A study by the same group in the longitudinal DATATOP cohort (deprenyl and tocopherol antioxidative therapy of Parkinsonism) which included individuals with early PD in a placebo-controlled clinical trial reported increased CSF pS129 and pS129/total α-synuclein ratio over 2 years of disease progression (Stewart et al., 2015). Here, SNCA is linked to Parkinson disease.