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

International Genetic Testing and Counseling Practices for Parkinson's Disease

BACKGROUND

There is growing clinical and research utilization of genetic testing in Parkinson's disease (PD), including direct-to-consumer testing.

OBJECTIVES

The aim is to determine the international landscape of genetic testing in PD to inform future worldwide recommendations.

METHODS

A web-based survey assessing current practices, concerns, and barriers to genetic testing and counseling was administered to the International Parkinson and Movement Disorders Society membership.

RESULTS

Common hurdles across sites included cost and access to genetic testing, and counseling, as well as education on genetic counseling. Region-dependent differences in access to and availability of testing and counseling were most notable in Africa. High-income countries also demonstrated heterogeneity, with European nations more likely to have genetic testing covered through insurance than Pan-American and Asian countries.

CONCLUSIONS

This survey highlights not only diversity of barriers in different regions but also the shared and highly actionable needs for improved education and access to genetic counseling and testing for PD worldwide. © 2023 International Parkinson and Movement Disorder Society.

The importance of on-site genetic counseling for prospective assisted reproductive technology patients

PURPOSE

To assess the value of having an onsite genetic counseling service integrated into an assisted reproductive technology (ART) center.

METHODS

Since January 2021, we have offered genetic counseling at our ART center for couples whose medical history suggests risk of transmission of a genetic disorder. The percentage of couples referred for genetic counseling, the distribution of couples according to reasons for consultation, the mode of transmission in cases of Mendelian disorders, and the frequency of mutations for those with identified genetic disorders were determined.

RESULTS

In an 18-month period, 150 of 1340 couples (11.2%) enrolled for ART treatment were referred to the genetic counseling unit. Two-thirds (99/150, 66.0%) were referred for a known genetic risk, a family history of a genetic disorder or chromosomal abnormality, a serious condition of unknown cause, or consanguinity. The remaining couples had a putative genetic risk (diminished ovarian reserve, high incidence of oocyte immaturity, recurrent abortion, or severe male infertility). Of the 99 with known genetic risk, 62 (62.7%), were approved for ART treatment, 23 (23.2%) were recommended prenatal or preimplantation testing, and 14 (14.1%) were referred for further testing before undergoing ART.

CONCLUSIONS

Our findings reveal great value in having an on-site genetic counseling unit for referral of ART patients. Such a unit makes the ART process smoother and safer for couples, and it lightens the burden of ART staff by removing responsibilities for which they are neither trained, nor should they have to assume.

Teaching perspectives on the communication of difficult news of genetic conditions to medical students

Informing parents that their child has a diagnosis of Down syndrome (DS) is a common example of the delivery of unexpected or difficult news. Expectations and life planning will change, and if detected prenatally, discussions might include the option of pregnancy termination. Medical school curricula currently include training in breaking unexpected news; however, it is difficult to teach and assess. We use the perspectives of clinicians, educators, and a medical student who is the parent of a child with DS to frame a discussion on teaching, practicing, and assessing communication of difficult news in human genetics during medical school.

Psychosocial Impact of Huntington's Disease and Incentives to Improve Care for Affected Families in the Underserved Region of the Slovak Republic

INTRODUCTION

Huntington's disease (HD) is often on the margin of standard medical practice due to its low prevalence, the lack of causal treatment, and the typically long premanifest window prior to the onset of the symptoms, which contrasts with the long-lasting burden that the disease causes in affected families.

METHODS

To capture these socio-psychological aspects of HD and map the experiences of affected individuals, persons at risk of HD, and caregivers, we created a questionnaire using a qualitative research approach. The questionnaire containing 16 questions was conducted online for a period of three months through patient associations in Slovakia and their infrastructures.

RESULTS

In total, we received 30 responses. The survey results, in particular, indicate insufficient counselling by physicians with explicitly missing information about the possibility of preimplantation genetic diagnostic. There was also a necessity to improve comprehensive social and health care in the later stages of the disease, raise awareness of the disease in the general health community, and provide more information on ongoing clinical trials.

CONCLUSION

The psychosocial effects, as well as the burden, can be mitigated by comprehensive genetic counselling as well as reproductive and financial guidelines and subsequent therapeutic programs to actively support patients, caregivers, children, and adolescents growing up in affected families, preferably with the help of local HD community association.

LIMITATIONS

We have used online data collection to reach a wider HD community, but at the same time, we are aware that the quality of the data we would obtain through face-to-face interviews would be considerably better. Therefore, future studies need to be conducted to obtain more detailed information.

Moving beyond disclosure: Stages of care in preclinical Alzheimer's disease biomarker testing

Alzheimer's disease (AD) begins with an asymptomatic "preclinical" phase, in which abnormal biomarkers indicate risk for developing cognitive impairment. Biomarker information is increasingly being disclosed in research settings, and is moving toward clinical settings with the development of cheaper and non-invasive testing. Limited research has focused on the safety and psychological effects of disclosing biomarker results to cognitively unimpaired adults. However, less is known about how to ensure equitable access and robust counseling for decision-making before testing, and how to effectively provide long-term follow-up and risk management after testing. Using the framework of Huntington's disease, which is based on extensive experience with disclosing and managing risk for a progressive neurodegenerative condition, this article proposes a conceptual model of pre-disclosure, disclosure, and post-disclosure phases for AD biomarker testing. Addressing research questions in each phase will facilitate the transition of biomarker testing into clinical practice.

Complexities in Genetic Counseling and Testing of Huntington's Disease: A Perspective from India

BACKGROUND

Huntington's Disease (HD) is an autosomal dominant, progressive neuropsychiatric illness caused by CAG repeat expansion. The high penetrance of the mutation and limited treatment options make it challenging for patients and caretakers. Proper counseling enables families to cope better and make informed life choices.

OBJECTIVE

To explore some complex issues in genetic counseling and testing (GCAT) in HD.

MATERIALS AND METHODS

Vignettes of patients who underwent genetic testing along with pre and post-test counseling at our GCAT clinic.

RESULTS

Case 1: Diagnosis of juvenile HD meant that the healthy parent was an obligate carrier of the mutation. Case 2: Consanguinity resulted in a dense prevalence of HD and >50% risk for the progeny. Case 3: Predictive testing in youth with healthy parents but affected uncles and aunts revealed a HD expansion.

CONCLUSIONS

HD can present with complex inheritance patterns and proper counseling is necessary for better outcomes.

Perceptions about Research Participation among Individuals at Risk and Individuals with Premanifest Huntington's Disease: A Survey Conducted by the European Huntington Association

There has been great progress in Huntington's disease (HD) research. Yet, effective treatments to halt disease before the onset of disabling symptoms are still unavailable. Scientific breakthroughs require an active and lasting commitment from families. However, they are traditionally less involved and heard in studies. Accordingly, the European Huntington Association (EHA) surveyed individuals at risk (HDRisk) and with premanifest HD (PreHD) to determine which factors affect their willingness to participate in research. Questions assessed research experience and knowledge, information sources, reasons for involvement and noninvolvement, and factors preventing and facilitating participation. The survey included 525 individuals, of which 68.8% never participated in studies and 38.6% reported limited research knowledge. Furthermore, 52% trusted patient organizations to get research information. Reasons for involvement were altruistic and more important than reasons for noninvolvement, which were related to negative emotions. Obstacles included time/financial constraints and invasive procedures, while professional support was seen as a facilitator. PreHD individuals reported less obstacles to research participation than HDRisk individuals. Overall, a high motivation to participate in research was noted, despite limited experience and literacy. This motivation is influenced by subjective and objective factors and, importantly, by HD status. Patient organizations have a key role in fostering motivation through education and support.

The Role of Genetic Testing for Parkinson's Disease

PURPOSE OF REVIEW

To describe current practices and attitudes about genetic testing for Parkinson's disease (PD) among neurologists, highlight the changing scene of genetic testing for PD, and provide guidance on facilitating PD genetic testing in a clinical practice.

RECENT FINDINGS

Since the 1990s, researchers have discovered several major gene variants contributing to PD etiology. A large body of literature now exists supporting the frequency of these variants in different populations and their effects on phenotype and clinical course. Recently, clinical trials have emerged with therapies targeting genetic forms of PD, specifically LRRK2 and GBA. Despite this growing knowledge, genetic testing for PD is not typically offered by neurologists including movement disorder specialists. Neurologists express concerns about the financial and practical issues of genetic testing as well as the potential impact on their patients. Researchers and specialists in the field are questioning this hesitation as clinical utility and consumer demand increase. Consideration of genetic testing for PD is shifting, as we enter a new era of precision medicine and gain clinical knowledge about PD. Barriers to testing, as perceived by clinicians, can be overcome with education, support, and involvement of multiple stakeholders with the goal of making PD genetic testing accessible to all patients.

Genetic counseling and testing practices for late-onset neurodegenerative disease: a systematic review

Objective

To understand contemporary genetic counseling and testing practices for late-onset neurodegenerative diseases (LONDs), and identify whether practices address the internationally accepted goals of genetic counseling: interpretation, counseling, education, and support.

Methods

Four databases were systematically searched for articles published from 2009 to 2020. Peer-reviewed research articles in English that reported research and clinical genetic counseling and testing practices for LONDs were included. A narrative synthesis was conducted to describe different practices and map genetic counseling activities to the goals. Risk of bias was assessed using the Qualsyst tool. The protocol was registered with PROSPERO (CRD42019121421).

Results

Sixty-one studies from 68 papers were included. Most papers focused on predictive testing (58/68) and Huntington’s disease (41/68). There was variation between papers in study design, study population, outcomes, interventions, and settings. Although there were commonalities, novel and inconsistent genetic counseling practices were identified. Eighteen papers addressed all four goals of genetic counseling.

Conclusion

Contemporary genetic counseling and testing practices for LONDs are varied and informed by regional differences and the presence of different health providers. A flexible, multidisciplinary, client- and family-centered care continues to emerge. As genetic testing becomes a routine part of care for patients (and their relatives), health providers must balance their limited time and resources with ensuring clients are safely and effectively counseled, and all four genetic counseling goals are addressed. Areas of further research include diagnostic and reproductive genetic counseling/testing practices, evaluations of novel approaches to care, and the role and use of different health providers in practice.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00415-021-10461-5.

Applying available knowledge and resources to alleviate familial and sporadic neurodegenerative disorders

Here I present the scientific rationale and implementation strategies for elimination of early-onset neurodegenerative disorders (EONDD) from future generations, and for risk reduction and treatments for the more common late-onset neurodegenerative disorders (LONDD). Young adults with a family history of an EONDD should be educated on the genetics and familial burden of EONDD. They can then be genotyped and, if positive for the mutation, counseled as to how they can ensure that none of their children will be affected by choosing either adoption or in vitro fertilization and preimplantation genetic testing. LONDD risk reduction will require education of physicians and patients on the benefits of regular intermittent bioenergetic and cognitive challenges (exercise, intermittent fasting, intellectual challenges and social engagement) for brain health, and on specific risk-reduction regimens. Regulations will be required to counteract the disease-promoting mercenary practices of the processed food and pharmaceutical industries. Clinical trials of pharmacological interventions should shift to small trials of agents that substantially mimic mechanisms of action of exercise and intermittent fasting to bolster neuronal bioenergetics and stress resistance.

Positive Attitudes and Therapeutic Misconception Around Hypothetical Clinical Trial Participation in the Huntington's Disease Community

Background:

New therapies that could modify the disease course of Huntington’s disease (HD) are entering clinical trials. However, conceptions about clinical research from the HD community are unknown. This knowledge could help inform patient-clinician discussions surrounding clinical trial participation.

Objective:

The purpose of this study was to assess clinical trial attitudes and understanding in the HD community.

Methods:

We developed a survey incorporating two measures of trial understanding and attitudes and the impact of therapeutic route of administration on hypothetical trial participation. The survey was distributed via emails, flyers, and social media through HD-related organizations.

Results:

There were 73 responses. Individuals self-reported as clinically diagnosed with HD, gene positive but asymptomatic, or primary caregivers. Respondents viewed clinical trials positively and generally viewed trials as safe. Individuals with prior HD-related research experience were less likely to have negative expectations about trials than those without research experience (p = 0.002), and women had higher information needs than men (p = 0.001). Individuals with HD were more likely than the other groups to experience therapeutic misconception (p = 0.002). All respondents were able to appraise risks and benefits of research but exhibited optimism about trial outcomes. Willingness to participate was highest when the route of administration was minimally invasive.

Conclusions:

While the HD community views clinical trials positively, patients with HD are at high risk for therapeutic misconception and all groups are optimistic about trial outcomes. Limitations of this study include a small sample that may be inclined to view research positively given past trial participation and interest in participating in HD surveys. However, the findings from this study can be used to strengthen informed consent during HD clinical trial recruitment.

Chorea

PURPOSE OF REVIEW

This article provides an overview of the approach to chorea in clinical practice, beginning with a discussion of the phenomenologic features of chorea and how to differentiate it from other movement disorders. The diagnostic approach, clinical features of important acquired and genetic choreas, and therapeutic principles are also discussed. Practical clinical points and caveats are included.

RECENT FINDINGS

C9orf72 disease is the most common Huntington disease phenocopy, according to studies in the European population. Anti-IgLON5 disease can present with chorea. The role of immunotherapies in Sydenham chorea has increased, and further clinical studies may be useful. Benign hereditary chorea is a syndrome or phenotype due to mutations in several genes, including NKX2-1, ADCY5, GNAO1, and PDE10A. New-generation presynaptic dopamine-depleting agents provide more options for symptomatic treatment of chorea with fewer adverse effects. Deep brain stimulation has been performed in several choreic disorders, but features other than chorea and the neurodegenerative nature should be taken into consideration. Studies on genetic interventions for Huntington disease are ongoing.

SUMMARY

Clinical features remain crucial in guiding the differential diagnosis and appropriate investigations in chorea. Given the complexity of most choreic disorders, treating only the chorea is not sufficient. A comprehensive and multidisciplinary approach is required.

Identification of Biomarkers in Neuropsychiatric Disorders Based on Systems Biology and Epigenetics

Clinically useful biomarkers are available for some neuropsychiatric disorders like fragile X syndrome, Rett syndrome, and Huntington’s disease. Despite many decades of research on the pathogenesis of neuropsychiatric disorders like schizophrenia (SZ), bipolar disorder (BD), and major depressive disorder (MDD), the exact pathogenesis of these disorders remains unclear, and there are no clinically useful biomarkers for these disorders. However, there is increasing evidence that abnormal epigenetic mechanisms of gene expression contribute to the pathogenesis of SZ, BD, and MDD. Both systems (or network) biology and epigenetics (a component of systems biology) attempt to make sense of biological systems that are highly dynamic and multi-compartmental. This article suggests that systems biology, emphasizing the epigenetic component of systems biology, could help identify clinically useful biomarkers in neuropsychiatric disorders like SZ, BD, and MDD.

Predictive testing for Huntington disease over 24 years: Evolution of the profile of the participants and analysis of symptoms

BACKGROUND

Huntington disease (HD) is a devastating neurodegenerative autosomal dominant genetic condition. Predictive testing (PT) is available through a defined protocol for at-risk individuals. We analyzed the over-24-years evolution of practices regarding PT for HD in a single center.

METHODS

We gathered data from the files of all individuals seeking PT for HD in Lyon, France, from 1994 to 2017.

RESULTS

448 out of 567 participants had exploitable data. Age at consultation dichotomized over 24 years toward an eightfold increase in individuals aged >55 (2/94 vs. 30/183; 2% to 16%; p < .0001) and twice as many individuals aged 18-20 (3/94 vs. 12/183; 3%-7%; p < .05). Motives for testing remained stable. The rate of withdrawal doubled over 24 years (9/94 vs. 38/183; 9%-21%; p < .02). Independently of the time period, less withdrawal was observed for married, accompanied, at 50% risk, and symptomatic individuals, and in those able to explicit the motives for testing or taking the test to inform their children. We also assessed the consistency between the presence of subtle symptoms compatible with HD found before the test by the team's neurologist, and the positivity of the molecular test. The concordance was 100% (17/17) for associated motor and cognitive signs, 87% (27/31) for isolated motor signs, and 70% (7/10) for isolated cognitive signs. Furthermore, 91% (20/22) of individuals who requested testing because they thought they had symptoms, were indeed found carriers.

CONCLUSION

This over-24 years study underlines an increasing withdrawal from protocol and a dichotomization of participants' age. We also show a strong concordance between symptoms perceived by the neurologist or by the patient, and the subsequent positivity of the predictive molecular test.

The C9orf72 hexanucleotide repeat expansion presents a challenge for testing laboratories and genetic counseling

C9orf72 hexanucleotide repeat expansions are the most common known cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Genetic testing for C9orf72 expansions in patients with ALS and/or FTD and their relatives has become increasingly available since hexanucleotide repeat expansions were first reported in 2011. The repeat number is highly variable and the threshold at which repeat size leads to neurodegeneration remains unknown. We present the case of an ALS patient who underwent genetic testing through our Motor Neurone Disease Clinic. We highlight current limitations to analysing and interpreting C9orf72 expansion test results and describe how this resulted in discordant reports of pathogenicity between testing laboratories that confounded the genetic counselling process. We conclude that patients with ALS or FTD and their at-risk family members, need to be adequately counselled about the limitations of current knowledge to ensure they are making informed decisions about genetic testing for C9orf72. Greater collaboration between clinicians, testing laboratories and researchers is required to ensure risks to patients and their families are minimised.

Genetic testing for Huntington’s disease: A thematic analysis of online support community messages

Huntington’s disease is a fatal late-onset genetic illness that causes motor, cognitive and psychiatric disorders. Individuals considering genetic testing may benefit from online social support. This study investigates how genetic testing is discussed within health forums. A total of 337 messages written by 58 individuals were analysed using deductive thematic analysis. Discussions examined three themes: deciding to be tested (enquiring about symptoms and starting a new family), preparing for the test (information seeking and attending appointments) and receiving the results (positive and negative results). Forums can reduce the uncertainty of ambiguous symptoms and provide ongoing personalised support before, during and after a genetic test.