Origin of amniotic fluid group-specific component.

Abstract

THE use of amniotic fluid for the prenatal diagnosis of genetic disease has prompted investigations into the origin of amniotic fluid protein. Several observations (refs. 1–5 and R. G. S. and D. J. H. B., manuscript in preparation) have suggested that the foetus contributes protein to the fluid early in pregnancy, and it has also been claimed that during this time amniotic fluid is an extension of the foetal extracellular space6,7. Conversely, in term amniotic fluid, the serum proteins transferrin and group-specific component (Gc) have been found to be of maternal origin8–10. Serum proteins make up the great majority of amniotic fluid protein at all stages of gestation, but it is not known whether maternal or foetal serum is the source early in gestation. In this study, Gc polymorphism is used to investigate this point.