Such a concept would be consistent with the published, but still unexplained, twin findings that there is a significant reduction of total α-synuclein at the protein level in CSF (e.g., (Mollenhauer et al. 2013; Kang et al. 2013) and at the mRNA level in venous blood (Locascio et al. 2015), even in de novo PD patients. The gene discussed is SNCA; the disease is Parkinson disease.