title: Spatial Discrimination Threshold Abnormalities are not Detected in a Pilot Study of DYT6 Dystonia Mutation Carriers.
abstract: BACKGROUND
  Spatial discrimination thresholds (SDTs) assess somatosensory integration, and provide a window into better understanding the pathophysiology of dystonia. They are abnormal in some focal dystonias, but normal in DYT1 dystonia. It is unknown whether SDTs are altered in DYT6 gene mutation carriers (C).
  
  
  METHODS
  SDTs were assessed in 17 DYT6 C (including eight manifesting carriers), 15 DYT1 C (including seven manifesting carriers) and 34 controls, using a standardized grating orientation task. Subjects were asked to recognize the orientation of Johnson-Van Boven-Philips (JVP) dome gratings on either index fingertip until 40% or more answers were incorrect. SDTs between indexes were calculated and averaged, with a final SDT assigned to each subject, and tertiles for control SDTs were constructed.
  
  
  RESULTS
  SDTs of DYT6 C or DYT1 C were comparable to those of controls, and not more likely to be in the worst tertile (p = 0.8 for DYT6 C vs. controls and p = 1.0 for DYT1 C vs. controls). This was independent of gene expression.
  
  
  CONCLUSIONS
  DYT6 carriers do not have impaired SDTs with the JVP dome paradigm. The normal SDT pattern thus suggests shared sensory physiologic patterns with DYT1 dystonia.
authors: Department of Neurology, Beth Israel Medical Center, New York, New York, United States of America.
authors: Andres F
authors: AF
authors: Deik
authors: Sean
authors: S
authors: O'Riordan
authors: Marta San
authors: MS
authors: Luciano
authors: Vicki L
authors: VL
authors: Shanker
authors: Deborah
authors: D
authors: Raymond
authors: Susan B
authors: SB
authors: Bressman
authors: Rachel
authors: R
authors: Saunders-Pullman
keywords: DYT1; DYT6; dystonia; sensory discrimination threshold