Centrally, analysis from postmortem tissue identified decreased striatal VMAT2 immunoreactivity as well as decreased VMAT2 activity from isolated synaptic vesicles, whereas peripheral analysis revealed decreased VMAT2 mRNA in circulating platelets from Parkinson’s disease patients suggesting a possible systemic deficiency in Parkinson’s disease pathogenesis15–18. This evidence concerns the gene SLC18A2 and Parkinson disease.