Approximately 15% of patients harbor pathogenic or likely pathogenic mutations in genes linked to PD [α-synuclein (SNCA), leucine-rich repeat kinase 2 (LRRK2), Parkin (PRKN), PTEN induced kinase 1 (PINK1), Parkinson’s disease protein 7 (DJ-1)] or genetic risk factors like the glucocerebrosidase gene (GBA1). The gene discussed is SNCA; the disease is Parkinson disease.