part of part of has part has part characteristic of inheres in has modifier alpha-Neu5Ac-(2->3)-beta-D-Gal-(1->3)-[alpha-L-Fuc-(1->4)]-D-GlcNAc Abnormal circulating carbohydrate concentration Elevated circulating CA19-9 concentration 2019-02-21T13:26:41Z Elevated circulating cancer antigen 19-9 concentration HP:0034603 The concentration of carbohydrate antigen 19-9 (CA19-9) in the blood circulation is above the upper limit of normal. CA 19-9, also known as sialyl Lewis A, is a tetrasaccharide overexpressed on a wide range of cancerous cells. CA 19-9 is a tumor-associated carbohydrate antigen (TACAs) that is both a local (anchored on cell surface or tumor site) and shed (in systemic circulation) antigen. CA 19-9 is expressed at low levels in normal tissues but overexpressed in cancer cells. CA 19-9 is also referred to as sialyl Lewis-a (sLea). It is expressed on the surface of cancer cells as a glycolipid and as an O-linked glycoprotein. Subsequently, CA 19-9 was also identified in the tissue and sera of patients with other gastrointestinal tumors including esophageal, gastric, biliary and pancreatic cancer. CA 19-9 is derived from an aberrant pathway during production of its normal counterpart disialyl Lewis-a which has one extra sialic acid residue attached through a 2-to-6 linkage. Disialyl Lewis-a is normally expressed on the epithelial surface of digestive organs, serves as a ligand for monocytes and macrophages, and helps in immunosurveillance. Epigenetic silencing of the gene for 2-to-6 sialyl transferase during early stages of carcinogenesis leads to abnormal synthesis and accumulation of sialyl Lewis-a (CA 19-9). Elevated circulating carbohydrate antigen 19-9 concentration Elevated cancer Ag 19-9 level Elevated circulating sialylated Lewis a antigen concentration abnormal increased amount blood