Transabdominal villus sampling in early second trimester: A safe sampling method for women of advanced age

Transabdominal chorionic villus sampling (TA-CVS) was performed in 707 viable singleton pregnancies to exclude chromosomal abnormalities. Maternal age ranged between 36 and 49 years (mean 37·9 years); gestational age varied between 10·2 and 18·3 weeks (mean 13·3 weeks). In 639 women (90·4 per cent), a sufficient amount of chorionic tissue (⩾ 10 mg) was obtained after one needle insertion; in 66 women (9·3 per cent) two insertions were needed. An abnormal chromosome pattern was established in 19 cases (2·9 per cent). Vaginal bleeding or spotting within 28 days after TA-CVS occurred in 11 cases (1·5 per cent). The completed follow-up of 678 chromosomally normal pregnancies showed an overall fetal loss rate of 2·6 per cent before 28 weeks. The overall perinatal mortality was 0·9 per cent. When relating fetal loss to gestational age at TA-CVS, this was 6·6 per cent in women sampled before 12 weeks against only 1·8 per cent after 12 weeks. At the same time, the percentage of fetal loss occurring within 2 weeks following the procedure was 75 and 30 per cent, respectively. It is suggested that these data reflect the decline in spontaneous abortion rate during this particular period of pregnancy. It is concluded that TA-CVS is an effective procedure which, when performed after the natural decrease of fetal loss, appears to be a safe option for women of advanced maternal age.     

Transabdominal chorionic villus sampling: Fetal loss rate in relation to maternal and gestational age

In this paper we report the fetal loss rate in relation to both maternal and gestational age in 1764 pregnant women who underwent transabdominal chorionic villus sampling (TA-CVS) between January 1986 and August 1990. The fetal loss rate, considered as a proportion of continuing pregnancies, decreased with advancing gestational age at sampling from 4.3 per cent before 9 weeks to 0.4 per cent at or after 13 weeks, the difference being statistically significant (p <0.025). The fetal loss rate increased from 1.6 per cent in women under 30 to 2.4 per cent in women of 40 years or over, but the difference was not statistically significant. Considering that the total fetal loss rate before 28 weeks' gestation was on average 1.91 percent (1.3 per cent under 35 years and 2.8 per cent in women of 35 or over), we believe that TA-CVS is a safe and effective technique for prenatal diagnosis of genetic diseases.     

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.     

Utilization of prenatal cytogenetic diagnosis in women of advanced maternal age in Australia, 1979–1982

This paper reports the results of a complete national survey to measure utilization rates of prenatal cytogenetic diagnosis (P.C.D.) in women of advanced maternal age in Australia. P.C.D. has been available throughout Australia for the last decade. Every laboratory in Australia providing a P.C.D. service for the years 1979–1982 took part in this study. Utilization rates (both National and State rates) by ages of mothers, are presented. Big interstate differences exist. The 1982 National P.C.D. utilization rate for pregnant women who were 40 years of age and over was 38.8 per cent, and this rate has shown an average annual increase of 9 per cent. In those four States which offered P.C.D. to pregnant women of 35 years or over the median utilization rate was 20 per cent. These Australian rates indicate an under-utilization of P.C.D. services with (in 1982) 50–80 per cent of ‘at risk’ women not being tested. Factors which influence this are discussed.     

First-trimester prenatal diagnosis of hypophosphatasia: Experience with 16 cases

We have carried out first-trimester prenatal diagnosis of hypophosphatasia in 1 6 pregnancies with a 1 in 4 risk of this condition. The liver/bone/kidney isoenzyme of alkaline phosphatase was measured in chorionic villus samples using a specific monoclonal antibody and an enzymatic amplification system. Fifteen of the 16 pregnancies were correctly predicted, while one has been lost to follow up. We suggest that this assay system is likely to be superior to DNA-base methods for the first-trimester prenatal diagnosis of hypophosphatasia.     

46,XY,dup(10q) in direct CVS preparation and mosaic 48,XXXY,dup(10q) in CVS long-term culture and fetal tissue

Chorionic villus sampling (CVS) was performed on a 40-year-old woman at 9 1/2 menstrual weeks because of advanced maternal age. The direct preparation showed 46,XY,dup(10)(q11.2q23.2). CVS long-term culture and fetal tissue revealed a rare additional abnormality: 48,XXXY,dup(10)(q11.2q23.2). This abnormality represented the major cell line (>85 per cent in 691 cells) in an (XY)/XXY/XXXY/(XXXXY) mosaic (all cell lines presumably bearing the dup(10q); the presence of XY and XXXXY cell lines is uncertain). To our knowledge, this is the first report of trisomy 10q11-q23 and of prenatally detected 48,XXXY in chorionic villi. The mosaic could have resulted from early post-zygotic non-disjunctions in a 46,XY,dup(10q) or 47,XXY,dup(10q) zygote. The results from DNA studies of four polymorphisms, mapped to Xp and Xq, support this theory. The literature on prenatally detected cases with sex chromosome tetrasomy and pentasomy and those with additional autosomal abnormalities is reviewed. The reported case underlines the problem of false-negative findings when only direct CVS preparations are karyotyped.     

Prenatal diagnosis of thalassemia major by fetal blood analysis: Experience with 1000 cases

In this report we have summarized our experience with the prenatal diagnosis of β-thalassemia in 1000 pregnancies followed at least until 12 months after birth. In the majority of these cases, the thalassemia lesion was the nonsense mutation at the codon corresponding to amino acid 39, which produces the hematological phenotype of β-thalassemia. Fetal blood sampling was carried out by placental aspiration, by which a sufficient amount of fetal blood for analysis was obtained in the majority of cases (99 per cent). The fetal mortality associated with fetal blood sampling was 6·3 per cent. Those placental samples contaminated by maternal cells were successfully purified by Ørskov lysis. Fetal blood was analysed by globin chain synthesis on CM–52 columns, which gave reliable results. Two misdiagnoses (0·2 per cent) have been made of which one was due to a non-globin protein co-migrating with the β-chains while the other resulted from a misclassification of the type of thalassemia segregating in the family.     

Conceiving a fetus for bone marrow donation: An ethical problem in prenatal diagnosis

We present a family who sought prenatal diagnosis in order to bear a healthy child to serve as an HLA–identical bone marrow donor for their son affected with Wiskott–Aldrich syndrome. They intended to abort HLA-incompatible fetuses who would have been unsuitable bone marrow donors. This case led us to conclude that prenatal diagnosis should not be used to benefit a third party or facilitate the conception or abortion of a fetus for the purpose of generating an organ for transplantation. The limits of parental autonomy and physician responsibility are discussed.     

Fetal two-dimensional doppler echocardiography (colour flow mapping) and its place in prenatal diagnosis

One hundred and fifty fetuses between 16 and 38 weeks of gestation were studied by fetal echocardiography using colour-coded two-dimensional Doppler echocardiography. Two-dimensional, M-mode, and Doppler spectral analyses were also performed. In 14 fetuses, structural and/or functional abnormalities were detected. Abnormalities were correctly ruled out in all the other fetuses. The advantages of two-dimensional Doppler echocardiography are (1) rapid screening for flow abnormalities in the fetal heart, and thus shortening of the Doppler examination time; (2) rapid diagnosis of valvular regurgitation, valvular stenosis, and abnormal shunting of blood across the interatrial and interventricular septa; and (3) facilitation of the diagnosis of complex congenital heart defects which in certain cases is possible only by using two-dimensional Doppler echocardiography.     

Diagnosis and prenatal diagnosis of epidermolysis bullosa herpetiformis (Dowling-Meara) in a mother,two affected children,and an affected fetus

In utero skin biopsy was performed on a fetus at risk of an uncertain form of epidermolysis bullosa (EB). The mother had produced two affected offspring diagnosed variously as having junctional or dystrophic EB. The two offspring and the fetus were products of different fathers. The mother claimed to have no disease and on clinical examination was without blisters. Examination of the fetal skin biopsy by light and electron microscopy revealed separation of the epidermal sheet from the majority of the biopsy sample, although occasional remnants of basal cells remained associated with the basement membrane. Aggregations of keratin filaments were observed within basal cells of the detached epidermis and in the attached basal cell remnants. The diagnosis was thus suggested to be epidermolysis bullosa Dowling-Meara. Re-review of the clinical and laboratory data from the affected infants revealed a clinical and histological pattern consistent with this diagnosis. Further discussion with the mother revealed that her skin had blistered as a child and that she presently had hyperkeratotic palms and soles. This history is consistent with the autosomal dominantly inherited epidermolysis bullosa herpetiformis (Dowling-Meara). This is the first reported prenatal diagnosis of EB Dowling—Meara. The morphological criteria of intraepidermal blistering and clumped keratin filaments within basal and immediately suprabasal cells characteristic of an affected individual postnatally also identified an affected fetus. There is, however, insufficient experience to be certain that these findings will hold from region to region in the body or among all affected fetuses, and thus prenatal diagnosis on a morphological basis should still be made with caution.     

Technical and theoretical considerations in the HLA typing of amniotic fluid cells for prenatal diagnosis and paternity testing

HLA typing of amniotic fluid cells has been used for the prenatal diagnosis of the HLA linked diseases congenital adrenal hyperplasia (21-OH-deficiency (21-OH-def) type) and complement C4 deficiency and it has also been used for the prenatal de termination of paternity. There are, however, technical difficulties in this test associated with the weak expression of some B locus antigens on amniotic fluid cells, and theoretical difficulties related to associations between particular HLA antigens and the 21-OH-def allele. Since certain HLA-B locus antigens are found in significantly increased frequencies among patients with 21-OH-def, there is a relatively high incidence of HLA-B homozygosity among the patients and over 40 percent of the parents of these patients share one or more HLA-B locus antigens. Results of some prenatal HLA typing tests may thus be difficult to interpret, and supplementary tests should be used whenever possible. HLA typing of amniotic cells is, however, the only available procedure for prenatal diagnosis of C4 deficiency and it is the best available procedure for prenatal determination of paternity. A modification of our original procedure allows HLA typing to be performed with increased numbers of HLA typing sera, and sera with optimum reactivity for amniotic fluid cells have now been selected for the definition of most of the more commonly expressed HLA antigens. Although amniotic fluid cells do not express DR antigens, amniotic fluid cells can be typed for the HLA-linked marker glyoxalase I (GLO) and this may be the informative for prenatal diagnosis in some cases.     

Prenatal diagnosis of X-linked mental retardation with fragile (X) using fetoscopy and fetal blood sampling

Pure fetal blood, (uncontaminated with maternal blood), was obtained from two male fetuses at risk for X-linked mental retardation with fragile(X) at Xq27–28 by direct vision fetoscopy and fetal blood sampling. Both were shown to have this fragile site on the X chromosome while nine other fetal blood samples from pregnancies at risk for other X-linked diseases, or haemoglobinopathies did not show fragile sites at Xq27–28, and a blood sample from an abortus showed only 1 fragile site in 95 mitoses. Both pregnancies were terminated, cultures established from fetal tissues, and the diagnosis confirmed in each case. The problems of demonstrating the fragile site in tissues other than fetal blood in these pregnancies (such as amniotic fluid cells or fibroblasts from fetal tissues) are discussed.     

Sacrococcygeal teratoma: Prenatal diagnosis with elevated alphafetoprotein and acetylcholinesterase in amniotic fluid

A sacrococcygeal teratoma was suspected by ultrasound examination at 24 weeks gestation. The amniotic fluid alphafetoprotein was markedly elevated, as was maternal serum AFP. Gel electrophoresis of amniotic fluid showed an acetylcholinesterase band. Labour began at 25 weeks gestation and the chromosomally normal male fetus was found to have a sacrococcygeal teratoma equal to three-quarters of the weight of the fetus.     

Prenatal diagnosis of Huntington's disease (HD): Experiences with six cases and PCR

In the course of a 2-year predictive testing programme for Huntington's disease (HD), six couples from a total of 52 applicants requested prenatal testing. In each case, the pregnancy was in the first or second trimester when the couples were referred for DNA diagnosis. In five cases, exclusion testing was offered; in one case, a person at risk with an increased risk of being a gene carrier requested prenatal diagnosis. In all cases, informative markers for prenatal testing could be determined. Whenever possible, the newer technique of polymerase chain reaction (PCR) for D4S125 was applied to perform rapid prenatal diagnosis. Two couples withdrew before chorionic villus sampling was undertaken; prenatal diagnosis was completed in the remaining four cases. After exclusion testing, two pregnancies were determined to have an increased risk and two fetuses to have a low risk of being HD gene carriers.     

First-trimester prenatal diagnosis of homozygous (14;21) translocation in a fetus with 44 chromosomes

A (14;21) homozygous Robertsonian translocation was detected by first-trimester prenatal diagnosis. The related parents were heterozygous for the same translocation. At birth the baby was physically normal and had a normal psychomotor development. Together with a few previous observations in living homozygotes for (13;14) translocations, this case corroborates the idea that these subjects with 44 chromosomes are healthy without dysmorphic features.     

Fetal erythroblasts from maternal blood identified with 2,3-bisphosphoglycerate (BPG) and in situ hybridization (ISH) using Y-specific probes

Different types of fetal nucleated cells can be found in maternal blood, providing the possibility of non-invasive prenatal diagnosis. For this purpose, we have studied fetal erythroblasts. We discovered that haemoglobin-containing cells treated with 2,3-bisphosphoglycerate (BPG) can be visualized by a peroxidase reaction, which at the same time visualizes an in situ hybridization (ISH) signal, specific for the X, Y or 21 chromosome. In order to prove that the BPG-positive cells were erythroid, an anti-glycophorin A (GPA) antiserum combined with a staphylococcal rosette technique was used. To enrich for erythroblasts, leukocytes were depleted from maternal blood by treatment with anti-CD45 monoclonal antibody and passage over an anti-mouse IgG-coated glass bead column. To evaluate the potential of the method for clinical use, we studied maternal blood samples from 18 women referred to us for prenatal diagnosis between 6 and 19 weeks of gestation. Erythroblasts were found in 13 out of 14 normal pregnancies. Erythroblasts with a Y-signal were found as early as 9 weeks of gestation, but at 6 weeks the Y-signal was seen in BPG-negative cells only. These cells showed an epithelioid morphology indicating that they were cytotrophoblasts. The BPG-ISH method provides a simple technique for identifying erythroblasts and simultaneously visualizing a desired probe.     

Mutation analysis for prenatal diagnosis and heterozygote detection of Gaucher disease type III (norrbottnian type)

A single base substitution in exon 10 of the glucocerebrosidase gene was detected in families affected by Gaucher disease (GD) type III. This mutation, which results in the substitution of proline for leucine in position 444 of glucocerebrosidase, has been shown to result in type III GD in a Swedish population. Three fetuses at risk for GD type III were diagnosed as homozygous for the mutation and the pregnancies were terminated. In a fourth pregnancy, one parent was excluded as being a carrier and the risk of having a child affected by GD was ignored. Direct analysis of common mutations causal to GD is now available and improves prenatal diagnosis in families where the molecular defect has been characterized.     

Amniotic fluid pregnancy-specific β1-glycoprotein (SP1) in Meckel's syndrome: A new test for prenatal diagnosis?

Amniotic fluid levels of pregnancy-specific β₁-glycoprotein (SP₁) were elevated in four pregnancies with Meckel's syndrome at 16 and 26 weeks, and the levels of hCG were also elevated in three out of four cases. These findings suggest a potential new application of SP₁ measurement for prenatal diagnosis.     

Neonatal alloimmune thrombocytopenia due to anti-P1A1 (anti-hpa-1a): Importance of paternal and fetal platelet typing for assessment of fetal risk

Neonatal alloimmune thrombocytopenia (NAIT), which usually involves sensitization to P1^A1 (HPA-1a), may have devastating complications for the fetus. These may be prevented by antenatal treatment of severe cases with either maternally administered high-dose gamma-globulin and/or repeated intrauterine platelet transfusions. Determination of the paternal platelet phenotype is useful for counselling parents who have had one or more affected pregnancies. This report of an unaffected pregnancy in a woman with a history of previous pregnancies complicated by NAIT illustrates the role of paternal and fetal platelet phenotyping in managing existing pregnancies at risk of NAIT.