SYNJ1 and Parkinson disease: While SYNJ1 is most notably known as a PD gene (Krebs et al., 2013; Quadri et al., 2013; Olgiati et al., 2014; Kirola et al., 2016; Taghavi et al., 2018; Xie et al., 2019; Lesage et al., 2021), it has also been linked with several other mental illnesses associated with dopaminergic dysfunction, including autism (Wang et al., 2015), bipolar disorder (Saito et al., 2001; Kato et al., 2007), and schizophrenia (Arion et al., 2007; Rodríguez-López et al., 2018).