CHN1 encodes alpha2-chimaerin, a RacGAP (Rac guanosine triphosphatase-activating protein) that regulates small GTPase signaling and functions as a phorbol ester receptor 1. In neuronal development, CHN1 serves as a direct effector of EPHA4 in axon guidance, with critical importance in ocular motor axon pathfinding and the assembly of cranial motor neuron circuits 12. Gain-of-function mutations in CHN1 cause Duane retraction syndrome type 2 (DURS2), a congenital eye movement disorder resulting from aberrant extraocular muscle innervation by brainstem motor neurons 13. Beyond its developmental neurological function, CHN1 exhibits pathological roles in multiple cancers. In gastric and cervical carcinomas, CHN1 is upregulated and promotes cancer progression through distinct mechanisms: in cervical cancer, it activates the Akt/GSK-3β/Snail pathway to induce epithelial-mesenchymal transition 4, while in esophageal squamous cell carcinoma, the TBX18-CHN1-RhoA axis promotes radioresistance 5. High CHN1 expression correlates with poor survival and immune infiltration patterns in gastric cancer 6. Recent evidence suggests CHN1 may serve as a biomarker for atopic dermatitis-associated depression through immune regulatory networks 7. These findings establish CHN1 as a multifunctional regulator with critical roles in developmental neurobiology and pathological significance in cancer progression and immune-mediated conditions.