title: Electrophysiologic features of SYT2 mutations causing a treatable neuromuscular syndrome.
abstract: OBJECTIVE
  To describe the clinical and electrophysiologic features of synaptotagmin II (SYT2) mutations, a novel neuromuscular syndrome characterized by foot deformities and fatigable ocular and lower limb weakness, and the response to modulators of acetylcholine release.
  
  
  METHODS
  We performed detailed clinical and neurophysiologic assessment in 2 multigenerational families with dominant SYT2 mutations (c.920T>G [p.Asp307Ala] and c.923G>A [p.Pro308Leu]). Serial clinical and electrophysiologic assessments were performed in members of one family treated first with pyridostigmine and then with 3,4-diaminopyridine.
  
  
  RESULTS
  Electrophysiologic testing revealed features indicative of a presynaptic deficit in neurotransmitter release with posttetanic potentiation lasting up to 60 minutes. Treatment with 3,4-diaminopyridine produced both a clinical benefit and an improvement in neuromuscular transmission.
  
  
  CONCLUSIONS
  SYT2 mutations cause a novel and potentially treatable complex presynaptic congenital myasthenic syndrome characterized by motor neuropathy causing lower limb wasting and foot deformities, with reflex potentiation following exercise and a uniquely prolonged period of posttetanic potentiation.
authors.affiliation: From the Institute of Neuroscience (R.G.W., B.A.S.H.) and John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine (B.B., R.M.L., R.H., H.L.), Newcastle University, Newcastle, UK; Department of Neurology (D.N.H., E.L.L., J.E.S.), University of Rochester Medical Center, NY; Department of Neurology (J.L.A.), Dartmouth Hitchcock Clinic, Geisel School of Medicine, Hanover, NH; The Picower Institute for Learning and Memory (J.T.L.), Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA; and Dr. John T. Macdonald Department of Human Genetics and Hussman Institute for Human Genomics (S.Z.), University of Miami, Miller School of Medicine, Miami, FL. Roger.whittaker@newcastle.ac.uk.
authors.forename: Roger G
authors.initials: RG
authors.lastname: Whittaker
authors.affiliation: From the Institute of Neuroscience (R.G.W., B.A.S.H.) and John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine (B.B., R.M.L., R.H., H.L.), Newcastle University, Newcastle, UK; Department of Neurology (D.N.H., E.L.L., J.E.S.), University of Rochester Medical Center, NY; Department of Neurology (J.L.A.), Dartmouth Hitchcock Clinic, Geisel School of Medicine, Hanover, NH; The Picower Institute for Learning and Memory (J.T.L.), Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA; and Dr. John T. Macdonald Department of Human Genetics and Hussman Institute for Human Genomics (S.Z.), University of Miami, Miller School of Medicine, Miami, FL.
authors.forename: David N
authors.initials: DN
authors.lastname: Herrmann
authors.affiliation: From the Institute of Neuroscience (R.G.W., B.A.S.H.) and John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine (B.B., R.M.L., R.H., H.L.), Newcastle University, Newcastle, UK; Department of Neurology (D.N.H., E.L.L., J.E.S.), University of Rochester Medical Center, NY; Department of Neurology (J.L.A.), Dartmouth Hitchcock Clinic, Geisel School of Medicine, Hanover, NH; The Picower Institute for Learning and Memory (J.T.L.), Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA; and Dr. John T. Macdonald Department of Human Genetics and Hussman Institute for Human Genomics (S.Z.), University of Miami, Miller School of Medicine, Miami, FL.
authors.forename: Boglarka
authors.initials: B
authors.lastname: Bansagi
authors.affiliation: From the Institute of Neuroscience (R.G.W., B.A.S.H.) and John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine (B.B., R.M.L., R.H., H.L.), Newcastle University, Newcastle, UK; Department of Neurology (D.N.H., E.L.L., J.E.S.), University of Rochester Medical Center, NY; Department of Neurology (J.L.A.), Dartmouth Hitchcock Clinic, Geisel School of Medicine, Hanover, NH; The Picower Institute for Learning and Memory (J.T.L.), Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA; and Dr. John T. Macdonald Department of Human Genetics and Hussman Institute for Human Genomics (S.Z.), University of Miami, Miller School of Medicine, Miami, FL.
authors.forename: Bashar Awwad Shiekh
authors.initials: BA
authors.lastname: Hasan
authors.affiliation: From the Institute of Neuroscience (R.G.W., B.A.S.H.) and John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine (B.B., R.M.L., R.H., H.L.), Newcastle University, Newcastle, UK; Department of Neurology (D.N.H., E.L.L., J.E.S.), University of Rochester Medical Center, NY; Department of Neurology (J.L.A.), Dartmouth Hitchcock Clinic, Geisel School of Medicine, Hanover, NH; The Picower Institute for Learning and Memory (J.T.L.), Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA; and Dr. John T. Macdonald Department of Human Genetics and Hussman Institute for Human Genomics (S.Z.), University of Miami, Miller School of Medicine, Miami, FL.
authors.forename: Robert Muni
authors.initials: RM
authors.lastname: Lofra
authors.affiliation: From the Institute of Neuroscience (R.G.W., B.A.S.H.) and John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine (B.B., R.M.L., R.H., H.L.), Newcastle University, Newcastle, UK; Department of Neurology (D.N.H., E.L.L., J.E.S.), University of Rochester Medical Center, NY; Department of Neurology (J.L.A.), Dartmouth Hitchcock Clinic, Geisel School of Medicine, Hanover, NH; The Picower Institute for Learning and Memory (J.T.L.), Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA; and Dr. John T. Macdonald Department of Human Genetics and Hussman Institute for Human Genomics (S.Z.), University of Miami, Miller School of Medicine, Miami, FL.
authors.forename: Eric L
authors.initials: EL
authors.lastname: Logigian
authors.affiliation: From the Institute of Neuroscience (R.G.W., B.A.S.H.) and John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine (B.B., R.M.L., R.H., H.L.), Newcastle University, Newcastle, UK; Department of Neurology (D.N.H., E.L.L., J.E.S.), University of Rochester Medical Center, NY; Department of Neurology (J.L.A.), Dartmouth Hitchcock Clinic, Geisel School of Medicine, Hanover, NH; The Picower Institute for Learning and Memory (J.T.L.), Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA; and Dr. John T. Macdonald Department of Human Genetics and Hussman Institute for Human Genomics (S.Z.), University of Miami, Miller School of Medicine, Miami, FL.
authors.forename: Janet E
authors.initials: JE
authors.lastname: Sowden
authors.affiliation: From the Institute of Neuroscience (R.G.W., B.A.S.H.) and John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine (B.B., R.M.L., R.H., H.L.), Newcastle University, Newcastle, UK; Department of Neurology (D.N.H., E.L.L., J.E.S.), University of Rochester Medical Center, NY; Department of Neurology (J.L.A.), Dartmouth Hitchcock Clinic, Geisel School of Medicine, Hanover, NH; The Picower Institute for Learning and Memory (J.T.L.), Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA; and Dr. John T. Macdonald Department of Human Genetics and Hussman Institute for Human Genomics (S.Z.), University of Miami, Miller School of Medicine, Miami, FL.
authors.forename: Jorge L
authors.initials: JL
authors.lastname: Almodovar
authors.affiliation: From the Institute of Neuroscience (R.G.W., B.A.S.H.) and John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine (B.B., R.M.L., R.H., H.L.), Newcastle University, Newcastle, UK; Department of Neurology (D.N.H., E.L.L., J.E.S.), University of Rochester Medical Center, NY; Department of Neurology (J.L.A.), Dartmouth Hitchcock Clinic, Geisel School of Medicine, Hanover, NH; The Picower Institute for Learning and Memory (J.T.L.), Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA; and Dr. John T. Macdonald Department of Human Genetics and Hussman Institute for Human Genomics (S.Z.), University of Miami, Miller School of Medicine, Miami, FL.
authors.forename: J Troy
authors.initials: JT
authors.lastname: Littleton
authors.affiliation: From the Institute of Neuroscience (R.G.W., B.A.S.H.) and John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine (B.B., R.M.L., R.H., H.L.), Newcastle University, Newcastle, UK; Department of Neurology (D.N.H., E.L.L., J.E.S.), University of Rochester Medical Center, NY; Department of Neurology (J.L.A.), Dartmouth Hitchcock Clinic, Geisel School of Medicine, Hanover, NH; The Picower Institute for Learning and Memory (J.T.L.), Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA; and Dr. John T. Macdonald Department of Human Genetics and Hussman Institute for Human Genomics (S.Z.), University of Miami, Miller School of Medicine, Miami, FL.
authors.forename: Stephan
authors.initials: S
authors.lastname: Zuchner
authors.affiliation: From the Institute of Neuroscience (R.G.W., B.A.S.H.) and John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine (B.B., R.M.L., R.H., H.L.), Newcastle University, Newcastle, UK; Department of Neurology (D.N.H., E.L.L., J.E.S.), University of Rochester Medical Center, NY; Department of Neurology (J.L.A.), Dartmouth Hitchcock Clinic, Geisel School of Medicine, Hanover, NH; The Picower Institute for Learning and Memory (J.T.L.), Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA; and Dr. John T. Macdonald Department of Human Genetics and Hussman Institute for Human Genomics (S.Z.), University of Miami, Miller School of Medicine, Miami, FL.
authors.forename: Rita
authors.initials: R
authors.lastname: Horvath
authors.affiliation: From the Institute of Neuroscience (R.G.W., B.A.S.H.) and John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine (B.B., R.M.L., R.H., H.L.), Newcastle University, Newcastle, UK; Department of Neurology (D.N.H., E.L.L., J.E.S.), University of Rochester Medical Center, NY; Department of Neurology (J.L.A.), Dartmouth Hitchcock Clinic, Geisel School of Medicine, Hanover, NH; The Picower Institute for Learning and Memory (J.T.L.), Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA; and Dr. John T. Macdonald Department of Human Genetics and Hussman Institute for Human Genomics (S.Z.), University of Miami, Miller School of Medicine, Miami, FL.
authors.forename: Hanns
authors.initials: H
authors.lastname: Lochmüller
mesh_terms: D015761:4-Aminopyridine / Q000031:analogs & derivatives / Q000494:pharmacology / Q000627:therapeutic use; D000293:Adolescent; D000328:Adult; D000368:Aged; D000077770:Amifampridine; D002648:Child; D055724:Electrophysiological Phenomena; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D020294:Myasthenic Syndromes, Congenital / Q000188:drug therapy / Q000235:genetics / Q000503:physiopathology*; D026902:Potassium Channel Blockers / Q000494:pharmacology / Q000627:therapeutic use; D011729:Pyridostigmine Bromide / Q000494:pharmacology / Q000627:therapeutic use; D012018:Reflex / Q000187:drug effects / Q000502:physiology; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D050861:Synaptotagmin II / Q000235:genetics*; D055815:Young Adult
chemical_list: D026902:Potassium Channel Blockers; C494262:SYT2 protein, human; D050861:Synaptotagmin II; D015761:4-Aminopyridine; D011729:Pyridostigmine Bromide; D000077770:Amifampridine