FIGURE 2.

(A) Overlaid Total Ion Current Chromatograms (TICCs) of RapiFluor-MS labeled IgG N-glycans from a patient with MOGS-CDG (red line) and control (black line). Major changes of specific glycoforms are noted in patient profile by red arrows. The presence of disease-specific oligomannose N-glycan biomarkers (Glc₃Man₇GlcNAc₂) is highlighted with a double red circle. (B) Extracted ion chromatograms (EICs) of major RapiFluor-MS labeled biantennary and sialylated N-glycans identified in serum of patient 1 with TMEM199-CDG (green line), patient 2 with TMEM199-CDG (red line) and control (black line). Disialo-isomers eluted at RT 27.6 and 26.4 min depending on NeuAc linkage positions, monosialo-biantennary species eluted at RT 24.4 min whereas monogalacto- monosialo- isomers, if present, eluted at two different retention times due to differential Gal-NeuAc elongation at the two branches, respectively. (C) Comparison of the extracted ion chromatograms (EICs) of the RapiFluor-MS labeled oligomannose serum N-glycans Man_{5 – 9}GlcNAc₃ from a patient with ALG12-CDG (blue chromatogram), a patient with MAN1B1-CDG (orange chromatogram), and a healthy control (green chromatogram). Dotted lines refer to linkages that should be missing in the final structure. Reproduced with the modification and permissions from Messina et al. (2021).