PCDHA2 (protocadherin alpha 2) is a calcium-dependent cell adhesion molecule involved in establishing and maintaining neuronal connections. As a member of the protocadherin family, it mediates protein-protein interactions at the plasma membrane and plays roles in nervous system development 1. Mechanistically, PCDHA2 functions as a neuronal cell adhesion gene critical for proper brain circuitry formation. Its expression is sensitive to environmental perturbations; maternal immune activation during pregnancy downregulates PCDHA2 alongside other schizophrenia-associated cell adhesion genes in fetal mouse brains, particularly affecting cortical excitatory neurons and inhibitory interneurons 1. Clinically, PCDHA2 has emerged as a disease-relevant biomarker across multiple pathologies. In thyroid cancer, PCDHA2 was identified as a high-risk lipid metabolism-related gene associated with poor overall survival and serves as an independent prognostic factor 2. In hepatocellular carcinoma, PCDHA2 was identified within a TPX2-related ceRNA regulatory network affecting HCC prognosis 3. In melanoma, PCDHA2 harbors missense mutations associated with increased lung metastatic potential, and its expression levels predict patient survival 4. Additionally, PCDHA2 expression is modulated by RBL2/p130 tumor suppressor inactivation in Burkitt lymphoma 5, suggesting roles in cancer cell growth regulation.