Alongside KO mouse models of PRKN, PINK1, and DJ-1, models of SNCA and LRRK2 gene mutations have failed to exhibit the basic phenotypes seen with PD, such as resting tremor, bradykinesia, rigidity, and postural instability; thus, their utility lies in identifying genetic and pharmacological modifiers of α-synuclein-induced neurodegeneration [227]. The gene discussed is LRRK2; the disease is Parkinson disease.