TY - JOUR
T1 - A complement C4–derived glycopeptide is a biomarker for PMM2-CDG
AU - Garapati, Kishore
AU - Budhraja, Rohit
AU - Saraswat, Mayank
AU - Kim, Jinyong
AU - Joshi, Neha
AU - Sachdeva, Gunveen S.
AU - Jain, Anu
AU - Ligezka, Anna N.
AU - Radenkovic, Silvia
AU - Ramarajan, Madan Gopal
AU - Udainiya, Savita
AU - Raymond, Kimiyo
AU - He, Miao
AU - Lam, Christina
AU - Larson, Austin
AU - Edmondson, Andrew C.
AU - Sarafoglou, Kyriakie
AU - Larson, Nicholas B.
AU - Freeze, Hudson H.
AU - Schultz, Matthew J.
AU - Kozicz, Tamas
AU - Morava, Eva
AU - Pandey, Akhilesh
N1 - Publisher Copyright:
Copyright: © 2024, Garapati et al.
PY - 2024
Y1 - 2024
N2 - BACKGROUND. Diagnosis of PMM2-CDG, the most common congenital disorder of glycosylation (CDG), relies on measuring carbohydrate-deficient transferrin (CDT) and genetic testing. CDT tests have false negatives and may normalize with age. Site-specific changes in protein N-glycosylation have not been reported in sera in PMM2-CDG. METHODS. Using multistep mass spectrometry–based N-glycoproteomics, we analyzed sera from 72 individuals to discover and validate glycopeptide alterations. We performed comprehensive tandem mass tag–based discovery experiments in well-characterized patients and controls. Next, we developed a method for rapid profiling of additional samples. Finally, targeted mass spectrometry was used for validation in an independent set of samples in a blinded fashion. RESULTS. Of the 3,342 N-glycopeptides identified, patients exhibited decrease in complex-type N-glycans and increase in truncated, mannose-rich, and hybrid species. We identified a glycopeptide from complement C4 carrying the glycan Man5GlcNAc2, which was not detected in controls, in 5 patients with normal CDT results, including 1 after liver transplant and 2 with a known genetic variant associated with mild disease, indicating greater sensitivity than CDT. It was detected by targeted analysis in 2 individuals with variants of uncertain significance in PMM2. CONCLUSION. Complement C4–derived Man5GlcNAc2 glycopeptide could be a biomarker for accurate diagnosis and therapeutic monitoring of patients with PMM2-CDG and other CDGs.
AB - BACKGROUND. Diagnosis of PMM2-CDG, the most common congenital disorder of glycosylation (CDG), relies on measuring carbohydrate-deficient transferrin (CDT) and genetic testing. CDT tests have false negatives and may normalize with age. Site-specific changes in protein N-glycosylation have not been reported in sera in PMM2-CDG. METHODS. Using multistep mass spectrometry–based N-glycoproteomics, we analyzed sera from 72 individuals to discover and validate glycopeptide alterations. We performed comprehensive tandem mass tag–based discovery experiments in well-characterized patients and controls. Next, we developed a method for rapid profiling of additional samples. Finally, targeted mass spectrometry was used for validation in an independent set of samples in a blinded fashion. RESULTS. Of the 3,342 N-glycopeptides identified, patients exhibited decrease in complex-type N-glycans and increase in truncated, mannose-rich, and hybrid species. We identified a glycopeptide from complement C4 carrying the glycan Man5GlcNAc2, which was not detected in controls, in 5 patients with normal CDT results, including 1 after liver transplant and 2 with a known genetic variant associated with mild disease, indicating greater sensitivity than CDT. It was detected by targeted analysis in 2 individuals with variants of uncertain significance in PMM2. CONCLUSION. Complement C4–derived Man5GlcNAc2 glycopeptide could be a biomarker for accurate diagnosis and therapeutic monitoring of patients with PMM2-CDG and other CDGs.
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U2 - 10.1172/jci.insight.172509
DO - 10.1172/jci.insight.172509
M3 - Article
C2 - 38587076
AN - SCOPUS:85189825826
SN - 2379-3708
VL - 9
JO - JCI Insight
JF - JCI Insight
IS - 7
M1 - e172509
ER -