GPC6 (glypican 6) is a cell surface heparan sulfate proteoglycan anchored to the plasma membrane by a glycosyl-phosphatidylinositol linkage 1. As a member of the glypican family, GPC6 primarily functions as a coreceptor regulating growth factor signaling pathways, particularly Wnt, Hedgehog, fibroblast growth factors, and bone morphogenetic proteins 1. The protein can facilitate Wnt signaling by stabilizing interactions between Wnts and their Frizzled receptors, and this regulatory activity is only partially dependent on heparan sulfate chains 1. GPC6 demonstrates tissue-specific expression, being most abundant in ovary, liver, and kidney 2. The gene is located on chromosome 13 in a tandem cluster with GPC5, forming one of the largest human genes at approximately 1-2 Mb 3. Clinically, GPC6 is associated with omodysplasia-1, a skeletal dysplasia caused by loss-of-function variants that impair bone growth through reduced Hedgehog signaling activity 4. Additionally, GPC6 expression correlates with CD8+ T-lymphocyte infiltration in early-stage ovarian cancer and serves as a favorable prognostic marker for patient survival 5. The protein has also been implicated in Alzheimer disease risk in African American populations 6.