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.

From the patient to the population: Use of genomics for population screening

Genomic medicine is expanding from a focus on diagnosis at the patient level to prevention at the population level given the ongoing under-ascertainment of high-risk and actionable genetic conditions using current strategies, particularly hereditary breast and ovarian cancer (HBOC), Lynch Syndrome (LS) and familial hypercholesterolemia (FH). The availability of large-scale next-generation sequencing strategies and preventive options for these conditions makes it increasingly feasible to screen pre-symptomatic individuals through public health-based approaches, rather than restricting testing to high-risk groups. This raises anew, and with urgency, questions about the limits of screening as well as the moral authority and capacity to screen for genetic conditions at a population level. We aimed to answer some of these critical questions by using the WHO Wilson and Jungner criteria to guide a synthesis of current evidence on population genomic screening for HBOC, LS, and FH.

Breast cancer in West Africa: molecular analysis of BRCA genes in early-onset breast cancer patients in Burkina Faso

BACKGROUND

Breast cancer (BC) is the most commonly diagnosed cancer and the second leading cause of cancer-related deaths among women in Africa after cervical cancer. Even if the epidemiological data are now aligned with those relating to industrialized countries, the knowledge concerning breast cancer in Africa, particularly in Western Africa, still lack clinical data, medical treatments, and the evaluation of genetic and non-genetic factors implicated in the etiology of the disease. The early onset and the aggressiveness of diagnosed breast cancers in patients of African ancestry strongly suggest that the genetic risk factor may be a key component, but so far, very few studies on the impact of germ line mutations in breast cancer in Africa have been conducted, with negative consequences on prevention, awareness and patient management. Through Next Generation sequencing (NGS), we analyzed all of the coding regions and the exon-intron junctions of BRCA1 and BRCA2 genes-the two most important genes in hereditary breast cancer-in fifty-one women from Burkina Faso with early onset of breast cancer with or without a family history.

RESULTS

We identified six different pathogenic mutations (three in BRCA1, three in BRCA2), two of which were recurrent in eight unrelated women. Furthermore, we identified, in four other patients, two variants of uncertain clinical significance (VUS) and two variants never previously described in literature, although one of them is present in the dbSNP database.

CONCLUSIONS

This is the first study in which the entire coding sequence of BRCA genes has been analyzed through Next Generation Sequencing in Burkinabe young women with breast cancer. Our data support the importance of genetic risk factors in the etiology of breast cancer in this population and suggest the necessity to improve the genetic cancer risk assessment. Furthermore, the identification of the most frequent mutations of BRCA1 and BRCA2 in the population of Burkina Faso will allow the development of an inexpensive genetic test for the identification of subjects at high genetic cancer risk, which could be used to design personalized therapeutic protocols.

Physician and patient determinants of prognostic counseling in idiopathic REM sleep-behavior disorder

OBJECTIVES/BACKGROUND

Prognostic counseling about the risk for developing overt neurodegenerative disorders for patients with idiopathic REM sleep-behavior disorder (iRBD) and isolated REM sleep without atonia (iRSWA) is difficult, given lack of disease-modifying interventions and uncertainty in accurate prognostication for individuals. We aimed to analyze patient and physician characteristics associated with documented prognostic discussions for patients with iRBD and iRSWA.

PATIENTS/METHODS

We retrospectively reviewed the medical records for 138 (112 iRBD and 26 iRSWA) patients seen at the Mayo Clinic between 2012 and 2015. We analyzed physician and patient demographics, initial complaint, and other information discussed during office visits. We then comparatively analyzed the impact of physician and patient characteristics on documented prognostic discussions using Chi Square or Fischer's exact test.

RESULTS

Mean iRBD patient age was 65.0 ± 13.0, and mean iRSWA age was 58 ± 15 years. Seventy-eight (69.6%) iRBD and 22 (84.6%) iRSWA patients were men. Sixty-two (55%) iRBD and three (12%) iRSWA patients received prognostic counseling about phenoconversion risk. iRBD was a secondary complaint in 67 (59.8%). Patients over age 60 years and those having iRBD as a chief complaint more frequently received prognostic discussions than those with opposite characteristics (all p < 0.05). Patient sex and antidepressant use were not associated with counseling. Sleep neurologists disclosed prognostic information most frequently, with male more likely than female clinicians to disclose prognoses.

CONCLUSIONS

Several patient and physician characteristics appear to influence documented prognostic counseling for iRBD/RSWA patients. Future studies of iRBD/RSWA patients' preferences are needed to clarify ethically appropriate physician-patient communication concerning prognosis.

Population screening for BRCA1/BRCA2 mutations: lessons from qualitative analysis of the screening experience

PURPOSE

Population screening for BRCA1/BRCA2. mutations is being considered for Ashkenazi Jews (AJ) because 2.5% carry recurrent deleterious mutations and effective cancer prevention exists. This study aimed to provide a qualitative focus on perspectives of individuals, particularly carriers, who were tested through a screening trial. In this trial, the pretest process included only written information.

METHODS

Interviews were performed with 26 carriers and 10 noncarriers who participated in a BRCA population screening trial for AJ.

RESULTS

Attitudes toward screening were generally positive. The main motivator for testing was knowledge of BRCA status to enable cancer risk reduction. Knowledge of carrier status, although challenging, was thus viewed as health-empowering. The screening paradigm was sensed as increasing awareness and as overcoming access, referral, and familial barriers. Streamlining the pretest process was positively perceived as offering gradual, stepwise knowledge commensurate with test results. Participants were concerned that health systems provide the necessary conceptual and infrastructural framework and that individual autonomy be maintained.

CONCLUSIONS

BRCA screening in AJ is viewed favorably, even by carriers. Stepwise acquisition of knowledge based on test results was viewed as most relevant to the screening context. Screening program development should account for safeguarding autonomy and providing requisite post-test services.Genet Med advance online publication 01 December 2016.

Genetic testing of LRRK2 in Parkinson's disease: is there a clinical role?

Genetic testing has played an important role for the diagnosis of many rare monogenic disorders. However, the role and limitations of genetic testing have generated considerable debate in the medical community. In recent years, the identification of several monogenic genes in Parkinson's disease (PD), a common neurodegenerative disorder, has led to calls for genetic testing guidelines for this disorder. Genetic testing of LRRK2 provides an excellent platform to highlight some of the pertinent issues (generic and specific) related to genetic testing in PD. The identification of a common recurrent mutation (G2019S) worldwide provides an opportunity for developing guidelines that are applicable internationally. However, the incomplete penetrance of the mutation and the lack of clarity of the pathogenicity of many other reported LRRK2 mutations call for cautious implementation of genetic testing programs. The clinical utility of genetic testing is compounded by easy accessibility of Direct to Consumer genetic services and the relative lack of regulation on reliability of service providers in internet advertisements. Based on current literature, genetic testing of LRRK2 (particularly for G2019S) certainly has a clinical role, though it is applicable primarily in select scenarios and in certain at-risk populations.