Presentation and care of a family with Huntington disease in a resource-limited community

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.

Childhood-Onset Spinocerebellar Ataxia 3: Tongue Dystonia as an Early Manifestation

Background

Dystonia is a relatively common feature of spinocerebellar ataxia 3 (SCA3). Childhood onset of SCA3 is rare and typically associated with either relatively large, or homozygous, CAG repeat expansions.

Case report

We describe a 10-year-old girl with SCA3, who presented with tongue dystonia in addition to limb dystonia and gait ataxia due to a heterozygous expansion of 84 repeats in ATXN3.

Discussion

Diagnosis of the SCAs can be challenging, and even more so in children. Tongue dystonia has not previously been documented in SCA3.

Diagnosis of Spinocerebellar Ataxia in the West Indies

Background

Access to medical care in many regions is limited by socioeconomic status, at both the individual and the community level. This report describes the diagnostic process of a family residing on an underserved Caribbean island where routine neurological care is typically addressed by general practitioners, and genetic diagnosis is not available through regular medical channels. The diagnosis and management of neurodegenerative disorders is especially challenging in this setting.

Case Report

We diagnosed a family with spinocerebellar ataxia type 3 (SCA3) in an underdeveloped nation with limited access to genetic medicine and no full-time neurologist.

Discussion

Molecular diagnosis of the SCAs can be challenging, even in developed countries. In the Caribbean, genetic testing is generally only available at a small number of academic centers. Diagnosis in this family was ultimately made by utilizing an international, pro bono, research-based collaborative process. Although access to appropriate resources, such as speech, physical, and occupational therapies, is limited on this island because of economic and geographical factors, the provision of a diagnosis appeared to be ultimately beneficial for this family. Identification of affected families highlights the need for access to genetic diagnosis in all communities, and can help direct resources where needed.

Huntington's disease-like disorders in Latin America and the Caribbean

Diseases with a choreic phenotype can be due to a variety of genetic etiologies. As testing for Huntington's disease (HD) becomes more available in previously resource-limited regions, it is becoming apparent that there are patients in these areas with other rare genetic conditions which cause an HD-like phenotype. Documentation of the presence of these conditions is important in order to provide appropriate diagnostic and clinical care for these populations. Information for this article was gathered in two ways; the literature was surveyed for publications reporting a variety of genetic choreic disorders, and movement disorders specialists from countries in Latin America and the Caribbean were contacted regarding their experiences with chorea of genetic etiology. Here we discuss the availability of molecular diagnostics for HD and for other choreic disorders, along with a summary of the published reports of affected subjects, and authors' personal experiences from the regions. While rare, patients affected by non-HD genetic choreas are evidently present in Latin America and the Caribbean. HD-like 2 is particularly prevalent in countries where the population has African ancestry. The incidence of other conditions is likely determined by other variations in ethnic background and settlement patterns. As genetic resources and awareness of these disorders improve, more patients are likely to be identified, and have the potential to benefit from education, support, and ultimately molecular therapies.