The family of UDP GalNAc:polypeptide N acetylgalactosaminyltransferases (GalNAc transferases, GALNTs) carry out the addition of N acetylgalactosamine on serine, threonine or possibly tyrosine residues on a wide variety of proteins, and most commonly associated with mucins (Wandall et al. 1997). This reaction takes place in the Golgi apparatus (Rottger et al. 1998). There are 20 known members of the GALNT family, 15 of which have been characterised and 5 candidate members which are thought to belong to this family based on sequence similarity (Bennett et al. 2012). The GALNT-family is classified as belonging to CAZy family GT27. Defects in one of the GALNT family, GALNT12 (Guo et al. 2002) (MIM: 610290) can result in decreased glycosylation of mucins, mainly expressed in the digestive organs such as the stomach, small intestine and colon, and may play a role in colorectal cancer 1 (CRCS1; MIM:608812). CRCS1 is a complex disease characterised by malignant lesions arising from the inner walls of the colon and rectum (Guda et al. 2009, Clarke et al. 2012).

The family of UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferases (GalNAc-transferases, GALNTs) carry out the addition of N-acetylgalactosamine (GalNAc) on serine or threonine residues of proteins, especially mucins. This is the initial reaction in the formation of O-linked oligosaccharide biosynthesis (Guo et al. 2002). Defects in one of the GALNT family, GALNT12, can result in decreased glycosylation of mucins, mainly expressed in the digestive organs such as the stomach, small intestine and colon, and may play a role in colorectal cancer 1 (CRCS1; MIM:608812). CRCS1 is a complex disease characterised by malignant lesions arising from the inner walls of the colon and rectum. Mutations implicated in CRCS1 are M1I, T491M, Y395* (Guda et al. 2009), D303N and Y396C (Clarke et al. 2012).

Polypeptide N-acetylgalactosaminyltransferase 12