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

Hereditary transthyretin amyloidosis overview

Hereditary amyloidogenic transthyretin (ATTRv) amyloidosis is a rare autosomal dominantly inherited disorder caused by mutations in the transthyretin (TTR) gene. The pathogenetic model of ATTRv amyloidosis indicates that amyloidogenic, usually missense, mutations destabilize the native TTR favouring the dissociation of the tetramer into partially unfolded species that self-assemble into amyloid fibrils. Amyloid deposits and monomer-oligomer toxicity are the basis of multisystemic ATTRv clinical involvement. Peripheral nervous system (autonomic and somatic) and heart are the most affected sites. In the last decades, a better knowledge of pathomechanisms underlying the disease led to develop novel and promising drugs that are rapidly changing the natural history of ATTRv amyloidosis. Thus, clinicians face the challenge of timely diagnosis for addressing patients to appropriate treatment. As well, the progressive nature of ATTRv raises the issue of presymptomatic testing and risk management of carriers. The main aim of this review was to focus on what we know about ATTRv so far, from pathogenesis to clinical manifestations, diagnosis and hence patient's monitoring and treatment, and from presymptomatic testing to management of carriers.

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.

Recommendations for pre-symptomatic genetic testing for hereditary transthyretin amyloidosis in the era of effective therapy: a multicenter Italian consensus

Hereditary transthyretin amyloidosis (ATTRv, v for variant) is a late-onset, autosomal dominant disease caused by progressive extracellular deposition of transthyretin amyloid fibrils, leading to organ damage and death. For other late-onset fatal diseases, as Huntington’s disease, protocols for pre-symptomatic genetic testing (PST) are available since decades. For ATTRv, limited experience has been reported to date, mostly gathered before the availability of approved therapies. We aimed at developing recommendations for a safe and feasible PST protocol in ATTRv in the era of emerging treatments, taking also into account Italian patients’ characteristics and healthcare system rules. After an initial survey on ongoing approaches to PST for ATTRv in Italy, two roundtable meetings were attended by 24 experts from 16 Italian centers involved in the diagnosis and care of this disease. Minimal requirements for PST offer and potential critical issues were highlighted. By November 2019, 457 families affected by ATTRv with 209 molecularly confirmed pre-symptomatic carriers were counted. The median age at PST was 41.3 years of age, regardless of the specific mutation. Half of the Italian centers had a multidisciplinary team, including a neurologist, an internist, a cardiologist, a medical geneticist and a psychologist, although in most cases not all the specialists were available in the same center. A variable number of visits was performed at each site. Experts agreed that PST should be offered only in the context of genetic counselling to at risk individuals aged 18 or older. Advertised commercial options for DNA testing should be avoided. The protocol should consist of several steps, including a preliminary clinical examination, a pre-test information session, an interval time, the genetic test and a post-test session with the disclosure of the test results, in the context of an experienced multidisciplinary team. Recommendations for best timing were also defined. Protocols for PST in the context of ATTRv can be refined to offer at risk individuals the best chance for early diagnosis and timely treatment start, while respecting autonomous decisions and promoting safe psychological adjustment to the genetic result.

Predictive Genetic Counseling for Neurodegenerative Diseases: Past, Present, and Future

Predictive genetic counseling for neurodegenerative diseases commenced with Huntington's disease (HD). Because the psychological issues and outcomes have been best studied in HD, the HD genetic counseling and testing protocol is still accepted as the gold standard for genetic counseling for these diseases. Yet, advances in genomic technology have produced an abundance of new information about the genetics of diseases such as Alzheimer's disease, frontotemporal dementia, amyotrophic lateral sclerosis, and Parkinson's disease. The resulting expansion of genetic tests together with the availability of direct-to-consumer testing and clinical trials for treatment of these diseases present new ethical and practical issues requiring modifications to the protocol for HD counseling and new demands on both physicians and genetic counselors. This work reviews the history of genetic counseling for neurodegenerative diseases, its current practice, and the future direction of genetic counseling for these conditions.

Predictive genetic testing in Huntington's disease: should a neurologist be involved?

International guidelines on Huntington's Disease recommend neurological examination in the predictive testing trajectory. Experiences and personal wishes of persons at risk of Huntington's Disease regarding this topic have never been evaluated. The objective was to provide an overview of the experiences of Dutch at-risk persons, opting for predictive testing, in consulting a neurologist before and after DNA analysis. Persons who were counseled in four Dutch clinics between 2017 and 2019 were retrospectively or prospectively approached for a questionnaire which listed topics as experiences with consultation and personal wishes. From 71 participants, 44 participants visited a neurologist. 41 participants indicated their visit to a neurologist as positive (93.2%). The majority of participants (n = 59) desired consulting a neurologist. Thirty-two participants indicated consultation shortly after (Desired After Group) and twenty-seven before DNA analysis (Desired Before Group) as personal wish. The Desired Before Group consisted of a significantly higher number of participants who actually consulted a neurologist before predictive testing (n = 26) compared with the number of participants who actually consulted a neurologist after DNA analysis in the Desired After Group (n = 11) (p < 0.001). The Desired After Group (n = 19) had a significantly higher number of Huntington's disease gene expansion carriers compared with the Desired Before Group (n = 5) (p 0.003). Participants are content with consultation. However, persons without the gene expansion still feel the need to get in touch with a neurologist. Therefore, offering a consultation with a neurologist before DNA analysis might be beneficial for all.

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.

Investigating the role of genetic counseling in neuromuscular disease considering life events

Genetic diagnoses are becoming a routine in the medical practice of neuromuscular diseases. Many diagnoses, however, can have an influence on relatives and family members and thus must be handled carefully by genetic counseling (GC). Here, we aimed to assess the purpose of undergoing GC to verify the utility of collaborations between clinical and genetic divisions. We investigated consecutive GC cases of neuromuscular disease and examined the role of GC. Our study included 102 cases who underwent GC in our hospital from July 2005 to March 2018: 86.3% were women and 45.1% were in their 30's. Disease explanation was the most common reason for attending GC (29.4%), followed by prenatal diagnosis (25.5%), pre-symptomatic diagnosis (17.6%), and carrier diagnosis (14.7%). Clients typically visited the hospital for GC when some kind of life event occurred, such as marriage, had a desire to bear a child, or a change in the condition of the proband. Clinicians should be conscious of such life events from the perspective of both the client and their relatives, and guide the GC at an appropriate time. Overall, the degree of recognition of genetic risk by clients differed; thus, it is important for GC to determine the status of each unique situation and respond individually.

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.