Tn antigen

{{Technical|date=December 2011}}

Tn antigen refers to the monosaccharide structure N-acetylgalactosamine (GalNAc) linked to serine or threonine by a glycosidic bond, considered as an antigen.I. Brockhausen, H. Schachter, P. Stanley, Essentials of Glycobiology, 2nd edition. A. Varki, R. Cummings, J. Esko, Eds, Cold Spring Harbor (NY): Cold Spring Harbor Laboratory Press; 2009. Chapter 9, O-GalNAc Glycans The initials stand for Thomsen-nouveau. Tn antigen is expressed in most carcinomas.{{cite book |last1=Zhou |first1=Qun |title=Recent Progress in Glycotherapy |date=6 December 2016 |publisher=Bentham Science Publishers |isbn=978-1-68108-391-9 |page=8 |url=https://books.google.com/books?id=Ql7PDQAAQBAJ&pg=PA8 |language=en}}

Addition of an additional galactose monosaccharide creates a disaccharide antigen: the Thomsen-Friedenreich antigen (Gal(b1-3)GalNAc). The sialyl Tn antigen (STn antigen) is formed by elongation with sialic acid (Neu5Ac(α2-6)GalNAc) rather than galactose.