Analysis of Transferrin and α1‐Fetoprotein in Amniotic Fluid and Neonatal Serum: a Possible Means for Indirect Prenatal Diagnosis of the Carbohydrate‐deficient Glycoprotein Syndrome

Abstract

A new type of inborn error of glycoprotein metabolism has recently been identified (CDG syndrome). The disease has systemic manifestations but mainly involves the nervous system. The most striking biochemical abnormality is the presence of secretory glycoproteins that are partially deficient in their carbohydrate moieties, the most pronounced of which is seen in serum transferrin. The basic genetic defect of the syndrome has not yet been identified. This study was carried out in order to provide a basis for indirect prenatal diagnosis by qualitative and quantitative analyses of a corresponding carbohydrate‐deficiency in transferrin and also in α1‐fetoprotein in amniotic fluid. On isoelectric focusing both glycoproteins normally showed a carbohydrate (sialic acid (‐dependent microheterogeneity in amniotic fluid as well as in neonatal serum which in transferrin differed from adult serum. Reference values of total transferrin (TT) and carbohydrate‐deficient isotransferrins (CDT) during gestation were determined. Analysis of the microheterogenity of these glycoproteins by isoelectric focusing or determination of the CDT/TT ratio in amniotic fluid might provide a possibility for prenatal diagnosis of this syndrome. It was also shown that neonatal diagnosis is possible by analysis of serum transferrin.