsoory
authors.affiliation: The Danish Epilepsy Centre, Filadelfia Dianalund, DK-4293, Denmark ; Institute for Regional Health Services, University of Southern Denmark Odense, Denmark.
authors.forename: Helle
authors.initials: H
authors.lastname: Hjalgrim
authors.affiliation: Department of Cellular and Molecular Medicine, The Panum Institute, University of Copenhagen Copenhagen, DK-2100, Denmark.
authors.forename: Niels
authors.initials: N
authors.lastname: Tommerup
authors.affiliation: Department of Biological Chemistry, Weizmann Institute of Science Rehovot, 76100, Israel.
authors.forename: Anthony H
authors.initials: AH
authors.lastname: Futerman
authors.affiliation: The Danish Epilepsy Centre, Filadelfia Dianalund, DK-4293, Denmark ; Institute for Regional Health Services, University of Southern Denmark Odense, Denmark.
authors.forename: Rikke S
authors.initials: RS
authors.lastname: Møller
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Southern Denmark Odense M, DK-5230, Denmark.
authors.forename: Nils J
authors.initials: NJ
authors.lastname: Færgeman