Two decades of Huntington disease testing: patient's demographics and reproductive choices

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.

Impact of Huntington Disease Gene-Positive Status on Pre-Symptomatic Young Adults and Recommendations for Genetic Counselors

Huntington disease (HD) is an autosomal dominant, progressive neurodegenerative disorder for which there is no cure. Predictive testing for HD is available to asymptomatic at-risk individuals. Approximately half of the population undergoing predictive testing for HD consists of young adults (≤35 years old). Finishing one's education, starting a career, engaging in romantic relationships and becoming a parent are key milestones of young adulthood. We conducted a qualitative study to explore how testing gene-positive for HD influences young adults' attainment of these milestones, and to identify major challenges that pre-symptomatic young adults face to aid the development of targeted genetic counseling. Results of our study demonstrate that 1) knowing one's gene-positive status results in an urgency to reach milestones and positively changes young adults' approach to life; 2) testing positive influences young adults' education and career choices, romantic relationships, and family planning; 3) young adults desire flexible and tailored genetic counseling to address needs and concerns unique to this population. Findings of this study contribute to the understanding of the impact of predictive testing for HD on young adults, and highlight issues unique to this population that call for further research, intervention and advocacy.

Gene worlds

Drawing from a critical sociology of knowledge perspective, we situate the production of genetic information within relevant political, financial, and professional contexts. We consider as well the broad range of social conditions that render genetic knowledge salient in clinical settings and for population health. This sociological analysis of genetic knowledge highlights how genetic knowledge flourishes and shapes social environments and how in turn environments select for particular forms of genetic knowledge. We examine the role of the laboratory, regulatory state, and social movements in the production of genetic knowledge and the clinic, family, and population health as critical sites where genetic knowledge becomes actionable.

Genetic testing preferences in families containing multiple individuals with epilepsy

OBJECTIVE

To examine genetic testing preferences in families containing multiple individuals with epilepsy.

METHODS

One hundred forty-three individuals with epilepsy and 165 biologic relatives without epilepsy from families containing multiple affected individuals were surveyed using a self-administered questionnaire. Four genetic testing scenarios were presented, defined by penetrance (100% vs. 50%) and presence or absence of clinical utility. Potential predictors of genetic testing preferences were evaluated using generalized estimating equations with robust Poisson regression models. The influence of 21 potential testing motivations was also assessed.

RESULTS

For the scenario with 100% penetrance and clinical utility, 85% of individuals with epilepsy and 74% of unaffected relatives responded that they would definitely or probably want genetic testing. For the scenario with 100% penetrance but without clinical utility, the proportions who responded that they would want testing were significantly lower in both affected individuals (69%) and unaffected relatives (57%). Penetrance (100% vs. 50%) was not a significant predictor of genetic testing interest. The highest-ranking motivations for genetic testing were the following: the possibility that the results could improve health or health care, the potential to know if epilepsy in the family is caused by a gene, and the possibility of changing behavior or lifestyle to prevent seizures.

SIGNIFICANCE

Interest in epilepsy genetic testing may be high in affected and unaffected individuals in families containing multiple individuals with epilepsy, especially when testing has implications for improving clinical care.