LRRK2 and Parkinson disease: Some NMS may antedate the onset of PD motor syndrome in substantial number of patients carrying LRRK2 G2019S mutation, indicating that a premotor phase similar to that occurring in IPD probably occurs in this genetic form of PD, and that common physiopathological mechanism probably underlie the onset and progression of the disease in both LRRK2 G2019S PD and IPD.