The role of Gpnmb in different diseases, especially neurodegenerative diseases, becomes complex, particularly due to potential variations in its function when bound to cells or present in a soluble form (Tanaka et al., 2012; Neal et al., 2018; Xie et al., 2019; Saade et al., 2021; Zhu et al., 2022). This evidence concerns the gene GPNMB and neurodegenerative disease.