Alimentary, my dear Watson? The challenges of enteric α-synuclein as a Parkinson's disease biomarker

ABSTRACT An accurate early diagnostic test for Parkinson's disease (PD) is a critical unmet need. Recently, independent groups using different histological techniques have reported that the presence of alpha‐synuclein (α‐syn) in colonic biopsy tissue is able to distinguish living patients with PD from those without the disease. In addition, a further study has suggested that the presence of α‐syn in colonic biopsy tissue may be evident in early or even prodromal PD. However, several questions remain regarding the translation of these findings into using the assessment of α‐syn deposition in the enteric nervous system as a diagnostic biomarker for prodromal PD. Here we address critical issues related to the location and quantification of enteric α‐syn, detection of α‐syn with currently available histological techniques, timing of detection of α‐syn deposition, and, most crucially, whether enteric α‐syn can distinguish those with PD from both healthy individuals and individuals with other related diseases. We conclude that, although enteric α‐syn is a very exciting prospect, further studies will be vital to determine whether enteric α‐syn deposition has the potential to be the biomarker for prodromal PD that the field so desperately seeks. © 2013 International Parkinson and Movement Disorder Society