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Uptake of presymptomatic predictive testing for Huntington's disease.

Predictive testing by means of gene probes was offered to 110 adults at risk of Huntington's disease (HD). A further 91 individuals spontaneously sought predictive testing. Acceptance rates were highest (85.1%) amongst 47 individuals who spontaneously sought testing and were referred from outside the region, and lowest (15.5%) among the 110 invited to consider predictive testing. Many expressed an interest in predictive testing, then withdrew. Fetal exclusion testing was rarely requested, and then only by individuals who lacked the necessary pedigree structure for predictive testing for themselves.

Adult↗

Molecular analysis and predictive testing in retinoblastoma.

Predictive testing using molecular analysis is an integral part of contemporary retinoblastoma management. We have made extensive use of segregation analysis for risk assessment in both familial and sporadic disease. Investigation of loss of heterozygosity in tumor samples proved to be invaluable for the identification of linkage phase. In many families, however, accurate carrier risk assessment depends on direct identification of the causative R B I mutation. Consequently, we have developed methods for rapid mutation screening. Using these techniques, mutation analysis can now be offered to an increasing number of individuals.

DNA Mutational Analysis↗

Contact allergy: predictive testing in man.

Predictive tests are of value in forecasting the response of a population to a sensitizer; diagnostic testing is used to determine what substances may actually be producing dermatologic problems. Skin sensitization predictive and diagnostic data for the eleven most frequently encountered skin sensitizers in Western Europe, Canada and the United States are reviewed. These compounds include two drugs (benzocaine and neomycin), two cosmetic ingredients (p-phenylenediamine and balsam of Peru), four preservatives (formaldehyde, ethylenediamine, parabens and mercurials) and three ingredients of wearing apparel (nickel, chromium and thiram). Many of the data were collected by the North American Contact Dermatitis Group and the International Contact Dermatitis Research Group on tests with 1,200 and 4,825 dermatologic patients, respectively; the remainder were obtained by individual investigators with smaller groups of subjects. The data obtained by various investigators are discussed in relation to the factors which affect the extent and degree of sensitization which they can cause.

Allergens↗

Understanding the decision to take the predictive test for Huntington disease.

The predictive test for Huntington disease (HD) has allowed those at risk to determine gene status prior to symptoms. The purpose of this research was to understand the motivation and the anticipated reactions of those requesting the test. Forty persons at 50% risk for HD and 31 companions participated in a structured personal interview as part of the predictive test protocol. Reasons for taking the test centered on the reduction of anxiety and uncertainty associated with being at risk and enhanced planning and decision making. Participants also believed that taking the test would produce more positive than negative outcomes. With a favorable result, most anticipated a reduction of anxiety, a more normal future, and relief knowing their children would be at a very low risk. Most also cited benefits as more likely than consequences with an unfavorable result. Making the most of life, easier planning, and reduced uncertainty were rated as more likely than any of the adverse impacts, including short-term depression and becoming frightened. Almost all participants (95%) said they would rather learn that they have the HD gene than remain at 50% risk. The uncertainty, anxiety, and chronic stress associated with being at risk appears to underlie the motivation of many seeking the predictive test for HD.

Adult↗

Impact on couple relationships of predictive testing for Huntington disease: a longitudinal study.

Since predictive testing has been available for Huntington disease (HD) and similar adult-onset neurodegenerative disorders, research into the psychosocial impact of test results has focussed on those receiving results, and to a lesser extent, on their partners. Few studies have examined the impact of predictive testing on the couple relationship, particularly from the perspective of family systems theory. This longitudinal study compared the level of marital adjustment of 23 couples in which the at-risk partner is undergoing predictive testing for HD (the testing group) with that of 20 couples in which the at-risk partner is not undergoing testing (the non-testing group). Participating couples completed a relationship measure, the Dyadic Adjustment Scale, at baseline and on two subsequent occasions. Using non-parametric tests, comparisons were made at each phase between the couple scores of the testing and non-testing groups but no significant differences were found in the levels of marital adjustment. Within the testing group the same comparisons were made for the carrier and non-carrier subgroups, and a significant difference was found at the final phase. There was an increase in the level of marital adjustment for the carrier group and a decrease for the non-carrier group. Together with trends observed in the data, this finding suggests a need for greater attention to be given to the potential impact of predictive testing on the couple relationship. Offering couples pre-result relationship assessment and referral for couple therapy, if warranted, may enhance the quality of professional support during the predictive testing process.

Adaptation, Psychological↗

A worldwide assessment of the frequency of suicide, suicide attempts, or psychiatric hospitalization after predictive testing for Huntington disease.

Prior to the implementation of predictive-testing programs for Huntington disease (HD), significant concern was raised concerning the likelihood of catastrophic events (CEs), particularly in those persons receiving an increased-risk result. We have investigated the frequency of CEs-that is, suicide, suicide attempt, and psychiatric hospitalization-after an HD predictive-testing result, through questionnaires sent to predictive-testing centers worldwide. A total of 44 persons (0.97%) in a cohort of 4,527 test participants had a CE: 5 successful suicides, 21 suicide attempts, and 18 hospitalizations for psychiatric reasons. All persons committing suicide had signs of HD, whereas 11 (52.4%) of 21 persons attempting suicide and 8 (44.4%) of 18 who had a psychiatric hospitalization were symptomatic. A total of 11 (84.6%) of 13 asymptomatic persons who experienced a CE during the first year after HD predictive testing received an increased-risk result. Factors associated with an increased risk of a CE included (a) a psychiatric history </=5 years prior to testing and (b) unemployed status. The frequency of CEs did not differ between those persons receiving results of predictive testing through linkage analysis in whom there was only changes in direction of risk and those persons receiving definitive results after analysis for the mutation underlying HD. These findings provide insights into the frequency, associated factors, and timing of CEs in a worldwide cohort of persons receiving predictive-testing results and, as such, highlight persons for whom ongoing support may be beneficial.

Cohort Studies↗

Attitudes toward predictive testing for Alzheimer's disease in a student population.

Attitudes toward predictive testing for Alzheimer's disease and knowledge about this disease were investigated in a group of medical and psychology students. Overall, knowledge was poor and their own chance of getting Alzheimer's disease was mostly perceived as small. About half the students thought the development of a predictive test for Alzheimer's disease important, while the other half held the opposite view. Considerable variability was also observed in the judgement of the (dis)advantages of such a test. Only a minority of the students would like to have a predictive test themselves. Important arguments against a predictive test concerned the absence of a treatment for Alzheimer's disease and the emotional burden of a positive test result. Arguments in favour dealt with the ability to make plans for the future and to prepare oneself for the disease. The divergence in attitudes and opinions reflects the complexity of predictive testing for Alzheimer's disease. Stepwise regression revealed that knowledge about Alzheimer's disease and, to a lesser extent, risk perception are significant predictors of attitudes toward predictive testing. However, they only explain a small part of the variance in attitudes. Moreover, why attitudes are less positive when knowledge and perceived susceptibility increase is not clear.

Adult↗

Attitudes of neurologists, psychiatrists, and psychotherapists towards predictive testing for Huntington's disease in Germany.

Predictive testing for Huntington's disease (HD) in Germany is performed by genetic counsellors, neurologists, psychiatrists, and psychotherapists. In order to evaluate the attitudes of neurologists, psychiatrists, and psychotherapists in Germany towards predictive testing for HD, a postal questionnaire was sent to this group. Two German Bundesländer were chosen, Baden Württemberg (BW) and Niedersachsen (NS). Of 469 persons interviewed the response rate was 32.6%. The questionnaire consisted of 17 items assessing sociodemographic data, acquaintance with HD patients, lay organisations, attitudes towards genetic counselling, presymptomatic and prenatal DNA testing, and reproduction of persons at risk for HD. More than 70% of the subjects were well informed about predictive DNA testing but knowledge about the details of the test procedure, especially the World Federation of Neurology (WFN) and International Huntington Association (IHA)1 recommendations, was quite low (11.8%). Nevertheless, the majority would recommend predictive testing for HD although they anticipated problems for the probands. The majority of our respondents favoured psychological test and post-test counselling for those tested. Concerning reproduction, most subjects favoured prenatal testing or that persons at risk should refrain from having children. We found that the opinions of practitioners and at risk persons differed with respect to the predictive DNA test and, particularly, to prenatal testing. Therefore the testing procedure could be improved if practitioners were better informed about the DNA test in general and about the attitudes and wishes of their patients.

Attitude of Health Personnel↗

Psychological functioning before predictive testing for Huntington's disease: the role of the parental disease, risk perception, and subjective proximity of the disease.

BACKGROUND: Psychometric testing of participants in predictive DNA testing for Huntington's disease (HD) has shown that 15% of the subjects at risk for HD had at least mild depression or a high score for general anxiety or both in the pre-test period. The main aim of the study was the delineation of variables associated with pre-test distress of applicants for predictive testing for HD. Based on theoretical considerations, four specific hypotheses were tested regarding the role of (1) the test participant's age at the (perceived) parental onset of HD, (2) the affected parent's sex, (3) the perception of the risk for HD, and (4) the subjective proximity of the disease. Secondly, these four variables were used in multiple regression analyses to select the best predictors of pre- and post-test psychological functioning (one year after the test). Increasing the understanding of pre- and post-test distress is important for developing better counselling and support strategies for test applicants. METHODS: Data were collected by means of clinical interviews and psychometric questionnaires during the pre- and post-test (one year after the test) counselling sessions for predictive testing for HD. RESULTS: We found significant associations of the participant's age at the parental onset, the subjective proximity of the disease onset, and the perceived risk with pre-test psychometric measures of psychological functioning. Multiple regression analyses showed that the best predictors of pre-test functioning were the perceived proximity of the disease onset and its interaction with risk perception. Regarding post-test functioning, none of the proposed variables had a unique contribution beyond that accounted for by pre-test psychological functioning. CONCLUSIONS: Test participants who are close to the perceived age of onset of HD and who have a pessimistic risk perception should be given special attention during pre-test counselling because of their possible negative affective condition at that time. Pre-test psychological measures were the best predictors of post-test distress, irrespective of the test result. Suggestions for future longitudinal research are formulated. This kind of research should enable clinical geneticists and mental health professionals to refine the pre- and post-test counselling strategies for predictive DNA testing, not only for HD, but also for other incurable late onset disorders.

Adult↗

Perception of predictive testing for Huntington's disease by young women: preferring uncertainty to certainty?

Opinions on the implications of predictive testing for Huntington's disease were evaluated in a group of 169 women (aged 21-35 years) with interest in psychosocial issues, but with no special pre-existing knowledge or training in genetics. Predictive testing for Huntington's disease (HD) is considered to be a test case for predictive testing for other late onset diseases, monogenic as well as multifactorial disorders. In the hypothetical situation of having a 50% risk for developing HD, about half of the group expressed interest in a predictive test. As to the question of giving results of predictive tests to third parties, the group would be very reluctant to inform the employer or the insurer, but not their own family. Prenatal testing for late onset diseases was considered acceptable by half of the women; only one quarter of the total group would terminate a pregnancy of a child that might develop a late onset disease. The assessment of attitudes towards predictive testing was carried out within the context of a global evaluation of perceived advantages and disadvantages of genetic counselling. The attitudes towards predictive testing were systematically associated with perceiving 'having more certainty about the future' as an advantage of genetic counselling and with rejecting 'knowing everything in advance' as a disadvantage.

Adult↗

Huntington disease: a case study describing the complexities and nuances of predictive testing of monozygotic twins.

When a candidate for predictive testing for the Huntington disease gene is a monozygotic twin, confidentiality of the co-twin's diagnosis and autonomy of participation are among the critical genetic counseling issues. Predictive testing can proceed when twins voluntarily and simultaneously request counseling and evaluation in an HD testing program. This case describes a young man referred for predictive testing to an HD testing site on the East Coast of the United States. Family history revealed a twin brother of unknown zygosity who resided on the West Coast of the United States. The genetic counselors on opposite coasts collaborated to provide genetic counseling and evaluation for voluntary, informed predictive testing of the twins, protecting their rights while observing national protocol guidelines

Adult↗

The prospect of predictive testing for personal risk: attitudes and decision making.

As predictive tests for medical problems such as genetic disorders become more widely available, it becomes increasingly important to understand the processes involved in the decision whether or not to seek testing. This study investigates the decision to pursue the possibility of testing. Individuals (one group who had already contemplated the possibility of predictive testing and one group who had not) were asked to consider predictive testing for several diseases. They rated the likelihood of opting for testing and specified the reasons which they believed had affected their decision. The ratio of the numbers of reasons stated for testing and the numbers of reasons stated against testing was a good predictor of the stated likelihood of testing, particularly when the reasons were weighted by utility (importance). Those who had previously contemplated testing specified more emotional reasons. It is proposed that the decision process is internally logical although it may seem illogical to others due to there being idiosyncratic premises (or reasons) upon which the decision is based. It is concluded that the Utility Theory is a useful basis for describing how people make decisions related to predictive testing; modifications of the theory are proposed.

Adult↗

Prognostic significance of DNA patterns and resistance-predictive tests in non-small cell lung carcinoma.

In a cooperative study, 240 surgical specimens of patients with non-small cell lung carcinomas (NSCLC) were investigated by means of flow cytometry, xenotransplantation to athymic mice and, an in vitro short-term test for predicting resistance. Aneuploidy was found in 83% of the tumors, and 20% showed more than one aneuploid DNA stemline. Patients with both aneuploid tumors and tumors with more than one DNA stemline had a significantly shorter survival rate than those with only diploid or only one DNA stemline. Patients whose tumors showed a low G0/G1-cell proportion or a high proliferation pool (S and G2/M-cell proportion) died earlier. A relationship could not be discerned between growth of tumors in nude mice or establishment of cell lines and the prognosis for the patients. Patients with in vitro-resistant tumors died earlier under chemotherapy than those with in vitro-sensitive tumors. Patients treated by radiation survived longer if the tumors were resistant in vitro. Thus, DNA patterns and in vitro short-term tests for predicting resistance represent useful tools for prognostic evaluation of patients with NSCLC.

Adult↗

Molecular genetic predictive testing for Alzheimer's disease: deliberations and preliminary recommendations.

Forty-one participants representing diverse professional back-grounds attended a workshop on genetic predictive testing for familial Alzheimer's disease (FAD) on January 23, 1993 at Surrey Place Centre in Toronto, Canada. Rapidly emerging molecular genetic findings in AD indicate that predictive testing is now technologically feasible for selected individuals, although defining eligibility criteria remains problematic. Legal, ethical, biomedical, and psychosocial issues related to establishing predictive testing programs for AD were discussed at the workshop. This article reflects these discussions, provides the current biomedical background for them and examines the Huntington's disease (HD) predictive testing experience. Observations concerning molecular genetic predictive testing for AD in light of its genetic heterogeneity and clinical characteristics, such as usual later age of onset than HD, are presented. It is proposed that predictive testing for AD can now be cautiously offered in a research setting primarily according to the recommendations contained within the Ethical Issues Policy Statement on Huntington's Disease Molecular Genetics Predictive Test. However, in their application to AD, some points in the statement are considered to require emphasis, modification, or currently to be of uncertain applicability. This represents an initial step in an on-going process of debate concerning AD that will be required as new advances occur in genetic and clinical research and in bioethics.

Aged↗

Risk reversals in predictive testing for Huntington disease.

The first predictive testing for Huntington disease (HD) was based on analysis of linked polymorphic DNA markers to estimate the likelihood of inheriting the mutation for HD. Limits to accuracy included recombination between the DNA markers and the mutation, pedigree structure, and whether DNA samples were available from family members. With direct tests for the HD mutation, we have assessed the accuracy of results obtained by linkage approaches when requested to do so by the test individuals. For six such individuals, there was significant disparity between the tests. Three went from a decreased risk to an increased risk, while in another three the risk was decreased. Knowledge of the potential reasons for these changes in results and impact of these risk reversals on both patients and the counseling team can assist in the development of strategies for the prevention and, where necessary, management of a risk reversal in any predictive testing program.

Adult↗

Proceed with care: direct predictive testing for Huntington disease.

The cloning of the Huntington disease (HD) gene allows highly accurate predictive testing using direct analysis of the CAG repeat. This new test provides results with almost complete certainty but poses unique counseling issues related to direct testing for an adult-onset disease. These include testing individuals who are at 25% risk, without the need for blood from a 50% at risk relative; the assessment of symptomatic individuals; the need for ongoing counseling despite simplification of laboratory procedures; and counseling of persons from families who represent a new mutation for HD. This paper describes protocols for direct predictive testing for adult and prenatal assessment, on the basis of the experience of the Canadian Collaborative Study on Predictive Testing (CCSPT). Over the past 8 years, we have provided > 400 results by using linked markers and, more recently, 416 results by using direct assessment of CAG expansion in the HD gene. The vast majority (86%) of requests for direct predictive testing have been from persons who have not previously received results by using linked markers. Despite the ability to now directly assess for the mutation associated with HD, we still recommend assessment of DNA from an affected relative, as this may significantly enhance the accuracy of information to be provided to the at-risk individual. Distance from a genetics center has previously limited the availability of testing, and therefore we have developed approaches to providing predictive testing in the patient's own community.

Adult↗

Dilemmas of anonymous predictive testing for Huntington disease: privacy vs. optimal care.

Some persons at risk for Huntington disease (HD) seek predictive testing under the protection of anonymity to reduce the risk of insurance discrimination for themselves and their families. While Canadian and European health care systems seem to limit insurance discrimination to life and disability insurance, U.S. residents do not have national health insurance and are concerned about health insurance discrimination. Two persons residing outside Canada requested predictive testing anonymously. Their primary reason for doing so was to avoid the risks of medical insurance discrimination. After a detailed preparatory session and agreement to counselling and to receipt of results in person, we agreed to provide anonymous testing to these persons. One participant, whose psychological assessment was unremarkable, coped well with the predictive testing process and did not have the CAG expansion. The other participant had considerable emotional problems prior to testing, which necesitated postponement of discussion of results and referral for psychiatric assessment and support. Both participants had difficulty maintaining anonymity. The provision of anonymous predictive testing raises several problems. With anonymous testing, clinicians cooperate with participants to exclude insurance companies from information. This may invalidate the contract with insurance companies. A policy response by insurance companies or a universal health care system to protect individuals is preferable. Individuals who request anonymous testing may be precisely those most vulnerable and in need of additional support and counselling. However, the preservation of anonymity is a burden to participants and may frustrate the clinicians' ability to establish rapport in counselling and to provide appropriate follow-up typically available through genetic counselling in predictive testing programs.

Adult↗