Familial PD cases, accounting for less than the 10% of PD, originate from mutations in α-SYN (SNCA), PARKIN (PRKN), ubiquitin C-terminal hydrolase L1 (UCHL-1), PTEN-induced putative kinase 1 (PINK1), protein deglycase (DJ-1) (PARK7) and leucine-rich repeat kinase 2 (LRRK2) (PARK8) genes. This evidence concerns the gene LRRK2 and Parkinson disease.