The congenital disorder of glycosylation type IID, also called CDG IId or CDG2D is a recessive genetic disorder caused by an autosomal mutation in the B4GALT1 gene which encodes the protein beta-1,4-galactosyltrasnferase 1. This protein is responsible for the conversion of D-glucose and uridine diphosphategalactose to alpha-lactose and uridine 5’-diphosphate. This reaction occurs in the mammary glands during lactation, and may be present during oligosaccharide synthesis in glycoproteins. This is a type II disorder, which means that the glycosylation steps affected are trimming, elongation and processing of glycans, whereas in type I disorders, the steps that are disrupted are assembly of oligosaccharides and their transfer. CDG disorders are characterized by mental and motor retardation, as well as increased levels of transferrins in the serum.

Congenital Disorder of Glycosylation CDG-IId References

Lactose Synthesis References