Prenatal diagnosis in type IIA von Willebrand disease.

A prenatal diagnosis for fetal disease was performed at 20 weeks gestation in a severely affected patient with type IIA von Willebrand disease. In the fetal cord blood sample obtained under ultrasound guidance, the level of von Willebrand ristocetin cofactor activity was similar to that of von Willebrand factor antigen, and all the multimers were present. These results were compared to those obtained in 51 normal fetuses of similar gestational age (19-21 weeks). Normal fetuses showed slightly lower levels of von Willebrand factor than normal adults and in addition to all adult multimers, the presence of unusual large forms. This data compared with the case, allowed the exclusion of the diagnosis of type IIA von Willebrand disease in our patient's fetus. This was confirmed at birth in the cord blood.

Prenatal diagnosis with biotinylated chromosome specific probes.

We have used a Y-chromosome specific DNA probe in a controlled study to determine the presence of Y-chromosome material and to detect numerical abnormalities in uncultured amniotic fluid cells by fluorescent hybridization. Using this non-radioactive method, we correctly predicted fetal sex within 48 h in all but 3 of 54 cases and identified an XYY syndrome. The technique was previously tested with no false-positive or false-negative results on cultured interphase or metaphase nuclei of fetal fibroblasts and adult T-lymphocytes. Fluorescent in situ hybridization was applied to long-term fixed cytogenetic preparations up to 44 months old and was shown to be reliable.

Prenatal diagnosis of hemophilia by fetal blood sampling under ultrasound guidance.

In utero fetal blood sampling was performed in 55 cases for prenatal diagnosis of hemophilia A and B. Fifteen fetuses were found to be affected. However, with this new procedure, it was possible to demonstrate that fetuses were not hemophiliacs in 40 cases. Therefore, pregnancy was not interrupted; these infants were born and definitely proven to be normal. There were no diagnostic errors.

Vitamin K dependent proteins in fetal hemostasis at mid trimester of pregnancy.

The vitamin K dependent coagulation factor activities were measured in 63 normal human fetuses from 19 to 28 weeks of pregnancy. These activities were included between 9 to 28 percent of normal adult levels. Prothrombin antigen, factor IX antigen and protein C were also measured. There is a good correlation between prothrombin procoagulant activity and antigenicity, suggesting that low level of these vitamin K dependent proteins in fetuses is probably a consequence of liver immaturity.