Plasma α-synuclein is decreased in subjects with Parkinson's disease

alpha-Synuclein (alpha SN) is implicated in Parkinson's disease (PD) and is the major component of Lewy bodies (LBs). Although alpha SN is mainly expressed in neuronal cells and exists as cytoplasmic protein, it haas been found in body fluids including cerebrospinal fluid and blood. This study explored plasma alpha SN as a diagnostic marker for PD. Western blot analysis was used to characterize plasma alpha SN compared to brain alpha SN. Plasma alpha SN of 16 kDa migrates with the same mobility as its brain counterpart and recombinant alpha SN on denatured polyacrylamide gels and reacted with three different antibodies against the C-terminal and NAC regions of the alpha SN protein. The alpha SN levels in plasma from PD subjects are significantly lower than that in age-matched controls (p = 0.001), and the alpha SN levels in patients with early-onset PD are lower than that in both late-onset PD and controls. This initial study indicates that measurement of alpha SN in plasma can provide support for a clinical diagnosis of Parkinson's disease and warrants further study in a larger population. (c) 2006 Elsevier Inc. All rights reserved.