Albumin as a glycoprotein biomarker in congenital disorders of glycosylation.

Congenital disorders of glycosylation (CDG) are rare inherited disorders resulting from defects in cellular glycosylation machinery. Albumin has recently been shown to be N-glycosylated at two non-canonical glycosylation sites. We applied multiplexed mass spectrometry-based glycoproteomics to identify site-specific N-glycosylation alterations in albumin from patients with PMM2-CDG, MPI-CDG, SRD5A3-CDG, MAN1B1-CDG and PGM1-CDG. Our findings demonstrate that the glycosylation of albumin is indeed affected in CDG and indicate a potential role for albumin-derived glycopeptides as diagnostic biomarkers.