RGS2 and Parkinson disease: LRRK2 mutations cause shortening of the dendritic tree and are among the primary genetic causes of Parkinson's disease.41, 45 Reduced RGS2 expression was observed in the striata of LRRK2-mutated and sporadic Parkinson's disease patients.45 In addition, RGS2 rs4606 polymorphism is a risk allele for schizophrenia43 and is associated with antipsychotic-induced parkinsonism.42 RGS2 has also been suggested to be implicated in antioxidant defense.50