The goals of this study are 1. To compare the functional effects of the LRRK2 G2385R variant among carriers with and without Parkinson's disease (PD) and non-carriers with and without PD 2. To investigate the relationship between functional effects of the LRRK2 G2385R variant and PD associated phenotype 3. To investigate the biomarkers associated with PD conversion in the LRRK2 G2385R variant carriers 4. To compare the immune-related differences between PD patients/unaffected individuals with and without the LRRK2 G2385R mutation, and to investigate the effects of immune dysfunction on the clinical expression of PD