Predictive testing for Huntington's disease with use of a linked DNA marker

Huntington's disease: nearly four decades of human molecular genetics

Huntington's disease (HD) is a devastating neurogenetic disorder whose familial nature and progressive course were first described in the 19th century but for which no disease-modifying treatment is yet available. Through the active participation of HD families, this disorder has acted as a flagship for the application of human molecular genetic strategies to identify disease genes, understand pathogenesis and identify rational targets for development of therapies.

Huntington's Disease Pathogenesis: Two Sequential Components

Historically, Huntington's disease (HD; OMIM #143100) has played an important role in the enormous advances in human genetics seen over the past four decades. This familial neurodegenerative disorder involves variable onset followed by consistent worsening of characteristic abnormal movements along with cognitive decline and psychiatric disturbances. HD was the first autosomal disease for which the genetic defect was assigned to a position on the human chromosomes using only genetic linkage analysis with common DNA polymorphisms. This discovery set off a multitude of similar studies in other diseases, while the HD gene, later renamed HTT, and its vicinity in chromosome 4p16.3 then acted as a proving ground for development of technologies to clone and sequence genes based upon their genomic location, with the growing momentum of such advances fueling the Human Genome Project. The identification of the HD gene has not yet led to an effective treatment, but continued human genetic analysis of genotype-phenotype relationships in large HD subject populations, first at the HTT locus and subsequently genome-wide, has provided insights into pathogenesis that divide the course of the disease into two sequential, mechanistically distinct components.

Perspectives on Genetic Testing and Return of Results from the First Cohort of Presymptomatically Tested Individuals At Risk of Huntington Disease

This qualitative study gathered opinions about genetic testing from people who received presymptomatic testing for Huntington's disease (HD) 20-30 years ago and have lived with the implications of that testing for decades. During the last section of a semi-structured interview, participants were asked open-ended questions about their opinions on the importance of autonomy in the decision to be tested for HD, whether a formal HD testing protocol is necessary, whether physician ordering for HD is acceptable without a formal protocol, whether online direct-to-consumer (DTC) genetic testing for HD is acceptable, and whether incidental/secondary findings should be returned in the context of whole exome/genome sequencing. Most-but not all-participants were in favor of an individual's right to decide whether and when to pursue HD testing, use of a formal HD testing protocol, and returning medically actionable secondary findings. However, the majority of participants were opposed not only to physician ordering and DTC HD testing in the absence of a formal protocol but also to returning a secondary finding of an expanded HD allele. This study presents the opinions of a unique and extremely well-informed cohort on issues that need to be taken into careful consideration by genetic counselors and other medical professionals who are developing genetic testing protocols, making decisions about the availability of genetic tests, and making decisions about whether and how to return incidental findings.

Predictive testing of minors for Huntington's disease: The UK and Netherlands experiences

A consistent feature of predictive testing guidelines for Huntington's disease (HD) is the recommendation not to undertake predictive tests on those < 18 years. Exceptions are made but the extent of, and reasons for, deviation from the guidelines are unknown. The UK Huntington's Prediction Consortium has collected data annually on predictive tests undertaken from the 23 UK genetic centers. DNA analysis for HD in the Netherlands is centralized in the Laboratory for Diagnostic Genome Analysis in Leiden. In the UK, 60 tests were performed on minors between 1994 and 2015 representing 0.63% of the total number of tests performed. In the Netherlands, 23 tests were performed on minors between 1997 and 2016. The majority of the tests were performed on those aged 16 and 17 years for both countries (23% and 57% for the UK, and 26% and 57% for the Netherlands). Data on the reasons for testing were identified for 36 UK and 22 Netherlands cases and included: close to the age of 18 years, pregnancy, currently in local authority care and likely to have less support available after 18 years, person never having the capacity to consent and other miscellaneous reasons. This study documents the extent of HD testing of minors in the UK and the Netherlands and suggests that, in general, the recommendation is being followed. We provide some empirical evidence as to reasons why clinicians have departed from the recommendation. We do not advise changing the recommendation but suggest that testing of minors continues to be monitored.

Factors related to genetic testing in adults at risk for Huntington disease: the prospective Huntington at-risk observational study (PHAROS)

Huntington disease (HD) is a late onset ultimately fatal neurodegenerative disorder caused by a cytosine-adenine-guanine ( CAG) triplet repeat expansion in the Huntingtin gene which was discovered in 1993. The PHAROS study is a unique observational study of 1001 individuals at risk for HD who had not been previously tested for HD and who had no plans to do so. In this cohort, 104 (10%) individuals changed their minds and chose to be tested during the course of the study but outside of the study protocol. Baseline behavioral scores, especially apathy, were more strongly associated with later genetic testing than motor and chorea scores, particularly among subjects with expanded CAG repeat length. In the CAG expanded group, those choosing to be tested were older and had more chorea and higher scores on the behavioral section of the unified Huntington's disease rating scale at baseline than those not choosing to be tested. Following genetic testing, 56% of subjects with CAG < 37 had less depression when compared to prior to testing, but depression generally stayed the same or increased for 64% of subjects in the expanded group. This finding suggests that approaches to testing must continue to be cautious, with appropriate medical, psychological and social support.

Genetic counseling and testing for Huntington's disease: A historical review

This manuscript describes the ways in which genetic counseling has evolved since John Pearson and Sheldon Reed first promoted "a genetic education" in the 1950s as a voluntary, non-directive clinical tool for permitting individual decision making. It reviews how the emergence of Huntington's disease (HD) registries and patient support organizations, genetic testing, and the discovery of a disease-causing CAG repeat expansion changed the contours of genetic counseling for families with HD. It also reviews the guidelines, outcomes, ethical and laboratory challenges, and uptake of predictive, prenatal, and preimplantation testing, and it casts a vision for how clinicians can better make use of genetic counseling to reach a broader pool of families that may be affected by HD and to ensure that genetic counseling is associated with the best levels of care. © 2016 Wiley Periodicals, Inc.

22 Years of predictive testing for Huntington's disease: the experience of the UK Huntington's Prediction Consortium

Huntington's disease (HD) is a progressive neurodegenerative condition. At-risk individuals have accessed predictive testing via direct mutation testing since 1993. The UK Huntington's Prediction Consortium has collected anonymised data on UK predictive tests, annually, from 1993 to 2014: 9407 predictive tests were performed across 23 UK centres. Where gender was recorded, 4077 participants were male (44.3%) and 5122 were female (55.7%). The median age of participants was 37 years. The most common reason for predictive testing was to reduce uncertainty (70.5%). Of the 8441 predictive tests on individuals at 50% prior risk, 4629 (54.8%) were reported as mutation negative and 3790 (44.9%) were mutation positive, with 22 (0.3%) in the database being uninterpretable. Using a prevalence figure of 12.3 × 10(-5), the cumulative uptake of predictive testing in the 50% at-risk UK population from 1994 to 2014 was estimated at 17.4% (95% CI: 16.9-18.0%). We present the largest study conducted on predictive testing in HD. Our findings indicate that the vast majority of individuals at risk of HD (>80%) have not undergone predictive testing. Future therapies in HD will likely target presymptomatic individuals; therefore, identifying the at-risk population whose gene status is unknown is of significant public health value.

Generation after generation: exploring the psychological impact of providing genetic services through a cascading approach

PURPOSE

The provision of genetic services often occurs in a cascading fashion within families experiencing inherited diseases. This study examines whether previous family experiences with genetic services influences levels of psychological well-being of family members receiving services later.

METHODS

Two hundred ninety-seven persons from 38 families with Lynch syndrome completed questionnaires before receiving genetic services. Baseline levels of test-related distress, depressive symptoms, and cancer worries were assessed in relationship to the (1) amount of time elapsed since services were provided to the index case and (2) generation of the family member relative to the index case.

RESULTS

Family members in the same generation as the index case experienced significant increases in test-related distress (P = 0.003) and cancer worry (P = 0.001) with increasing time between receipt of genetic test results by the index case and provision of services to family members. Change in the number of depressive symptoms was not significant (P = 0.17).

CONCLUSION

The provision of genetic services through a cascading approach significantly increases distress and worry among family members within the same generation as the index case who receive services at increasingly distant time intervals. Additional research is needed to explore social influences after the introduction of genetic services.

Presymptomatic diagnosis in Huntington's disease: the Mexican experience

Huntington's disease (HD) is an autosomal dominant progressive, disabling neurodegenerative disorder, for which there is no effective treatment. Predictive testing (PT) for this illness began in 1986 and by 1993 it became more precise after cloning of the gene and the discovery of a CAG repeat expansion as the underlying cause. The objective of this paper is to illustrate the implementation and results of a PT program in a group of at-risk Mexican individuals with 12 years of follow-up. Our PT program conforms to the guidelines proposed by the International Huntington Association and the HD Working group of the World Federation of Neurology. Seventy-five individuals requested the testing, four of them did not fulfill the inclusion criteria, and five abandoned the program voluntarily before receiving the test results. Therefore, 66 results were delivered to 41 noncarriers and 25 mutation carriers. We did not have any catastrophic event, but 4 individuals with normal results and 11 mutation carriers were depressed. Even if this is a small sample, it is the first report of PT in a Latin-American population in which we have been faced with the same problems referred to in larger series.

Risk reduction and health promotion behaviors following genetic testing for adult-onset disorders

Although clinical genetic testing is available for over 1,000 inherited disorders, consequences of predictive genetic testing have been most extensively examined for hereditary breast and ovarian cancer (HBOC), hereditary colon cancer, and Huntington disease (HD). These focus primarily on psychological, ethical, legal, and social aspects of genetic testing. Genetic testing may also provide information that can lead to behaviors that promote health and reduce risk for disease, reflecting options available for the disorder for which the person is at risk. However, regardless of condition, people completing a genetic test may inform relatives about the results of the test and implications for their risk to develop the condition. Literature on risk reduction behaviors and communication focuses on families with HBOC or colorectal cancer. Few reports document behaviors for other conditions. This paper presents a systematic review of the research literature on risk reduction and health promotion behaviors following clinical genetic testing for adult onset conditions, primarily HBOC, familial colon cancers, and HD. Insights gleaned from this review are discussed as a basis for planning monitoring of health promotion and risk-reduction behaviors for genetic testing for present and future use.

Genetic criteria for Huntington's disease pathogenesis

Genetic analysis aims to identify the variations in DNA sequence whose functional consequences produce heritable variations in phenotype. In one of the first successes of unbiased molecular genetic analysis in human disease, the Huntington's disease (HD) gene was mapped and cloned without any prior knowledge of the nature of its protein product or of the molecular defect that underlies the characteristic phenotype of the disorder. However, while the cloning of HD and recognition of its trinucleotide repeat expansion spawned a plethora of approaches to investigating HD through its distinctive neuropathology, the role for genetic strategies in HD research did not end there. The use of genetic analysis has remained a critical tool for defining the characteristics of the mechanism that triggers the pathogenic process, permitting the investigation of early events that occur long before traditionally recognized pathology. Delineation of these events can reveal molecular targets for development of therapies that prevent onset of HD. Most recently, an extension of genetic analysis to the identification of non-linked genetic variations that alter the course of HD pathogenesis has offered the promise of identifying modifier genes to reveal biological pathways active throughout the disease process and to provide valid targets for pharmacological intervention. Thus, unbiased genetic strategies have not only provided a crucial entrée into molecular investigation of HD via a root cause that was previously unsuspected, they also represent a continuing route to accelerate the ultimate goal of developing an effective treatment for HD.

To know or not to know: a review of behaviour and suicidal ideation in preclinical Huntington's disease

OBJECTIVE

At present, the problems associated with suicidal ideation and suicide in Huntington's disease (HD), worldwide, are much the same as 2 decades ago. This study seeks to investigate the psychological complications of predictive testing in HD at risk populations.

METHODS

The key problems of predictive testing, fear of acquiring carrier status, psychological consequences, autonomy, and rights to know are discussed.

RESULTS

This review (1) describes psychological affect and problems of persons facing the decision to test for HD, (2) discusses suicidal ideation, behaviour, and catastrophic events associated with predictive testing, (3) assesses ethical questions raised in the genetic counselling, (4) questions whether counsellors should promote or advocate predictive testing, and finally (5) discusses what professionalism actually is in genetic counselling.

CONCLUSION

The need for professional counselling, using a well designed protocol, and the importance of focusing on the suicide risk of participants in predictive testing programs are emphasized.

PRACTICE IMPLICATIONS

The counsellor has an obligation to provide adequate information. The professionals should not promote nor advocate presymptomatic DNA-testing. Depression, hopelessness, anxiety, emotional distress, suicidal tendencies, and social dysfunction grading should be considered in predictive testing of HD.

The perceived advantages and disadvantages of presymptomatic testing for Machado-Joseph disease: development of a new self-response inventory

This study describes the construction of a self-response inventory to evaluate the perception of advantages and disadvantages of the Machado-Joseph disease presymptomatic testing, in 44 individuals at-risk for this disease. The results showed that the reliability of this inventory was satisfactory. Factor analysis revealed a bidimensional structure: perceived advantages (pros) and perceived disadvantages (cons) of presymptomatic testing. Social desirability was found unrelated to the total scores of our inventory. Additional correlation studies, with other scales, confirmed the convergent validity of the instrument. These results suggest adequate construct validity. This inventory thus seems to be a proper instrument to assess expectations involved in the decision-making process of Machado-Joseph disease presymptomatic testing.

BRCA1/2 testing in hereditary breast and ovarian cancer families II: Impact on relationships

Members of hereditary breast and ovarian cancer (HBOC) families often express concern during genetic counseling about the impact of BRCA1/2 testing on close relatives. Yet whether there are likely to be adverse effects of either the decision to undergo genetic testing or the results of testing on family relationships is unknown. One purpose of this study was to assess the impact on close family relationships. Within a randomized trial of breast cancer genetic counseling methods, members of 13 HBOC families were offered BRCA1/2 testing for a known family mutation. The Family Relationship Index (FRI) of the Family Environment Scale (FES) was used to measure perceived family cohesion, conflict, and expressiveness at baseline and again 6-9 months following the receipt of test results, or at the equivalent time for those who declined testing. Participants (n = 212) completed baseline and follow-up questionnaires. Comparisons were made between testers and non-testers as well as between those who tested positive and negative for the family mutation. One hundred eighty-one participants elected to undergo genetic testing (85%) and 47 (26%) were identified to have a mutation. After adjusting for baseline family relationship scores, counseling intervention, gender and marital status, non-testers reported a greater increase in expressiveness (P = 0.006) and cohesion (P = 0.04) than testers. Individuals who tested positive reported a decrease in expressiveness (P = 0.07), although as a trend. Regardless of test decision or test result, those who were randomized to a client-centered counseling intervention reported a decrease in conflict (P = 0.006). Overall, study results suggest that undergoing genetic testing and learning ones BRCA1/2 status may affect family relationships. Those individuals who declined testing reported feeling closer to family members and more encouraged to express emotions to other family members demonstrating potential benefit from the offer of testing. Since those who tested positive reported feeling less encouraged to express their emotions within the family, we recommend helping clients to identify others with whom they feel comfortable sharing their thoughts and feelings about their positive gene status and increased cancer risk.

Psychologic distress after disclosure of genetic test results regarding hereditary nonpolyposis colorectal carcinoma

BACKGROUND

To the authors' knowledge, there have been few studies of the psychologic distress after disclosure of genetic test results for hereditary nonpolyposis colorectal carcinoma (HNPCC). The objectives of this study were to identify the prevalence rates and predictors of psychologic distress and to evaluate the feelings of guilt after disclosure of the test results in Japanese probands and unaffected relatives.

METHODS

Probands and unaffected relatives were interviewed immediately after the first genetic counseling session for HNPCC and again 1 month after disclosure of the genetic test results. The prevalence of major and minor depression, acute stress disorder (ASD), posttraumatic stress disorder (PTSD), and posttraumatic stress symptoms (PTSS) were assessed using the Structured Clinical Interview based on the Diagnostic and Statistical Manual of Mental Disorders, 3rd edition revised (DSM-III-R) or the DSM-IV; feelings of guilt were investigated using a numeric scale and a semistructured interview.

RESULTS

Among 47 participants who completed the baseline interview, 42 participants (89%) completed the 1-month follow-up interview. Although none of the participants met the criteria for major depression, ASD, or PTSD at the follow-up interview, 3 of 42 participants (7%) met the criteria for minor depression and 2 participants (5%) had PTSS. The only predictor of psychologic distress found was the presence of a history of major or minor depression (odds ratio, 19.41; 95% confidence interval, 1.42-264.95; P < 0.05). Five of 42 participants (12%) had feelings of guilt.

CONCLUSIONS

Disclosure of genetic test results for HNPCC may not cause significant psychologic distress in Japanese probands or relatives. However, healthcare providers should not neglect to assess these individuals for psychologic responses, such as minor depression and PTSS.

Prevalence of Major Depression One Year after Predictive Testing for Huntington's Disease

Psychiatric hospitalizations, completed suicides, and suicide attempts are rare after predictive testing for Huntington's disease (HD). Case studies have shown that major depression can be a consequence of being tested, although no studies have shown how common this is. The present study evaluated the prevalence of major depression during the first year after disclosure. We conducted retrospective data and chart reviews of 153 persons (50 testing positive, 103 testing negative) evaluated every 3 months for depression. There was no significant baseline difference in the percentage of "positives" and "negatives" who had pre-testing major depressive episodes (14% vs. 12%, respectively). A senior psychiatrist reviewed data from the Schedule for Affective Disorders and Schizophrenia-Change Version, from the Beck Depression Inventory, and from clinical notes for every follow-up contact completed. The 1-year prevalence of major depression among positives was 6.0%, compared to 3.0% among negatives (p = 0.30), and an estimated 3% population prevalence. One-year prevalence of clinically significant depressive symptoms, whether or not major depression was diagnosed, was 20.0% in positives and 12.6% in negatives (p = 0.17). Although not statistically significant, depressive symptoms and major depression occurred more frequently among those who tested positive. Despite some evidence to the contrary, including our own studies, a positive predictive test for HD is not psychologically benign. Clinical testing programs should assess patients for depressive symptoms after testing, and patients with clinically significant complaints should be referred to a mental health professional.

Psychological consequences and predictors of adverse events in the first 5 years after predictive testing for Huntington's disease

The promise of genetic medicine is to provide information, based on genotype, to persons not yet sick about their risk of future illness. However, little is known of the long-term psychological effects for asymptomatic persons learning their risk of having a serious disease. Predictive genetic testing for Huntington's disease (HD) has been offered for the longest time for any disease. In the present study, the psychological consequences of predictive testing were assessed prospectively in individuals at risk for HD during seven visits over 5 years. Questionnaires of standard measures of psychological distress (the General Severity Index of the Symptom Check List-90-Revised), depression (the Beck Depression Inventory), and general well-being (the General Well-Being Scale) were administered to the participants. A significant reduction in psychological distress was observed for both result groups throughout 2 years (p < 0.001) and at 5 years (p = 0.002). Despite the overall improvement of the psychological well-being, 6.9% (14 of 202) of the participants experienced an adverse event during the first 2 years after predictive testing that was clinically significant. The frequency of all defined adverse events in the participants was 21.8%, with higher frequency in the increased risk group (p = 0.03) and most occurring within 12 months of receiving results.

Predictive, pre-natal and diagnostic genetic testing for Huntington's disease: the experience in Canada from 1987 to 2000

Predictive and pre-natal testing for Huntington's Disease (HD) has been available since 1987. Initially this was offered by linkage analysis, which was surpassed by the advent of the direct mutation test for HD in 1993. Direct mutation analysis provided an accurate test that not only enhanced predictive and pre-natal testing, but also permitted the diagnostic testing of symptomatic individuals. The objective of this study was to investigate the uptake, utilization, and outcome of predictive, pre-natal and diagnostic testing in Canada from 1987 to April 1, 2000. A retrospective design was used; all Canadian medical genetics centres and their affiliated laboratories offering genetic testing for HD were invited to participate. A total of 15 of 22 centres (68.2%), currently offering or ever having offered genetic testing for HD, responded, providing data on test results, demographics, and clinical history. A total of 1061 predictive tests, 15 pre-natal tests, and 626 diagnostic tests were performed. The uptake for predictive testing was approximately 18% of the estimated at-risk Canadian population, ranging from 12.5% in the Maritimes to 20.7% in British Columbia. There appears to have been a decline in the rate of testing in recent years. Of the predictive tests, 45.0% of individuals were found to have an increased risk, and a preponderance of females (60.2%) sought testing. A greater proportion of those at < or = 25% risk sought predictive testing once direct CAG mutation analysis had become available (10.9% after mutation analysis vs 4.7% before mutation analysis, p = 0.0077). Very few pre-natal tests were requested. Of the 15 pre-natal tests, 12 had an increased risk, resulting in termination of pregnancy in all but one. Diagnostic testing identified 68.5% of individuals to be positive by mutation analysis, while 31.5% of those with HD-like symptoms were not found to have the HD mutation. The positive diagnostic tests included 24.5% of individuals with no known prior family history of HD.

Adverse selection and categorical discrimination in the health insurance markets: the effects of genetic tests

In this paper, the effects of new methods for risk classification, e.g., genetic tests, on health insurance markets are studied using an insurance model with state contingent utility functions. The analysis focuses on the case of treatment costs higher than the patient's willingness to pay where standard models of asymmetric information are not applicable. In this case, the benefit from signing a fair insurance contract will be positive only if illness probability is low. In contrast to the common perception, additional risk classification under symmetric information can be efficiency enhancing. Under asymmetric information about illness risks, however, there can be complete market failure.

The psychological impact of genetic testing for Alzheimer disease

Information regarding one's genetic risk for a particular disease might effectively inform medical, financial, and reproductive decisions and perhaps promote established risk reduction behaviors. However, genetic testing may also lead to significant levels of anxiety, depression, or other forms of distress, especially when psychological coping strategies and social reserves are not adequate to manage positive or inconclusive results. This paper focuses on the psychological impact of predisposition genetic for Alzheimer disease (AD). We present stress and coping models that capture the essence of this impact and discuss the potential role of counseling and follow-up interventions. The discussion draws primarily from the experiences of professionals working with other diseases, and seeks to expand that experience into the AD arena. In addition, we emphasize two issues we believe need additional attention in the psychological literature regarding genetic testing and counseling: (i) the psychosocial vulnerability of individuals being tested and, (ii) the sociocultural context of the AD patient and their family members.

The future of genetic counselling: an international perspective

The focus of clinical genetics, and thus genetic counselling, is forecast to expand from the diagnosis and prediction of rare, often untreatable conditions, to the prediction of common, often treatable or preventable conditions. Whether this evolution is likely to proceed rapidly or at a pace that permits sensible integration of molecular genetic tools is unknown and a source of debate. It is clear, however, that genetic discoveries will modify the way in which disease and risk are conceptualized. Here, we predict how genetic counselling, specifically for more common diseases, might be provided in the decades to come. We envisage an expansion of professional roles and expertise for many health care providers and highlight the need for counselling practices to become more evidence based. Although we support an evidentiary-based approach to the integration of genetic testing into practice, genetic advance is unlikely to occur in an orderly and standardized manner within countries, much less among different countries and health care systems. Geneticists will become increasingly involved in professional education and policy-making regarding genetic testing and screening programs.

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.

Course of distress experienced by persons at risk for an autosomal dominant inheritable disorder participating in a predictive testing program: an explorative study. Rotterdam/Leiden Genetics Workgroup

OBJECTIVE

To compare the effects of predictive DNA testing on participants at risk for either Huntington disease (HD), or familial adenomatous polyposis (FAP), or hereditary breast and ovarian cancer (HBOC).

METHOD

Psychological distress was measured with the Impact of Event Scale before testing and at 1 week and 6 months after the test result, in individuals at 50% risk for either HD (N = 25), FAP (N = 23), or HBOC (N = 10).

RESULTS

A marginally significant trend was found indicating that carriers of the disease genes tended to show unchanged levels of distress during the study period whereas noncarriers showed the expected decrease. Men reported significantly less distress than women, and 1 week after the test result male noncarriers showed a sharp significant increase in the reported distress followed by a steady decline up to 6 months later.

CONCLUSIONS

The course of distress over time reported by carriers and noncarriers of the three disease genes was similar, which leads one to conclude that the previous experience with predictive testing for Huntington Disease may be a useful paradigm. However, those formerly at risk for HD reported more distress than those at risk for FAP and HBOC. From our clinical experience we learned that individuals at risk for FAP and HBOC are more inclined to ward off the emotions involved. Additional qualitative studies should be undertaken to investigate this.

Reconsidering genetic antidiscrimination legislation

In response to the awareness that genetic discrimination is a significant problem, many states have passed or are passing legislation regulating the use of genetic information. Authors discuss the weaknesses as well as the strengths of such legislation, and recommend that the laws be redrafted to prohibit discrimination on the basis of any type of predictive medical information.

Psychological aspects of genetic counselling: a review of the experience with Huntington's disease

Presymptomatic DNA-testing for adult-onset diseases has serious psychological consequences. Here the psychological consequences of presymptomatic DNA-testing for Huntington's disease are reviewed. Both carriers and non-carriers experience emotional reactions after disclosure of their test result. However, up to today no long-term adverse emotional consequences have been revealed. Future research on other adult-onset genetic diseases should provide information about the reactions of children. In genetic counselling, attention should be paid to the reactions of people with a decreased risk. Genetic counselling must focus on the whole family and not on the individual applicant.

Psychological opportunities and hazards in predictive genetic testing for cancer risk

Although the availability of genetic tests seems like an unequivocally favorable turn of events, they are, in fact, not without controversy. At the center of the controversy is a question regarding the risks and benefits of genetic testing. Many geneticists, ethicists, psychologists, and persons at risk for cancer are concerned about the potentially adverse psychological effects of genetic testing on tested persons and their families. In addition, the screening and interventions that are useful in the general population remain to be shown effective in those with high genetic cancer risk. Consequently, there have been calls for caution in moving genetic testing out of research laboratories and into commercial laboratories until their impact and the effectiveness of cancer prevention strategies can be studied. This article examines the arguments and data for and against this caution, citing examples related to hereditary nonpolyposis colon cancer and drawing upon literature on testing for other genetic diseases.

Issues in genetic testing for susceptibility to alcoholism: lessons from Alzheimer's disease and Huntington's disease

Evidence from family, twin, and adoption studies suggest a heritable basis for alcoholism. However, alcoholism is likely to be genetically heterogeneous, and any genetic connection is likely to be in the form of genes conferring an increased risk or susceptibility. In this study, we present the evidence for a genetic component for alcoholism, and examine the precedent for genetic testing and screening for genetic susceptibility using Huntington's disease and Alzheimer's disease as examples. Finally, we discuss the preparations that need to be made before taking any findings about the genetics of alcoholism from the research laboratory into the clinic.

Emotional and functional impact of DNA testing on patients with symptoms of Huntington's disease

The potential impact of DNA testing on asymptomatic subjects at risk for Huntington's disease (HD) has been addressed by numerous studies, but the effect of revealing the genetic results to patients with a clinically established diagnosis of HD has not been previously evaluated. We studied 36 patients, with equal distribution of men and women, mean age 53.9 (SD 12.3) years (range 25-76) and mean duration of symptoms of 11.2 (SD 7.7) years (range 2-33), whose clinical diagnosis of HD was confirmed by expanded CAG repeats (> 40). Coping strategies and depression levels were assessed before the results of DNA testing were imparted. The assessments were repeated two weeks and three months after the results were explained to the patients and their relatives and were compared to the baseline assessments. This group of HD patients was compared with 10 patients who had similar symptoms but the diagnosis of HD was excluded by normal CAG repeats (< 30). Although some patients with HD expressed a subjective reaction to the positive result (four were "surprised", one was "frustrated", and one "devastated"), there were no differences in any psychological scores including Beck Depression Inventory, functional capacity, symptom interference, independence scale, and other measures of mood and behaviour two weeks and three months later. Similarly, no change was noted in any of these measures in the non-HD group. These results suggest that mood and coping strategies are unaffected by DNA confirmation of diagnosis in symptomatic patients with HD.

Exploration of the effects of predictive testing for Huntington disease on intimate relationships

The focus in predictive testing for Huntington disease is beginning to shift from individuals at risk to an examination of the effects on other relatives, particularly on spouses and partners. We examine the effects of participating in a predictive testing program for 25 couples. When assessed prior to testing, spouses were significantly more depressed than their at-risk partners. After pretest counseling, 6 (24%) of the couples chose not to pursue testing. At baseline, these 6 couples had significantly higher levels of psychological distress and marital dysfunction than couples who did choose to complete testing. Of the 19 couples completing testing, 5 received an increased risk result and 14 received a decreased risk result. Prior to testing, the partners of individuals who later received an increased risk result exhibited higher levels of marital distress. At 3- and 6-month follow-ups, high-risk couples were significantly more distressed than low-risk couples. These levels of distress improved somewhat at 9 months after testing, but began to climb again at 12 months. Individuals at increased risk were significantly more distressed at all points during follow-up as compared to individuals at low risk. No significant differences were found between the partners of high- and low-risk individuals at 3, 6, 9, and 12 months after disclosure.(ABSTRACT TRUNCATED AT 250 WORDS)

Demand for predictive genetic testing for Huntington's disease in Australia, 1987 to 1993

OBJECTIVE

To assess the demand for genetic testing for Huntington's disease among at-risk individuals and for prenatal testing among parents at risk of transmitting the disease, from January 1987 to March 1993.

METHODS

Questionnaires were sent to all State coordinators of genetic testing services.

RESULTS

One hundred and ninety adults (5.5% of those at risk) and 56 fetuses were tested. Nine per cent more women than men used the service. Most people tested were married and had offspring. Men generally presented for testing at an older age than women.

CONCLUSION

The low uptake for testing is not surprising given the severity and untreatability of the illness. Careful monitoring is required, particularly of the effects on individuals told of their genetic status and of possible abuse of the information by third parties.

Psychological costs and benefits of predictive testing for Huntington's disease

The impact of predictive genetic testing for Huntington's disease (HD) was assessed in 68 persons at high (n = 17) or low risk (n = 51) for the disease at one to six years following disclosure of test results. There was consensus in both groups that knowledge of HD genetic status was beneficial. A majority of persons felt relief from wondering and uncertainty. High-risk persons identified greater family closeness and financial security. For low-risk persons, the knowledge that their children were spared offered great consolation. Negative effects in high-risk persons were psychological burden (worry, guilt). Even for low-risk subjects, there was a period of adjustment and, in some, disappointment that low risk had not alleviated problems unrelated to HD. Although the majority of marriages were unaffected by testing, some persons in both groups reported that their marriages sustained positive or negative impact. Despite mixed consequences, most did not regret being tested. The benefits of testing appear to outweigh its drawbacks, at least among this self-selected group of research participants. We also must conclude, however, that predictive genetic testing will result in negative as well as positive consequences, regardless of test outcome.

Self-selection in predictive testing for Huntington's disease

Several studies have reported favorable psychological reactions to predictive testing for Huntington's disease (HD). However, few at-risk persons have been tested, and there is evidence that some at-risk people avoid testing because they fear being unable to cope with the information. Favorable psychological reactions may result from self-selection of persons who believe they are better-equipped to handle "bad news." We surveyed 32 at-risk persons who had considered, but not chosen, testing and 66 persons who had been previously tested. Twelve persons decided not to be tested (No group); 20 persons postponed testing until some later date (Maybe group). Of the two untested groups, a significantly greater number of the No group had not been tested because they anticipated problems associated with their emotional reactions. The persons in the Tested group had less often anticipated problems with their emotional reactions; and among the minority who had anticipated some problems, most did not question their ability to cope. We conclude that the Tested persons are psychologically selected for favorable responses to genetic testing. Surveys of health professionals suggest that a sizable minority would disclose genetic disease risk whether or not people want it. Thus, people who would not choose to be tested might be persuaded to do so, or have results thrust upon them. We should be wary about assuming that the generally favorable reactions to HD testing will continue when testing becomes more widespread, as is likely to happen with simplification of the technology and acceptance of these tests by the medical community.

Predictive testing for Huntington disease: social characteristics and knowledge of applicants, attitudes to the test procedure and decisions made after testing

An investigation has been made of the social characteristics and knowledge and experience of Huntington disease (HD) for the first 80 individuals considering presymptomatic testing (applicants) at the medical genetics centres in Edinburgh and Glasgow and of attitudes to the test procedure and decisions made after testing for those who received a result. Sixty-one percent of applicants were female and 31% were over 40 years old. Almost all had a symptomatic parent but 38% did not know HD was in their family until they were over 25 years old and 48% had never received genetic counselling. Thirty-eight percent of applicants first heard of the test at the genetic clinic, 20% from a relative and 20% from the media, but none had received information from their GP. Thirty-one applicants did not have the test because they voluntarily withdrew (17 individuals), their family structure was unsuitable or no informative result was possible (11 individuals), or they were diagnosed clinically as being affected (3 individuals). Those who voluntarily withdrew did not differ significantly from the 49 who received a result in social characteristics or knowledge and experience of HD. Twenty-two individuals were found to be at increased risk (IR) (> 50% of becoming affected) and 27 to be at decreased risk (DR) (< 50% of becoming affected). There was a median period of 9 months between entering the test procedure and receiving a result and the main criticism of the procedure was that it took too long to complete and several individuals experienced considerable anxiety while awaiting their result.(ABSTRACT TRUNCATED AT 250 WORDS)

Ethical and social issues in presymptomatic testing for Huntington's disease: a European Community collaborative study. European Community Huntington's Disease Collaborative Study Group

An analysis of social and ethical aspects of presymptomatic testing for Huntington's disease has been carried out, based on data on linked DNA markers, from four major testing centres in different European Community countries (Belgium, Italy, Netherlands, and United Kingdom). Information was available on 603 applicants, with 213 final results given, of which 32% gave an increased risk. A series of specific issues and problems were documented systematically for all applicants, results being given on frequency of occurrence and illustrated by individual case histories. The principal issues could be grouped as problems of inappropriate referral, problems involving relatives, and problems relating to disclosure of results. At least one important problem was encountered in 46% of applicants, emphasising the importance of expert counselling, preparation, and support of applicants, and of close liaison between clinical, counselling, and laboratory staff. The extensive and detailed information available for Huntington's disease from this and other studies will be of considerable value in relation to genetic testing for other late onset genetic disorders and will be even more relevant to Huntington's disease now that specific mutation analysis is possible for this disorder.

Molecular genetics in neurology

There has been remarkable progress in the identification of mutations in genes that cause inherited neurological disorders. Abnormalities in the genes for Huntington disease, neurofibromatosis types 1 and 2, one form of familial amyotrophic lateral sclerosis, fragile X syndrome, myotonic dystrophy, Kennedy syndrome, Menkes disease, and several forms of retinitis pigmentosa have been elucidated. Rare disorders of neuronal migration such as Kallmann syndrome, Miller-Dieker syndrome, and Norrie disease have been shown to be due to specific gene defects. Several muscle disorders characterized by abnormal membrane excitability have been defined as mutations of the muscle sodium or chloride channels. These advances provide opportunity for accurate molecular diagnosis of at-risk individuals and are the harbinger of new approaches to therapy of these diseases.

Presymptomatic testing for Huntington's disease: a world wide survey. The World Federation of Neurology Research Group on Huntington's Disease

World wide data on presymptomatic testing for Huntington's disease using closely linked DNA markers show that 1479 persons at risk received completed test results up to the end of 1991. Testing has been carried out in 19 countries, with at least 88 centres involved, and numbers have levelled off after a peak in 1990. Only 5% of those at risk have been tested in six countries with the longest established programmes. Continued monitoring of international data will be of value in assessing the spread and impact of genetic testing, not only for Huntington's disease, but for other serious genetic disorders of later life.

Trinucleotide repeat length instability and age of onset in Huntington's disease

The initial observation of an expanded and unstable trinucleotide repeat in the Huntington's disease gene has now been confirmed and extended in 150 independent Huntington's disease families. HD chromosomes contained 37-86 repeat units, whereas normal chromosomes displayed 11-34 repeats. The HD repeat length was inversely correlated with the age of onset of the disorder. The HD repeat was unstable in more than 80% of meiotic transmissions showing both increases and decreases in size with the largest increases occurring in paternal transmissions. The targeting of spermatogenesis as a particular source of repeat instability is reflected in the repeat distribution of HD sperm DNA. The analysis of the length and instability of individual repeats in members of these families has profound implications for presymptomatic diagnosis.

On attitudes and appreciation 6 months after predictive DNA testing for Huntington disease in the Dutch program

We have studied the 6-month follow-up attitudes of 63 individuals, after predictive testing for Huntington disease (HD). Reducing uncertainty (81%) and family planning (60%) were the major reasons for taking the test. Twenty-four individuals were diagnosed as having an increased risk (+/- 98%), and 39 a decreased risk (+/- 2%). Among those with an increased risk, denial or minimization of the ultimate impact of the increased risk result was observed. Most of them (84%) rated their current life situation, at the very least, as being good. Twenty-one percent of individuals with an increased risk who originally planned to have a family, decided to refrain from having children. Sixty percent of those with increased risk who still wished to have children, would choose to have prenatal testing. In most individuals with increased risk, the test result did not increase the previously expected control over their own future. Half of the partners of persons with increased risk acknowledged the burden of the future disease. Half had no one in whom they could confide. They showed loyalty to the denial and avoidance reactions of their spouses. Half of the individuals with decreased risk denied the impact of the result, as reflected by absence of relief, and emotional numbness. A third of persons with decreased risk experienced involvement with problems of affected relatives. We found that 20% of all participants were discontented with the support given by their general practitioner, who is normally regarded as being the most significant professional for aftercare. Our findings suggest that the perpetuation

Presymptomatic DNA-testing for Huntington disease: pretest attitudes and expectations of applicants and their partners in the Dutch program

We studied the baseline attitudes, prior to testing, of 70 applicants at risk for Huntington disease (HD) and their partners in the Dutch presymptomatic DNA-testing program. Two thirds of the applicants were female; 36% already had children. The main reason (60%) for undertaking the test was for family planning. Other reasons were either to reduce uncertainty (43%) or to obtain certainty (38%). Partners of applicants stated that planning for the future was for them the most important reason (76%). Significantly more at-risk females (42%) than males (16%) anticipated an unfavorable test outcome. Quite remarkably, most applicants and partners denied that a positive result might have adverse effects on either personal mood, quality of life, or marriage. Only a few did not expect that a favorable result would induce relief. The eventual outcome of the test was expected to enable applicants to gain control over their future, whatever the results. Hence, we propose that the applicants form a self-selected group, based on their expectation that they will not be emotionally affected by either result.