SNCA and Parkinson disease: Corresponding authors of all included publications were contacted, and individual-level data were collected on almost 4000 individuals from 92 centers in 42 countries, including affected and unaffected carriers of pathogenic variants in genes implicated in monogenic PD (including SNCA, LRRK2, VPS35, PRKN, PINK1, PARK7/DJ-1, and the PD risk gene GBA1).1 More recently, another global science project was initiated: the Global Parkinson’s Genetics Program (GP2; https://gp2.org).