Meta-Biol

• Pathways

The family of beta 4-galactosyltransferases (B4GALTs) is composed by at least six known members that mediate the transfer of galactose to N-glycan structures and either to begin or elongate keratan chains. Defective B4GALT1 is associated with congenital disorder of glycosylation type IId (B4GALT1-CDG, CDG-2d; MIM:607091), in which clinical symptoms are dominated by dysmorphic features, psychomotor and mental retardation, hypotonia, as well as blood coagulation abnormalities (Hansske et al. 2002). The mutant R345Kfs*6 results in a truncated, inactive polypeptide. Analysis of oligosaccharides from serum transferrin from these patients reveals loss of sialic acid and galactose residues (Hansske et al. 2002).