Diagnosing inborn errors of metabolism where protein glycosylation is defective.
Abnormal transferrin glycoforms are associated with inborn errors of protein glycosylation including the carbohydrate-deficient glycoprotein syndromes (CDG), galactosaemia and fructosaemia.They are also found in certain acquired conditions, such as alcohol dependency syndromes.
CDG is characterised by neurological involvement that can be associated with multivisceral abnormalities and is classified into Type 1 and Type 11 forms.
- CDG Type 1 – disrupted synthesis of the lipid- linked oligosaccharide precursor
- CDG Type 11 – malfunctioning of the trimming/ processing of protein-bound oligosaccharide chain.
In galactosaemia and fructosaemia the abnormal pattern reverts to normal in approximately 4-6 weeks of treatment.
Serum – SST or Plain (red top) Tube
Neuroimmunology and CSF Laboratory, UCL Queen Square Institute of Neurology, London
Note that the test is unreliable in detecting inborn errors of protein glycosylation in neonates younger than 1 month, owing to the confounding influence of transferrin of maternal origin and in neonates who have recently received a transfusion.