Since the discovery of LRRK2 gene as a causative factor for the autosomal dominant form of PD as well as sporadic PD [62], various LRRK2 mouse models have been developed, including (1) LRRK2 knockout (KO), (2) LRRK2 knock-down (KD), (3) overexpression of wildtype (WT) or variant LRRK2, and (4) KI of LRRK2 variants, for elucidating LRRK2 biology and pathophysiology. This evidence concerns the gene LRRK2 and Parkinson disease.