Synergistic use of glycomics and single-molecule molecular inversion probes for identification of congenital disorders of glycosylation type-1

J Inherit Metab Dis. 2022 Jul;45(4):769-781. doi: 10.1002/jimd.12496. Epub 2022 Mar 28.


Congenital disorders of glycosylation type 1 (CDG-I) comprise a group of 27 genetic defects with heterogeneous multisystem phenotype, mostly presenting with nonspecific neurological symptoms. The biochemical hallmark of CDG-I is a partial absence of complete N-glycans on transferrin. However, recent findings of a diagnostic N-tetrasaccharide for ALG1-CDG and increased high-mannose N-glycans for a few other CDG suggested the potential of glycan structural analysis for CDG-I gene discovery. We analyzed the relative abundance of total plasma N-glycans by high resolution quadrupole time-of-flight mass spectrometry in a large cohort of 111 CDG-I patients with known (n = 75) or unsolved (n = 36) genetic cause. We designed single-molecule molecular inversion probes (smMIPs) for sequencing of CDG-I candidate genes on the basis of specific N-glycan signatures. Glycomics profiling in patients with known defects revealed novel features such as the N-tetrasaccharide in ALG2-CDG patients and a novel fucosylated N-pentasaccharide as specific glycomarker for ALG1-CDG. Moreover, group-specific high-mannose N-glycan signatures were found in ALG3-, ALG9-, ALG11-, ALG12-, RFT1-, SRD5A3-, DOLK-, DPM1-, DPM3-, MPDU1-, ALG13-CDG, and hereditary fructose intolerance. Further differential analysis revealed high-mannose profiles, characteristic for ALG12- and ALG9-CDG. Prediction of candidate genes by glycomics profiling in 36 patients with thus far unsolved CDG-I and subsequent smMIPs sequencing led to a yield of solved cases of 78% (28/36). Combined plasma glycomics profiling and targeted smMIPs sequencing of candidate genes is a powerful approach to identify causative mutations in CDG-I patient cohorts.

Keywords: CDG type 1 (CDG-I); congenital disorders of glycosylation (CDG); diagnostics by mass spectrometry; glycomics; multi-omics; smMIPs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Congenital Disorders of Glycosylation* / diagnosis
  • Congenital Disorders of Glycosylation* / genetics
  • Glycomics
  • Glycosylation
  • Humans
  • Mannose
  • Mannosyltransferases / genetics
  • N-Acetylglucosaminyltransferases
  • Oligosaccharides
  • Polysaccharides / genetics


  • Oligosaccharides
  • Polysaccharides
  • ALG11 protein, human
  • ALG13 protein, human
  • ALG3 protein, human
  • Mannosyltransferases
  • N-Acetylglucosaminyltransferases
  • Mannose