[Carbohydrate-deficient glycoprotein syndrome]

Carbohydrate-deficient glycoprotein syndrome is characterized by mental retardation, ataxia, hepatopathy during infancy, cerebellar hypoplasia, peripheral neuropathy, internal strabismus, growth retardation and stroke-like episodes. Since the description of female siblings with unique clinical and biochemical features by Jaeken (1980) and the discovery of unique isoforms of serum transferrin in the patients by Jaeken (1984), more than 120 patients have been diagnosed. The biochemical marker is asialo- and disialo-transferrin. We have found the first Japanese patients and, through analysing serum glycoproteins from these patients, we was noted that multiple serum glycoproteins contain abnormal fractions, on isoelectric focusing. By analysing the sugar chain of transferrin, we have found that the abnormality is caused by a defect in the transfer of asparagine-N-linked oligosaccharide. Recently, two clinical and biochemical variants have been reported. One, characterized by severe mental retardation, no cerebellar hypoplasia, no peripheral neuropathy, diasirotransferrin dominancy, has proven to have a deficiency of N-acetylglucosaminyltransferase II, by Jaeken (1993).