Who and Why? Requests for Presymptomatic Genetic Testing for Amyotrophic Lateral Sclerosis/Frontotemporal Dementia vs Huntington Disease

Individuals' experiences in genetic counseling and predictive testing for familial amyotrophic lateral sclerosis

As clinical genetic testing in the amyotrophic lateral sclerosis (ALS) diagnostic setting increases, the identification of at-risk family members has also expanded. No practice guidelines specifically for predictive genetic testing exist, and few studies about the psychological impacts of testing in this subgroup have occurred, limiting the ability to tailor recommendations and counseling in this community. We surveyed asymptomatic individuals at risk for inheriting an ALS-associated gene mutation. The 80-question survey was designed using a combination of validated measures (General Anxiety Disorder; FACToR; Decision Regret Scale) and original items. Ninety participants completed the survey, including those who completed predictive genetic testing (N = 42) and those who did not (N = 48). Gene positive individuals experienced greater negativity, uncertainty, and overall psychological impairment (p = 0.002; p < 0.001; p = 0.001). Individuals who had not undergone testing reported thinking about their risk multiple times per day and experiencing more decisional regret than those who tested (p = 0.006). In terms of decision-making, being prepared for potential clinical drug trials was a more important potential benefit among those who underwent testing (p = 0.026). Participants valuing preparedness for clinical drug trials supports the concept that genetic testing for ALS will increase as research in gene-targeted therapeutics progresses. This study describes factors relevant to the genetic testing decision-making process and adaptation to results from the perspective of at-risk individuals, which can ultimately guide genetic counseling practice in this population.

Preimplantation Genetic Testing for Adult-Onset Neurodegenerative Disease: Considerations for Access, Utilization, and Counseling

Preimplantation genetic testing for monogenic conditions (PGT-M), formerly called preimplantation genetic diagnosis, is a specialized assisted reproduction technique that aims to reduce the risk of a pregnancy inheriting a monogenic condition. Despite calls to increase awareness and prepare neurologists for discussing PGT-M with patients and their families, no guidelines currently exist. When introducing PGT-M to those who may be interested in using it, there are major factors for discussion, including (1) genetic considerations (e.g., requirement for a confirmed genetic diagnosis; timing of genetic test results); (2) practical considerations (e.g., access to PGT-M and genetic services); (3) technical considerations (e.g., factors that can affect the success rate of PGT-M); and (4) psychosocial and ethical considerations (e.g., predictive testing for asymptomatic family members; family dynamics and values). Here, our team of neurologists and specialized genetic counselors discusses the current state of genetic characterization in adult-onset neurodegenerative conditions and highlights the major factors that should be considered when discussing PGT-M with families.

Toward genetic counseling practice standards for diagnostic testing in amyotrophic lateral sclerosis and frontotemporal dementia

Objective: Genetic counseling and diagnostic genetic testing are considered part of the multidisciplinary care of individuals with amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). We aimed to investigate the ideal components of genetic counseling for ALS/FTD diagnostic testing amongst various stakeholders using an online, modified Delphi survey. Methods: Experts in genetic counseling and testing for ALS/FTD were purposively then snowball recruited and included genetic health professionals, health professionals outside of genetics and consumer experts (patients, relatives, and staff representatives from ALS/FTD support organizations). First-round items were informed by two systematic literature reviews and qualitative interviews with patients and families who had experienced diagnostic testing. Analysis of each round informed the development of the subsequent round and the final results. Results: Forty-six experts participated in the study, 95.65% completed both rounds. After round one, items were updated based on participant responses and were presented again for consensus in round two. After round two, a high level of consensus (≥80% agreement) was achieved on 16 items covering various topics related to genetic counseling service delivery, before and after diagnostic testing is facilitated. Conclusions: Genetic counseling for individuals with ALS/FTD and their families should include the provision of client-centered counseling, education and support throughout. The items developed are adaptable to varied healthcare settings and may inform a standard of genetic counseling practice for health professionals who facilitate testing and counseling discussions. This area of work is timely, given demand for testing is likely to increase as more genotype-driven clinical trials become available.

Antisense therapies in neurological diseases

Advances in targeted regulation of gene expression allowed new therapeutic approaches for monogenic neurological diseases. Molecular diagnosis has paved the way to personalized medicine targeting the pathogenic roots: DNA or its RNA transcript. These antisense therapies rely on modified nucleotides sequences (single-strand DNA or RNA, both belonging to the antisense oligonucleotides family, or double-strand interfering RNA) to act specifically on pathogenic target nucleic acids, thanks to complementary base pairing. Depending on the type of molecule, chemical modifications and target, base pairing will lead alternatively to splicing modifications of primary transcript RNA or transient messenger RNA degradation or non-translation. The key to success for neurodegenerative diseases also depends on the ability to reach target cells. The most advanced antisense therapies under development in neurological disorders are presented here, at the clinical stage of development, either at phase 3 or market authorization stage, such as in spinal amyotrophy, Duchenne muscular dystrophy, transthyretin-related hereditary amyloidosis, porphyria and amyotrophic lateral sclerosis; or in earlier clinical phase 1 B, for Huntington disease, synucleinopathies and tauopathies. We also discuss antisense therapies at the preclinical stage, such as in some tauopathies, spinocerebellar ataxias or other rare neurological disorders. Each subtype of antisense therapy, antisense oligonucleotides or interfering RNA, has proved target engagement or even clinical efficacy in patients; undisputable recent advances for severe and previously untreatable neurological disorders. Antisense therapies show great promise, but many unknowns remain. Expanding the initial successes achieved in orphan or rare diseases to other disorders will be the next challenge, as shown by the recent failure in Huntington disease or due to long-term preclinical toxicity in multiple system atrophy and cystic fibrosis. This will be critical in the perspective of new planned applications to premanifest mutation carriers, or other non-genetic degenerative disorders such as multiple system atrophy or Parkinson disease.