CLRN3 (clarin 3) is a cell-surface glycoprotein with emerging roles in cancer immunology and cellular differentiation. Primary Function: CLRN3 functions as a cell-surface marker and protein-binding molecule involved in cell identification and differentiation processes 1. Mechanism: CLRN3 is highly enriched during late-stage hepatocyte differentiation from induced pluripotent stem cells and facilitates purification of homogeneous hepatocyte populations through fluorescence-activated cell sorting 1. Disease Relevance: CLRN3 has been identified as a significant factor in multiple malignancies. In colorectal cancer, CLRN3 expression correlates with CD8+ T-cell infiltration and tumor progression; CLRN3 knockdown attenuates malignant biological behavior while overexpression promotes it 2. In endometrial carcinoma, CLRN3 represents a methylation-driven gene with disease-specific dysregulation compared to breast cancer 3. Additionally, a CLRN3 genetic variant (rs6482992) is associated with cognitive outcomes in Parkinson's disease patients 4. Clinical Significance: CLRN3 shows promise as a biomarker for cancer prognosis and immunotherapy response prediction, particularly in colorectal cancer risk stratification based on CD8+ T-cell-related gene signatures 2.