Prenatal Diagnosis: A Directive Approach to Genetic Counseling Using Decision Analysis

The decision which prospective parents face concerning mid-trimester amniocentesis for prenatal diagnosis was examined by decision analysis. The prospective parents'' decision depends on the likelihood of the birth of a child affected by a genetic disorder, the risk of amniocentesis, and the probability that the diagnoses provided by the amniocentesis will be correct. The couple''s decision must also depend on their attitudes toward each possible outcome. The likelihoods of the outcomes can be obtained from appropriate medical consultation, while the relative costs or burdens of the outcomes should be obtained from the prospective parents. A truly informed decision for this couple can then be formulated from these probabilities and values, thus allowing genetic counseling to be more directive. The technique is illustrated for the prenatal diagnosis of Down''s syndrome, meningomyelocele, and Duchenne muscular dystrophy.     

Some legal implications of advances in human genetics.

The law which, to some extent at least, reflects contemporary mores, has not kept pace with the recent scientific advances in genetics. Because of the rate of advance in the science of genetics there is a real risk that we shall know how to change the traditional nature of man before we possess the knowledge necessary to enable us to use the new knowledge for humane purposes. Clonal reproduction may produce a creature who, for the purposes of the law, especially the criminal law, which defines when a child becomes a human being in terms of "old-fashioned" motherhood, may not be a human being, so that putting him to death may not be homicide. Similarly, in vitro fertilization and development in an artificial uterus may result in the "birth" of one who, though having human attributes, may not, in law, be a human being. While cloning and in vitro fertilization may not have immediate legal implications because of the state of the art, genetic manipulation in the form of amniocentesis has very real legal implications now because it is a matter of current practice. The assumption that detection of genetic abnormality in the foetus is a beneficial development because it enables parents to have the option of terminating the pregnancy, though valid in the United Kingdom and the United States, is invalid in Canada. Abortion on demand is not part of the law in Canada and the liberalization of the abortion provisions of the Criminal Code of Canada in 1969 expressly avoided including as a criterion for therapeutic abortion the risk that the child, if born, would be likely to suffer from such physical or mental abnormalities as to be seriously handicapped. Beyond the more technical issues raised by scientific advances, however, lies the fundamental question whether a handicapped life is a life not worth living.     

Report on the Moscow symposium on biological research in schizophrenia

Abstract

Genetic counseling, second trimester amniocentesis, reliable techniques for analyzing fetal amniotic fluid and selective abortion together have the potential to prevent a variety of serious birth defects. Advances in technique and/or changing patterns of childbearing may place a large number of women in age groups where genetic counseling programs are recommended. However, attitudes toward abortion may be a critical variable in ascertaining the potential of genetic counseling programs to reduce birth defects. If opposition to abortion is based on a moral commitment, greater awareness of genetic counseling programs will lead to opposition to these programs. If attitudes toward abortion are based upon an evaluative process, such opposition is less likely to occur. Using a sample of women from the Rochester, New York, area (N = 1,616) whose attitudes toward abortion match U.S. estimates, we find that the greater the knowledge about prenatal screening, the less prevalent are attitudes opposed to abortion in circumstances necessary for birth defect reduction. This relationship holds when controlled for religion and family size. We conclude that educational and counseling programs concerning the potential benefits of prenatal screening are unlikely to arouse opposition to these programs.     

Ectogenesis,abortion and a right to the death of the fetus

Many people believe that the abortion debate will end when at some point in the future it will be possible for fetuses to develop outside the womb. Ectogenesis, as this technology is called, would make possible to reconcile pro‐life and pro‐choice positions. That is because it is commonly believed that there is no right to the death of the fetus if it can be detached alive and gestated in an artificial womb. Recently Eric Mathison and Jeremy Davis defended this position, by arguing against three common arguments for a right to the death of the fetus. I claim that their arguments are mistaken. I argue that there is a right to the death of the fetus because gestating a fetus in an artificial womb when genetic parents refuse it violates their rights not to become a biological parent, their rights to genetic privacy and their property rights. The right to the death of the fetus, however, is not a woman's right but genetic parents’ collective right which only can be used together.     

Fetal mortality at the time of chorionic villi sampling

Summary To estimate the background fetal loss rates among women who might be candidates for chorionic villi sampling (CVS) for prenatal diagnosis, we examined the frequency of spontaneous abortion and of non-viable fetuses in two groups of women thought to be pregnant at 8–12 weeks' gestation. Among 1519 women over 35 years given an appointment for amniocentesis 1978–1981, 9.8% had a spontaneous abortion prior to 16 weeks' gestation. For those under observation before week 12, the loss rate by 16 weeks was 15.3%. Among all 190 candidates for elective termination of pregnancy between 6 and 12 weeks' gestation, 12.6% were found to have a non-viable fetus at the scheduled date of abortion. The frequency of non-viability was 14% among those seen before week 12. The data suggest that the background loss rate between the time of CVS and the time of amniocentesis is approximately 1–2% and is unlikely to be higher than 9%. Until randomized clinical trials of the procedure are completed we will not know how much, if at all, the loss rate associated with CVS is increased above this background. Nevertheless, knowledge of these background risk estimates may be useful in counseling women considering participating in trials of CVS.     

Increased risk of abortion following Neospora caninum abortion outbreaks: a retrospective and prospective cohort study in four dairy herds

Explosive abortion outbreaks in 4 Dutch dairy herds during 1992 to 1994 are reported. In 50 of 51 fetuses submitted during the first 3 wk of the outbreaks characteristic histological lesions compatible for infection with Neospora caninum were seen. Diagnosis of infection was confirmed by immunohistochemistry in 40 fetuses (78%). No evidence for other abortifacients was found. The abortion risk of the herds was investigated in a prospective and retrospective cohort study. The prospective study showed that cows aborting during the outbreaks and N. caninum seropositive nonaborting cows had a two- to three-fold increased risk of abortion compared with N. caninum seronegative cows. Retrospective examination showed that seropositive nonaborting cows had an increased risk of abortion before the outbreaks, which may indicate that these animals were infected with N. caninum prior to the outbreaks. It is concluded that serostatus can be used for selective culling of cows to decrease future risk of abortion in dairy herds.     

Ectogestation ethics: The implications of artificially extending gestation for viability,newborn resuscitation and abortion

Recent animal research suggests that it may soon be possible to support the human fetus in an artificial uterine environment for part of a pregnancy. A technique of extending gestation in this way (“ectogestation”) could be offered to parents of extremely premature infants (EPIs) to improve outcomes for their child. The use of artificial uteruses for ectogestation could generate ethical questions because of the technology’s potential impact on the point of “viability”—loosely defined as the stage of pregnancy beyond which the fetus may survive external to the womb. Several medical decisions during the perinatal period are based on the gestation at which infants are considered viable, for example decisions about newborn resuscitation and abortion, and ectogestation has the potential to impact on these. Despite these possible implications, there is little existing evidence or analysis of how this technology would affect medical practice. In this paper, we combine empirical data with ethical analysis. We report a survey of 91 practicing Australian obstetricians and neonatologists; we aimed to assess their conceptual understanding of “viability,” and what ethical consequences they envisage arising from improved survival of EPIs. We also assess what the ethical implications of extending gestation should be for newborn and obstetric care. We analyze the concept of viability and argue that while ectogestation might have implications for the permissibility of neonatal life-prolonging treatment at extremely early gestation, it should not necessarily have implications for abortion policy. We compare our ethical findings with the results of the survey.     

Amniotic Fluid Cells; Prenatal Sex Prediction and Culture

Sex chromatin studies were carried out on small amounts of amniotic fluid obtained by amniocentesis or from intact amniotic sacs removed at hysterotomy. Provided that satisfactory preparations were obtained the accuracy of fetal sexing was 87%. Nevertheless, in the management of a pregnancy in which there is a risk of a serious X-linked recessive disorder, repeat amniocentesis may be necessary to ensure satisfactory specimens.Of 90 samples of fluid cultured, satisfactory growth was obtained in 49; the success rate was not increased by the addition of stimulants to the culture medium. It is suggested that between the 13th and the 16th week of pregnancy is the optimum time for amniocentesis to obtain cells for culture, since sufficient cells are then present in a small volume of fluid and therapeutic abortion would still be possible once the results were available.     

Examination of fetuses after induced abortion for fetal abnormality.

OBJECTIVE--To determine the accuracy of midtrimester diagnosis of fetal abnormality by examination and investigation of fetuses after induced abortion. DESIGN--Prospective study over five years of fetuses aborted in the midtrimester because of abnormalities detected by ultrasonography and amniocentesis. Techniques included a full external examination by a clinical geneticist with experience in dysmorphology and other investigations including necropsy. SETTING--Regional genetic centre. PARTICIPANTS--Clinicians working within the North Western region who wished to use the service offered. RESULTS--133 Fetuses were aborted because of abnormalities detected on ultrasonography and 115 because of abnormal findings on amniotic fluid analysis. In a further two cases fetal abnormality was diagnosed by molecular genetic and biochemical techniques. Among the fetuses with abnormal scans the pretermination diagnosis was changed or refined in a way which affected genetic counselling in 53 of 133 cases. Among the 115 fetuses diagnosed as abnormal by amniocentesis the pretermination diagnosis was confirmed in 112 cases and altered in three. CONCLUSION--Fetuses aborted because of abnormalities detected by screening should be examined by suitably experienced clinicians, both for accurate genetic counselling of the families and for quality control of the tests employed.     

Studying parents and grandparents to assess genetic contributions to early-onset disease

Suppose DNA is available from affected individuals, their parents, and their grandparents. Particularly for early-onset diseases, maternally mediated genetic effects can play a role, because the mother determines the prenatal environment. The proposed maximum-likelihood approach for the detection of apparent transmission distortion treats the triad consisting of the affected individual and his or her two parents as the outcome, conditioning on grandparental mating types. Under a null model in which the allele under study does not confer susceptibility, either through linkage or directly, and when there are no maternally mediated genetic effects, conditional probabilities for specific triads are easily derived. A log-linear model permits a likelihood-ratio test (LRT) and allows the estimation of relative penetrances. The proposed approach is robust against genetic population stratification. Missing-data methods permit the inclusion of incomplete families, even if the missing person is the affected grandchild, as is the case when an induced abortion has followed the detection of a malformation. When screening multiple markers, one can begin by genotyping only the grandparents and the affected grandchildren. LRTs based on conditioning on grandparental mating types (i.e., ignoring the parents) have asymptotic relative efficiencies that are typically >150% (per family), compared with tests based on parents. A test for asymmetry in the number of copies carried by maternal versus paternal grandparents yields an LRT specific to maternal effects. One can then genotype the parents for only the genes that passed the initial screen. Conditioning on both the grandparents' and the affected grandchild's genotypes, a third log-linear model captures the remaining information, in an independent LRT for maternal effects.     

Evolutionary and transmission dynamics of reassortant H5N1 influenza virus in Indonesia

H5N1 highly pathogenic avian influenza (HPAI) viruses have seriously affected the Asian poultry industry since their recurrence in 2003. The viruses pose a threat of emergence of a global pandemic influenza through point mutation or reassortment leading to a strain that can effectively transmit among humans. In this study, we present phylogenetic evidences for the interlineage reassortment among H5N1 HPAI viruses isolated from humans, cats, and birds in Indonesia, and identify the potential genetic parents of the reassorted genome segments. Parsimony analyses of viral phylogeography suggest that the reassortant viruses may have originated from greater Jakarta and surroundings, and subsequently spread to other regions in the West Java province. In addition, Bayesian methods were used to elucidate the genetic diversity dynamics of the reassortant strain and one of its genetic parents, which revealed a more rapid initial growth of genetic diversity in the reassortant viruses relative to their genetic parent. These results demonstrate that interlineage exchange of genetic information may play a pivotal role in determining viral genetic diversity in a focal population. Moreover, our study also revealed significantly stronger diversifying selection on the M1 and PB2 genes in the lineages preceding and subsequent to the emergence of the reassortant viruses, respectively. We discuss how the corresponding mutations might drive the adaptation and onward transmission of the newly formed reassortant viruses.     

The use of cloned Y chromosome-specific DNA probes for fetal sex determination in first trimester prenatal diagnosis

Summary Prenatal diagnosis by chorion biopsy in the first trimester of pregnancy has advantages over second trimester amniocentesis because diagnosis can be achieved at 9–12 weeks gestation, reducing prenatal anxiety and avoiding the trauma of late abortion. DNA can be prepared from chorionic villus biopsies in sufficient quantity and purity for use in prenatal diagnosis systems using specific DNA probes hybridised to restriction endonuclease digests.DNA probes derived from the Y chromosome have been used to determine fetal sex. The use of such probes means that the chromosomal sex of the fetus can be identified more quickly than by chromosome preparation and more accurately than by sex chromatin staining, and has the additional advantage that the same DNA preparation can be used for other diagnostic tests. A dot hybridisation method has been successfully used to provide even more rapid results than conventional hybridisation to Southern blots of restriction endonuclease digests.There is a risk that Y chromosome-specific DNA probes for sex determination may be subject to error if the parents have extreme Y chromosome variants such as a small or non-fluorescent Y or a Y autosome chromosome translocation. The precise extent to which such chromosome variants may lead to error has been investigated. Even extreme Y chromosome variants totally lacking fluorescence were identified as male by the cloned probes used. However, Y autosome translocations carried by females could cause error if not identified in the parents. The value of the probes has been confirmed provided that parental chromosomes and DNA are examined in parallel with the chorionic biopsy material     

Brighter yellow blue tits make better parents

Whether or not bird ornaments are a signal for direct (e.g. good parents) or indirect (e.g. good genes) benefits to prospective partners in sexual selection is controversial. Carotene coloration in Parus species is directly related to the ingestion of caterpillars, so that a brightly carotene-coloured tit may be signalling its ability to find caterpillars, a main high-quality food source for good fledgling development, and hence its parental abilities. If carotene-based plumage coloration is related to the good-parent hypothesis, we predict that yellow plumage brightness of tit fathers should be positively correlated to their investment in offspring provisioning. Here, we use cross-fostering experiments in blue tits (Parus caeruleus) to show that chick development (as measured by tarsus length) is related to yellowness of the foster father, but not to that of the genetic parents. Using these data, we were able to measure, for the first time to our knowledge, the separate contribution of genetic and environmental factors (i.e. parental plumage coloration) to chick development, and hence parental investment. Our data, which relate carotenoid coloration to models of good parents, and data from other authors, which relate ultraviolet coloration to good-genes models, stress that different kinds of coloration within an individual may provide different units of information to prospective females.     

The natural history of cytogenetically abnormal fetuses detected at midtrimester amniocentesis which are not terminated electively: new data and estimates of the excess and relative risk of late fetal death associated with 47,+21 and some other abnormal karyotypes.

We report the results of an ongoing survey of rates of spontaneous death of fetuses with chromosome abnormalities detected at second-trimester amniocentesis in which the mother did not elect abortion. Estimated excess risks (and conservative 90% confidence intervals) of spontaneous fetal death for various cytogenetic abnormalities are as follows: 47,+21, 25.6% (18.0%-34.0%); 47,+18, 63.8% (49.3%-79.8%); 47,+13, 36.5% (11%-69.7%); 45,X, 65.3% (41.0%-84.2%); and mosaic 45,X/46,XX, 10.8% (1.0%-26.8%). There is little evidence for an excess risk of fetal death, at least following amniocentesis, for 47,XXX, 47,XXY, or 47,XYY. The excess risks of fetal death were adjusted for the likelihood that a fetus of normal karyotype would undergo spontaneous fetal death in a population of older maternal age similar to that in which prenatal cytogenetic diagnosis is undertaken. The absolute fetal death rates when this factor is ignored are about 3.5% higher (i.e., may be derived by adding 3.5% to the values given). The excess risks are those which are most appropriate for use in estimating the contribution of chromosome abnormalities to spontaneous fetal death.     

Chromosome Analysis before Birth and its Value in Genetic Counselling

Chromosome analysis of amniotic cell cultures was achieved in 29 out of 30 consecutive patients who were referred for genetic counselling during pregnancy. Amniocentesis was performed without any apparent untoward maternal or fetal complication. The only pregnancy terminated was that of a carrier of X-linked granulomatous disease, in whom the amniotic cells showed that the fetus was male and also had Down''s syndrome (trisomy G). Chromosome analysis in the remaining 28 patients showed normal karyotypes. The interval between amniocentesis and a definitive karyotype varied from 7 to 31 (average 18·4) days.The reliability of chromosome analysis from amniotic cell culture and of fetal sex determination by means of the sex chromatin and Y-fluorescence techniques was studied further in amniotic fluid from cases of therapeutic abortion and of rhesus incompatibility. The fetal sex was correctly determined in all cases. It is concluded that antenatal diagnosis of genetic disease by amniocentesis now permits a more practical approach to genetic counselling.     

Transparent Meta-Analysis: Does Aging Spare Prospective Memory with Focal vs. Non-Focal Cues?

Background

Prospective memory (ProM) is the ability to become aware of a previously-formed plan at the right time and place. For over twenty years, researchers have been debating whether prospective memory declines with aging or whether it is spared by aging and, most recently, whether aging spares prospective memory with focal vs. non-focal cues. Two recent meta-analyses examining these claims did not include all relevant studies and ignored prevalent ceiling effects, age confounds, and did not distinguish between prospective memory subdomains (e.g., ProM proper, vigilance, habitual ProM) (see Uttl, 2008, PLoS ONE). The present meta-analysis focuses on the following questions: Does prospective memory decline with aging? Does prospective memory with focal vs. non-focal cues decline with aging? Does the size of age-related declines with focal vs. non-focal cues vary across ProM subdomains? And are age-related declines in ProM smaller than age-related declines in retrospective memory?

Methods and Findings

A meta-analysis of event-cued ProM using data visualization and modeling, robust count methods, and conventional meta-analysis techniques revealed that first, the size of age-related declines in ProM with both focal and non-focal cues are large. Second, age-related declines in ProM with focal cues are larger in ProM proper and smaller in vigilance. Third, age-related declines in ProM proper with focal cues are as large as age-related declines in recall measures of retrospective memory.

Conclusions

The results are consistent with Craik''s (1983) proposal that age-related declines on ProM tasks are generally large, support the distinction between ProM proper vs. vigilance, and directly contradict widespread claims that ProM, with or without focal cues, is spared by aging.     

Moral and religious influences on the amniocentesis decision

Abstract

As early as 1973 Fletcher documented moral problems families encountered as they struggled with the decision of whether or not to have amniocentesis. In this study we asked 202 women accepting and 50 women rejecting amniocentesis extensive questions about religious beliefs, behaviors, and beliefs about abortion. Members of small Protestant denominations were the most conservative. Catholics and other Protestants were intermediate with smaller differences between these middle groups. Those respondents claiming no religion or one of a non‐Christian denomination were the most liberal. Net predictors of acceptance of amniocentesis included respondents’ support for laws permitting abortion for medical reasons, negative responses about belief in the sanctity of life, having insurance, and the respondents’ political affiliation. Education and religious attendance were the most consistent net predictorsof moral attitudes. We concluded that the amniocentesis decision is influenced by many religious beliefs but is not completely determined by these.     

Reproduction abnormalities and twin pregnancies in parents of sporadic patients with oculo-auriculo-vertebral spectrum/Goldenhar syndrome

A great number of case reports on concordant and discordant twins with oculo-auriculo-vertebral spectrum (OAVS) suggest that there might be an association between reproductive abnormalities, twinning and OAVS. The etiology of OAVS is unknown, but may involve epigenetic dysregulation of the oocyte or early embryo. We collected data on fertility and pregnancy outcome of 72 parents of patients with sporadic OAVS. We also evaluated prospective follow-up data on 3.372 fetuses and children conceived by intracytoplasmatic sperm injection (ICSI). Parental age, duration of menstrual cycle and the incidence of spontaneous abortion was not different when compared to the German population. However, there is an excess of parents who have used assisted reproductive techniques (ART; retrospective P = 0.038, prospective P = 0.023) and an excess of twins among naturally conceived patients with OAVS (P = 0.0025). An excess of ART conceptions and monozygotic twinning in OAVS is compatible with the concept of overripeness ovopathy as proposed by Jongbloet (Maandschr Kindergeneeskd 36:352–367, 1968).     

Accepting Adoption’s Uncertainty: The Limited Ethics of Pre-Adoption Genetic Testing

An increasing number of children are adopted in the United States from countries where both medical care and environmental conditions are extremely poor. In response to worries about the accuracy of medical histories, prospective adoptive parents increasingly request genetic testing of children prior to adoption. Though a general consensus on the ethics of pre-adoption genetic testing (PAGT) argues against permitting genetic testing on children available for adoption that is not also permitted for children in general, a view gaining traction argues for expanding the tests permitted. The reasoning behind this view is that the State has a duty to provide a child with parents who are the best “match,” and thus all information that advances this end should be obtained. While the matching argument aims to promote the best interests of children, I show how it rests on the claim that what is in the best interests of children available for adoption is for prospective adoptive parents to have their genetic preferences satisfied such that the “genetics” of the children they end up adopting accurately reflects those preferences. Instead of protecting a vulnerable population, I conclude, PAGT contributes to the risks of harm such children face as it encourages people with strong genetic preferences to adopt children whose genetic backgrounds will always be uncertain.     

Phenotypic and Evolutionary Consequences of Social Behaviours: Interactions among Individuals Affect Direct Genetic Effects

Traditional quantitative genetics assumes that an individual''s phenotype is determined by both genetic and environmental factors. For many animals, part of the environment is social and provided by parents and other interacting partners. When expression of genes in social partners affects trait expression in a focal individual, indirect genetic effects occur. In this study, we explore the effects of indirect genetic effects on the magnitude and range of phenotypic values in a focal individual in a multi-member model analyzing three possible classes of interactions between individuals. We show that social interactions may not only cause indirect genetic effects but can also modify direct genetic effects. Furthermore, we demonstrate that both direct and indirect genetic effects substantially alter the range of phenotypic values, particularly when a focal trait can influence its own expression via interactions with traits in other individuals. We derive a function predicting the relative importance of direct versus indirect genetic effects. Our model reveals that both direct and indirect genetic effects can depend to a large extent on both group size and interaction strength, altering group mean phenotype and variance. This may lead to scenarios where between group variation is much higher than within group variation despite similar underlying genetic properties, potentially affecting the level of selection. Our analysis highlights key properties of indirect genetic effects with important consequences for trait evolution, the level of selection and potentially speciation.