Microheterogeneity of serum glycoproteins in patients with chronic alcoholabuse compared with carbohydrate-deficient glycoprotein syndrome type I

Background: Chronic alcohol abuse alters the normal N-glycosylation of tran sferrin, producing the carbohydrate-deficient transferrin isoforms. This al teration could be similar to that present in patients with carbohydrate-def icient glycoprotein syndrome type 1 (CDG1). We thus compared the alteration s of N-glycans present in patients with alcoholism and patients with CDG1. Methods: The N-glycans of serum glycoproteins were compared in sera of pati ents with alcoholism, patients with CDG1, and controls by two-dimensional e lectrophoresis, neuraminidase, peptide:N-glycosidase F, and endoglycosidase F2 treatments. A specific antibody directed against the amino acid sequenc e surrounding the N-432 N-glycosylation site of transferrin was prepared (S Z-350 antibody). Results: In patients with alcoholism, the abnormal transferrin and alpha(1) -antitrypsin isoforms were devoid of a variable number of entire N-glycan m oieties and were identical with those present in CDG1. In the serum of pati ents with alcoholism, this finding was less pronounced than in CDG1. In con trast to CDG1, there was no decrease in clusterin or serum amyloid P in pat ients with alcoholism. The SZ-350 antibody recognized only transferrin isof orms with one or no N-glycan moieties. Conclusion: Antibodies directed against specific N-glycosylation sites of g lycoproteins could be useful for developing more specific immunochemical te sts for the diagnosis of chronic alcohol abuse. (C) 1999 American Associati on for Clinical Chemistry.