CDG syndromsE77.1

CDG stands for "Congenital Defects of Glycosylation". The term "CDG" covers hereditary defects in glycoprotein biosynthesis. They belong to the group of genetically determined metabolic defects. These are usually severe multi-organ diseases with frequently pronounced neurological disorders.

Several subtypes of CDG syndromes are now known. Their genetic defects have often been elucidated. They are classified according to the localization and function of the respective mutated gene and not according to clinical aspects. By means of NGS panel diagnostics, 43 genes for different CDG types can currently be investigated.

CDG means Congenital Disorder of Glycosylation. Glycosylation is the linking of sugar chains to different biomolecules such as proteins and fats. There are different linkages of sugar chains to proteins. The known diseases of glycosylation involve N-glycosylation, in which sugar chains are synthesized to a specific amino acid, in specific sequence with other amino acids. Sugar chains play an essential role on numerous proteins; for example, the blood group characteristics A, B, and O are composed of different sugar chains. Numerous other proteins are linked to sugar chains and are referred to accordingly as glycoproteins.

Since the function of many glycoproteins is restricted when the sugar chains are missing or defective, numerous deficiencies often occur in the case of related diseases. However, there are also diseases that affect only one organ or one cell system.

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4. van Tol W et al (2019) O-glycosylation disorders pave the road for understanding the complex human O-glycosylation machinery. Curr Opin Struct Biol 56:107-118.