LRRK2 and Parkinson disease: Although these molecular and cellular changes are observed only in the kidney but not in the brain of LRRK2-/- mice, they are very similar to processes that are thought to be involved in PD pathogenesis, making LRRK2-/- kidneys a relevant and valuable in vivo model to study the physiological function of LRRK2 and to identify the downstream cellular and molecular pathways.