title: Development of a Biochemical Diagnosis of Parkinson Disease by Detection of α-Synuclein Misfolded Aggregates in Cerebrospinal Fluid.
abstract: OBJECTIVE
  Parkinson disease (PD) is a highly prevalent and incurable neurodegenerative disease associated with the accumulation of misfolded α-synuclein (αSyn) aggregates. An important problem in this disease is the lack of a sensitive, specific, and noninvasive biochemical diagnosis to help in clinical evaluation, monitoring of disease progression, and early differential diagnosis from related neurodegenerative diseases.
  
  
  OBJECTIVE
  To develop a novel assay with high sensitivity and specificity to detect small quantities of αSyn aggregates circulating in cerebrospinal fluid (CSF) of patients affected by PD and related synucleinopathies.
  
  
  METHODS
  The strategy evaluated in this proof-of-concept study uses the protein misfolding cyclic amplification (PMCA) technology that detects minute amounts of misfolded oligomers by taking advantage of their ability to nucleate further aggregation, enabling a very high amplification of the signal. The technology was first adapted with synthetic αSyn oligomers prepared in vitro and used to screen in 2 blinded cohorts of CSF samples from German and Japanese patients with PD (n = 76) and individuals serving as controls affected by other neurologic disorders (n = 65), neurodegenerative diseases (n = 18), and Alzheimer disease (n = 14). The kinetics of αSyn aggregation were measured by αSyn-PMCA in the presence of CSF samples from the participants to detect αSyn oligomeric seeds present in this biological fluid. The assays were conducted from November 15, 2013, to August 28, 2015.
  
  
  METHODS
  Kinetic parameters correlated with disease severity at the time of sample collection, measured by the Hoehn and Yahr scale, with the lowest grade indicating unilateral involvement with minimal or no functional impairment, and the highest grade defining patients with complete confinement to wheelchair or bed.
  
  
  RESULTS
  Studies with synthetic αSyn aggregates showed that αSyn-PMCA enabled to detect as little as 0.1 pg/mL of αSyn oligomers. The αSyn-PMCA signal was directly proportional to the amount of αSyn oligomers added to the reaction. A blinded study of CSF samples correctly identified patients affected by PD with an overall sensitivity of 88.5% (95% CI, 79.2%-94.6%) and specificity of 96.9% (95% CI, 89.3%-99.6%). The αSyn-PMCA results for different patients correlated with the severity of the clinical symptoms of PD (Japanese cohort: rs = -0.54, P = .006; German cohort: rs = -0.36, P = .02).
  
  
  CONCLUSIONS
  The findings suggest that detection of αSyn oligomers by αSyn-PMCA in the CSF of patients affected by PD may offer a good opportunity for a sensitive and specific biochemical diagnosis of the disease. Further studies are needed to investigate the usefulness of αSyn-PMCA to monitor disease progression and for preclinical identification of patients who may develop PD.
authors.affiliation: Mitchell Center for Alzheimer's Disease and Related Brain Disorders, The University of Texas School of Medicine at Houston.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Shahnawaz
authors.affiliation: Department of Neurology, Kyoto Prefectural University of Medicine, Kyoto, Japan3Department of Molecular Pathobiology of Brain Diseases, Kyoto Prefectural University of Medicine, Kyoto, Japan4Japan Agency for Medical Research and Development-Core Research for Evolutionary Medical Science and Technology, Tokyo, Japan.
authors.forename: Takahiko
authors.initials: T
authors.lastname: Tokuda
authors.affiliation: Department of Neurology, Higashi Matsudo Municipal Hospital, Matsudo, Japan.
authors.forename: Masaaki
authors.initials: M
authors.lastname: Waragai
authors.affiliation: Mitchell Center for Alzheimer's Disease and Related Brain Disorders, The University of Texas School of Medicine at Houston.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Mendez
authors.affiliation: Department of Neurology, Kyoto Prefectural University of Medicine, Kyoto, Japan3Department of Molecular Pathobiology of Brain Diseases, Kyoto Prefectural University of Medicine, Kyoto, Japan.
authors.forename: Ryotaro
authors.initials: R
authors.lastname: Ishii
authors.affiliation: Paracelsus-Elena-Klinik Kassel, Kassel, Germany7Institute of Neuropathology, University Medical Center Goettingen, Goettingen, Germany8Clinic for Neurosurgery, University Medical Center, Goettingen, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Trenkwalder
authors.affiliation: Paracelsus-Elena-Klinik Kassel, Kassel, Germany7Institute of Neuropathology, University Medical Center Goettingen, Goettingen, Germany9Department of Neurosurgery, University Medical Center Goettingen, Goettingen, Germany.
authors.forename: Brit
authors.initials: B
authors.lastname: Mollenhauer
authors.affiliation: Mitchell Center for Alzheimer's Disease and Related Brain Disorders, The University of Texas School of Medicine at Houston.
authors.forename: Claudio
authors.initials: C
authors.lastname: Soto
mesh_terms: D016229:Amyloid beta-Peptides / Q000134:cerebrospinal fluid / Q000737:chemistry; D001669:Biochemical Phenomena; D003955:Diagnostic Tests, Routine; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D020961:Lewy Body Disease / Q000134:cerebrospinal fluid; D008297:Male; D019578:Multiple System Atrophy / Q000134:cerebrospinal fluid; D017063:Outcome Assessment, Health Care; D010300:Parkinson Disease / Q000134:cerebrospinal fluid / Q000175:diagnosis / Q000209:etiology; D010446:Peptide Fragments / Q000134:cerebrospinal fluid / Q000737:chemistry; D011237:Predictive Value of Tests; D066263:Protein Aggregation, Pathological / Q000150:complications*; D057165:Proteostasis Deficiencies / Q000150:complications*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D051844:alpha-Synuclein / Q000134:cerebrospinal fluid*; D016875:tau Proteins / Q000134:cerebrospinal fluid / Q000737:chemistry
chemical_list: D016229:Amyloid beta-Peptides; D010446:Peptide Fragments; D051844:alpha-Synuclein; C075222:amyloid beta-protein (1-42); D016875:tau Proteins