LRRK2 and Parkinson disease: The diverse spectrum of pathogenic mutations within the multiple domains of LRRK2 protein and the complex mechanisms by which these mutations influence the development of PD, including changes in LRRK2 kinase activity, alterations in autophagic activity, and modifications in the clearance capacity of α-Syn protein, etc. In summary, whether it is LRRK2 'gain-of-function' or 'loss-of-function', these changes may lead to an imbalance in protein homeostasis within neuronal cells, resulting in varying degrees of neuronal damage.