GPNMB and Parkinson disease: So far, GPNMB has been reported to be involved in cancer diseases (Onaga et al., 2003; Kuan et al., 2006; Rose et al., 2010), non-alcoholic steatohepatitis (Katayama et al., 2015), inflammatory bowel disease (IBD), Niemann Pick disease-type C (Marques et al., 2016), Gaucher disease (Murugesan et al., 2018), amyotrophic lateral sclerosis (ALS) (Tanaka et al., 2012; Nagahara et al., 2015) and PD.