DDOST (dolichyl-diphosphooligosaccharide-protein glycosyltransferase non-catalytic subunit) is a critical non-catalytic component of the oligosaccharyltransferase (OST) complex that catalyzes N-linked protein glycosylation in the endoplasmic reticulum 1. As part of the OST complex, DDOST facilitates the cotranslational transfer of a defined N-glycan to asparagine residues within nascent polypeptide chains, a fundamental posttranslational modification required for proper protein folding and function 2. All OST subunits, including DDOST, are essential for maximal enzymatic activity and assembly of functional glycosylation complexes 3. DDOST dysregulation contributes to multiple disease pathologies. Biallelic DDOST mutations cause DDOST-congenital disorder of glycosylation (DDOST-CDG), characterized by developmental delay, failure to thrive, and abnormal transferrin glycosylation patterns 4. In cancer, DDOST is frequently upregulated and promotes oncogenic pathways. In pancreatic cancer, DDOST knockdown increases endoplasmic reticulum stress, oxidative stress, and apoptosis 1. In hepatocellular carcinoma, DDOST maintains EGFR glycosylation and downstream signaling; targeting DDOST sensitizes tumors to lenvatinib and immunotherapy 5. In colorectal cancer, DDOST regulates CTSD N-glycosylation, affecting ferroptosis-related pathways and metastasis 6. DDOST overexpression in gliomas correlates with poor prognosis and immunosuppressive microenvironments 7. These findings establish DDOST as both a disease biomarker and potential therapeutic target.