Die Anwendung von molekulargenetischen Techniken in der Neurochemie

Research in molecular neurobiology has recently entered a new phase of rapid development as a result of the application of the techniques of molecular genetics. This is illustrated by recent work on the electric ray (Torpedo marmorata and T. californica), whose electric organ is a rich source of cholinergic synapses. Other examples from recent literature of the application of the recombinant DNA technique to the mammalian central nervous system are given and possible future developments are discussed.     

Fetal cholecystomegaly: A prenatal marker of aneuploidy

The fetal gall bladder can now be easily identified during the second and third trimesters using high-resolution ultrasonography. In this report we present eight fetuses with an enlarged gall bladder detected on prenatal ultrasonography at a mean gestational age of 24.6 weeks (range 19–31 weeks). Additional ultrasonographic findings were present in four cases: fetal anomalies and intrauterine growth retardation in three and polyhydramnios in one. Of those cases associated with fetal anomalies, one woman underwent amniocentesis at 21 weeks revealing trisomy 18. The other two declined prenatal karyotyping; neonatal karyotyping revealed trisomy 13 in one and trisomy 18 in the other. Although an enlarged fetal gall bladder can be a normal variant in the second and third trimesters, the prenatal detection of cholecystomegaly should prompt a search for associated anomalies and other markers of aneuploidy. If found, prenatal karyotyping should be considered.     

Prenatal diagnosis of mosaic 4p – in a fetus with trisomy 21

Mosaicism for the Wolf-Hirschhorn syndrome, del(4)(p16), is extremely rare and has not been reported in association with a numerical chromosome abnormality. We report the prenatal diagnosis of mosaic del(4)(p16) and non-mosaic trisomy 21 in a 16-week female fetus. The pregnancy ended in spontaneous abortion at 34 weeks secondary to fetal demise. The fetus had features of both 4p – and trisomy 21.     

Prenatal diagnosis of herlitz junctional epidermolysis bullosa by amniocentesis

Herlitz junctional epidermolysis bullosa (HJEB) is a severe blistering disorder which usually results in death during infancy. We have previously shown that the anchoring filament protein laminin-5 (kalinin/nicein), which mediates keratinocyte attachment and dermal–epidermal cohesion, is abnormally expressed in individuals with HJEB. Laminin-5 was detected by Western blot analysis in amniotic fluid from 44 consecutive normal secondtrimester control pregnancies, but was undetectable in second-trimester amniotic fluid from four pregnancies with fetuses affected by HJEB. In one case of severe non-Herlitz JEB, laminin-5 was detected in both amniotic fluid and skin. In human amniotic fluid, the laminin-5 a3 subunit was processed to a major 165 kD species and a minor 145 kD species and the β2 subunit was partially processed to 105 kD. Although laminin-5 was covalently associated with laminin-6 (K-laminin) in amniotic membrane, no covalent interaction was detected in amniotic fluid. Laminin-5 from amniotic fluid strongly supported keratinocyte attachment. These results suggest that Western blot analysis of second-trimester amniotic fluid is useful in determining the prenatal diagnosis of HJEB and that laminin-5 may serve a physiologically important function in amniotic fluid.     

Fetal nuchal oedema and antenatal diagnosis of trisomy 10

Trisomy 10 was detected at amniocentesis undertaken following observation of fetal nuchal oedema. This is the first report of fetal trisomy 10 in association with nuchal oedema. The physical features of fetal trisomy 10 are described.     

Prenatal diagnosis of congenital gastric outlet obstruction

A case of gastric outlet obstruction diagnosed prenatally at 22 weeks' gestation is described. The differential diagnosis and the clinical management of this rare condition are discussed, and an updated literature review is presented.     

Accuracy of amniotic fluid testing before 21 weeks' gestation in prenatal diagnosis of congenital cytomegalovirus infection

Cytomegalovirus (CMV) is the most common cause of intrauterine infection. Recent publications show amniocentesis to have an 81–100 per cent sensitivity in antenatal diagnosis after 21 weeks' gestation. Testing before 21 weeks' gestation is less well documented. We performed 36 amniocenteses between 14 and 20 weeks' gestation. The sensitivity was 45 per cent and the specificity 100 per cent. Implications and possible causes of this low sensitivity are discussed.     

Prenatal diagnosis of inborn errors in peroxisomal β-oxidation

In recent years, an increasing number of inherited diseases in man have been recognized in which there is an impairment in the peroxisomal β-oxidation of very-long-chain fatty acids. In general, these disorders are associated with severe neurological and physical abnormalities and death within the first years of life. In this paper we describe our experience with regard to the prenatal diagnosis of a number of different inborn errors of peroxisomal β-oxidation. Eleven pregnancies at risk were monitored by measuring very-long-chain fatty acid levels as well as very-long-chain fatty acid β-oxidation in cultured chorionic villous fibroblasts and/or amniotic fluid cells. Five affected fetuses were identified. It is concluded that prenatal diagnosis in this group of diseases can be done reliably using cultured chorionic villous fibroblasts or amniotic fluid cells.