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PubMed1993

Reproductive technologies for prenatal diagnosis.

Reproductive genetic technology provides unprecedented opportunities for pregnant women and their families to obtain direct information about the genetic makeup of their developing fetus. Ultrasonography, maternal serum markers, amniocentesis, chorionic villus sampling and percutaneous umbilical blood sampling already offer opportunities for prenatal diagnosis in early pregnancy. New techniques, such as preimplantation, prenatal diagnosis and fetal cell sorting offer opportunities for prenatal diagnosis in even earlier stages of pregnancy.

Amniocentesis↗
PubMed1998

Potential of assisted breeding techniques for the conservation of endangered mammalian species in captivity: a review.

An alarming worldwide extinction of animal species is taking place as a result of the activities of the increasing global human population. The original ranges of many animal species are being reduced and fragmented and, in some cases, they have been reduced to perilously small relict populations. The adverse genetic consequences of these restrictions are becoming clear, as are possible methods for their alleviation. The concept of ex situ genetic management of small captive populations of endangered species with a view to re-introducing them into the wild is attracting increasing interest. Modern reproductive techniques will play an important role in such programmes, and it is likely that an increasing number of veterinarians will become involved. However, the literature describing the aims and methods of reproductive genetic management is scattered and often not readily available to interested veterinary surgeons. The aim of this review is to deal with this problem by describing some potential approaches to the captive breeding of endangered species.

Animal Husbandry↗
PubMed1990

Reproductive planning after genetic counselling: a perspective from the last decade.

Studies from the last decade on factors influencing reproductive planning after genetic counselling were reviewed. Increased possibilities of DNA-analysis and prenatal diagnosis might have brought about a shift in the paramountcy of factors influencing reproductive planning after genetic counselling. In contrast to the literature in the seventies, the magnitude of the genetic risk was no longer found to be one of the decisive factors in postcounselling reproductive planning. Instead, the interpretation of the risk as high or low and the desire to have children appeared to be paramount. The impact of new developments in DNA-analysis in prenatal diagnosis and presymptomatic testing will be an important subject for future studies on factors influencing reproductive planning.

Female↗
PubMed1984

Genetic counseling and reproductive uncertainty.

Of 836 fertile women seeking genetic counseling, 544 (65%) reported that their major reason for doing so was to obtain information to help in deciding if they should have a child. Thirty-four percent of these 836 women entered counseling uncertain about undertaking a pregnancy in the next 2 years. After counseling, 28% of the 836 had uncertain pregnancy intentions. These included 66% of those who were uncertain and 11% of those who were reproductively certain before counseling. Stepwise logistic regression identified the following as independently and significantly associated with reproductive uncertainty after counseling: 1) uncertainty before counseling; 2) uncertainty about ideal family size; 3) concern about the effects of an affected child on the client's social life; 4) perceived serious problems caring for a child with a birth defect now living at home; and 5) new concerns raised in counseling. Reproductive uncertainty after counseling was not related to characteristics of the risked birth defect, level of risk, treatment potential, or client learning of medical and genetic facts. These data suggest that genetic counseling will not eliminate reproductive uncertainty for many clients, because this uncertainty is related to factors mainly outside the usual scope of counseling.

Adolescent↗
PubMed1972

Inheritance during parthenogenesis in Daphnia magna.

Natural populations of Daphnia magna have been found which are polymorphic for electrophoretic variants of supernatant malic dehydrogenase, esterase, and alkaline phosphatase. Using these enzyme variants as genetic markers it has been possible to demonstrate the absence of recombination during parthenogenetic reproduction. Genetic uniformity is expected within parthenogenetic clones derived from a single female.

Alkaline Phosphatase↗
PubMed2006

Sexual reproduction reshapes the genetic architecture of digital organisms.

Modularity and epistasis, as well as other aspects of genetic architecture, have emerged as central themes in evolutionary biology. Theory suggests that modularity promotes evolvability, and that aggravating (synergistic) epistasis among deleterious mutations facilitates the evolution of sex. Here, by contrast, we investigate the evolution of different genetic architectures using digital organisms, which are computer programs that self-replicate, mutate, compete and evolve. Specifically, we investigate how genetic architecture is shaped by reproductive mode. We allowed 200 populations of digital organisms to evolve for over 10 000 generations while reproducing either asexually or sexually. For 10 randomly chosen organisms from each population, we constructed and analysed all possible single mutants as well as one million mutants at each mutational distance from 2 to 10. The genomes of sexual organisms were more modular than asexual ones; sites encoding different functional traits had less overlap and sites encoding a particular trait were more tightly clustered. Net directional epistasis was alleviating (antagonistic) in both groups, although the overall strength of this epistasis was weaker in sexual than in asexual organisms. Our results show that sexual reproduction profoundly influences the evolution of the genetic architecture.

Biological Evolution↗
PubMed2005

The genetic basis of reproductive isolation: insights from Drosophila.

Recent studies of the genetics of speciation in Drosophila have focused on two problems: (i) identifying and characterizing the genes that cause reproductive isolation, and (ii) determining the evolutionary forces that drove the divergence of these "speciation genes." Here, I review this work. I conclude that speciation genes correspond to ordinary loci having normal functions within species. These genes fall into several functional classes, although a role in transcriptional regulation could prove particularly common. More important, speciation genes are typically very rapidly evolving, and this divergence is often driven by positive Darwinian selection. Finally, I review recent work in Drosophila pseudoobscura on the possible role of meiotic drive in the evolution of the genes that cause postzygotic isolation.

Animals↗
PubMed1993

Tomorrow's prenatal genetic testing. Should we test for 'minor' diseases?

New genetic knowledge will make it possible to test prenatally for a wide range of fetal genetic characteristics. One consequence will be an expansion of potential reasons for selective abortion following prenatal testing. It will likely become possible for patients to request prenatal testing and abortion not only for serious diseases but also relatively mild diseases, late-onset diseases, treatable diseases, elevated risks for common diseases, and eventually nondisease characteristics, such as height and body build. Two main ethical views concerning prenatal testing have been advocated: (1) Prenatal testing should be restricted to the "most severe" disorders, involving profound retardation, severe physical handicaps, or prolonged physical suffering and (2) Patients' requests for prenatal tests should be honored except for diseases considered to be "too minor." At least two additional views can be identified: (3) Physicians should honor requests for prenatal testing for diseases, including relatively minor ones, but not requests pertaining to nondisease characteristics and (4) All requests for prenatal tests should be honored. A difficulty with the first and second views is that they deviate from the norm of nondirectiveness in prenatal testing and counseling. The problems with the fourth view are that it leads to abortions for morally trivial reasons and that attempts to design our children could adversely affect parent-child relationships and exacerbate current social inequities. These considerations support the third view, which holds that the future role of reproductive genetic testing and counseling should be based on the imperfect, but helpful, distinction between disease and nondisease.

Ethics, Medical↗
PubMed1995

The reproductive and neural toxicities of acrylamide and three analogues in Swiss mice, evaluated using the continuous breeding protocol.

Acrylamide is a known genetic, reproductive, and neural toxicant, although it is not known if one effect is predominant. The toxicities of several structural analogues of acrylamide have been incompletely characterized, and the relative sensitivity of the second generation is not known. The present studies were designed to explore the relationship between neurotoxicity and reproductive toxicity, to further characterize the toxicities of three acrylamide analogues, and to evaluate the relative sensitivity of a second generation to these compounds. For the F0 generation, male and female Swiss CD-1 mice were provided drinking water containing acrylamide (ACR; 3, 10, 30 ppm), N,N'-methylenebisacrylamide (MBA; 10, 30, 60 ppm), N-(hydroxymethyl)acrylamide (HMA; 60, 180, 360 ppm), or methacrylamide (MACR; 24, 80, 240 ppm) during and after a 14-week cohabitation. The last litter was reared and dosed after weaning until mating at 74 +/- 10 days of age with the same level of compound given to the parents Neurotoxicity was assessed at several times in both generations by measuring forelimb and hindlimb grip strength. In the F0 generation, ACR caused an 11% decrease in pup number without measurable neurotoxicity; female fertility was not affected. Although both generations consumed the same amount of ACR, there were larger changes in the fertility-related endpoints in the F1 mice than in the F0's, with no concomitant change in organ weights or sperm parameters. In F0 mice, MBA reduced the number of live pups and their adjusted weight, with no neurotoxicity and no change in F0 female reproduction. MBA caused greater adverse effects in the second generation, concomitant with increased consumption. In the F0 generation, HMA caused the largest decrease in pup number during cohabitation (26%) together with a small effect on grip strength. Female reproduction was not affected. The second generation consumed more HMA and showed slightly greater toxic effects. In both generations, MACR was negative for both neurotoxicity and reproductive toxicity. Dominant-lethal studies showed that the fertility effects for ACR, MBA, and HMA could be explained by a male-mediated increase in postimplantation loss. These studies found that dominant lethality occurred without structural effects on the reproductive system in the presence of only minor effects on grip strength and without detectable neural histopathology. Female reproduction was not significantly affected by these compounds at the doses used. Thus, these data confirm the male as the affected gender and that the reproductive toxicity was greater than motoneuron toxicity when measured as grip strength.

Acrylamide↗
PubMed2002

Preimplantation genetic diagnosis.

Preimplantation genetic diagnosis (PGD) is an evolving technique that provides a practical alternative to prenatal diagnosis and termination of pregnancy for couples who are at substantial risk of transmitting a serious genetic disorder to their offspring. Samples for genetic testing are obtained from oocytes or cleaving embryos after in vitro fertilization. Only embryos that are shown to be free of the genetic disorders are made available for replacement in the uterus, in the hope of establishing a pregnancy. PGD has provided unique insights into aspects of reproductive genetics and early human development, but has also raised important new ethical issues about assisted human reproduction.

Aneuploidy↗
PubMed2004

Over a decade of experience with preimplantation genetic diagnosis: a multicenter report.

OBJECTIVE: To review a 12-year experience of the world's three largest preimplantation genetic diagnosis (PGD) centers. DESIGN: Multicenter analysis of the clinical outcome of PGD. SETTING: In vitro fertilization programs at the Reproductive Genetics Institute, Chicago, Illinois; Saint Barnabas Medical Center, West Orange, New Jersey; and SISMER, Bologna, Italy. PATIENT(S): Poor-prognosis IVF patients, patients carrying balanced chromosomal translocations, and couples at risk for producing children with Mendelian disorders. INTERVENTION(S): In vitro fertilization, intracytoplasmic sperm injection, polar body removal, blastomere biopsy, and ET. MAIN OUTCOME MEASURE(S): DNA or chromosomal analysis of biopsied polar bodies or blastomeres, implantation and clinical pregnancy rates, and live-born pregnancy outcome. RESULT(S): A total of 754 babies have been born as a result of 4,748 PGD attempts, which shows the expanded application and the practical relevance of PGD for single-gene disorders, chromosomal aneuploidies and translocations, late-onset diseases with genetic predisposition, and nondisease testing in couples at need for human leukocyte antigens-matched offspring for treatment of affected siblings. CONCLUSION(S): Preimplantation genetic diagnosis is evolving to become a clinical option for couples at risk for producing offspring with Mendelian diseases, has a positive numerical impact in standard assisted reproduction practices through aneuploidy testing, and reduces by at least fourfold the spontaneous abortion rate in couples carrying translocations.

Blastula↗
PubMed2003

Referral for genetic counselling during pregnancy: limited alertness and awareness about genetic risk factors among GPs.

BACKGROUND: In many countries, GPs play a key role in the referral to other medical specialists. Referral for reproductive genetic counselling during a pregnancy of women with a genetic risk factor already present before pregnancy has many disadvantages. Nevertheless, some 10-20% of the counsellees who attend a Department of Clinical Genetics for the first time are pregnant. OBJECTIVES: We aimed to explore the role of the GP in referring women for genetic counselling during, instead of before a pregnancy. METHOD: The GPs of 100 pregnant women who received genetic counselling were invited to participate in the study and asked to complete a questionnaire. The topics were: initiation and discussion of aspects of referral to the Department of Clinical Genetics; reasons for the referral during, instead of before a pregnancy; knowledge of genetic counselling; attitudes towards genetic counselling before a pregnancy; and attitudes towards abortion. RESULTS: To our surprise, 29% of the GPs indicated that they had not been involved in the referral to the Department of Clinical Genetics at all. Furthermore, the referral was initiated by the patient herself in most cases (40%) and by the GPs in 31% of the cases. Of the GPs who were involved in the referral, most of them (79%) talked to their patients to different extents about what to expect from their visit to the Department of Clinical Genetics; however, potential choices after an adverse outcome at prenatal diagnosis were discussed less often (60%). The main reason for referring the patient during, instead of before her pregnancy was because the GP was unaware of a potential risk factor before pregnancy (71%) and, consequently, never had a chance to talk about a referral before (71%). Other reasons for referral during pregnancy mentioned by the GPs were reassuring the patient about the health of her unborn child (32%) and the wish of the patient to be referred during pregnancy (31%). GPs considered their knowledge of clinical genetics to be limited (mean score 5, on a scale from 0 to 10). The majority of the GPs were in favour of genetic counselling taking place before, instead of during pregnancy, and they had no great objections to abortion. CONCLUSIONS: During pregnancy, the gatekeeper function of the GP in the referral for genetic counselling is undermined. Limited alertness and awareness among GPs about genetic risk factors in their patients played a major role in this undermined function and in the less appropriate timing of referral. Neither insufficient knowledge nor barriers to acceptance explained this lack of alertness and awareness. We advocate the implementation of routine family history taking in general practice.

Chi-Square Distribution↗
PubMed2001

Successful Day 5 embryo transfer and pregnancies resulting after transport of embryos by air for biopsy and genetic analysis.

PURPOSE: Case studies of four in vitro fertilization (IVF) cycles where embryo transport by commercial airline followed by biopsy and genetic analysis with subsequent culture to Day 5 and resulting ongoing pregnancy. METHOD: Retrospective clinical case study of 4 patients requiring preimplantation genetic diagnosis (PGD) testing. Normally fertilized embryos were transported in a battery-powered portable incubator by commercial airline following evaluation for fertilization under controlled conditions from the Center for Assisted Reproduction, Bedford, Texas to the Reproductive Genetic Institute, Chicago, Illinois. Following Day 3 embryo biopsy and genetic analysis, embryos were transported back to the Center for Assisted Reproduction for Day 5 embryo transfer. RESULTS: Ongoing clinical pregnancy resulted for all patients receiving embryo transfer. CONCLUSION: These results demonstrate the feasibility of embryo transport by air for centers that do not have the in-house capabilities to perform genetic analysis. With successful pregnancies obtained through extended culture to Day 5, embryos requiring genetic analysis can be successfully transported by air, tested, and returned to the initial facility for embryo transfer without time restriction.

Adult↗
PubMed1999

Role of reproductive technologies and genetic resource banks in animal conservation.

In combination with modem reproductive technologies, there is potential to use frozen and stored germplasm (genetic resource banks) to support conservation measures for the maintenance of genetic diversity in threatened species. However, turning this idea into reality is a complex process, requiring interdisciplinary collaboration and clearly defined goals. As the number of species deserving the attention of conservation scientists is overwhelmingly large, yet detailed knowledge of reproductive physiology is restricted to relatively few of them, choosing which species to conserve is one of the most difficult issues to be tackled. Besides the direct application of technologically advanced reproductive procedures, modern approaches to non-invasive endocrine monitoring play an important role in optimizing the success of natural breeding programmes. Through the analysis of urine and faecal samples, this type of technology provides invaluable management information about the reproductive status of diverse species. For example, it is possible to diagnose pregnancy and monitor oestrous cycles in elephants and rhinos without causing stress through restraint for sample collection. In this review, we identify the potential contribution of reproductive biology and genetic resource banks to animal conservation, but also highlight the complexity of issues determining the extent to which this potential can be achieved.

Animals↗
PubMed2000

Genetic parameters for reproductive traits of Holstein cattle in California and Minnesota.

Genetic parameters for five reproductive traits were estimated using data from 51,528 Holstein cows that were inseminated from April to September 1998 in 1717 herds in California and Minnesota. Nonreturn rate and veterinary-confirmed pregnancy rate at 60 and 90 d after insemination were evaluated using linear and threshold models, including an additive genetic effect for the cow being inseminated and a random environmental effect for the service bull. Interval from calving to first insemination was evaluated using a linear model, including an additive genetic effect for the cow being inseminated. Linear model heritability estimates for 60-d (90-d) nonreturn rate were 1.4% (1.5%) in California and 4.1% (2.7%) in Minnesota. Corresponding estimates for 60-d (90-d) confirmed pregnancy rate were 1.4% (2.3%) in California and 1.0% (2.0%) in Minnesota; the proportion of cows with veterinary data available 60 d after breeding was 86% in California and 55% in Minnesota. Threshold model heritability estimates were slightly higher than linear model estimates in California but were lower in Minnesota, presumably because 25% of the herd-season classes in Minnesota contained either all successes or all failures. Linear model repeatability estimates for the service bull effect on 60-d (90-d) nonreturn rate were 0.5% (0.4%) in California and 0.3% (0.3%) in Minnesota. Corresponding estimates for 60-d (90-d) confirmed pregnancy rates were 0.6% (0.2%) in California and 0.1% (0.4%) in Minnesota. Threshold model estimates were slightly higher than linear model estimates in both states. Heritability estimates for the interval from calving to first insemination were 5.8% in California and 6.1% in Minnesota. Despite the low parameter estimates, variation was present among animals, and it should be possible to identify sires that possess superior or inferior reproductive characteristics.

Animals↗
PubMed2006

The perceived personal control (PPC) questionnaire as an outcome of genetic counseling: reliability and validity of the instrument.

The perceived personal control (PPC) questionnaire was developed by Berkenstadt and colleagues as an outcome measure for the evaluation of the process of genetic counseling. The present study aimed to further assess the psychometric properties of a Dutch version of the instrument. Data were used from two samples. A reproductive genetic counseling sample (n = 140), which included pregnant and non-pregnant women, and a cancer genetic counseling sample (n = 181), also consisting of women only. Counselees completed questionnaires before and following their first consultation. Besides the PPC these questionnaires addressed counselees' degree of concern, risk perception and satisfaction with the consultation. The following psychometric properties were assessed: acceptability, internal consistency, dimensionality, and validity. The instrument was well accepted as indicated by few missing items. The internal consistency was good for the total PPC (Cronbach's alpha: 0.79-0.81), reasonable for the original subscales of 'decisional' and 'behavioral control' (>0.60), but unacceptable for the subscale of 'cognitive control' (<0.60). The original three-factor solution was not confirmed; a one-factor solution proved most stable. Significant differences between pre- and post-counseling PPC scores support the PPC's construct validity. Concurrent validity was confirmed by positive associations with counselees' satisfaction although non-significant (concern) and unexpected (risk perception) results were also found. When used as a one-dimensional scale, the PPC has its value as an outcome measure in research addressing genetic counseling. However, the instrument's validity needs to be further assessed.

Adolescent↗
PubMedDate not supplied

Genetic selection for reproductive photoresponsiveness in deer mice.

Seasonal breeding is common in mammals, particularly in habitats outside the tropics. Climate and availability of food are the ultimate factors that usually dictate the optimal time of year for a mammal to breed; however, day length (photoperiod) often serves as the proximal cue to signal the onset or cessation of seasonal reproduction. Some individuals in some populations of deer mice are reproductively responsive to photoperiod, while other individuals in the same population are not. As shown here, selection can dramatically alter the frequency of photoresponsiveness in a laboratory population in only two generations. To our knowledge this is the first demonstration of selection for reproductive photoresponsiveness in any mammal. By implication, some wild populations of deer mice must use multiple, genetic-based reproductive strategies, and the degree to which each such strategy is exhibited must be subject to rapid change in response to both seasonally and momentarily changing climatic and dietary conditions.

Animals↗