Predictive gene testing for Huntington disease and other neurodegenerative disorders

Genetic risk for Huntington Disease and reproductive decision-making: A systematic review

Huntington Disease (HD) is an incurable autosomal dominant single gene neurodegenerative disorder. Typical onset is between 30 and 40 years and characterised by motor difficulties, cognitive impairment, and behavioural and personality changes. The availability of reproductive testing means that affected and at-risk individuals can make reproductive decisions with genetic risk in mind. We aimed to summarise the literature on reproductive decision-making in the context of HD risk in terms of outcomes and the subjective experiences of at-risk individuals. Five databases were searched. Findings were synthesised using Framework analysis to identify common factors across results of quantitative and qualitative studies. Twenty five studies met inclusion criteria. Framework analysis identified the following key areas: 'The relationship between reproductive intentions and HD genetic risk', 'Views on assistive options', 'Complexity and challenges in reproductive decision-making', 'Actual reproductive outcomes', and 'Other factors influencing reproductive decision-making'. Quality of included studies was mixed. Reproductive decision making in the context of HD risk was found to be a complex and emotionally challenging process. Further research is required into reproductive decision-making and outcomes among those not utilising assistive options, and in developing a model of reproductive decision-making in HD.

Initial psychometric analysis of novel instruments to assess decisional distress and decisional uncertainty in women who have considered using preimplantation genetic testing

OBJECTIVE

To analyze psychometric properties of two novel instruments assessing decisional distress and uncertainty experienced by individuals considering preimplantation genetic testing (PGT).

METHODS

The new PGT Decisional Distress instrument (22 items) assesses negative/positive emotions. The new PGT Decisional Uncertainty instrument assesses Clarity about test benefits/disadvantages (5 items) and Certainty of having adequate information/support to make a good decision (7 items). Scales ranged from 0 to 4. Psychometrics (central tendencies, internal consistency reliability, and discriminant validity) were evaluated. Stratified analysis by decision stage was conducted. All participants had considered or used PGT in the previous 6 months.

RESULTS

N = 106 females (mean age 36.5 ± 4.8 years; 16% non-Caucasian; 9% Hispanic) across 16 US states completed an online anonymous questionnaire. On average, respondents reported minimal distress (mean 0.96), high clarity (mean 3.26), and high certainty (mean 3.06), particularly those who had already decided compared to undecided women (P ≤ .02). Instruments had excellent internal consistency (Cronbach's α's 0.92-0.94) and displayed sufficient inter-individual variability (SD's 0.75-0.89). Correlations confirmed expected patterns of association between instruments (P's < .01), indicating discriminant validity.

CONCLUSION

We document initial reliability and validity of new instruments to measure emotional distress and uncertainty in female patients who have recently considered PGT for single-gene or chromosomal disorders.

Public Willingness to Undergo Presymptomatic Genetic Testing for Alzheimer's Disease

Presymptomatic genetic testing (PGT) for Alzheimer's disease (AD) is available for at-risk individuals. This study aimed to investigate the public perception of PGT in Saudi Arabia and determine variables that might influence the decision to undergo PGT. A questionnaire link was posted on Twitter by the Saudi Alzheimer's Disease Association and was made publicly available on social media networks. A total of 2935 people participated, of which 59.9% were willing to undergo PGT. Of these, 26.8% reported having a family history of AD, and 0.24% had two family members with early onset AD. The reasons cited for willingness to undergo PGT included the following: to adopt a healthier lifestyle, to ensure appropriate family and financial planning, to seek early treatment, and to relieve anxiety. In multiple logistic regression analysis, willingness to undergo PGT was negatively associated with having a self-reported family history of dementia (OR 0.81, 95% CI 0.68-0.96) and was positively associated with marital status (OR 1.39, 95% CI 1.13-1.70). In conclusion, PGT for AD seems to be well accepted in this large Saudi cohort. The reasons cited are similar to those reported elsewhere in the literature.

A case-note review of continued pregnancies found to be at a high risk of Huntington's disease: considerations for clinical practice

Huntington's disease (HD) is a severe neurodegenerative condition that impacts the whole family. Prenatal diagnosis by direct or exclusion testing is available for couples at risk of transmitting HD to their children. An ethical problem can arise after prenatal diagnosis for HD if a known 'high risk' pregnancy is continued to term: international guidelines emphasise that this situation should be avoided where possible, as it removes the resulting child's future right to make an informed, autonomous decision about predictive testing. The UK Huntington's Disease Predictive Testing Consortium recorded 21 pregnancies that were tested, identified as high-risk and then continued. In this qualitative study, health professionals reviewed the case notes of 15 of these pregnancies. This analysis generated guidelines for clinical practice. It is recommended that practitioners: (i) remind couples of the long-term consequences of continuing a high risk pregnancy, (ii) ensure couples understand the information provided, (iii) collaborate closely with other professionals involved in the couple's prenatal care, (iv) prepare couples for the procedural aspects of prenatal diagnosis and a possible termination of pregnancy, (v) allow time for in-depth pre-test counselling, (vi) explain the rationale for only making prenatal diagnosis available subject to conditions, whilst allowing for human ambivalence and acknowledging that these 'conditions' cannot be enforced, (vii) monitor the whole clinical process to ensure that it works 'smoothly', (viii) recommend couples do not disclose the result of the prenatal test to protect the confidentiality and autonomy of the future 'high-risk' child, and (ix) offer on-going contact and support.

Review of patient decision-making factors and attitudes regarding preimplantation genetic diagnosis

The increasing technical complexity and evolving options for repro-genetic testing have direct implications for information processing and decision making, yet the research among patients considering preimplantation genetic diagnosis (PGD) is narrowly focused. This review synthesizes the literature regarding patient PGD decision-making factors, and illuminates gaps for future research and clinical translation. Twenty-five articles met the inclusion criteria for evaluating experiences and attitudes of patients directly involved in PGD as an intervention or considering using PGD. Thirteen reports were focused exclusively on a specific disease or condition. Five themes emerged: (1) patients motivated by prospects of a healthy, genetic-variant-free child, (2) PGD requires a commitment of time, money, energy and emotions, (3) patients concerned about logistics and ethics of discarding embryos, (4) some patients feel sense of responsibility to use available technologies, and (5) PGD decisions are complex for individuals and couples. Patient research on PGD decision-making processes has very infrequently used validated instruments, and the data collected through both quantitative and qualitative designs have been inconsistent. Future research for improving clinical counseling is needed to fill many gaps remaining in the literature regarding this decision-making process, and suggestions are offered.

1993-2014: two decades of predictive testing for Huntington's disease at the Medical Genetics Unit of the University of Genoa

Background

Predictive testing for Huntington's disease has been available at the Medical Genetics Unit of the University of Genoa from 1987. In 1989, an integrated counseling protocol (geneticist, psychologist, and neurologist) was developed following International Guidelines.

Methods

This is a retrospective analysis of the clinical charts and motivation questionnaires of persons seeking predictive testing through direct DNA analysis from 1993 until 2014, with the aim to evaluate their individual characteristics, motivations, and the outcomes of the counseling protocol.

Results

A total of 299 persons (164 women, 135 men) applied for predictive testing. Most applicants’ features and motivations were similar to those previously described, but surprisingly the percentage of completed protocols was higher among men, 68.5% versus 53.5% (P = 0.011). Likewise, persons over 25 years of age were more likely to take the test than younger applicants (18–25 years): 63.4% versus 48.1% (P = 0.043). In addition, relationship status, having children, and the gender of the affected parent showed different effects on the decision about testing in males and females. No catastrophic reactions were reported during the study period.

Conclusions

We observed that factors influencing the decision‐making process might differ between males and females, and that predictive testing appears a safe procedure if framed within an integrated counseling protocol.

Predictive genetic testing for amyotrophic lateral sclerosis and frontotemporal dementia: genetic counselling considerations

Once a gene mutation that is causal of amyotrophic lateral sclerosis (ALS) and/or frontotemporal dementia (FTD) is identified in a family, relatives may decide to undergo predictive genetic testing to determine whether they are at risk of developing disease. Recent advances in gene discovery have led to a pressing need to better understand the implications of predictive genetic testing. Here we review the uptake of genetic counselling, predictive and reproductive testing, and the factors that impact the decision to undergo testing, for consideration in clinical practice. The literature suggests that the factors impacting the decision to undergo testing are complex due to the nature of these diseases, absence of available preventative medical treatment and variable age of onset in mutation carriers. Gaining further insight into the decision-making process and the impact of testing is critical as we seek to develop best-practice guidelines for predictive testing for familial ALS and FTD.

Presentation and care of a family with Huntington disease in a resource-limited community

BACKGROUND

In high-income countries patients with Huntington disease (HD) typically present to healthcare providers after developing involuntary movements, or for pre-symptomatic genetic testing if at familial risk. A positive family history is a major guide when considering the decision to perform genetic testing for HD, both in affected and unaffected patients. Management of HD is focused upon control of symptoms, whether motor, cognitive, or psychiatric. There is no clear evidence to date of any disease-modifying agents. Referral of families and caregivers for psychological and social support, whether to HD-focused centers, or through virtual communities, is viewed as an important consequence of diagnosis. The experience of healthcare for such progressive neurodegenerative diseases in low- and middle-income nations is in stark contrast with the standard of care in high-income countries.

METHODS

An extended family with many members affected with an autosomal dominantly inherited movement disorder came to medical attention when one family member presented following a fall. Apart from one family member who was taking a benzodiazepine for involuntary movements, no other affected family members had sought medical attention. Members of this family live on several resource-limited Caribbean islands. Care of the chronically ill is often the responsibility of the family, and access to specialty care is difficult to obtain, or is unavailable. Computed tomography scan of one patient's brain revealed severe caudate atrophy and moderate generalized cortical atrophy. Genetic diagnosis of HD was obtained.

RESULTS

Through family recollection and by direct observation we identified four generations of individuals affected with HD. Outreach programs and collaborations helped to provide medical imaging and genetic diagnosis. Additionally these efforts helped with patient and family support, education, and genetic counseling to many members of this family.

CONCLUSIONS

Affected members of this family have limited healthcare access, and rely heavily on family support for care. Genetic and clinical diagnosis of these patients was impeded by lack of resources and lack of access to specialty care. Importantly, obtaining a definitive diagnosis has had a positive impact for this family by facilitating genetic counseling, education, community outreach, and dispelling myths regarding this hereditary disease and its progression.

Prospective Evaluation of Predictive DNA Testing for Huntington's Disease in a Large German Center

We present a prospective study of counselees seeking predictive testing for Huntington's disease at the Huntington Center North Rhine-Westphalia (Bochum, Germany) between 2010 and 2012. The aim was to observe the decision-making process of at-risk individuals and explore their experiences following the decision as well as the impacts of positive and negative mutation results. Data were collected using two standardized questionnaires as well as via a semi-standardized telephone interview one year after the initial counseling session. Seventy-two  individuals participated in at least one of the three phases of the survey, including 31 individuals in the telephone interview. Sociodemographic data were in accordance with previous reports. The process of predictive testing was generally perceived in a positive manner, with almost all interviewees reporting a balanced emotional state one year after initial counseling, regardless of the decision for or against the test. The most important reasons named in favor of or against testing were assembled as well as different aspects regarding the satisfaction with the reached decision. In line with and expanding previous observations on gender-related differences in decision-making, our results suggest that gender-related aspects should be more strongly taken into account in genetic counseling during the predictive testing and counseling processes.

Suicidal behavior and assisted suicide in dementia

BACKGROUND

Concerns about suicide risk in people with dementia have been increasing in recent years along with a discourse about rational suicide and assisted suicide.

METHODS

A systematic narrative literature review of suicidal behavior and assisted suicide in persons with dementia.

RESULTS

Most studies that have examined the spectrum of suicidal ideation, attempted suicide and suicide in dementia have methodological limitations but the overall suicide risk does not appear to be increased. When suicidal behavior does occur, common themes include the presence of psychiatric comorbidity, mainly depression; occurrence early in the dementia course with preserved insight and capacity; and an increased risk in younger people. The emerging discourse on rational and assisted suicide has been spurred by early and pre-symptomatic diagnosis and poses a number of ethical challenges for clinicians including the role of proxy decision-makers.

CONCLUSIONS

Although dementia might not confer a significant overall risk for suicidal behavior, clinicians still need to consider the potential for suicide in vulnerable individuals particularly early in the dementia course.

Genetic testing and counseling in the diagnosis and management of young-onset dementias

Young-onset dementia is hereditary, multifactorial, or sporadic. The most common hereditary dementias include Alzheimer disease, frontotemporal degeneration, Huntington disease, prion diseases, and cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy. Careful attainment of family history assists with diagnosis and determining the likelihood of a genetic cause, and can direct genetic testing. The type of genetic testing depends on confidence of the diagnosis, patient's and affected relatives' symptoms, and the number of disease genes. Single gene, disease-specific gene panels, and large dementia panels are available. Genetic counseling should be given and informed consent obtained. Predictive testing follows the Huntington disease protocol.

Public perceptions of presymptomatic testing for Alzheimer disease

OBJECTIVE

To explore the self-expressed desire for, envisioned reaction to, and basic understanding of presymptomatic Alzheimer disease (AD)-related genetic and biomarker tests.

PATIENTS AND METHODS

The Alzheimer's Prevention Registry is an online community of people at least 18 years of age who are interested in AD prevention research for purely informational purposes or to be considered for possible research participation in future studies. Information about presymptomatic testing and an online multiple choice format survey were posted from November 1, 2012, through June 20, 2013, on the registry website.

RESULTS

Of 4036 respondents, 80.8% (3195/3952) wanted genetic testing if paid by insurance and 58.7% (2261/3851) if it would cost them at least $100. A total of 80.2% (3112/3879) wanted biomarker testing. If at high risk for AD, 90.5% (3478/3841) endorsed that they would "pursue a healthier lifestyle," but 11.6% (427/3706) endorsed "seriously consider suicide." The implication of a positive genetic test result was incorrectly understood by 13.1% (500/3812) and 32.6% (1255/3848) failed to view a positive biomarker test result as evidence of increased risk for or the presence of AD.

CONCLUSION

Despite efforts to increase public awareness of AD, our survey results suggest that greater education of the public is needed. Interested patients should probably undergo psychological screening to identify those at high risk of adverse psychological outcomes, and disclosure of presymptomatic test results should be anchored to tangible constructive action plans, such as healthy lifestyle changes, long-term care planning, and, when available and appropriate, participation in research trials.