Unsaturated B12-binding proteins in amniotic fluid of cystic fibrosis-affected foetus.

The authors hypothesized the possibility of quantitative or qualitative abnormalities of amniotic fluid B12-binding proteins in cystic fibrosis. Seven cystic fibrosis and 59 normal amniotic fluids sampled between 17.5 and 18.5 gestational weeks were studied by radioimmunogel filtration, radioisotope technique, and isoelectric focusing chromatography. In normal amniotic fluid there was an increase of unsaturated B12-binding capacity from 16 to 41 weeks of gestation. There was no statistically significant difference in unsaturated B12-binding capacity, molecular weights and isoelectric points of haptocorrin, transcobalamin 2, and intrinsic factor between cystic fibrosis and normal amniotic fluid. Cobalamin-binding proteins study cannot help in the antenatal diagnosis of cystic fibrosis.