Diagnostic application of first trimester trophoblast sampling in 100 pregnancies

Placental mosaicism in the era of chromosomal microarrays

OBJECTIVE

Placental mosaicism for a subset of a chromosome, a structural chromosomal aberration, is thought to be a very rare finding in chorionic villus samples. Here, we present clinical and laboratory data on five cases with such mosaicism for structural chromosomal aberrations.

METHODS

During a period of 6 months, chromosomal microarray was carried out on DNA extracted from 100 uncultured chorion villous samples from high-risk pregnancies.

RESULTS

In five of 100 consecutively collected samples (5/100), mosaicism for a structural chromosomal aberration was detected. The mosaic aberration was subsequently detected in fetal tissue in three of the five cases.

CONCLUSION

Chromosomal microarray can detect placental mosaicism for structural chromosomal aberrations. This kind of mosaicism may be more frequent than previously anticipated, and the fetal involvement seems difficult to predict. These findings highlight the complexity of mosaicism for structural chromosomal aberrations in prenatal samples in the chromosomal microarray era.

Prenatal diagnosis in two families with autosomal, p47(phox)-deficient chronic granulomatous disease due to a novel point mutation in NCF1

OBJECTIVE

Prenatal diagnosis was required in two unrelated families with chronic granulomatous disease (CGD) patients who lacked expression of p47(phox) protein; thus a search for mutations in NCF1 was undertaken.

METHODS

Gene scanning was applied to establish the relative number of coding and pseudo-NCF1 genes. PCRs specific for coding NCF1 cDNA and coding NCF1 exon-7 genomic DNA were devised.

RESULTS

The normal 1:2 ratio of coding and pseudo-NCF1 genes was found in the patients. Sequencing of the RT-PCR product specific for mRNA from the coding NCF1 genes revealed a novel homozygous G579A mutation in both patients, changing the TGG codon for Trp193 into the TAG stop codon. This mutation was confirmed in genomic DNA. The parents of both patients were found to be heterozygotes for this mutation. In the chorionic villus DNA of the first family a heterozygous G579A mutation was found. Postpartum, functional NADPH oxidase tests were normal. In the second family, this mutation was present in homozygous form in the chorionic villus DNA. Following termination of the pregnancy, the diagnosis of p47(phox)-deficient CGD was confirmed on DNA extracted from fetal blood.

CONCLUSION

This is the first report of prenatal diagnosis in p47(phox)-deficient CGD.

Chorionic villus sampling: clinical experience of the initial 750 cases

OBJECTIVE

To assess the factors that might influence the success rate, safety and reliability of chorionic villus sampling (CVS) and to evaluate the relationship between CVS and other congenital anomalies.

DESIGN

Analysis of the outcome of 750 cases of CVS (730 cases with transcervical and 20 cases with transabdominal).

SETTING

The outpatient prenatal genetic clinic of a university tertiary care center.

SUBJECT

Seven hundred and fifty pregnant women that underwent CVS for prenatal genetic diagnosis from 7 to 12 weeks of gestation.

RESULTS

Advanced maternal age was the most common indication for CVS (32.8%). The overall sampling success rate was 98.0% (735/750), representing 93.9% at 7 to 8 weeks, 98.1% at 9 to 10 weeks, and 98.3% at 11 to 12 weeks of gestation. The majority of cases (93.1%) required one or two aspirations. Cytogenetic analysis routinely included direct overnight and long-term culture methods which revealed 16 abnormalities (2.2%). Of 735 cases in which CVS was successful, 700 advanced to normal offspring, 17 had therapeutic termination, and 18 resulted in spontaneous abortions; there was an overall fetal loss rate of 2.4% (18/750).

CONCLUSION

CVS in early pregnancy is a relatively safe and reliable method of prenatal genetic diagnosis capable of replacing genetic amniocentesis. However, it must be done by experienced personnel. No congenital anomalies were found to be related to CVS in this series.

Paracentric inversions in humans: a review of 446 paracentric inversions with presentation of 120 new cases

We present a large review of 446 cases of paracentric inversions (PAI), including 120 new cases, to assess their incidence, distribution, inheritance, modes of ascertainment, interchromosomal effects, viable recombinant offspring, and clinical relevance. All 23 autosomes and sex chromosomes had inversions. However, none were identified in chromosome arms 18p, 19q, 20q, and Yp. PAI were most commonly reported in chromosomes 1, 3, 5, 6, 7, 11, and 14 and less frequently in chromosomes 4, 16, 17, 18, 19, 20, 21, 22, and Y. Inversions were most common in chromosome arms 6p, 7q, 11q, and 14q and observed least in chromosome arms 2p, 2q, 3q, 4q, and 6q. Frequently encountered breakpoints included 3(p13p25), 6(p12p23), 6(p12p25), 7(q11q22), and 11(q21q23). Ascertainment was primarily incidental (54.5%), mental retardation and/or congenital anomalies (22.2%), spontaneous abortions (11.4%), associations with syndromes (3.0%), and infertility (2.0%) accounted for the remainder. Ascertainment was neither related to the length of the inverted segment nor to specific inversions except for PAI of Xq which often presented with manifestations of Ullrich-Turner syndrome. Sixty-six percent of PAI were inherited while 8.5% were de novo. Recombination was observed in 17 cases, 15 of which resulted in a monocentric chromosomal deletion or duplication. No common factors were identified that suggested a tendency towards recombination. The incidence of viable recombinants was estimated to be 3.8%. This review documents that PAI are perhaps more commonly identified than suggested in previous reviews. Despite the possible bias of ascertainment in some cases, there may be associated risks with PAI that require further examination. Our data suggest that PAI carriers do not appear to be free of risks of abnormalities or abnormal progeny and caution is recommended when counseling.

Chorionic villi sampling: laboratory experience with 4,000 consecutive cases

Experience with 4,000 consecutive CVS cases shows that 1) the combination of both the direct and culture methods greatly reduces false diagnoses and maternal cell contamination; 2) the time interval between the sampling procedure and processing of villus specimens influences the quality of direct preparations; 3) maternal cell contamination (MCC) can be minimized with dissection of CVS specimens. We have compiled a large volume of confined placental mosaicism (CPM) cases to serve as a resource in interpreting mosaic cytogenetic findings. It was noted that, in up to 92% of the mosaic cases, the abnormal cell line was confined to the placenta. The frequency of true chromosomal mosaicism was 0.2%, and is not different from that for amniocentesis.

Cytogenetic analysis of 2928 CVS samples and 1075 amniocenteses from randomized studies

We report cytogenetic results from a randomized Danish chorionic villus sampling (CVS) and amniocentesis (AC) study including 2928 placental and 1075 amniotic fluid specimens processed in the same laboratory. The results are presented in groups comparing CVS with amniocentesis and transabdominal (TA) CVS with transcervical (TC) CVS as randomized. More abnormalities and more ambiguous diagnostic problems were found in placental tissues than in amniotic cells. There were no diagnostic errors and no incorrect sex predictions. Mosaicism was detected in 1 per cent of all cases of CVS (discordancies included). When confirmation studies were done, 90 per cent were found to be confined to the placenta. Eight cases (0.7 per cent) of mosaicism/pseudomosaicism were seen in amniotic fluid specimens, and two cases of five with confirmation studies were confirmed in the fetus. The rate of mosaicism/pseudomosaicism in CVS and AC specimens differed (p < 0.05). The rate of pseudomosaicism in cultures of villi and amniotic fluid cells was 0.5 and 0.6 per cent, respectively. Single-cell aneuploidy was observed in 1.8 per cent of villi and 1.4 per cent of amniotic fluid cell specimens. Maternal cell contamination (MCC) was seen more often after TC sampling (4.5 per cent) compared with TA sampling (1.5 per cent), but posed no problems in interpretation. Compared with the processing of cultured specimens, the short-term method of preparation of villi in our laboratory doubled the technicians' workload. For practical and economic reasons we have ceased the routine use of short-term preparations.

Prenatal diagnosis in a family with X-linked chronic granulomatous disease with the use of the polymerase chain reaction

In the X-linked form of chronic granulomatous disease (X91 degrees CGD), the genetic defect is linked to the CYBB locus on the X chromosome. We studied a family with a genetic defect in this gene, consisting of a G----A substitution at the fifth base of the 5' donor splice site of intron 3. This mutation leads to skipping of exon 3 after transcription of the gene. The expectant mother was diagnosed as a carrier. Analysis of polymerase chain reaction (PCR)-amplified genomic DNA from a chorionic villus biopsy (CVB) showed the same mutation in the male fetus. After termination of the pregnancy, the diagnosis was confirmed by conventional methods. This is the first time that PCR has been used for prenatal diagnosis of CGD.

Nuclear and chromosomal replication patterns in chorionic villi cells by bromodeoxyuridine labelling and DNA flow cytometry

Cell kinetics of chorionic villi (CV) were studied by BrdUrd-incorporation detected by fluorescence-plus-Giemsa and BrdUrd-antibody techniques, and by DNA flow cytometry. Growth characteristics of long-term cultures of CV resembled fibroblasts with a total cell cycle time of 26 h, final S phase of 9 h, penultimate S phase of 16 h and G2/M phase of 3-4 h. Especially useful for a quick routine diagnostic approach, Ultroser RG, a commercially available serum supplement, significantly increased cell proliferation and stabilized cell cycle lengths to a total cell cycle time of 14 h, final S phase of 7 h, penultimate S phase of 6 h and G2/M phase of 4 h. Moreover, mitotic activity steadily increased in cultured CV, when studying six successive subculturings. This reflects adaptation to the culture conditions rather than an inherent response of cultured CV cells of increasing passage numbers. Native villi exposed to BrdUrd immediately after biopsy show lower rates of uptake than do aliquots after overnight incubation. As shown by BrdUrd-pulse labelling studies, more than 7 h are required to overcome the proposed 'biopsy stress'. This correlates with routine diagnostic techniques, in which many more metaphase cells are observed in short-term cultures than in direct preparations.

Follow-up and pregnancy outcome after a diagnosis of mosaicism in CVS

In 2103 consecutive diagnostic chorionic villus samples, examined in a 4-year period in our clinical genetics unit, 26 samples (1.2 per cent) presented chromosomal mosaicism in the direct and/or long-term culture preparations. Only once (46,XX/47,XX,+9) was the mosaicism confirmed in the fetus. In the cytogenetic follow-up studies of the remaining 25 pregnancies, in no cases could the aberration be confirmed in amniotic fluid or fetal tissue. One patient requested a termination after the CVS result. Of the remaining 24 pregnancies, four (16.7 per cent) ended in a spontaneous abortion. These findings suggest an association between placental mosaicism and fetal loss.

Prenatal paternity testing by DNA analysis

Prenatal paternity testing was evaluated by DNA analysis in chorionic villus biopsies obtained during the 7th-22nd weeks of gestation. Using highly polymorphic variable number of tandem repeats (VNTR) probes, we analysed four cases consisting of mother/child/alleged father trios. In all cases, we were able to detect maternal and paternal alleles and could establish or exclude paternity. The application of DNA analysis represents a new important diagnostic aid for all cases that require a prenatal identification of paternity.

Randomized clinical trial of transabdominal versus transcervical chorionic villus sampling methods

The relative advantages and disadvantages of transabdominal (TA) and transcervical (TC) chorionic villus sampling (CVS) in terms of fetal risks and efficacy were evaluated in a clinical trial conducted on 1194 women randomized at 7-12 weeks' gestation. The results of the study indicate that, if any, the relative risk of fetal loss following either procedure is less than double that of the alternative technique when performed by a skilled operator. Overall, the fetal loss rate (spontaneous abortions following randomization, terminations of pregnancy, and perinatal deaths) is 16.5 and 15.5 per cent, respectively, among women allocated to TA- and TC-CVS. The two procedures are equally effective, although TA-CVS is associated with a significantly lower rate of repeat device insertions; on the other hand, a higher weight of chorionic tissue is obtained, on average, with TC-CVS. Bleeding is more common following TC-CVS, while peritoneal reaction developed only after TA-CVS. No diagnostic problems specifically related to one sampling technique were identified.

Chromosomal analysis of colonic adenomatous polyps

Chromosomal analysis of 25 colonic adenomatous polyps was performed by a direct method similar to that used in prenatal diagnosis of chromosomal aberration on chorionic villi. Fourteen lesions showed an abnormal karyotype. Two changes were recurrent: trisomy 7 (observed in eight cases) and trisomy 13 (observed in seven cases). No monosomy of the short arm of chromosome 17 was observed even at the level of two polyps with in situ carcinoma lesions.

The predictive value of cytogenetic diagnosis after CVS: 1500 cases

The cytogenetic results of 1500 chorionic villus samples (CVS) are presented. In these 1500 samples, 23 samples (1.5 per cent) could not be provided with a diagnosis because of laboratory failure. This failure rate dropped from 3 per cent in the first 500 samples to 0.2 per cent in the last 500. In the remaining 1477 samples, 58 (3.9 per cent) chromosomal aberrations were found. Of these, 21 (36 per cent) proved not to represent the karyotype of the fetus proper. Predictive values of (different groups of) chromosomal aberrations in CVS are calculated. The impact of (differences between) the predictive value for some major chromosomal aberrations is discussed. A tissue- and chromosome-specific selection mechanism is postulated.

Variation of lysosomal enzyme activity with gestational age in chorionic villi

The activities of 14 lysosomal enzymes in chorionic villi at gestational ages of 6-12 weeks were assayed. Arylsulphatases A and B, alpha-glucosidase and beta-glucuronidase activities increased with advancing gestational age. When compared with the activity in cultured amniotic fluid cells, arylsulphatase A, beta-galactosidase, alpha-glucosidase, heparan N-sulphatase, alpha-L-iduronidase, alpha-mannosidase, neuraminidase, and sphingomyelinase showed significant differences. All except beta-glucuronidase showed lower activity in chorionic villi than in cultured amniotic fluid cells. Prenatal diagnosis using chorionic villi was possible except for alpha-L-iduronidase. Storage at -20 degrees C up to 42 days did not significantly affect activity. The results emphasize the importance of using fresh or frozen age-matched control tissue for diagnosis.

Advances in prenatal diagnosis. Social-psychological and policy issues

Chorionic villus sampling (CVS), a new technique for prenatally diagnosing chromosomal and genetic disorders, may soon replace amniocentesis. This procedure, performed by inserting a catheter through the pregnant woman's cervix or through the abdomen and removing cells from the placenta, has the advantages of being available earlier in the pregnancy than amniocentesis (at 9 to 11 weeks gestational age) and of yielding results in a shorter time. Although the medical aspects of the procedure are being investigated, its psychosocial and policy implications have not been studied systematically. These issues include the subjective assessment of risk that prompts women to choose or to reject CVS, the implications of earlier diagnosis for feelings about abortion, the potential of negative findings (i.e., the absence of the designated disorder) for well-being during the remainder of the pregnancy, the ramifications of first trimester identification of fetal sex, equity of access to prenatal diagnosis, and the possible over-utilization of these procedures. Drawing on previous research regarding amniocentesis and more recent research concerning CVS, this article discusses the potential implications of CVS.

Chorionic villus sampling (CVS). Randomized study of efficacy of two transcervical biopsy methods: aspiration canulas and small forceps

A randomized study of two transcervical biopsy methods was performed. One method involved the use of an aspiration catheter and the other a tissue biopsy forceps. 120 chorionic villus samplings were performed in 30 patients. The percentage of success in taking biopsies and the resulting number of karyotypes were identical in both groups. The amount of removed trophoblastic tissue was greater when the forceps was employed. When the aspiration catheter was used, a sufficient amount of trophoblastic tissue was obtained for karyotyping purposes. It was easier to insert the aspiration catheter than the forceps. The echogenicity of the catheter and forceps were identical. The aspiration catheter has two advantages. Firstly, it is malleable and fits to the anatomy of the cervical canal and the site from which the biopsy is to be taken. Secondly, it is disposable.

Chorionic villus sampling--short-term versus long-term culture in a subtle 2; 18 translocation

Prenatal diagnosis on chorionic villous tissue was performed for a woman with the karyotype 46,XX,t(2;18)(q32;q12)--a subtle 'difficult' translocation. The case illustrates the necessity of good quality cytogenetics for accurate prenatal diagnosis. For chorionic villi this can be obtained only with long-term culture.

Cell cycle studies in chorionic villi

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 late-labelling 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 4 h, and a mid-S phase of 10-16 h. 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 72 h, 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.

Extra embryonic/fetal karyotypic discordance during diagnostic chorionic villus sampling

From a total of 1312 diagnostic chorionic villus samplings (CVS) there were 22 which showed discordance between the karyotype of the chorionic villi and that of the fetus. This frequency was some 20-fold higher than that reported at amniocentesis. In the majority of discordant cases, the fetal karyotype was normal while the placental karyotype was mosaic. In four cases, the placental karyotype was non-mosaic (a trisomy 16, a monosomy X, and two tetraploids) while the fetal karyotype was normal. In one case, the placenta was trisomy 18 while the fetus was mosaic. There were two 'false-negative' results where short-term methods showed only normal cells while both long-term cultures of chorionic villi and fetal cells were mosaic, in one 46,XY/47,XXY and in the other 46,XY/47,XY,+21.

Prenatal cytogenetic diagnosis after transabdominal chorionic villus sampling in the first trimester

First trimester prenatal cytogenetic diagnosis was attempted in 350 pregnancies after transabdominal chorionic villus sampling. The cytogenetic investigation was performed using both a short-term method (24 h incubation) and cell culture. Adequate samples were obtained in 99.1 per cent and in all these cases the fetal karyotype was established. A chromosome abnormality was found in 2.0 per cent of cases. A discrepancy between the karyotype obtained after 24 h incubation and the karyotype in cell culture was observed in 2.3 per cent. Maternal cell contamination in the cultures was confirmed in 13 of 181 cases where the 24 h incubation revealed a male karyotype. Studies of culture morphology showed that colonies of convoluted cells may serve as a marker for contamination with maternal cells in culture. For the present, we recommend using a short-term method as well as cell culture for cytogenetic investigation until the problems with karyotype discrepancy and maternal cell contamination have been further clarified.

Transabdominal chorionic villus sampling for fetal genetic diagnosis. Technical and obstetrical evaluation of 100 cases

First trimester fetal diagnosis was established in 100 pregnancies at risk by transabdominal chorionic villus sampling (TA-CVS). Forty-eight per cent of the women were 35 years or more at the time of sampling. Using the double needle technique, both the aspiration and the diagnostic success rate were 100 per cent. The mean amount of villi aspirated was 28.2 mg (10-50 mg). The mean needle time was 3 min. Vaginal spotting appeared in 2 per cent of the women. Four women had therapeutic abortion due to abnormal findings and one for social reasons. Three fetuses with normal karyotypes were lost. Excluding the therapeutic abortions, the fetal loss rate was 3.2 per cent. The fetal loss rate in the amniocentesis control group (n = 200) was 3.6 per cent. The cytogenetic diagnosis was carried out by the direct preparation technique as well as by chorion villus cultivation. All karyotypes were confirmed by lymphocyte cultures from umbilical cord blood or heel blood from the newborn or from aborted fetal tissue. Transabdominal CVS is deemed a safe and easy tool for achieving chorionic villi in the first trimester.

Chorionic villi sampling: a nursing perspective

A relatively new procedure, chorionic villi sampling is now available as an alternative method for prenatal diagnoses of genetic disorders during pregnancy. Indications, procedures, risks, advantages, and nursing implications of this procedure are defined and described. Readers are thereby provided with current information concerning prenatal genetic diagnosis that may be passed on to patients in need of this information.

The use of pregnancy serum to obtain trophoblastic cell cultures

A method for obtaining trophoblastic cell cultures from first-trimester human placental villi is described. The essential feature of the method is the use of serum from a pregnant woman in the culture medium. Using this technique, pure cultures of trophoblastic cells are produced in 88 per cent of cases.

Physiologic assessment of fetal compromise: biomarkers of toxic exposure

Understanding the physiologic and endocrinologic basis of fetal development is a major goal of perinatal biology. During the past decade a number of technological developments have allowed more precise evaluation of the fetus in utero and diagnosis of abnormalities. Despite these methodological achievements, however, there are no specific biological markers currently available to indicate that exposure to a given xenobiotic is associated with a cellular, subcellular, or pharmacodynamic event. This paper evaluates the following issues: What are some of the unique physiologic and endocrinologic features of the fetal milieu intérieur? What problems are peculiar to fetal assessment? Of what value are techniques such as ultrasonography, amniocentesis, chorionic villus sampling, fetoscopy, and fetal blood and tissue sampling for obtaining appropriate biomarkers? What are some examples of validated biomarkers and their applicability? What promising biomarkers are on the horizon? What are some of the promising techniques such as the evaluation of fetal body movements, breathing activity, electronic heart rate monitoring, and nuclear magnetic resonance? How may molecular probes be of value as biological markers of fetal compromise? What are some of the major research gaps and needs, and how should research priorities be set? Some of these topics are addressed. Moreover, the more general role(s) that various diagnostic methods and biological markers can have in an understanding of the regulation of fetal growth and differentiation and the role of xenobiotics in affecting the normal course of events are discussed.

Chromosome mosaicism and maternal cell contamination in chorionic villi

While chorionic villus sampling allows both early and rapid prenatal diagnosis of chromosome disorders, the accuracy of this technique has not been fully established. Maternal cell contamination and pseudomosaicism represent two major sources of diagnostic error. Combined use of both direct chromosome preparations and villus cultures is important in overcoming these problems. Direct preparations of villus tissue allow recognition of maternal cell contamination of villus cultures. Conversely, villus cultures yield higher resolution chromosomes and may be helpful in differentiating between true versus pseudomosaicism when two or more cell lines are identified in direct chromosome preparations. Preliminary data suggest that analysis of direct preparations from multiple individually processed villus fragments may also be of value in this regard. Until more experience is gained, mid-trimester amniocentesis should be offered to CVS patients when mosaicism is encountered.

Prenatal diagnosis of chromosomal abnormalities from chorionic biopsy samples: improved success rate using a modified direct method

Several methods for fetal chromosome analysis using chorionic biopsy samples were compared. A modified direct method for culturing villi was considered to be the method of choice and details are presented of 186 pregnancies tested prenatally. The success rate in obtaining a fetal karyotype with the direct method was 93 per cent. The fetal loss rate in the prenatal series was 4.3 per cent and congenital abnormalities in the babies already born did not differ from the expected incidence.

Chorionic villus sampling: improved method for preparation of karyotypes after short-term incubation

A method for the isolation and trypsin-Giemsa banding of metaphases obtained after short-term incubation (48 h) of cytotrophoblast cells from chorionic villus sample is described. A new slide-making instrument, developed expressly to enhance the spreading of chromosomes from metaphases released from small tissue pieces, is responsible for the increase yield of analysable metaphases in this protocol.

Homozygous paracentric inversion 12 in a mentally retarded boy: a case report and review of the literature

A mentally retarded male was found to be homozygous for a paracentric inversion of the long arm of chromosome 12(inv(12)(q21.1q23.2]. His parents, who are first cousins, and his phenotypically normal younger brother are inversion heterozygotes. Homozygous structural rearrangements are discussed and cases of paracentric inversions, including a further nine previously unpublished, are reviewed.

Lack of sampling site variation in chorion villus biopsy as assessed by DNA, enzymatic, morphological and cytogenetical analyses

A study of villus samples from eight random sites on five electively aborted chorion sacs was performed to determine any significant differences in yield, quality and composition of DNA, iduronate sulphate sulphatase activity and karyotype status. The villi were also examined for their histological characteristics (e.g. stem, intermediate or terminal villi) and for HCG and BGP immuno-reactivities. The overall findings indicated no significant site to site variations in any of the parameters studied. It is therefore proposed that any villus should be equally suitable for prenatal diagnosis.

First trimester diagnosis of cystinosis using intact chorionic villi

Cystinosis was diagnosed in the first trimester of pregnancy by studies of uptake and retention of [35S]-cystine by intact biopsy samples of chorionic villi. The diagnosis was confirmed by similar studies on cell cultures of villi and fetal skin fibroblasts.

Federal regulations for fetal research: a case for reform

In 1974 the National Commission for the Protection of Human Subjects of Biomedical and Behavioral Research considered many aspects of fetal research. The Commission received some detailed ethical, legal, and scientific analyses, invited public testimony, and recommended guidelines for biomedical research involving the human fetus. One of the authors of the present article (KJR) chaired the Commission. Many of its recommendations became federal regulations on fetal research issued in 1975.

These regulations explicitly govern only research “conducted by the Department of Health and Human Services (DHHS) or funded in whole or in part by a Department grant, contract, cooperative agreement or fellowship.” However, as Baron pointed out in his legal review, they effectively cover all federally funded institutions, regardless of the source of the funds the institution may be using for fetal research.

Admixture of maternal metaphases in first trimester direct chromosome preparations?

The autoradiographic labelling of different cell types in chorionic villi and decidual tissue was investigated after [3H]-thymidine incorporation in vitro. Although the extent of labelling was found to be lower in decidual than in villus tissue the possibility that direct chromosome preparations may contain maternal metaphases should be considered. The need for careful selection of villi for direct cytogenetic analysis was stressed.

Abnormal karyotype in the chorion, not confirmed in a subsequently aborted fetus

An abnormal fetal karyotype, containing a del 16(q21-qter) as an extra chromosome, was diagnosed in all 14 metaphases examined in a sample of chorionic villous biopsy material. After elective abortion a mosaicism for this cell-line together with a normal one was detected in the chorionic tissue. Fibroblast cultures from several fetal skin biopsies all revealed a normal karyotype.

The Role of Ultrasound in Chorionic Villus Sampling

The use of ultrasound as a guidance tool for chorionic villi sampling for prenatal diagnosis in the first trimester is discussed. Three sampling techniques used in the first trimester are reviewed: endoscopy, blind aspiration, and the combination of endoscopy and aspiration with ultrasound guidance. A review of the literature found that ultrasound guidance provided the highest success rate in obtaining chorionic villi for chromosomal analysis and enzyme determination. Concerns regarding proper scanning technique for localizing the implantation site for sampling are discussed.

Prenatal diagnosis of Hunter syndrome using chorionic villi

A case of the Hunter syndrome diagnosed prenatally using chorionic villi is presented. Chorion biopsy was performed in the 10th week of pregnancy. The sample was examined for karyotype and for iduronate sulfatase activity. The fetus was male and the enzyme activity reduced to 4 per cent of normal. Termination of pregnancy occurred at the 11th week.

Cytogenetic analysis of chorionic villi: a technical assessment

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.

First trimester fetal karyotyping: one thousand diagnoses

Cytogenetic investigations for diagnostic purposes were performed on 1000 first trimester samples of chorionic villi (CVS) in two laboratories using similar techniques. Fetal karyotyping was the primary indication for CVS in 912 and maternal age was the major indication in 758 of them. The risk category "previous child/fetus with chromosome abnormality" included 74 diagnoses, while the category "chromosome abnormality in one of the parents" included 38 diagnoses. Sex determination was the primary indication for CVS in 53 pregnancies. The overall incidence of chromosomal abnormalities was 70, of which 47 were balanced and 23 unbalanced. The results are detailed for each of the risk categories and the incidence of abnormal karyotypes is given for each year of maternal age. In the maternal age of 35-37 years the incidence of unbalanced karyotypes was 2.9% and in the years 38 onwards it was 6.6%. The incidence of unbalanced karyotypes was about 4% when the sampling was made in the weeks 9 to 12 but six abnormal karyotypes were found among 39 CVS performed at the eight week of gestation. The 11 trisomies of the type not found at birth were clustered between the 8th and the 10th week of pregnancy. The technical problems encountered in this experience and the preliminary estimates of fetal loss are discussed.