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Serum N-glycomics of a novel CDG-IIb patient reveals aberrant IgG glycosylation

Rare genetic mutations of the mannosyl-oligosaccharide glucosidase (MOGS) gene affecting the function of the mannosyl-oligosaccharide glucosidase (glucosidase I) are the cause of the congenital disorder of glycosylation IIb (CDG-IIb). Glucosidase I specifically removes the distal α1,2-linked glucose from the protein bound precursor N-glycan Glc3Man9GlcNAc2, which is the initial step of N-glycan maturation. Here, we comparatively analyzed N-glycosylation of the whole serum proteome, serum-derived immunoglobulin G (IgG), transferrin (TF), and α-1-antitrypsin (AAT) of a female patient who is compound heterozygous for 2 novel missense mutations in the MOGS gene, her heterozygous parents, and a sibling with wildtype genotype by multiplexed capillary gel electrophoresis coupled to laser induced fluorescence detection (xCGE-LIF) at unprecedented depth.