GBA1 and Parkinson disease: In recent decades, several monogenic causes have been identified as associated with the pathogenesis of PD, such as pathogenic variants of alpha-synuclein (SNCA), leucine-rich repeat kinase 2 (LRRK2), parkin (PRKN), PTEN-induced putative kinase 1 (PINK1), and glucocerebrosidase (GBA) genes [1, 2].