FZD3 (frizzled class receptor 3) is a seven-transmembrane G-protein coupled receptor located on chromosome 8 that functions as a Wnt signaling receptor with critical roles in neural development and cancer biology 1. The receptor transduces signals through both canonical Wnt/β-catenin pathways and non-canonical planar cell polarity (PCP) pathways; activation by Wnt ligands (e.g., Wnt5A, Wnt5B) recruits and phosphorylates disheveled proteins at the membrane, leading to either GSK-3 inhibition and nuclear β-catenin accumulation or activation of downstream effectors including RAC1 and JNK 23. FZD3 is essential for neurodevelopmental processes, controlling axon guidance and growth in major central and peripheral nervous system tracts, including the corpus callosum, corticospinal tract, and cranial motor nerves, while also regulating neural crest cell migration and inner ear sensory cell polarity 4. In melanoma, FZD3 promotes tumorigenesis independently of canonical Wnt signaling by activating MAPK pathways through a positive-feedback mechanism; elevated FZD3 mRNA correlates with metastatic progression and poor patient survival 5. Similarly, WNT5B-FZD3 signaling promotes non-small cell lung cancer malignancy via the PCP-JNK pathway 3. Genetic association studies initially suggested FZD3 polymorphisms might contribute to schizophrenia risk, but meta-analyses provide weak and inconsistent evidence, with effects potentially limited to specific populations 67.