Health-related quality-of-life assessment of prenatal diagnosis: chorionic villi sampling and amniocentesis

This study assesses the health-related quality-of-life (HRQL) effects of chorionic villi sampling (CVS) and genetic amniocentesis (GA), including both process and outcomes of prenatal diagnosis. The HRQL of 126 women participating in a randomized controlled clinical trial of CVS versus GA in Toronto and Hamilton, Ontario, was assessed in four interviews at weeks 8, 13, 18, and 22 of pregnancy. Statistical analyses included analysis of variance, repeated measures analysis of covariance, chi-square, Fisher's exact test, Student's t-tests, and paired t-tests. Utility scores for patients undergoing CVS exceeded those for GA patients at week 18 (p = 0.04). Utility scores for hypothetical health states did not differ significantly by trial arm. CVS results in slightly improved HRQL during prenatal diagnosis. This advantage needs to be weighed against the high disutility patients attach to infrequent outcomes associated with pregnancy losses, equivocal diagnoses, and diagnostic inaccuracy.     

Accumulated experience with prenatal diagnosis of menkes disease by neutron activation analysis of chorionic villi specimens

Since 1983, prenatal diagnosis of Menkes disease has been carried out by determining Cu in samples of chorionic villi from the fetus by means of radiochemical neutron activation analysis. Concentrations of Cu in chorionic villi from male fetuses later confirmed to have Menkes disease were invariably higher than previously reported values for normal controls. Out of 240 samples analyzed in the period 1983–1998, there were 71 from female fetuses that could be carriers of the Menkes genetic defect without suffering from the disease. Increased concentrations of Cu in these samples could not be attributed to the presence of this genetic defect, but might result from sporadic contamination of the samples before analysis. Such contamination also may occur in samples from male fetuses and thus raise the level of Cu in small, but normal specimens into the range characteristic of Menkes disease. In spite of a strict protocol for taking samples without contamination, a total of four false positives were reported during the period of investigation; no false negatives have occurred.     

Confined chorionic mosaicism in prenatal diagnosis

Summary Confined chorionic mosaicism, detected commonly on chorionic villus sampling (CVS) and occasionally in cultured amniotic fluid cells, is described in five pregnancies that showed confined chorionic mosaicism for trisomies 12, 13, 14, 17 and a marker chromosome. Cytogenetic findings in these pregnancies support the conclusion that within chorion some chromosomal mosaicism are confined to the trophectoderm derivatives while others to the extra-embryonic mesoderm. The etiology of confined chorionic mosaicism is discussed in relation to a significant role of multiple cell lineages contributing to the early development of placenta. The need is indicated for the use of both direct and long-term cultures in CVS prenatal diagnosis, and for the confirmatory testing of fetal blood or amniotic fluid in cases where mosaicism is detected in chorionic villi.     

Prenatal diagnosis of genetic diseases using chorionic villi

Chorionic villi biopsy allows first trimester prenatal diagnosis of some genetic diseases. In this study the results of 163 diagnoses are presented, and among these, 59 diagnoses of autosomal recessive metabolic diseases with 8 observations of congenital adrenal hyperplasia due to 21 OH deficiency and 6 observations of Fanconi anemia.     

Branching enzyme activity of cultured amniocytes and chorionic villi: prenatal testing for type IV glycogen storage disease.

Although type IV glycogen storage disease (Andersen disease; McKusick 23250) is considered to be a rare, autosomally recessive disorder, of the more than 600 patients with glycogenosis identified in our laboratory by enzymatic assays, 6% have been shown to be deficient in the glycogen branching enzyme. Most of the 38 patients with type IV glycogen storage disease who are known to us have succumbed at a very early age, with the exception of one male teenager, an apparently healthy 7-year-old male, and several 5-year-old patients. Fourteen pregnancies at risk for branching enzyme deficiency have been monitored using cultured amniotic fluid cells, and four additional pregnancies have been screened using cultured chorionic villi. Essentially no branching enzyme activity was detectable in eight samples (amniocytes); activities within the control range were found in five samples (three amniocyte and two chorionic villi samples); and five samples appeared to have been derived from carriers. In two of the cases lacking branching enzyme activity, in which the pregnancies were terminated and fibroblasts were successfully cultured from the aborted fetuses, no branching enzyme activity was found. Another fetus, which was predicted by antenatal assay to be affected, was carried to term. Skin fibroblasts from this baby were deficient in branching enzyme. Pregnancies at risk for glycogen storage disease due to the deficiency of branching enzyme can be successfully monitored using either cultured chorionic villi or amniocytes.     

Prenatal diagnosis of triploidy by transabdominal aspiration of chorionic villi

A case of triploidy identified in second trimester fetal diagnosis is presented. Cytogenetic study was undertaken in chorionic willi obtained by transabdominal placentocentesis. The diagnosis was confirmed by cytogenetic analysis of cultured amniotic fluid cells. The observation was revealed within a programme of combined ultrasound and cytogenetic prenatal monitoring, in association with maternal age. The fetus aborted at 23 weeks of pregnancy was abnormal, including congenital malformations and hypoplasia of internal organs and placenta.     

First-trimester diagnosis on chorionic villi obtained by direct vision technique

Summary An improved technique for direct vision chrionic biopsy that gives a clear view of the amniotic sac was developed. With this technique, used in 48 women prior to vacuum aspiration and in six cases for diagnosis (karyotyping or enzyme analysis), it was possible to obtain chorionic villi free from contamination by maternal tissue. It was also possible to pick out villi (rich in blood vessels and with abundant buds on their surface) found to be most capable of growing in vitro. In the diagnostic cases, the pregnancies have continued uneventfully since the sampling; one pregnancy is now in the 32nd week.     

Lysosomal hydrolase activity in chorionic villi and embryonic cells in culture

Summary Fourteen lysosomal enzymes were compared in 20 cultured cell lines from chorionic biopsy and corresponding embryonic tissue after voluntary abortions. Enzymatic expression appears to be similar in cultured cells from both sources with some slightly higher levels for chorionic villi. We stress the importance of culturing chorionic villi especially in the case of enzymes (-L-iduronidase) or diseases (I cell disease) whose expression is unusual in fresh trophoblast tissue.     

Cell cycle studies in chorionic villi

Summary We have studied the cell cycle of cells obtained from chorionic villi in direct and culture preparations by incorporation of the thymidine analogue BrdU to produce latelabelling or sister chromatid differentiation patterns. We have, therefore, been able to estimate the duration of the cell cycle and, more specifically, the length of some of its phases. While results for chorionic villus sample cells in culture resembled those obtained for fibroblasts, data for the spontaneously dividing trophoblastic cells in direct preparations were different. Villi exposed to BrdU immediately after sampling showed a slight delay in the incorporation of the analogue and a lower percentage of labelled cells compared to villi treated after an overnight incubation, probably due to a temporary effect of the sampling technique. Results from semi-direct protocols suggest that cells have a G2 of no more than 4h, and a mid-S phase of 10–16h. The G1 period is very variable. After 48 h incubation with BrdU, only 4% of cells reach their second generation, whereas this percentage increases up to 70% after 72h, indicating that under these experimental conditions most cells have a cell cycle of approximately 36 h. The average number of sister chromatid exchanges was similar in both direct preparations and cultures: 5.2±2.1 SCE per cell.     

Prenatal diagnosis of a true fetal tetraploidy in direct and cultured chorionic villi

Prenatal diagnosis of a true fetal tetraploidy in direct and cultured chorionic villi: Tetraploidy is characterized by four complete sets of chromosomes (4n= 92). Although it has been frequently reported in spontaneous abortions, tetraploidy is extremely rare in term pregnancy. Most of late surviving patients are diploid/tetraploid mosaics and present severe mental and physical impairment. Up to date, only five tetraploidies were ascertained in the prenatal stage in amniocytes and/or fetal blood lymphocytes. No one has been reported in chorionic villi probably because tetraploidy is generally considered in this tissue as a false positive result due to confined placental mosaicism (CPM) or placental culture artefacts. We report here on a case of tetraploidy detected in chorionic villi because of fetal cystic hygroma. We discuss the reliability of this diagnosis and propose guidelines in the follow-up of tetraploidies detected after chorionic villus sampling (CVS). Thus a misdiagnosis of this poor condition will be avoided at best and an appropriate genetic counseling will be given to the parents.     

Pyruvate carboxylase in the yeast pyc mutant

Pyruvate carboxylase deficiency was previously reported to be the biochemical lesion in a yeast mutant, designated pyc, which cannot utilize ethanol, acetate, pyruvate, aspartate, or oxaloacetate as the sole carbon source [C. Wills and T. Melham (1985) Arch. Biochem. Biophys. 236, 782-791; C. Wills et al. (1986) Arch. Biochem. Biophys. 246, 306-320]. We present evidence here that the level of pyruvate carboxylase activity as well as the native and subunit molecular weights of this enzyme are identical in the mutant and the wild type. In addition we have used immunocytochemical labeling to demonstrate the exclusively cytosolic localization of this enzyme in both the mutant and wild-type yeast.     

Alkaline phosphatase expression in human chorionic villi

The physicochemical properties and electrophoretic mobility of different isoforms of alkaline phosphatase were studied in chorionic villi. Based on selective inactivation and inhibition studies (thermal stability, inactivation by urea, EDTA and L(+)ascorbic acid and L-amino acid inhibition), evidence was obtained for the existence of two distinct types of alkaline phosphatase in trophoblast cells. One type is peculiar to chorionic villi while the other is also found in term placenta. Both show two isoforms. These two isoforms were observed with polyacrylamide gel electrophoresis, carried out at pH 6.0 and 9.5. It is suggested that the qualitative and quantitative methods of alkaline phosphatase analysis could be used for first trimester fetal diagnosis of severe infantile hypophosphatasia and for understanding genetic control during early fetal development.     

Pyruvate carboxylase: Mechanism of the second partial reaction

The stoichiometry of the products of the pyruvate carboxylase reaction has been investigated and shown to vary as the concentration of pyruvate was altered. At high concentrations of pyruvate, the ratio of orthophosphate liberated to oxaloacetate produced approached one, but as the pyruvate concentration was decreased, the ratio increased. On the basis of this evidence, a model for the reaction mechanism was proposed in which the

complex could react either with pyruvate to form oxaloacetate, or water to produce

and HCO₃^?. The nonproductive breakdown of the enzyme-substrate complex and the resulting lack of stoichiometry provides an explanation for the nonlinear double reciprocal plots obtained for both the overall reaction and the pyruvate:oxaloacetate exchange reaction. Since neither the rate of breakdown of the isolated

complex nor the rate of decarboxylation of oxaloacetate in the absence of pyruvate could account for the difference in the amount of the two products formed during the overall reaction, it was postulated that the presence of pyruvate was necessary for hydrolysis to occur. Rate equations were derived describing the dependence of the initial velocity of the release of oxaloacetate in the overall reaction and the rate of the pyruvate:oxaloacetate exchange reaction, on pyruvate concentration. By assigning appropriate values to the various rate constants, theoretical curves were generated and fitted to the experimental data.     

Cytogenetic analysis of chorionic villi: a technical assessment

Summary Eighty-five samples of chorionic villi from women undergoing prenatal diagnosis at 8 to 12 weeks' gestation were subjected to cytogenetic analysis. Samples were prepared by a direct technique that permits limited analysis within two hours and by a short-term culture technique that permits detailed structural analysis within one week. An adequate number of cell divisions for cytogenetic analysis was obtained from 96% of living fetuses. Using both the direct technique and short-term culture, satisfactory banded chromosomal preparations were made in 93% of cases. Eleven of 12 pregnancies (92%) shown by ultrasound to be dead shortly before sampling, had cytogenetic abnormalities. Further studies are needed to develop banding definition equivalent to that available on cultured amniocytes.     

Prenatal enzymatic diagnosis of Krabbe disease (globoid-cell leukodystrophy) using chorionic villi

Summary Sixteen pregnancies in families with children enzymatically diagnosed as having Krabbe disease (KD) were monitored for prenatal KD using the assay of galactosyl ceramide -galactosidase (GCG) in uncultured chorionic villi (CV), cultured CV, or cultured amniotic fluid cells (AFC). Prenatal KD diagnoses were made for 5 pregnancies on the basis of lower than 10% normal GCG activity in cultured CV or AFC. Uncultured CV were studied in 3 out of the 5 KD embryos, although the GCG activities of 14%–23% as compared with control villi were diagnostically inconclusive; the relatively high activities were considered to be caused by maternal GCG contamination of these very small villus samples. Although the villi from 6 of the other pregnancies yielded more conclusive results, the use of uncultured CV alone is not recommended for prenatal KD diagnosis, this material being subject to possible uncontrolled contamination with maternal enzyme.