GBA1 and Parkinson disease: Besides the disease causal SNCA mutations, there are other genetic risk factors for PD, including E3 ubiquitin-protein ligase parkin (parkin), Serine/threonine-protein kinase PINK1 (PINK1), Parkinson disease protein 7 (DJ-1), Leucine-rich repeat serine/threonine-protein kinase 2 (LRRK2) and glucocerebrosidase (GBA).