LRRK2 and Parkinson disease: Since the description of PD-associated mutations in the SNCA (8), other genes have been linked to autosomal dominant (AD) forms of familial PD, including LRRK2 and VPS35. In addition, there are clinically and genetically diverse early-onset (EO) autosomal-recessive (AR) forms of PD with associated genes like PRKN, PINK1, and DJ-1 that exhibit phenotypes similar to idiopathic PD, while other associated genes such as VPS13C and ATP13A2 combine atypical features of parkinsonism like dystonia and early cognitive impairment, along with a poor response to levodopa (9).