Genetic variants, such as rs6581593 in the LRRK2 locus, are associated with an increased risk of PD [197]. Biogen and Denali Therapeutics are conducting Phase 3 trials for BIIB122, a small-molecule LRRK2 kinase inhibitor, in PD patients with LRRK2 mutations (NCT05418673, NCT06602193) [198]. This evidence concerns the gene LRRK2 and Parkinson disease.