ST6GALNAC2 encodes an α-2,6-sialyltransferase that catalyzes the transfer of sialic acid to N-acetylgalactosamine (GalNAc) residues on O-linked glycoproteins, specifically targeting Tn and T antigens 1. This enzyme plays a crucial role in protein O-linked glycosylation within the Golgi apparatus, modifying glycan structures that influence cellular behavior and disease processes. In colorectal cancer, ST6GALNAC2 expression is regulated by microRNAs miR-182 and miR-135b, which target the gene to promote tumorigenesis and chemoresistance through the PI3K/AKT pathway 23. Unlike ST6GALNAC1, ST6GALNAC2 expression shows no significant differences between normal and malignant colorectal tissues 4. In IgA nephropathy, genetic variants in ST6GALNAC2 interact with C1GALT1 variants to influence disease susceptibility and severity through aberrant IgA1 O-glycosylation 5. Specifically, the ADG haplotype in the ST6GALNAC2 promoter reduces transcriptional activity and correlates with deficient α-2,6 sialic acid content on IgA1 molecules 6. The enzyme also functions in melanoma progression, where ST6GALNAC2 overexpression negatively regulates galectin-1 ligand activity, thereby inhibiting cell migration and growth 1. ST6GALNAC2 has been identified as a prognostic biomarker in gastric adenocarcinoma as part of neutrophil-related gene signatures 7.