Of relevance to our results is a report that CSF concentrations of α-synuclein soluble oligomers, suggested to be the most neurotoxic α-synuclein conformation (Winner et al., 2011), are also increased in healthy subjects with PD-associated LRRK2 mutations compared to healthy controls lacking these mutations (Aasly et al., 2014). The gene discussed is SNCA; the disease is Parkinson disease.