Personal experience with the application of carbohydrate-deficient transferrin (CDT) assays to the detection of congenital disorders of glycosylation

Congenital disorders of glycosylation (CDG) are genetic multisystemic disea ses due to various defects in the biosynthesis or processing of glycoprotei ns. Our aim is to present our experience in the selective screening of CDG syndrome in a paediatric population (421 patients) with clinical suspicion of the disease, analysing serum carbohydrate-deficient transferrin (CDT) by radioimmunoassay and/or immunoturbidimetry. We established the normal valu es for our paediatric population. The abnormal results were confirmed and c lassified by isoelectric focusing of serum sialotransferrins, and by enzyma tic and molecular studies. We found 14 patients (3.3%) with abnormal serum CDT; 11 of them were classified as CDG type Ia (CDG-Ia) and the other three showed altered isoelectrofocusing patterns but remain untyped and are unde r investigation. In conclusion, both CDT assays proved to be useful tools f or CDG screening. Isoelectric focusing is a simple procedure but it require s specific instruments that are not always available. Since the immunoturbi dimetric procedure is commonly used to monitor for recent excessive alcohol consumption in clinical laboratories and does not require special equipmen t, it may also be reliably used to screen for CDG in children under clinica l suspicion.