The function of Ensembl gene identifier ENSG00000110328 (GALNT18, polypeptide N-acetylgalactosaminyltransferase 18) is as follows. Catalyzes the initial reaction in O-linked oligosaccharide biosynthesis, the transfer of an N-acetyl-D-galactosamine (GalNAc) residue from UDP-GalNAc to a serine or threonine residue on the protein receptor. .