Considering that LRRK2 transgenic models investigated so far are characterized by various levels and spatial/temporal patterns of LRRK2 expression (mutant or wild-type), it is difficult to conclude if LRRK2-related PD is associated with a primary damage of DAergic cells in the midbrain or with an isolated dysfunction of striatal DAergic terminals. This evidence concerns the gene LRRK2 and Parkinson disease.