TCN1 (transcobalamin 1) is a vitamin B12-binding protein with femtomolar affinity that protects cobalamin in the stomach's acidic environment 1. The gene resides on chromosome 11 and contains nine exons within 12 kb of genomic DNA, with structural similarity to intrinsic factor 1. TCN1 is primarily expressed in neutrophil secondary granules and serves as a marker for late-stage myeloid differentiation 1. Beyond its canonical role in vitamin B12 transport, TCN1 has emerged as a significant pathophysiological factor in multiple diseases. In cancer contexts, TCN1 promotes cell growth and malignancy: in colorectal cancer, it enhances proliferation and invasion via the ITGB4 pathway 2, while in lung adenocarcinoma, high TCN1 expression correlates independently with poor overall survival 3. TCN1 serves as a prognostic biomarker in cholangiocarcinoma 4. TCN1 also functions as an inflammatory regulator. It is upregulated in asthma, correlating with inflammatory markers (FeNO, IgE) and inversely with lung function 5. In psoriasis, TCN1 activates NF-κB signaling and promotes keratinocyte cell cycle progression 6. Early neutrophil TCN1 upregulation predicts prolonged organ dysfunction in severe influenza 7, and TCN1 is identified as a diagnostic biomarker in ulcerative colitis 8. These findings suggest TCN1 functions beyond B12 metabolism, operating as both a disease biomarker and potential therapeutic target in inflammatory and malignant conditions.