Further evidence that the VPS35[D620N] mutation stimulates LRRK2 activity comes from data derived from human peripheral blood cells from three patients with VPS35-associated PD bearing the VPS35[D620N] mutation: Rab10 phosphorylation is markedly elevated in neutrophils (Figure 5) as well as monocytes (Figure 7) isolated from VPS35[D620N] PD patients in comparison with those from healthy donors or age-matched idiopathic PD patients. The gene discussed is RAB10; the disease is Parkinson disease.