However, familial forms of PD, which comprises <10% of PD cases, have been linked to mutations occurring in PD-associated genes, such as SNCA (PARK1), LRRK2 (PARK8), PRKN (PARK2), PINK1 (PARK6), and DJ-1 (PARK7) [13,14]. The gene discussed is LRRK2; the disease is Parkinson disease.