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).