Previous studies have shown that missense mutations in the leucine-rich repeat kinase 2 (LRRK2) gene locus, particularly LRRK2 G2019S mutation, are common causes of late-onset familial and sporadic PD [115, 116], prompting interest in studying the pathogenic mechanisms of LRRK2-associated PD. Here, LRRK2 is linked to Parkinson disease.