Haptoglobin glycoforms in a case of carbohydrate-deficient glycoprotein syndrome

Alterations in haptoglobin (Hp) glycosylation were examined in the plasma o f the first patient with carbohydrate-deficient glycoprotein syndrome (CDGS ) who was described in Poland. Hp concentration in the CDGS patient plasma was low (240 mg/l) and the Hp phenotype was shown to be 2-2. Three glycofor ms of the Hp beta subunit were observed in SDS-PAGE in CDGS. The densitomet ric analysis and molecular weight determinations suggested that 50% of glyc oforms were fully glycosylated; 30% contained three out of four and 20% onl y two out of four glycan units compared to those that are present in Hp der ived from healthy people. Results with lectins (concanavalin A and Sambucus nigra, Maackia amurensis and Alleuria aurantia agglutinins) indicate that all three glycoforms of beta subunit of CDGS-Hp contained biantennary compl ex glycans terminated with alpha 2,6 bound sialic acid, but without fucose or alpha 2,3 linked sialic acid. Hp glycosylation abnormalities described i n this work suggest that this case was a type I carbohydrate-deficient glyc oprotein syndrome.