Prg2, also known as plasticity-related gene 2 or proteoglycan 2, plays multiple crucial roles. In neurons, it stabilizes membrane PI(3,4,5)P3 by inhibiting PTEN, which is essential for axon morphogenesis, specifically controlling the homeostasis of elongation and branch growth [2,4]. It is also involved in immune-related processes, with its protein product being associated with eosinophils [3,5].

In placenta previa and percreta, PRG2 protein levels are upregulated in fetal membranes and the placental disk, and it is mislocalized throughout the fetal membranes. This suggests a potential role in conditions related to abnormal placental development [1]. In bullous pemphigoid, dupilumab treatment is associated with down-regulation of PRG2, indicating its involvement in the activation of eosinophils in this autoimmune skin-blistering disease [5]. In a GWAS study on Sardinians, a rare PRG2:p.Ser148Pro mutation within the gene was found to have a large effect size on eosinophil scatter, potentially modifying eosinophil morphology [6].

In conclusion, Prg2 is involved in both neuronal development through the regulation of axon growth and in immune-related processes, with implications in diseases such as placenta-related disorders, autoimmune skin diseases, and potentially in relation to eosinophil-associated morphological changes. The study of Prg2 using genetic models, such as those hinted at in the research, could further clarify its exact functions and how it contributes to these biological processes and disease conditions.