In 2008, the Michael J. Fox Foundation established an international consortium to investigate LRRK2 (leucine-rich repeat kinase 2), which eventually included nine countries (Canada, China, France, Germany, Israel, Norway, Spain, Tunisia, and the United States). The methodology for subject recruitment is similar in most centers; Parkinson's disease (PD) participants are examined and screened for LRRK2 mutations, and a more thorough investigation is performed on those with mutations (and a subset of those without). All willing family members are then recruited so that LRRK2 carriers with and without PD, as well as non-carriers, may be examined.