We show that LRRK2 dependent pRab10Thr73 phosphorylation is significantly elevated over fourfold in all R1441G LRRKR2 mutation carriers irrespective of disease status while PD manifesting and non-manifesting G2019S mutation carriers as well as iPD samples lacked any such enhancement over controls. The gene discussed is LRRK2; the disease is Parkinson disease.