[Prenatal diagnosis of mucoviscidosis: biochemical technics and studies of affected fetuses].
The prenatal diagnosis of cystic fibrosis is based on microvillar enzymes values in amniotic fluid taken by amniocentesis at precisely the 17-18 weeks gestation age (15-16 weeks developmental age). In pregnancies with a cystic fibrosis affected fetus the values of the enzymes are depressed. Since microvillar enzymes are normal constituents of amniotic fluid, it is important 1. to have highly reproducible techniques and 2. to determine the range of the normal values and their variations in relation to the development of the fetus. Prenatal diagnosis was performed in more than 200 pregnancies with a 1 in 4 risk of cystic fibrosis and was based on significant modifications of 6 amniotic fluid enzymes values: gamma-glutamyl-transpeptidase, aminopeptidase and alkaline phosphatase (total and isoenzymes). Normal outcome was predicted in 135 pregnancies reaching term, 133 babies were normal and 2 were affected. On the basis of significantly abnormal enzymatic values an affected fetus was predicted in 57 pregnancies, 3 went to term, the infants were affected, 54 were terminated and the diagnosis of cystic fibrosis was confirmed in the examined fetuses. The decrease in amniotic fluid microvillar enzymes values is the result of an obstruction of the terminal ileum. Fetuses affected with cystic fibrosis developed an intestinal obstruction around the 15th week of developmental age which can be seen by ultrasound scanning in about fifty per cent of the cases. This obstruction persists in some fetuses and leads to a meconium ileus at birth.