Participants include those with a clinical diagnosis of Parkinson's, in particular those who have a first- or second-degree relative with Parkinson's, or who have young onset Parkinson's (age less than 50 at diagnosis) or are of Ashkenazi Jewish or North African Berber descent, or have a relative with a known genetic mutation in the LRRK2 gene, or who have a genetic mutation in the LRRK2 gene.  Inclusion Criteria:  Participant eligible for enrollment in the program must meet all of the following criteria:  Participant must be a person diagnosed with Parkinson's disease who is 18 years or older. Participant is under the care of a physician for their Parkinson's disease. Participant is able to read, write and understand English, and reside in a country where the shipment of biological samples is allowed. Participant is able to grant informed consent. In the case of participants, willing to participate in a free genetic testing program to determine if they carry the G2019S LRRK2 mutation. Willing to be notified of eligibility for clinical studies (if appropriate). Particpants who already believe they have tested positive for the mutation will be allowed to be retested through this program and be notified of potential eligibility for studies.  Exclusion Criteria:  Inability to meet any of the inclusion criteria. Participant has received on of the following advanced treatments to manage their Parkinson's: gene therapy, deep brain stimulation (DBS), injections into the brain, continuous infusion of medication into their stomach/intestines with a pump.