CBLIF (cobalamin binding intrinsic factor) is a glycoprotein that promotes vitamin B12 (cobalamin) absorption in the terminal ileum 1. The protein binds cobalamin in the stomach and facilitates its transfer from haptocorrin after pancreatic trypsin action 1. Following cobalamin binding, the CBLIF-cobalamin complex undergoes receptor-mediated endocytosis via interaction with the CUBN receptor (cubilin), enabling intestinal uptake through a chloroquine-sensitive transcytotic pathway 2. This transport process completes the enterohepatic cycle of cobalamin recirculation 1. CBLIF is synthesized not only in gastric parietal cells but also in other foregut-derived cells, and is secreted basally in the embryonic stomach without sialic acid modification 3. Clinically, mutations in CBLIF cause hereditary intrinsic factor deficiency, leading to cobalamin malabsorption and pernicious anemia. Additionally, polymorphisms in CBLIF and related B12 transport genes (particularly CUBN) have been associated with nonsyndromic cleft lip/palate susceptibility, suggesting roles in embryonic development beyond B12 metabolism 4. Diagnostic assays measure CBLIF activity and anti-IF blocking antibodies in pernicious anemia patients 5.