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Ultrasound screening in pregnancy: advancing technology, soft markers for fetal chromosomal aberrations, and unacknowledged ethical dilemmas.

Fetal ultrasound screening has become routine practice in many western countries. During the last decade, such screening has led to frequent situations characterised by clinical uncertainty due to the disclosure of soft markers in the unborn child. Soft markers are minor anatomical variations indicating a somewhat increased likelihood that the fetus has a chromosomal aberration, most frequently trisomy 21 (Down syndrome). This paper presents the results of a comprehensive literature search of the National Library of Medicine with emphasis on the chronological development of scientific knowledge in relation to soft markers and the link between advancing imaging technology and clinical counselling dilemmas. An analysis of the literature makes evident that many ultrasound examiners have counselled individual pregnant women on the basis of insufficient data. Moral dilemmas have thus emerged as a direct result of advancing medical technology, and healthy fetal lives prove to have been lost due to invasive diagnostic testing aimed at resolving clinical uncertainty. Ultrasound examiners have warned against a policy of disclosing all findings of soft markers to expectant parents, but no exploration of experiential aspects linked to the disclosure of fetal soft markers has yet been published in the medical literature. The emotional reactions of mothers are important to consider given their potential impact on the biological development of the fetus. In conclusion, this paper stresses the need for paying close attention to the crucial distinction between technology development and technology implementation in relation to prenatal testing. Furthermore, it provides strong arguments for scrutinising the interface between prenatal testing and human experience.

Biomarkers↗

Prenatal screening tests facilitate risk assessment.

Medical technology continues to improve services and testing to provide accurate and timely information for physicians and patients. New screening protocols in which information obtained in the first and second trimesters is integrated to improve detection and lower false positive rates have potential for safer and more effective prenatal care. Families still have difficult choices to make when confronted with the diagnosis of a birth defect. Inherent advantages of early detection are reassurance for low-risk women sooner, and for women with increased risk, more time to consider all options. Without doubt, improvements in risk assessment, diagnosis, and prevention will continue. The advantage offered by laboratory procedures is that the preliminary diagnosis can be made by simple, noninvasive screening tests.

Adult↗

Single cell PCR amplification of microsatellites flanking the COL7A1 gene and suitability for preimplantation genetic diagnosis of Hallopeau-Siemens recessive dystrophic epidermolysis bullosa.

BACKGROUND: Hallopeau-Siemens recessive dystrophic epidermolysis bullosa (HS-RDEB) is a severe inherited blistering skin disorder caused by mutations in the anchoring fibril type VII collagen gene, COL7A1. There is currently no effective treatment but DNA-based prenatal testing in families at risk of recurrence is possible, mostly involving chorionic villus sampling at 10-11 weeks' gestation. OBJECTIVES: An alternative method, for avoiding recurrence of HS-RDEB, is preimplantation genetic diagnosis (PGD). This involves DNA analysis of single blastomeres extracted from late cleavage stage embryos following in vitro fertilisation. METHODS: To establish PGD for HS-RDEB, we designed and optimised a sensitive single cell semi-duplex polymerase chain reaction (PCR) assay for two highly polymorphic dinucleotide repeat microsatellite markers, D3S1581 (telomeric) and D3S1289 (centromeric), close to the COL7A1 gene. RESULTS: We demonstrated high PCR efficiency, low allele drop out rates and no contamination in testing this assay on 50 single buccal cells of known heterozygous genotype and 13 research blastomeres from donated embryos. CONCLUSIONS: This semi-duplex PCR method provides robust, reproducible and informative amplification results for single cells. Moreover, this test has now been approved for clinical application by the UK Human Fertilisation and Embryology Authority (HFEA). As such, the development of PGD for HS-RDEB broadens the range of prenatal testing options and personal choice for couples at reproductive risk of this severe genetic skin disease.

Base Sequence↗

Partners of Huntington patients: implications of the disease and opinions about predictive testing and prenatal diagnosis.

Huntington's disease imposes a considerable burden on the patient and also on the family, especially on the partner. The present paper is based on a survey about the consequences of the disease from the point of view of the partner of the Huntington patient. The mental deterioration and the personality changes seem to be the most difficult aspects to cope with. The threat that their own children may later on develop the same disease is one of the most dramatic aspects. Most partners were aware of the availability of predictive testing for Huntington's disease and were concerned about the far-reaching consequences of the test result. There was a relatively high consensus that the test should only be delivered within a counseling context. Three out of four respondents were in favour of the availability of prenatal diagnosis for Huntington's disease.

Adaptation, Psychological↗

Prenatal diagnosis services in Greece.

The report presents the available prenatal diagnosis (PND) services in Greece. PND for chromosomal anomalies after amniocentesis was initiated in 1976 and became gradually widely accepted. Chorionic villus sampling was introduced in 1983. Approximately 6,500 women undergo PND for chromosomal anomalies annually, most of them for advanced maternal age. 700 cases are also tested prenatally each year for haemoglobinopathies. The study describes the PND services available in the country, the procedures currently used, the impact of prenatal testing on the prevention of genetic diseases and the legal issues concerning PND in Greece.

Chromosome Aberrations↗

Down syndrome prevention program in a population with an older maternal age.

OBJECTIVE: To investigate the effect of a relatively high proportion of pregnant women 35 years and older on the efficacy of prenatal screening for Down syndrome. METHODS: We obtained information on normal and abnormal cytogenetic and maternal serum marker studies for 1990 and 1992 from all 11 public and two private cytogenetic laboratories operating in Israel. RESULTS: In the Jewish Israeli population, 16.2-17.1% of all pregnant women are at least 35 years old. Thus, prenatal testing of all pregnant women at least 35 years old could have identified 62.8-66.5% of all Down syndrome cases. Screening by maternal serum markers would classify 9.28% of pregnancies as being at high risk for Down syndrome (greater than 1:386 at birth). The percentage of Down syndrome cases detected prenatally increased from 78 of 147 (53%) to 123 of 163 (75%) as a result of the increased use of prenatal testing from 11.3% to 19.4% of all pregnancies in 1990 and 1992, respectively. CONCLUSIONS: In a population with a high proportion of mothers at least 35 years old, as in the Jewish population in Israel, screening by maternal serum markers instead of by maternal age alone would leave the Down syndrome detection rate unchanged, but would lower the amniocentesis rate from 16.2-17.1% to 9.28%. In addition to the reduction in the expected fetal loss as a result of post-amniocentesis spontaneous abortion, this policy would also pay the cost of maternal serum marker testing of the entire pregnant population.

Adult↗