Prenatal morphology in meckel's syndrome (with special reference to polycystic kidneys and double encephalocele)

Prenatal morphology of Meckel's syndrome was studied in five fetuses of different gestational age, that had been aborted because ultrasonography and elevated amniotic AFP-levels indicated neural tube defect. Histologically, the enlarged polycystic kidneys were completely alike with respect to the type of involvement and differed only in the severity of changes. They could be identified as type III cystic kidneys according to the classification of Potter. Proliferation of hepatic bile ducts and slight cystic dilatation of pancreatic ducts is already evident in the youngest fetus. Additional cyst formation in the epididymis was found in one of the cases. Occipital encephalocele, located within an apical occipital bone defect was always associated with a second mostly occult encephalocele protruding through a separate defect of the basal occipital squame and of the first and second vertebral arch. It is assumed that double encephalocele represents a constant finding in Meckel's syndrome, indicating a specific pattern within the disturbance of neural tube closure.     

Amniotic fluid calcium concentration in the prenatal diagnosis of cystic fibrosis

Calcium concentrations were measured in supernatant amniotic fluid in order to establish whether they may be used as a marker for cystic fibrosis. No difference in values were found, whether the sample was derived from a normal pregnancy or from a pregnancy which resulted in a baby affected with cystic fibrosis.     

Fetal karyotype from cystic hygroma fluid

In cystic hygroma (CH) fetuses, hydrops fetalis and anamnios make it difficult or impossible to obtain amniotic fluid or cord blood for cytogenetic analysis. We report six cases of CH in which cytogenetic analysis was simply and successfully performed using nuchal fluid cells. The karyotypes were 47,XY, + 18,46,XY, 46,XX, and 45,X (n = 3).     

Microculture of fetal blood for prenatal cytogenetic studies from blood-stained amniotic fluid

An alternative method to the culture of amniotic fluid cells for prenatal diagnosis of chromosome disorders is proposed. Microculture of fetal blood can be used when fetal blood is drawn at amniocentesis through accidental puncture of the placenta. An easy discrimination of fetal red cells, a good response of fetal lymphocytes to PHA and the possibility of identification of the fetal karyotype from the maternal one are the technical bases of this method. This technique offers some undoubted advantages: a reduced need for repeating amniocentesis because of a lack of growth of AF cells due to massive contamination with red cells; a result may be obtained sooner. Thirty-seven cases out of 1092 amniocenteses were processed in this way (3·4 per cent). In two cases no mitoses were obtained but in the others the diagnosis was confirmed by the results of AF cell culture and/or by the outcome of pregnancy.     

Prenatal diagnosis of isovaleric acidaemia by enzyme and metabolite assay in the first and second trimesters

Isovaleric acidaemia (IVA) is caused by a deficiency of isovaleryl CoA dehydrogenase. The diagnosis can be established biochemically by the demonstration of increased levels of isovalerylglycine (IVG) and 3-hydroxyisovaleric acid in urine and by the deficiency of incorporation of radiolabel from [¹⁴C]isovaleric acid in macromolecules in cultured fibroblasts. This paper reports a consecutive series of 24 prenatal diagnoses in pregnancies at high risk, using both methods-metabolite and indirect enzyme assay. Affected fetuses were diagnosed in four pregnancies: three in the second trimester and one recent case in the first trimester. The latter represents the first reported case of a first-trimester diagnosis of IVA by direct analysis of chorionic villi. We also report the first demonstration of strongly accumulated IVG in the amniotic fluid in the 12th week of an affected pregnancy.     

Alpha-fetoprotein and acetylcholinesterase activity in first-and early second-trimester amniotic fluid

Normal ranges of amniotic fluid alpha-fetoprotein (AFP) and acetylcholinesterase activity (AChE) are described for gestational weeks 11–14 using rocket gel immunoelectrophoresis for AFP quantitation and a monoclonal antibody (4F19) enzyme antigen immunoassay for AChE activity measurement. The normal ranges were established by the examination of 281 amniotic fluid samples from 281 normal pregnancies. AFP was found to increase from a median level of 14.0 MIU/1 at 11 weeks to a maximum at 13 weeks (median=18.0 MIU/l) (P<0.05), thereafter falling (not significant). No AChE test result exceeded 4.8 nkat/l. In addition, AFP and AChE values for three cases of fetal malformation, identified by the biochemical analyses of amniotic fluid, are given. These cases included two fetuses with a neural tube defect and one fetus with an abdominal wall defect. Amniocentesis was performed at 10, 11, and 14 weeks, respectively. The AFP and AChE values were all high.     

Prenatal diagnosis of citrullinemia: Elevated levels of citrulline in the amniotic fluid in the three affected pregnancies

In three pregnancies at risk for citrullinemia affected fetuses were predicted both by strongly increased levels of citrulline in the amniotic fluid and by the reduced incorporation of ¹⁴C-citrulline into TCA-precipitable material in cultured amniotic fluid cells. The prenatal diagnoses of affected fetuses were confirmed after termination of the pregnancies by direct and indirect assays of argininosuccinate synthetase in the fetal livers and fibroblasts respectively. Measurement of the citrulline concentration in amniotic fluid appears to be a valuable adjunct in the prenatal diagnosis of citrullinemia.     

Prenatal diagnosis of 45,X/46,XX mosaicism: True mosaicism in only one of four primary cultures

45,X/46,XX mosaicism was found in only one of four primary amniotic fluid cultures. Repeat amniocentesis revealed 45,X/46,XX mosaicism in all four primary cultures. Mosaicism was confirmed in tissues from the abortus.     

Prenatal detection of the congenital nephrotic syndrome (Finnish type) by trehalase assay in amniotic fluid

We report relatively high trehalase activity in the amniotic fluid of two fetuses affected with the congenital nephrotic syndrome of the Finnish type. The results suggest that prenatal detection of this condition can be done on this basis in conjunction with the α-fetoprotein and acetylcholinesterase tests in amniotic fluid.