Galactose-deficient IgA1, or Gd-IgA1 for short, is a special form of the immunoglobulin A1 molecule in which O-glycosylation in the hinge region is incomplete.
Galactose deficient IgA1
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Normally, IgA1 carries several O-linked sugar residues in the hinge region, which contain galactose, among other things. In Gd-IgA1, the galactose is partially or completely missing from these O-glycans, so that more N-acetylgalactosamine (Tn antigen) or sialyl-Tn antigen is exposed.
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IgA nephropathy (Berger's disease): Gd-IgA1 is overproduced by B cells of the mucosa. The body's own autoantibodies (mostly IgG or IgA) recognize the exposed Tn structures. Immune complexes are formed which are deposited in the mesangia of the renal corpuscles and trigger glomerulonephritis.
In Schönlein-Henoch purpura (leukocytoclastic IgA vasculitis), an analogous mechanism can be detected that mainly takes place in the skin.
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Special ELISA tests or lectin-based assays (e.g. with Helix aspersa agglutinin) can measure the proportion of galactose-deficient IgA1 in the serum.
LiteratureThis section has been translated automatically.
- Zachova K et al. (2022) Galactose-Deficient IgA1 B cells in the Circulation of IgA Nephropathy Patients Carry Preferentially Lambda Light Chains and Mucosal Homing Receptors. J Am Soc Nephrol 33:908-917.