title: α-Synuclein and anti-α-synuclein antibodies in Parkinson's disease, atypical Parkinson syndromes, REM sleep behavior disorder, and healthy controls.
abstract: α-synuclein is thought to play a key role in Parkinson's disease (PD) because it is the major protein in Lewy bodies, and because its gene mutations, duplication, and triplication are associated with early-onset PD. There are conflicting reports as to whether serum and plasma concentrations of α-synuclein and anti-α-synuclein antibodies differ between PD and control subjects. The objectives of this study were to compare the levels of α-synuclein and its antibodies between individuals with typical PD (n=14), atypical Parkinson syndromes (n=11), idiopathic rapid eye movement sleep behavior disorder (n=10), and healthy controls (n=9), to assess the strength of association between these serum proteins, and to determine group sizes needed for a high probability (80% power) of detecting statistical significance for 25% or 50% differences between typical PD and control subjects for these measurements. Analysis of log-transformed data found no statistically significant differences between groups for either α-synuclein or its antibodies. The concentrations of these proteins were weakly correlated (Spearman rho=0.16). In subjects with typical PD and atypical Parkinson syndromes, anti-α-synuclein antibody levels above 1.5 µg/ml were detected only in subjects with no more than four years of clinical disease. Power analysis indicated that 236 and 73 samples per group would be required for an 80% probability that 25% and 50% differences, respectively, in mean α-synuclein levels between typical PD and control subjects would be statistically significant; for anti-α-synuclein antibodies, 283 and 87 samples per group would be required. Our findings are consistent with those previous studies which suggested that serum concentrations of α-synuclein and its antibodies are not significantly altered in PD.
authors.affiliation: Department of Neurology Research, Beaumont Health System, Royal Oak, Michigan, USA.
authors.forename: Lynnae M
authors.initials: LM
authors.lastname: Smith
authors.forename: Mya C
authors.initials: MC
authors.lastname: Schiess
authors.forename: Mary P
authors.initials: MP
authors.lastname: Coffey
authors.forename: Andrea C
authors.initials: AC
authors.lastname: Klaver
authors.forename: David A
authors.initials: DA
authors.lastname: Loeffler
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000906:Antibodies / Q000097:blood* / Q000276:immunology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000097:blood*; D020187:REM Sleep Behavior Disorder / Q000097:blood*; D051844:alpha-Synuclein / Q000097:blood* / Q000276:immunology*
chemical_list: D000906:Antibodies; D051844:alpha-Synuclein