Immunoglobulin levels in patients with carbohydrate-deficient glycoprotein syndrome type I.

Background: The characteristic feature of carbohydrate-deficient glycoprotein syndrome (CDGS) type I, a multisystemic disease, is underglycosylation of many serum glycoproteins, such as transferrin. A few cases of severe infections during childhood have been reported and an underlying immunodeficiency has been suggested. Because of this and the fact that all immunoglobulin (Ig) isotypes are glycoproteins we analysed the Ig levels in patients with CDGS I.

Methods: The serum concentrations of IgG1, IgG2, IgG3, IgG4, IgA, IgM, IgD and IgE, and the frequency of the G2m(23) allotype were measured by enzyme immunoassay in 15 patients with CDGS type I.

Results: Ten (67%) patients had an elevated level of at least one Ig, when compared to age-related reference ranges. No particular isotype was involved although a tendency towards high IgE levels was registered. The frequency of homozygous G2m(23)-negative CDGS patients (33%) was not different from that of blood donors (34%).

Conclusion: We conclude that CDGS I patients have no major changes in the serum levels of any specific Ig isotype. The severe infections observed in some CDGS patients are therefore unlikely to involve any Ig deficiency. Our results do not exclude that Ig of patients with CDGS may have altered physiological functions because of abnormal glycosylation.