This review was conducted by searching PubMed, Scopus, and Google Scholar databases using the keywords “Parkinson’s disease,” “α-synuclein,” “dopaminergic neurons,” “LRRK2,” “mitochondrial dysfunction,” “comorbidities,” “levodopa,” and “neuroinflammation.” Studies published in English between 2000 and 2025 were included. This evidence concerns the gene LRRK2 and Parkinson disease.