Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

This is a summary of: Gaifem, J. et al. A unique serum IgG glycosylation signature predicts development of Crohn’s disease and is associated with pathogenic antibodies to mannose glycan. Nat. Immunol. https://doi.org/10.1038/s41590-024-01916-8x (2024).