LRRK2 and Parkinson disease: Although most cases of PD, the so-called idiopathic PD (ID-PD), are of unknown cause, approximately 5% of them have been shown to have a genetic origin, with mutations in the leucine rich repeat kinase 2 (LRRK2) gene being the most frequent known cause of late-onset autosomal-dominant PD (L2-PD) (5).