LRRK2 and Parkinson disease: Having observed a longitudinal increase in pS129 in recently diagnosed PD patients, we next sought to examine the association between CSF pS129 and disease severity across a wider range of PD stages than has previously been examined, by studying early clinical PD in recently diagnosed subjects (DATATOP), moderate to severe clinical PD (multi-center collaborative cohort) and very early/preclinical PD (LRRK2 cohort).