Parkinson’s Disease: Patients’ Knowledge, Attitudes, and Interest in Genetic Counseling

Barriers to clinical genetic testing in movement disorders

PURPOSE OF REVIEW

The number of known genetic movement disorders and potential treatments for these disorders have grown rapidly over the last few decades. Despite this, genetic testing for movement disorders remains relatively underutilized in clinical practice. In this review, we explore a number of barriers that prevent more routine and widespread use of genetic testing for movement disorders.

RECENT FINDINGS

Cost and limited health insurance coverage as well as difficulty accessing genetic testing and counselling are major barriers to genetic testing and disproportionately affect low- and middle-income countries and specific sociodemographic groups. Clinician misperceptions and limited knowledge about genetic testing for movements disorders as well as patient and clinician concerns about the potential for genetic discrimination are further obstacles. Despite these barriers, several recent international collaborative studies have demonstrated the feasibility of delivering clinical genetic testing and genetic counselling for movement disorders on a large scale.

SUMMARY

Concerted action at multiple organizational levels (government, specialty societies, health insurance organizations, etc.) is required in order to address the identified barriers and improve utilization of genetic testing in movement disorders on a global scale.

Participant-reported personal utility of genetic testing for Parkinson's disease and interest in clinical trial participation

Genetic testing for Parkinson's disease (PD) is infrequently performed due to perceptions of low utility. We investigated the personal utility in PD GENEration and how results lead to enrollment in additional research studies. Participants (n = 972) underwent genetic testing, results disclosure, genetic counseling, and completed a survey examining the perceived personal utility of their results and interest in participating in additional studies. Most participants found their genetic test results useful, including satisfying curiosity (81%), feeling good about helping the medical community (80%), and having information to share with family (77%). There were no significant differences in responses based on result type. Forty-five percent of participants expressed interest in participating in research studies; whereas 16% of participants confirmed enrollment. Our results suggest that participants find personal utility in genetic testing regardless of results. Although participants may be interested in enrolling in additional research, they may need support and resources.

Parkinson's disease variant detection and disclosure: PD GENEration, a North American study

Variants in seven genes (LRRK2, GBA1, PRKN, SNCA, PINK1, PARK7 and VPS35) have been formally adjudicated as causal contributors to Parkinson's disease; however, individuals with Parkinson's disease are often unaware of their genetic status since clinical testing is infrequently offered. As a result, genetic information is not incorporated into clinical care, and variant-targeted precision medicine trials struggle to enrol people with Parkinson's disease. Understanding the yield of genetic testing using an established gene panel in a large, geographically diverse North American population would help patients, clinicians, clinical researchers, laboratories and insurers better understand the importance of genetics in approaching Parkinson's disease. PD GENEration is an ongoing multi-centre, observational study (NCT04057794, NCT04994015) offering genetic testing with results disclosure and genetic counselling to those in the US (including Puerto Rico), Canada and the Dominican Republic, through local clinical sites or remotely through self-enrolment. DNA samples are analysed by next-generation sequencing including deletion/duplication analysis (Fulgent Genetics) with targeted testing of seven major Parkinson's disease-related genes. Variants classified as pathogenic/likely pathogenic/risk variants are disclosed to all tested participants by either neurologists or genetic counsellors. Demographic and clinical features are collected at baseline visits. Between September 2019 and June 2023, the study enrolled 10 510 participants across >85 centres, with 8301 having received results. Participants were: 59% male; 86% White, 2% Asian, 4% Black/African American, 9% Hispanic/Latino; mean age 67.4 ± 10.8 years. Reportable genetic variants were observed in 13% of all participants, including 18% of participants with one or more 'high risk factors' for a genetic aetiology: early onset (<50 years), high-risk ancestry (Ashkenazi Jewish/Basque/North African Berber), an affected first-degree relative; and, importantly, in 9.1% of people with none of these risk factors. Reportable variants in GBA1 were identified in 7.7% of all participants; 2.4% in LRRK2; 2.1% in PRKN; 0.1% in SNCA; and 0.2% in PINK1, PARK7 or VPS35 combined. Variants in more than one of the seven genes were identified in 0.4% of participants. Approximately 13% of study participants had a reportable genetic variant, with a 9% yield in people with no high-risk factors. This supports the promotion of universal access to genetic testing for Parkinson's disease, as well as therapeutic trials for GBA1 and LRRK2-related Parkinson's disease.

Delivering Genetic Test Results for Parkinson Disease: A Qualitative Approach to Provider Experiences in the PD GENEration Study

Background and Objectives

The PD GENEration (PD GENE) study (NCT04057794) is an interventional clinical trial offering genetic testing with result disclosure and genetic counseling to individuals with Parkinson disease (PD). In general, experiences of those providing PD genetic testing and counseling in a research or clinical setting have not been extensively evaluated. In this study, providers' experiences when providing research result disclosure and genetic counseling to people with PD were explored with the goal of improving PD genetics services.

Methods

Qualitative semistructured interviews of all neurologists and genetic counselors who performed genetic test result disclosure and genetic counseling to at least 5 participants in the pilot portion of the PD GENE study were conducted. An inductive thematic analysis of the transcribed interviews identified core themes and subthemes for "lessons learned" and "challenges encountered."

Results

Interviews were conducted with 14 providers (7 neurologists and 7 genetic counselors) who described multiple lessons learned while disclosing genetic test results, including the ability to adapt to participant background and needs and the value of a well-structured and supportive study that also provides training and educational materials for the provider. Of importance, responses suggested that the PD GENE study answered a real need, highlighting a strong interest in the community. Providers also voiced several shared challenges including the complexities of PD and PD genetics, unexpected confusion on provider roles within a research study, and complicated family histories/dynamics.

Discussion

Providers in the pilot portion of the PD GENE study encountered enthusiasm and strong engagement from many of the participants, and they, too, voiced significant satisfaction about their roles and the mission of the study. They learned valuable lessons, and their comfort providing genetic test result disclosure and genetic counseling grew as the study progressed. Although there were challenges, they were deemed manageable. The results from this qualitative study can inform both the expanded PD GENE study and other providers offering genetic testing and counseling to their patients in a neurology setting. It will also allow for targeted PD provider education.

Genetic Testing of Movements Disorders: A Review of Clinical Utility

Currently, pathogenic variants in more than 500 different genes are known to cause various movement disorders. The increasing accessibility and reducing cost of genetic testing has resulted in increasing clinical use of genetic testing for the diagnosis of movement disorders. However, the optimal use case(s) for genetic testing at a patient level remain ill-defined. Here, we review the utility of genetic testing in patients with movement disorders and also highlight current challenges and limitations that need to be considered when making decisions about genetic testing in clinical practice.

Highlights

The utility of genetic testing extends across multiple clinical and non-clinical domains. Here we review different aspects of the utility of genetic testing for movement disorders and the numerous associated challenges and limitations. These factors should be weighed on a case-by-case basis when requesting genetic tests in clinical practice.

Genetic literacy and attitude towards genetic testing in patients with Parkinson's disease and their caregivers: A review of literature

BACKGROUND

Genetic literacy refers to an individual's ability to understand the basics of genetic concepts and apply them to health-related decisions. The level of genetic literacy influences attitude towards genetic testing and is, in turn, influenced by several other factors. Clinicians must be aware of the genetic literacy of their patients and their caregivers before advising genetic testing and/or undertaking pre and post-test counseling.

METHOD

A systematic review of literature in PubMed was carried out using keywords "Genetic testing", "Genetic counseling", "Knowledge", "Attitude", "Parkinson's disease" in various combinations.

RESULTS

Seven eligible studies with a total of 1837 individuals (patients with PD-1355 and patient caregivers-482) were identified. More than half the participants were well-versed in basic concepts of genetics (57.8%) and risks of inheriting PD (60.5%) while less than 10% were aware regarding the contribution of specific genes (e.g. LRRK2). Interest in diagnosis, treatment, prevention and facilitating PD research were central themes for positive attitude while apprehensions revolving around impact on employment and insurance and non-benefit were associated with negative attitudes. Possible associations included greater knowledge scores with positive attitudes towards genetic testing and older age for negative attitude towards testing. Insufficient data on attitudes toward prenatal testing, presymptomatic testing and clinicians' attitude toward testing was identified.

CONCLUSION

Patients with PD and their caregivers are aware of the role of genetics in the etiopathogenesis of their disease, which contributes to their positive attitude towards testing. Further studies exploring negative attitudes towards testing will help overcome the hurdles in genetic testing and counseling in this cohort of patients.

Patient understanding of pharmacogenomic test results in clinical care

OBJECTIVE

Previous research has not objectively assessed patients' comprehension of their pharmacogenomic test results. In this study we assessed understanding of patients who had undergone cytochrome P450 2C19 (CYP2C19) pharmacogenomic testing.

METHODS

31 semi-structured interviews with patients who underwent CYP2C19 testing after cardiac catheterization and had been sent a brochure, letter, and wallet card explaining their results. Answers to Likert and binary questions were summarized with descriptive statistics. Qualitative data were analyzed using a grounded theory approach, with particular focus on categorization.

RESULTS

No participants knew the name of the gene tested or their metabolizer status. Seven participants (23%) knew whether the testing identified any medications that would have lower effectiveness or increased adverse effects for them at standard doses ("Adequate Understanding"). Four participants (13%) read their results from the letter or wallet card they received but had no independent understanding ("Reliant on Written Materials"). Ten participants remembered receiving the written materials (32%).

CONCLUSION

A majority of participants who had undergone CYP2C19 PGx testing did not understand their results at even a minimal level and would be unable to communicate them to future providers.

PRACTICE IMPLICATIONS

Further research is necessary to improve patient understanding of PGx testing and their results, potentially through improving patient-provider communication.

Providing genetic testing and genetic counseling for Parkinson's disease to the community

PURPOSE

To evaluate the feasibility and impact of offering genetic testing and counseling to patients with Parkinson's disease (PD), with the potential to enroll in gene-targeted clinical trials and improve clinical care.

METHODS

A multicenter, exploratory pilot study at 7 academic hospital sites in the United States tracked enrollment and randomized participants to receive results and genetic counseling at local sites or by genetic counselors, remotely. Follow-up surveys measured participant/provider satisfaction, knowledge, and psychological impact.

RESULTS

From September 5, 2019 to January 4, 2021, 620 participants were enrolled and 387 completed outcome surveys. There were no significant differences in outcomes between local and remote sites, with both arms reporting high knowledge and satisfaction scores (>80%). Notably, 16% of those tested had reportable PD gene variants (pathogenic/likely pathogenic/risk allele).

CONCLUSION

Local clinicians, as well as genetic counselors, with educational support as needed, can effectively return genetic results for PD as we observed favorable outcome measures in both groups. Increasing access to PD genetic testing and counseling is urgent; this can inform future efforts to integrate genetic testing and counseling into clinical care for all those with PD.

Readiness for Parkinson's disease genetic testing and counseling in patients and their relatives in urban settings in the Dominican Republic

Genetic testing for Parkinson's disease (PD) is increasing globally, and genetic counseling is an important service that provides information and promotes understanding about PD genetics and genetic testing. PD research studies have initiated outreach to underrepresented regions in North America, including regions in Latin America, such as the Dominican Republic (DR); some studies may include return of genetic test results. Thus, understanding what individuals know about PD, genetic testing for PD, and their interest in speaking with a genetic counselor, is crucial when assessing readiness. In this cross-sectional study, a survey was distributed to people with Parkinson's disease (PwP) and their unaffected biological relatives in the DR. Questions assessed genetics knowledge, attitude toward genetic testing, and interest in genetic testing and counseling. Of 45 participants, 69% scored the maximum on the attitude scale, indicating an overall positive attitude toward genetic testing; 95% indicated interest in genetic testing for PD, and 98% were at least somewhat interested in meeting with a genetic counselor. The mean PD genetics knowledge score was similar to previously published data. Through free text responses, participants expressed a desire to know more about PD treatment and management, prevention, cause, and their personal risk for PD. These results provide further evidence of readiness for genetic testing in this country but also underscore some gaps in knowledge that should be addressed with targeted educational efforts, as part of building genetic testing and counseling capacities.

Genetic Testing in Parkinson's Disease

Genetic testing for persons with Parkinson's disease is becoming increasingly common. Significant gains have been made regarding genetic testing methods, and testing is becoming more readily available in clinical, research, and direct-to-consumer settings. Although the potential utility of clinical testing is expanding, there are currently no proven gene-targeted therapies, but clinical trials are underway. Furthermore, genetic testing practices vary widely, as do knowledge and attitudes of relevant stakeholders. The specter of testing mandates financial, ethical, and physician engagement, and there is a need for guidelines to help navigate the myriad of challenges. However, to develop guidelines, gaps and controversies need to be clearly identified and analyzed. To this end, we first reviewed recent literature and subsequently identified gaps and controversies, some of which were partially addressed in the literature, but many of which are not well delineated or researched. Key gaps and controversies include: (1) Is genetic testing appropriate in symptomatic and asymptomatic individuals without medical actionability? (2) How, if at all, should testing vary based on ethnicity? (3) What are the long-term outcomes of consumer- and research-based genetic testing in presymptomatic PD? (4) What resources are needed for clinical genetic testing, and how is this impacted by models of care and cost-benefit considerations? Addressing these issues will help facilitate the development of consensus and guidelines regarding the approach and access to genetic testing and counseling. This is also needed to guide a multidisciplinary approach that accounts for cultural, geographic, and socioeconomic factors in developing testing guidelines. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

The Genetic Testing Experience of Individuals with Parkinson's Disease

Background

The perspective and experiences of individuals with Parkinson's disease (PD) regarding genetic testing is limited.

Objectives

To determine if anticipated benefits and negative consequences of genetic testing noted in prior studies have occurred in a surveyed group of patients with PD and to identify reasons why some individuals with PD have not had testing.

Methods

Individuals were surveyed from 22 support/advocacy groups throughout the US. Information about patient demographics and genetic testing were assessed, along with the consequences experienced after testing or anticipated by those who have not had testing. Descriptive statistics, Pearson correlation coefficient, ANOVA, and independent sample t-test were utilized for data analysis.

Results

Of the genetic testing group (n = 78), most received testing through a research study (44.9%) or a Direct-to-Consumer company (46.2%). Most did not meet with a genetic counselor before (87.2%) or after testing (64.1%). Fewer positive and fewer negative consequences were reported after testing compared to the consequences anticipated by those who have not undergone testing (P < 0.001, all comparisons). Of the non-genetic testing group (n = 166), 49.4% did not undergo testing because they were not aware it was available and 38.0% because their doctor did not offer it.

Conclusions

Findings demonstrate the need for providers to have genetic testing discussions with PD patients, who may otherwise seek testing via Direct-to-Consumer companies or be unaware it is available. Collaborations with genetic counselors trained in providing anticipatory guidance may assist patients in forming more realistic expectations regarding the consequences experienced after genetic testing for PD.

Genome Sequencing in the Parkinson Disease Clinic

Background and Objectives

Genetic variants affect both Parkinson disease (PD) risk and manifestations. Although genetic information is of potential interest to patients and clinicians, genetic testing is rarely performed during routine PD clinical care. The goal of this study was to examine interest in comprehensive genetic testing among patients with PD and document reactions to possible findings from genome sequencing in 2 academic movement disorder clinics.

Methods

In 203 subjects with PD (age = 63 years, 67% male), genome sequencing was performed and filtered using a custom panel, including 49 genes associated with PD, parkinsonism, or related disorders, as well as a 90-variant PD genetic risk score. Based on the results, 231 patients (age = 67 years, 63% male) were surveyed on interest in genetic testing and responses to vignettes covering (1) familial risk of PD (LRRK2); (2) risk of PD dementia (GBA); (3) PD genetic risk score; and (4) secondary, medically actionable variants (BRCA1).

Results

Genome sequencing revealed a LRRK2 variant in 3% and a GBA risk variant in 10% of our clinical sample. The genetic risk score was normally distributed, identifying 41 subjects with a high risk of PD. Medically actionable findings were discovered in 2 subjects (1%). In our survey, the majority (82%) responded that they would share a LRRK2 variant with relatives. Most registered unchanged or increased interest in testing when confronted with a potential risk for dementia or medically actionable findings, and most (75%) expressed interest in learning their PD genetic risk score.

Discussion

Our results highlight broad interest in comprehensive genetic testing among patients with PD and may facilitate integration of genome sequencing in clinical practice.

Glucocerebrosidase mutations: A paradigm for neurodegeneration pathways

Biallelic (homozygous or compound heterozygous) glucocerebrosidase gene (GBA) mutations cause Gaucher disease, whereas heterozygous mutations are numerically the most important genetic risk factor for Parkinson disease (PD) and are associated with the development of other synucleinopathies, notably Dementia with Lewy Bodies. This phenomenon is not limited to GBA, with converging evidence highlighting further examples of autosomal recessive disease genes increasing neurodegeneration risk in heterozygous mutation carriers. Nevertheless, despite extensive research, the cellular mechanisms by which mutations in GBA, encoding lysosomal enzyme β-glucocerebrosidase (GCase), predispose to neurodegeneration remain incompletely understood. Alpha-synuclein (A-SYN) accumulation, autophagic lysosomal dysfunction, mitochondrial abnormalities, ER stress and neuroinflammation have been proposed as candidate pathogenic pathways in GBA-linked PD. The observation of GCase and A-SYN interactions in PD initiated the development and evaluation of GCase-targeted therapeutics in PD clinical trials.

Public perceived knowledge of, attitude toward, and use of genetic testing in urban China

Because most research about laypeople and genetic testing (GT) has been conducted in other nations than China, we conducted a study in urban China (a) to determine the perceived knowledge of, attitude toward, and use of GT there; (b) to identify influencing factors associated with the public's perceived knowledge, attitudes, and use of GT; and (c) to explore the relationship among public knowledge of, attitude toward, and use of GT. Our data came from a community-based survey in urban Dalian of 868 individuals. We used generalized ordered logit and logit models to examine factors associated with perceived knowledge of, attitude toward, and use of GT. We found that 67% of community members knew about GT, that 45% had a positive opinion of GT, and that only 4% accessed GT. Older people were more likely to have less perceived knowledge of GT and less likely to have a negative attitude toward it; these relationships were especially stronger among those aged ≥60 years. We also found that socially disadvantaged people were more likely to have less perceived knowledge of GT and more likely to have a negative opinion of it. Having a greater level of perceived knowledge was significantly correlated with increased odds of having a more positive or neutral attitude toward GT and of being more likely to access GT. Our findings may help policy makers design effective action plans and regulations regarding GT and genetic counseling services for laypersons in China.

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.

Outcomes of genetic test disclosure and genetic counseling in a large Parkinson's disease research study

Genetic testing for Parkinson's disease (PD) is growing as interventional clinical trials begin to enroll participants with PD who carry pathogenic variants in the LRRK2 or GBA genes. However, the impact of receiving genetic test results and the satisfaction with receiving genetic counseling among PD populations have not yet been studied. The purpose of this study was to evaluate (1) the psychological impact of genetic testing for PD and (2) satisfaction with genetic counseling. Surveyed participants (N = 875) were individuals with PD or at risk of developing PD, initially recruited for the Parkinson's Progression Marker Initiative (PPMI) study and currently enrolled in the Widespread Recruitment Initiative (WRI) at Indiana University. Individuals were surveyed following genetic test disclosure and genetic counseling regarding results from targeted testing for pathogenic variants in the LRRK2 and GBA genes. Participants were surveyed via two tools: a modified version of the Multidimensional Impact of Cancer Risk Assessment Survey (M-MICRA), which measured the psychological impact of genetic testing and the Genetic Counseling Satisfaction Survey (GCSS). Participants were divided into affected/unaffected and variant positive/negative groups for subset analyses. The majority of participants had favorable M-MICRA scores and were satisfied with the disclosure of the genetic test results and genetic counseling for PD. However, participants with PD and those with pathogenic variants had less favorable M-MICRA scores and lower satisfaction scores compared to those without disease or pathogenic variants. This information is valuable to providers performing genetic testing of and genetic counseling to people and families affected with PD. Individuals with PD and individuals with pathogenic variants may benefit from additional interventions.

Genetic Testing for Parkinson Disease: Are We Ready?

Purpose of Review

With the advent of precision medicine and demand for genomic testing information, we may question whether it is time to offer genetic testing to our patients with Parkinson disease (PD). This review updates the current genetic landscape of PD, describes what genetic testing may offer, provides strategies for evaluating whom to test, and provides resources for the busy clinician.

Recent Findings

Patients with PD and their relatives, in various settings, have expressed an interest in learning their PD genetic status; however, physicians may be hesitant to widely offer testing due to the perceived low clinical utility of PD genetic test results. The rise of clinical trials available for patients with gene-specific PD and emerging information on genotype-phenotype correlations are starting to shift this discussion about testing.

Summary

By learning more about the various genetic testing options for PD and utility of results for patients and their care, clinicians may become more comfortable with widespread PD genetic testing in the research and clinical setting.

Patient and Health Care Provider Needs and Preferences in Understanding Pharmacogenomic and Genomic Testing: A Meta-Data Analysis

Tests that feature genomic indicators can now be used to guide the pharmacological treatment of patients. To better identify the needs and preferences of patients and health care providers in facilitating their understanding of information related to such pharmacogenomic tests (PGx), a review of literature on knowledge translation and health literacy in the context of testing was conducted. Using a grounded theory-based approach, a comparative analysis of data from 36 studies meeting the criteria for the meta-data analysis has revealed the recurrence of three principal themes: (a) knowledge and understanding of genetics and pharmacogenomics; (b) experiences with genetic, genomic, or PGx testing (decision about the test, information delivery, and understanding of test results); and (c) educational/informational resources. This synthesis sheds light on each theme from the standpoint of both patients and health care providers and suggests avenues in which to direct efforts to support the introduction of pharmacogenomic tests in current practice.