title: A scan without evidence is not evidence of absence: Scans without evidence of dopaminergic deficit in a symptomatic leucine-rich repeat kinase 2 mutation carrier.
abstract: BACKGROUND
  The basis for SWEDD is unclear, with most cases representing PD mimics but some later developing PD with a dopaminergic deficit.
  
  
  METHODS
  We studied a patient initially diagnosed with SWEDD (based on (18)F-dopa PET) who developed unequivocal PD associated with a leucine-rich repeat kinase 2 p.G2019S mutation. Repeat multitracer PET was performed at 17 years' disease duration, including (+)[11C]dihydrotetrabenazine, [11C](N,N-dimethyl-2-(2-amino-4-cyanophenylthio) benzylamine (which binds the serotonin transporter), and (18)F-dopa.
  
  
  RESULTS
  The patient showed bilateral striatal dopaminergic denervation (right putamen 28% of age-matched normal, left putamen 33%). (18)F-dopa uptake was decreased, particularly on the left (mean 31% of normal vs. 45% on the more affected right side). Serotonin transporter binding was relatively preserved in the putamen (right mean 90% of normal, left 81%) and several cortical regions.
  
  
  CONCLUSIONS
  SWEDD can occur in genetically determined PD and may, in some cases, be the result of compensatory nondopaminergic mechanisms operating in early disease.
authors.affiliation: University of British Columbia, Vancouver, BC, Canada.
authors.forename: Daryl J
authors.initials: DJ
authors.lastname: Wile
authors.affiliation: University of British Columbia, Vancouver, BC, Canada.
authors.forename: Katie
authors.initials: K
authors.lastname: Dinelle
authors.affiliation: University of British Columbia, Vancouver, BC, Canada.
authors.forename: Nasim
authors.initials: N
authors.lastname: Vafai
authors.affiliation: University of British Columbia, Vancouver, BC, Canada.
authors.forename: Jessamyn
authors.initials: J
authors.lastname: McKenzie
authors.affiliation: University of British Columbia, Vancouver, BC, Canada.
authors.forename: Joseph K
authors.initials: JK
authors.lastname: Tsui
authors.affiliation: TRIUMF, Vancouver, BC, Canada.
authors.forename: Paul
authors.initials: P
authors.lastname: Schaffer
authors.affiliation: New York University School of Medicine, New York, New York, USA.
authors.forename: Yu-Shin
authors.initials: YS
authors.lastname: Ding
authors.affiliation: University of British Columbia, Vancouver, BC, Canada.
authors.forename: Matthew
authors.initials: M
authors.lastname: Farrer
authors.affiliation: University of British Columbia, Vancouver, BC, Canada.
authors.forename: Vesna
authors.initials: V
authors.lastname: Sossi
authors.affiliation: University of British Columbia, Vancouver, BC, Canada.
authors.forename: A Jon
authors.initials: AJ
authors.lastname: Stoessl
mesh_terms: D001921:Brain / Q000378:metabolism / Q000473:pathology*; D004298:Dopamine / Q000235:genetics* / Q000378:metabolism; D005260:Female; D006579:Heterozygote; D006801:Humans; D007930:Leucine / Q000378:metabolism; D000071158:Leucine-Rich Repeat Serine-Threonine Protein Kinase-2 / Q000235:genetics*; D008875:Middle Aged; D009154:Mutation / Q000235:genetics*; D010300:Parkinson Disease / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D049268:Positron-Emission Tomography / Q000379:methods; D011877:Radionuclide Imaging
chemical_list: C495280:LRRK2 protein, human; D000071158:Leucine-Rich Repeat Serine-Threonine Protein Kinase-2; D007930:Leucine; D004298:Dopamine
keywords: LRRK2; Parkinson's disease; SWEDD