Ratio of fetal to maternal DNA is less than 1 in 5000 at different gestational ages in maternal blood

Using Southern hybridization with the DNA probe pY3.4, we were not able to detect fetal DNA in blood of 36 pregnant women carrying male fetuses. Gestational ages ranged from 8-40 weeks of pregnancy. Using the same DNA probe, we were able to detect the male-specific signal in experimental dilution series down to 1/5000 on autoradiograms. We conclude that the ratio of fetal DNA in maternal circulation, in contrast to previous estimations, must be lower than 1/5000.

Benefits of placental biopsies for rapid karyotyping in the second and third trimesters (late chorionic villus sampling) in high-risk pregnancies

In a total of 301 placental biopsies in the second and third trimesters, 225 were performed because of suspicious ultrasonographic findings. In this group there was a high rate of aneuploidies (20%). As opposed to the alternative methods for rapid karyotyping, placental biopsies can easily be performed even in pregnancies with abnormal amounts of amniotic fluid. Oligohydramnios and polyhydramnios were key ultrasonographic findings in 38% of cases and were found to be associated with 22% of abnormal chromosomal findings. Suggestive ultrasonographic findings seem to justify the exclusive use of direct preparation.

'Late CVS' international registry compilation of data from 24 centres

Data on 2058 late CVS cases, i.e., placental biopsies after 12 completed weeks of pregnancy, were collected from 24 centres. Two major groups of indications with or without ultrasound findings suspicious of fetal chromosomal abnormalities can be differentiated. In the first group, the rates of cytogenetic anomalies (21 per cent) and fetal losses (10 per cent) are high. The respective figures for the low-risk group are 6 per cent for chromosome anomalies and 2 per cent for total fetal losses. To evaluate this rapidly spreading new method further, more data are required and will be collected by the CVS registry based in Philadelphia, U.S.A.

Transabdominal placental biopsy in the second and third trimesters of pregnancy: what is the risk of maternal contamination in DNA diagnosis?

We investigated the risk of maternal contamination in antenatal DNA diagnosis after second- and third-trimester transabdominal placental biopsy. For this purpose, we compared the restriction fragment length polymorphism (RFLP) patterns of 11 chorionic villus DNA samples after late chorionic villus sampling (CVS) with those of the corresponding maternal DNA. Ten of 11 aspirated tissue samples were not separated from maternal contamination before DNA extraction. All 11 mother-embryo pairs were informative for analysis of maternal contamination, ie, the mother showed one RFLP allele not present in the embryo. In none of the 11 cases did the fetal DNA show maternal contamination after molecular hybridization, although ten samples were contaminated with maternal tissue macroscopically and microscopically. Despite some maternal tissue admixture, the risk of contamination seems to be lower in the second- and third-trimester CVS than in first-trimester CVS, based on previous reports and our own experiences. This is most likely due to the anatomically closer contact of villi and decidua in the first trimester of pregnancy.

Beta-thalassemia problems in the Turkish population in the F.R.G

A sample of 165 normal Turkish probands (79 males, 86 females) living in the F.R.G. was screened for the presence of heterozygous beta-thalassemia as well as their knowledge and perception of thalassemias in general. Hematologic studies revealed two persons to be heterozygous for beta-thalassemia who had not known this before. This incidence of 1.2% in our sample of Turkish probands living in the F.R.G. is in accordance with the average range of 0.2-6% given by the World Health Organization for Turkey. The probands' places of origin in Turkey correlate well with the pattern of migration within the country, with most people coming from central Anatolia which is an area with a relatively low incidence of beta-thalassemia. Interviews conducted by a Turkish doctor revealed that the knowledge about thalassemias and the function of blood in general was extremely limited in our study population. On the other hand, 50% of the respondents would refrain from marriage or choose a different partner if both partners knew that they were heterozygous for thalassemia. 19% would still marry in this situation but refrain from having children. When asked about their most likely decision in the case of an early diagnosis of homozygous thalassemia, 78% said they would have a termination and only 15% would definitely go on with the pregnancy. About 65% felt that consanguineous marriage is a predisposing factor for diseases in the offspring. From our study it can be concluded that a large-scale screening program in the high-risk population which exists in most Mediterranean countries would be difficult regarding the more than one million people from Turkey living in the F.R.G. and would have to take into account the cultural and educational conditions of the Turkish minority. In general, if no Turkish-speaking specialist is available to explain the diagnostic possibilities, probably pre-pregnancy or early pregnancy testing would be the most appropriate way of reaching the couples at risk in the German medical system.

Molecular basis of beta-thalassemia in Turkey: detection of rare mutations by direct sequencing

Using restriction endonuclease analysis, oligonucleotide hybridization, and direct sequencing of amplified genomic DNA, we characterized 11 different mutations in the DNA of 26 patients from Turkey homozygous for beta-thalassemia. We found that mutations IVS-1 nt110, IVS-1 nt6, and the frameshift at codon 8 were the most frequent. By direct sequencing we characterized two very rare mutations not previously reported in the Turkish population: a frameshift +1 at codons 9/10 and a nonsense mutation at codon 15.

Validity of cytogenetic analyses from trophoblast tissue throughout gestation

Cytogenetic findings in the Münster Chorionic Villi Sampling (CVS) program are presented after 1,184 first trimester transcervical samplings and 131 second and third trimester placentacenteses. In the first trimester series the abnormality rate is low (2.4%) in patients with only an age-dependent aneuploidy risk. In this group terminations were performed in only 1.6% because of aneuploidy. True mosaicism was found more frequently after CVS, and the risk of maternal cell contamination seems higher as compared to amniocentesis. There are no obvious differences in the overall rate of diagnostic errors after both procedures, when metaphases after direct preparation and chorionic cell cultures are analysed and doubtful findings such as mosaicism are adequately followed up by amniocentesis. The cytogenetic techniques also offer a very rapid approach to karyotyping in the second and third trimester. We found a high rate of aneuploidy (15%) when placentacentesis was performed after sonographic diagnosis of fetal abnormalities. We conclude that cytogenetic analysis from trophoblast tissue is an accurate diagnostic tool applicable from first to third trimester of pregnancy.

[Psychological adjustment to abortion for genetic indications in the 2d trimester]

Based on a questionnaire analysis of 41 women after termination of pregnancy for genetic indications in the second trimester of pregnancy the predominant feelings in the different stages of the coping process were identified. Whereas during the hospitalization period helplessness and anger were the predominant emotions, later sadness prevailed. At the time of the abortion itself loneliness was one of the main complaints. This situation could probably be improved if more often the partners were present during the period of abortion induction. About 54% of the women indicated that a prenatal diagnosis in the first trimester would have improved their coping problems. It remains to be seen whether CVS in the first trimester will be of benefit in this respect. Even though there are methodological limitations in a retrospective questionnaire study our results clearly underline the necessity of special psychologic support which can probably partly be provided by a psychologist who is available in our prenatal program.

First-trimester diagnosis of Menkes disease: intermediate copper values in chorionic villi from three affected male fetuses

Chorionic villus samples with copper contents of 1.91, 4.2, 5.6, and 6.3 ng/mg were observed in four cases with male karyotypes. These values were outside the range for unaffected males (0.30-0.85 ng/mg), and three of them were outside the control range (0.20-2.39 ng/mg). But these three values were below the values previously observed for affected Menkes fetuses (12.0-24.8 ng/mg). Follow-up by 64Cu uptake studies on the amniotic fluid cells was performed in three of these cases. A combination of 64Cu uptake and chase experiments on the amniotic fluid cells showed more convincingly than 64Cu uptake per se the direct copper values of 4.2 and 5.6 ng/mg to correspond to affected fetuses. Amniotic fluid cells from the male fetus with the CV copper value of 1.9 ng/mg showed normal results. The CV copper value of 6.3 ng/mg was considered pathognomonic for Menkes disease. The pregnancy was terminated, and the diagnosis was confirmed on fetal fibroblasts. Maternal deciduum prepared from the placentae showed in one of the cases with an affected fetus copper values ranging from 1.5 to 5.7 ng/mg. In six additional diagnostic cases, the copper content was determined in both CV samples and maternal deciduum. In three of these cases with normal CV sample copper, maternal decidua values of 4.85-7.8 ng/mg copper were observed. These results show that maternal deciduum contamination of a CV sample could cause a false-positive diagnosis.

Cardiac defects in chromosomally abnormal human embryos of 10-14 weeks' gestation

Cardiac defects were studied in five chromosomally abnormal embryos of 10-14 weeks' gestation by free-hand microdissection of hearts measuring 2.5-6 mm in diameter. The type of cardiac malformation alone or in association with other anomalies helped to confirm the chromosome diagnosis established prenatally by chorionic villus sampling or after spontaneous abortion. It was suggestive of a chromosomal disorder in one case in which cytogenetic investigation had failed.

Rapid karyotyping for prenatal diagnosis in the second and third trimesters of pregnancy

Direct chromosome preparations were performed on placental villi obtained by ultrasound-guided needle aspiration between 18 and 37 weeks of pregnancy in 53 patients. The sampling yielded a sufficient amount of tissue with a maximum of two, and in most cases one, insertions. Placental biopsy is easily performed in cases of severe oligohydrammnios, where fetal blood sampling is usually more difficult. Direct karyotyping of placental villi is faster than chromosome analysis from fetal blood or application of the pipette method on amniotic fluid cells, and currently represents the most rapid approach to prenatal diagnosis of chromosomal abnormalities from the first to the third trimester of pregnancy.

Selective fetocide by direct intracardiac injection of isotonic potassium chloride

In multiple pregnancies with one abnormal fetus the active options are termination of pregnancy or selective fetocide. The different methods of selective fetocide are discussed and the intracardiac instillation of potassium chloride is described in a case report. Coagulation disturbances were not observed during follow-up.

Feto-maternal transfusion after chorionic villus sampling. Evaluation by maternal serum alphafetoprotein measurement

The alphafetoprotein (AFP) concentration in maternal serum was determined before and after chorionic villus sampling (CVS). A significant increase of 20% or more in the pre-CVS level was noted immediately after sampling in 59% of 837 pregnancies indicating some degree of feto-maternal haemorrhage. The increase in the AFP concentration in maternal serum was correlated with the weight of the tissue sample but not with the number of sampling attempts. A correlation of AFP increase and frequency of spontaneous abortions following CVS was suggested only in the group with an AFP increase of more than 100% or with a continuing rise in the first hour following CVS. CVS in early pregnancy obviously did not interfere with maternal serum AFP screening for neural tube defects in the second trimester. Although AFP measurement before and after CVS seems to have no immediate diagnostic application, in the research phase of CVS it may help to identify those procedures that are the least traumatic.

[Experiences with prenatal diagnosis of sickle cell anemia and thalassemias in the first trimester of pregnancy: various aspects for the obstetrician]

After an extensive educational campaign for the medical community in the area of the Westf. Wilhelms-University Münster five pregnancies at risk for sickle cell anemia and thalassemias were investigated during the first trimester of pregnancy. Following chorionic villi sampling in one case a sickle cell anemia and in two other cases a beta-thalassemia could be excluded. In two additional cases a homozygous beta-thalassemia was proven and in one of the cases the first trimester diagnosis was confirmed in the second trimester by fetal blood sampling. Because of the migration patterns in Europe there is currently a considerable demand for prenatal diagnosis of beta-thalassemias in West-Germany after proper information of the population at risk.

Estimating frequency of Kallmann syndrome among hypogonadic and among anosmic patients

The frequency of Kallmann syndrome (hypogonadotropic hypogonadism and anosmia, HHA) was estimated in patients presenting with hypogonadism and patients with anosmia. Of 791 hypogonadal males 19 had HHA. The frequency of HHA was about 1:25 (n = 8/189) in outpatients questioned about their sense of smell, about 1:50 (n = 11/579) in patients whose blood samples were sent to us for chromosome analysis, and about 1:30 (n = 19/605) in males with hypogonadism and 46,XY chromosomes. The relation of patients with HHA to those with Klinefelter syndrome was 1:10 (n = 19/186). From 24 patients presenting with anosmia we found 1 hitherto undiagnosed case of HHA. The mean age at diagnosis was 24.8 and 24.9 years in our cases and cases from literature, respectively. These data provide evidence that Kallmann syndrome is not infrequent and that most patients remain undiagnosed until the third decade of life. Earlier diagnosis is emphasized by questioning each hypogonadal patient about his sense of smell because therapeutic success seems to be age dependent.

Experience with 8 cases of prenatally diagnosed sacrococcygeal teratomas

Based on an analysis of eight prenatal diagnoses of sacrococcygeal teratomas and a review of the literature on this condition, sacrococcygeal teratoma can be accurately diagnosed which is related to significant fetal wastage as well as neonatal morbidity and mortality. These tumors are usually benign and the long-term morbidity, but not the overall survival rate, appears to be related to the American Academy of Pediatrics Surgical Section type of tumor. alpha-Fetoprotein can be normal or elevated and acetylcholinesterase in amniotic fluid can be present in spite of the polyhydramnios, but sonography can distinguish these lesions from neural tube defects. Nonimmune hydrops is an ominous sign, particularly in cases detected early in pregnancy. Timing and method of delivery are important considerations for neonatal survival with these lesions. However, normal survival with minimal morbidity is possible even in the largest of sacrococcygeal teratomas.

Chorionic villi sampling with an echogenic catheter: experiences of the first 500 cases

Using a newly developed CVS catheter with enhanced echogenicity we performed CVS in 501 consecutive cases. The abortion rate of 4.3% prior to 28 weeks of gestation in this series is within the background rate of controls matched for maternal age. The loss rate was clearly correlated to the number of insertions, time of sampling and sampling success. CVS is safest between 9 and 11 weeks of pregnancy. We recommend to restrict the number of insertions to a maximum of 3. The rate of failed samplings was 4, reflecting a low "aggressiveness in seeking a sample". Complete follow-up of 259 consecutive cases gave no indication of an increased rate of congenital anomalies following CVS in early pregnancy. In our study we also performed cervical swabs, pregnancy hormone testing, maternal serum AFP determination prior to and after CVS as well as maternal AFP screening at 16 weeks of pregnancy together with a detailed sonographic examination. We conclude that CVS can be considered now a safe and reliable diagnostic procedure, but requires further detailed documentation and close follow-up in controlled trials.

Inv dup (15): prenatal diagnosis and postnatal follow-up

A de novo inv dup (15) was diagnosed at amniocentesis. No physical abnormalities were detected after birth. The boy developed severe mental and motor retardation, which became obvious at 16 months of age.

[Prenatal diagnosis from chorionic villi: results in Münster]

We report on our experience with the first 46 diagnostic chorionic villi samplings in Münster. A new echogenic plastic catheter is used. The observed abortion rate is in accordance with international experience.

[Chromosome studies of chorionic villi: experiences following 118 diagnostic interventions]

We summarize our experience with chorionic villi cultures. Cell growth and chromosome analysis were successful in all cases. A significant admixture of maternal cells in chorionic villi cultures can be excluded by comparison of fluorescence polymorphisms between maternal and embryonic chromosomes.

[Sonographic diagnosis of holoprosencephaly in the 2d trimester]

Data on the sonographic diagnosis of holoprosencephaly in the second trimester are presented. Polyhydramnions was detected during outside ultrasound screening, and the lacking midline echo in association with hypotelorism and central face clefting allowed early diagnosis. The autopsy of the fetus confirmed the prenatal diagnosis, the parents subsequently had genetic counseling. The recurrence risk of holoprosencephaly depends on the specific etiology. Special ultrasound examination should be offered in subsequent pregnancies.

Autosomal recessive deafness with skeletal dysplasia and facial appearance of Marshall syndrome

We report on two sibs born to consanguineous parents with clinical and radiological features closely resembling those previously described by Insley and Astley [1974]. This observation provides further evidence for a distinct autosomal recessive condition with the facial appearance of Marshall syndrome, deafness, and skeletal dysplasia.

Trisomy 20 mosaicism

A further case of trisomy 20 mosaicism found at amniocentesis is presented. Pregnancy was terminated, the fetus showed facial dysmorphia and minor cardial and renal anomalies. 19 published reports of true trisomy 20 mosaicism at amniocentesis are reviewed. Five pregnancies resulted in obviously normal newborns. The significance of mostly minor anomalies found at autopsy of 7 fetuses remains unclear. With regard to genetic counselling the significance of trisomy 20 mosaicism is summarized as follows: (1) true trisomy 20 mosaicism in amniotic fluid cells reflects mosaicism of the fetus; (2) severe malformation is not a major feature of trisomy 20 mosaicism; (3) the risk of mental retardation is still undetermined, due to limited experience. However, there is no definite proof that the condition is harmful at all.