LRRK2 and Parkinson disease: In this systematic review, we screened 726 journal articles and selected 80 articles that contain information about the different aspects in the pathogenesis of LRRK2-associated PD, namely, α-Syn neurotoxicity, inflammation, glial–neuron crosstalk, mitochondrial dysfunction, vesicle trafficking, autophagy and lysosomal dysfunction, kinase signalling pathways, nucleus-related dysfunction, tau neurotoxicity, protein synthesis, Rab-LRRK2 interactions, multifactorial studies, and factors that control LRRK2 expression and its pathogenicity.