LRRK2 and Parkinson disease: The fact that LRRK2 expression is high in PBMCs under homeostatic conditions and further increased upon stimulation suggests its induction is likely to play a regulatory role in their effector functions; therefore, caution should be exercised when targeting LRRK2 as a potential therapeutic intervention in PD or CD as it is still unclear whether the high LRRK2 levels in immune cells are a protective or deleterious mechanism in the immune system.