Circulating ‘trophoblast’ cells in pregnancy have maternal genetic markers

A syncytiotrophoblast-associated antigen identified by the monoclonal antibody (McAb) H315 is detectable on the surface of a low proportion of peripheral blood cells in pregnant women, raising the possibility of a new approach to prenatal diagnosis of genetic disorders. We aimed at verifying the trophoblastic origin of H315⁺ cells and their use for prenatal diagnosis of β-thalassaemia. H315 ⁺ cells were separated from the peripheral blood of pregnant women: the DNA obtained from these cells in two selected cases was shown to have genetic markers indistinguishable from those of the mother and definitely different from the fetus. Our results suggest that H315 antigen is expressed by maternal cells and that prenatal diagnosis on peripheral blood of the mother using H315 McAb is not feasible.     

Immediate prenatal diagnosis of Zellweger syndrome by direct measurement of very long chain fatty acids in chorionic villus cells

We report a gas chromatographic-mass spectrometric method which allows the very long chain fatty acids content of trophoblastic tissue to be directly measured in samples collected by biopsy between 8 and 11 weeks of gestation. This method has been successfully applied to the detection of fetal Zellweger syndrome in two pregnant women who had previously delivered affected infants. In one of them, increased concentrations of C26:0 (0.254 versus 0.108±0.035 μ/mg proteins) and C24:0 (1.32 versus 0.815±0.325 μ/mg proteins) in trophoblast indicated that the fetus had Zellweger syndrome, a diagnosis confirmed by pathological findings after abortion. In the second case, the pregnancy was allowed to proceed, on the basis of normal concentrations of very long chain fatty acids in trophoblastic tissue, and its outcome was actually a healthy newborn.     

Two-dimensional spectrophotometry and pseudo-color representation of chemical reaction patterns

The formation of spatio-temporal patterns in layers of chemical and biochemical media is observed and quantified by a two-dimensional spectrophotometer based on a computerized video equipment with high spatial, temporal, and intensity resolution. Images are shown, to some extent, in pseudo-colors. The use of pseudo-colors and three-dimensional perspective representations enhances the perception of the information contained in an image and the inherent order of the spatial structures.     

Activity of biotin-dependent and gaba metabolizing enzymes in chorionic villus samples: Potential for 1st trimester prenatal diagnosis

We have documented the presence of five mitochondrial enzymes in samples of chorionic villus tissue and measured the levels of activity. Three of the enzymes catalyse biotindependent reactions. These are propionyl-CoA carboxylase, 3-methylcrotonyl-CoA carboxylase and pyruvate carboxylase. the other enzymes. 4-aminobutyric acid aminotransferase and succinic semialdehyde dehydrogenase, are involved inthe degradation of the central inhibitory neurotransmitter GABA. Distinct diseases in whichthere is deficiency of each of these enzymes have been documented in man. Significant levels of activity were observed for all five enzymes in chorionic villus tissue. This methodology should permit early prenatal diagnosis of deficiencies of these enzymes by chorionic villus biopsy in the first trimester.     

The cerebro-hepato-renal (Zellweger) syndrome: Prenatal detection based on impaired biosynthesis of plasmalogens

Prenatal diagnosis of the cerebro-hepato-renal (Zellweger) syndrome has been performed in 10 pregnancies at risk by measuring both the activity of acyl CoA: dihydroxyacetonephosphate acyltransferase (DHAP-AT) and the de novo plasmalogen biosynthesis, either in cultured amniotic fluid cells or in fibroblasts cultured from a chorionic villus biopsy. In 7 of the pregnancies both tests indicated no abnormality. All 7 continued to term and normal infants were delivered. However, in amniotic fluid cells from 2 fetuses affected by Zellweger syndrome unequivocal differences from control values were found. The activity of DHAP-AT was clearly deficient and the de novo plasmalogen biosynthesis was impaired. In one pregnancy at risk prenatal diagnosis was performed during the first trimester by measuring both the DHAP-AT activity and the de novo plasmalogen biosynthesis in fibroblasts cultured from a chorionic villi biopsy. From the deficient DHAP-AT activity and the impaired de novo plasmalogen biosynthesis it was concluded that the fetus was affected. This was confirmed biochemically after induced abortion. It can be concluded that measurement of the DHAP-AT activity and the de novo plasmalogen biosynthesis provides convenient methods for the early prenatal detection of Zellweger syndrome.