Possibility of prenatal diagnosis of hereditary triose phosphate isomerase deficiency

Prenatal diagnosis has been performed on umbilical cord blood of an 18 weeks fetus of heterozygous triosephosphate isomerase (TPI) deficient parents. After excluding maternal blood contamination, TPI activity was measured and found to be 60 per cent of the normal mean whereas the value of glucose-6-phosphate dehydrogenase activity was in the normal range of fetal blood. In addition, the analysis of the characteristics of fetal TPI, i.e. K_m measurements for glyceraldehyde-3-phosphate, heat stability tests and electrophoretic studies, did not show any evidence of a special form of TPI in fetal blood. These results were consistent with the heterozygous state and were confirmed at birth.     

Prenatal diagnosis of familial tuberous sclerosis following detection of cardiac rhabdomyoma by ultrasound

The authors report a case of tuberous sclerosis (TS), diagnosed by prenatal ultrasound, which was suspected by the detection of intracardiac tumours and confirmed by the family investigation. Cardiac rhabdomyomata can be visualized early on echography and must suggest this diagnosis. The place of genetic counselling and prenatal diagnosis in TS is examined.     

Progression of exencephaly to anencephaly in the human fetus—an ultrasound perspective

Exencephaly as a precursor of anencephaly is well delineated in animal studies. In humans, a similar though unproven embryologic sequence is postulated. In the case reported, serial ultrasound studies allowed us to identify a 16-week human exencephalic fetus and observe the cephalic changes during its progression to a classic anencephalic appearance.     

Sensitivity of chromosomal mosaicism detection by different tissue culture methods

In the field of prenatal cytogenetic diagnosis, two tissue culture methodologies are currently in use: the flask method, which examines mixed populations of cells, and the in situ method, which examines distinct colonies of cells. These two methods provide inherently different levels of sensitivity which can be made comparable by adjusting the number of cells examined depending on the methodology used and the number of colonies formed per ml of specimen. Assuming that there are 2 colonies per ml of amniotic fluid in a 20 ml specimen, in order to detect 10, 20, and 30 per cent mosaicism with 95 per cent confidence, 29, 14, and 9 colonies should be examined respectively by the in situ method. Similarly, 50, 17, and 10 cells must be analysed by the flask method.     

Prenatal analysis of the insulin receptor gene in a family with leprechaunism

Leprechaunism is an autosomal recessive disease characterized by intrauterine and postnatal growth restriction, loss of glucose homeostasis, and severe insulin resistance. This disease is caused by a failure of function of the insulin receptor and is lethal early in life. Here we report the prenatal diagnosis of leprechaunism in one consanguineous family, Atl-1, in which two homozygous-affected siblings died with leprechaunism. The mutation in their insulin receptor impaired insulin binding and altered receptor signalling. Prenatal diagnosis could not be accomplished using insulin binding to cultured amniocytes, but was possible using mutational analysis of the insulin receptor gene in DNA from amniotic cells.     

Artificial instillation of amniotic fluid as a new technique for the diagnostic evaluation of cases of oligohydramnios

In cases of severe oligohydramnios, sonographic diagnosis is hampered by poor visibility and by increased fetal flexion. Therefore, 74 artificial instillations of amniotic fluid were performed in 50 pregnancies by sonographic guidance. Fetal diseases included Potter's syndrome, obstructive uropathy, cystic kidneys (20 cases); Meckel's syndrome, C. de Lange syndrome, cytomegaly fetopathy (1 case each); VATER association (2 cases); triploidy (5 cases); severe intrauterine growth retardation (8 cases); and premature rupture of membranes (12 cases). By improved sonographic visibility and the observation of fetal behaviour (drinking, filling of stomach and bladder, voiding of bladder after artificial instillation of amniotic fluid), the fetal anatomy could be studied more accurately, malformations could be identified or excluded, and bladder function could be examined. Thus, differentiation between fetuses without functioning kidneys and those with severe intrauterine growth retardation becomes possible. Further, re-aspiration on the day following instillation permitted determination of the karyotype. Finally, the artificial instillation of amniotic fluid is a hazardous intervention (rupture of membranes, labour) and should be reserved only for a small number of selected cases with diagnostically unclear oligohydramnios. For these cases, it seems to be the method of choice permitting a variety of diagnostic information to be obtained.     

Prenatal diagnosis of Pompe's disease (type ii glycogenosis) in chorionic villus biopsy using maltose as a substrate

Uncultured trophoblasts obtained from chorionic villus biopsy during the gestation period of 8–12 weeks were assayed for alpha-glucosidase activity using maltose as the substrate. Only one major form of maltase activity with a pH optimum at 4.0 was demonstrated. Using this method, we performed prenatal diagnosis on three pregnancies at risk for the infantile form of type II glycogen storage disease. Two affected fetuses and one unaffected fetus were predicted and the diagnosis was subsequently confirmed. The maltose assay offered a direct, simple, and sensitive method for prenatal diagnosis of Pompe's disease in the first trimester.     

Prenatal diagnosis of metabolic diseases on chorionic villi obtained before the ninth week of pregnancy

Nine pregnancies at risk for various metabolic disorders were monitored by prenatal diagnosis on chorionic villi obtained between the sixth and ninth weeks of pregnancy. A diagnosis of an affected fetus was made in five cases (Sandhoff, Tay—Sachs (2), Pompe's, GMI), while metachromatic leukodystrophy, GM1 (2), and Pompe's were excluded in four cases. It is concluded that chorionic villi are a reliable tissue for prenatal diagnosis of metabolic disorders also when obtained before the ninth week.     

Sonographic diagnosis of fetal congenital cataracts

Five fetuses with congenital cataracts diagnosed in utero by ultrasound are reported. The fetuses, who were between 14 and 27 weeks' gestation, also had other severe malformations. The sonographic features of the cataracts are presented.