The genetic influence of alpha-synuclein in the development of PD is complex. Mutations in the alpha-synuclein (SNCA) and LRRK2 genes are linked to autosomal dominant forms of PD, while mutations in genes like Parkin, PINK1, DJ-1, and ATP13A2 are associated with autosomal recessive forms. The gene discussed is LRRK2; the disease is Parkinson disease.