CHST15 (carbohydrate sulfotransferase 15) is a type II transmembrane glycoprotein that catalyzes the transfer of sulfate groups from PAPS to chondroitin sulfate, specifically forming chondroitin sulfate E containing GalNAc(4,6-SO4) disulfate residues 1. The enzyme participates in proteoglycan biosynthesis that enables cellular interactions and signaling 2. CHST15 dysfunction is associated with multiple pathological conditions. Germline mutations in CHST15 predispose to familial myeloproliferative neoplasms by interacting with the JAK2-Stat3 signaling pathway, leading to increased JAK2V617F allele burden and enhanced proliferative potential 3. In cancer, CHST15 overexpression promotes tumor progression - it enhances proliferation in esophageal cancer cells through CHST15/ILKAP/CCND1 and CHST15/RABL6/PMAIP1 signaling axes 4, while its knockdown in pancreatic cancer reduces stromal density and myeloid-derived suppressor cells, enhancing tumor-infiltrating T cells 5. CHST15 also contributes to tissue fibrosis, with glucocorticoids preventing esophageal stenosis by downregulating CHST15 expression and subsequently reducing TGF-β1 and Collagen-I protein levels 6. Additionally, CHST15 variants show protective associations against malaria in African populations 7.