LRRK2 and Parkinson disease: Multiple mutations and normal genetic variations in the LRRK2 gene have been associated with disease.18 The six most common pathogenic mutations in LRRK2 associated with PD19 reside in the GTPase and kinase domains.20, 21 The most prevalent mutation is the G2019S mutation in the kinase domain.3 Although mutations in LRRK2 only account for 1–2% of all PD cases, they are particularly prevalent in individuals of Ashkenazi Jewish (29.7%) and North African Arab ancestry (41%) (ref. 3).