Clinical and genetic characteristics in patients with Huntington’s Disease from Argentina

Epidemiology of Huntington's Disease in Latin America: A Systematic Review and Meta-Analysis

BACKGROUND

Latin America has played a crucial role in advancing our understanding of Huntington's disease (HD). However, previous global reviews include limited data from Latin America. It is possible that English-based medical search engines may not capture all the relevant studies.

METHODS

We searched databases in Spanish, Portuguese, and English. The names of every country in Latin America in English-based search engines were used to ensure we found any study that had molecular ascertainment and provided general epidemiological information or subpopulation data. Additionally, we contacted experts across the region.

RESULTS

The search strategy yielded 791 citations; 24 studies met inclusion criteria, representing 12 of 36 countries. The overall pooled prevalence was 0.64 per 100,000 (prediction interval, 0.06-7.22); for cluster regions, it was 54 per 100,000 (95% CI, 34.79-84.92); for juvenile HD, it was 8.7% (prediction interval, 5.12-14.35), and 5.9% (prediction interval, 2.72-13.42) for late-onset HD. The prevalence was higher for Mexico, Peru, and Brazil. However, there were no significant differences between Central America and the Caribbean versus South America.

CONCLUSION

The prevalence of HD appears to be similar across Latin America. However, we infer that our findings are underestimates, in part because of limited research and underdiagnosis of HD because of limited access to molecular testing and the availability of neurologists and movement disorders specialists. Future research should focus on identifying pathways to improve access to molecular testing and education and understanding differences among different ancestral groups in Latin America. © 2024 International Parkinson and Movement Disorder Society.

Huntington's Disease in Chile: Epidemiological and Genetic Aspects

INTRODUCTION

Huntington's disease (HD) is a neurodegenerative, autosomal dominant disabling condition due to an expansion of the CAG trinucleotide in the HTT gene. Motor, psychiatric, and cognitive disorders characterize it. Chilean reports on HD in the era of molecular diagnosis were wanted.

METHODS

This is a retrospective analysis of a prospective cohort of patients with HD seen at the Center for Movement Disorders (CETRAM) in Chile between 2013 and 2019. Sociodemographic, genotype, and neuropsychiatric features were investigated.

RESULTS

One hundred three probands with HD were identified. The majority (63.1%) were born in the metropolitan region, followed by the VIII and V regions with 8.73% and 7.76%, respectively. When pedigrees were analyzed, ninety unrelated families encompassing 1,007 individuals were identified; among relatives, other 35 manifested HD, and 106 died of HD. Besides, five hundred seventy-nine individuals were at genetic risk. The minimum estimated prevalence of HD in Chile in 2019 was 0.72 × 100,000 inhabitants. The mean CAG repeats (CAGR) of 47.2 ± 10.74 for the expanded allele and 17.93 ± 2.05 for the normal allele. The mean age of onset was 41.39 ± 13.47 years. Juvenile cases represented 7.8% of this cohort, and 4.9% had a late onset. There was a negative correlation between the age of onset and the CAGR of the expanded allele (r =-0.84 p < 0.0001). Besides, 79.6% had a family history of HD.

CONCLUSIONS

This is the first report characterizing genetics, motor, and neuropsychiatric features in patients with HD in Chile. The mean length of CAGR expansion of the abnormal allele was similar to previous reports in North America (i.e., Mexico and Canada) and higher than that reported in the neighboring country of Argentina. According to previous estimations, the minimal prevalence of HD in Chile may be lower than expected.

Clinical, radiological, and genetic characteristics in patients with Huntington's disease in a Taiwanese cohort

Characteristics of Huntington's disease (HD) differ among various ethnicities. Few studies have explored the relationship between phenotypes and genotypes of HD in Asians. We evaluated the relationship between integrated clinical and imaging phenotypes and genotypes in a Taiwanese HD cohort, enrolling 123 HD patients genetically diagnosed between August 1994 and February 2019. The clinical presentations and brain magnetic resonance imaging characteristics were analyzed from 67 patients and examined the correlation with genetic findings. Chorea was the most common initial manifestation (66.1%), especially in patients with late-onset disease (onset age > 60 years old), followed by psychiatric symptoms (25%) and cognitive impairment (14.3%). Compared to patients with adult-onset HD, the prevalence of parkinsonism was significantly higher in juvenile-onset HD patients (onset age < 20 years old, p = .007). Disease burden, which was measured by CAG repeats and age, was significantly associated with atrophy in caudate nucleus (p = .004), followed by putamen (p = .029), nucleus accumbens (p = .002), thalamus (p = .003), and total cortical volume (p = .001) after correcting for total intracranial volume. Our findings, that provided the first series of Taiwanese HD patients, delineated the clinical, radiological, and genetic characteristics in Asian HD patients.

"Clinical Profile of Genetically Proven Huntington's Disease Patients from Eastern India"

Background and Aims:

To study the clinical profile of genetically proven Huntington's disease (HD) patients from eastern India.

Methods:

This cross sectional study selected patients of HD after genetic confirmation of expanded CAG repeats in Huntingtin (HTT) gene. We performed detail clinical evaluation including cognitive and neuropsychological assessment, and imaging of brain.

Results:

This study included 75 patients (male: 57.3%; female: 42.7%). Mean age at onset was 37.12 (range 16-62) years; juvenile variety (onset below 20 years) was detected in 5.3%. Paternal transmission was commoner. Manifestations at onset were motor in 81.3% patients, behavioral in 10.7% and cognitive impairment in 8%. After chorea, next common movement disorder was dystonia. Frontal lobe dysfunction was found in 77.3% patients. Behavioral disturbances were observed in 77.3% patients and commonly manifested as depression, irritable behavior and anxiety. Among the three onset groups (motor/behavioral/cognitive), there was no significant difference regarding age at onset, gender distribution, pattern of inheritance (paternal/maternal), and at the time of evaluation, all groups had essentially similar pattern of clinical features. Mean CAG repeat of the patients was 48.25 (range 40-79). Our study showed some differing clinical characteristics compared to previous studies from the Indian subcontinent.

Conclusion:

Clinical features in our study showed differences from previous studies from the Indian subcontinent. We had more cognitive-onset patients. However, behavioral onset was lower in our study. Motor, behavioral and cognitive onset groups of HD were comparable regarding demographics, family history, CAG repeat lengths and major clinical features at the time of evaluation.

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.

Deficits in temporal processing correlate with clinical progression in Huntington's disease

OBJECTIVES

Precise temporal performance is crucial for several complex tasks. Time estimation in the second-to-minutes range-known as interval timing-involves the interaction of the basal ganglia and the prefrontal cortex via dopaminergic-glutamatergic pathways. Patients with Huntington's disease (HD) present deficits in cognitive and motor functions that require fine control of temporal processing. The objective of the present work was to assess temporal cognition through a peak-interval time (PI) production task in patients with HD and its potential correlation with the Unified Huntington's Disease Rating Scale (UHDRS).

MATERIALS AND METHODS

Patients with molecular diagnosis of HD and controls matched by age, sex and educational level (n=18/group) were tested for interval timing in short- (3 seconds), medium- (6 seconds) and long (12 seconds)-duration stimuli.

RESULTS

Significant differences were observed in the PI task, with worse performance in HD compared to controls. Patients underestimated real time (left-shifted Peak location) for 6- and 12-second intervals (P<.05) and presented decreased temporal precision for all the intervals evaluated (P<.01). Importantly, a significant correlation was found between time performance and the UHDRS (P<.01). Patients' responses also deviated from the scalar property.

CONCLUSIONS

Our results contribute to support that timing functions are impaired in HD in correlation with clinical deterioration. Recordings of cognitive performance related to timing could be a potential useful tool to measure the neurodegenerative progression of movement disorder-related pathologies.

Study of the Huntington's disease IT-15 gene in different ethnic groups in Ecuador

This study aims to establish the current state of the IT-15 (HTT) gene in different Ecuadorian ethnic groups and patients by determining CAG triplet repeats, compared with the ethnicity of individuals. A total of 412 individuals were studied using nested polymerase chain reaction and Sanger sequencing: 75 individuals were indigenous (Kichwas), 211 mestizos, and 65 Afro-Ecuadorians. We included 31 patients who were clinically diagnosed with Huntington's disease (HD) and relatives of the affected patients (n = 30). Moreover, we correlated the presence of HD in Ecuadorian patients with 46 genetic ancestry-informative insertion-deletion polymorphic markers. We found that 77.20% had <28 CAG repetitions, 18.80% had mutable alleles, 2.27% had incomplete penetrance, and 1.70% reflected >39 repetitions. The average of CAG repetitions was 24 ± 3 for indigenous people; 28 ± 2 for mestizos; and 24 ± 3.2 repetitions for the Afro-Ecuadorians. The ancestral component showed that the main ancestry corresponded to Native Americans (0.873) and European ascendants (0.145), Africans were less represented in the evaluated population (0.018). There was a significant difference between the number of CAG repeats in mestizos and indigenous people (P < .01), suggesting that the Ecuadorian mestizo population has a risk factor for the gene mutation.

The global prevalence of Huntington's disease: a systematic review and discussion

The ascertained prevalence of Huntington's disease (HD) increased significantly following the provision of diagnostic testing. A systematic review was conducted to estimate the prevalence of HD in the post-diagnostic testing era. 22 studies with original data pertaining to the prevalence of HD (1993-2015) were included and analyzed. A global meta-analysis was not performed due to heterogeneity in study methods and geographical variation. The prevalence of HD is significantly lower in Asian populations compared with western Europe, North America and Australia. The global variation in HD prevalence is partly explained by the average CAG repeat lengths and frequency of different HTT gene haplotypes in the general population. Understanding the prevalence of HD has significant implications for healthcare resource planning.

Juvenile Huntington disease in Argentina

We analyzed demographic, clinical and genetic characteristics of juvenile Huntington disease (JHD) and it frequency in an Argentinean cohort. Age at onset was defined as the age at which behavioral, cognitive, psychiatric or motor abnormalities suggestive of JHD were first reported. Clinical and genetic data were similar to other international series, however, in this context we identified the highest JHD frequency reported so far (19.72%; 14/71). Age at onset of JHD is challenging and still under discussion. Our findings reinforce the hypothesis that clinical manifestations, other than the typical movement disorder, may anticipate age at onset of even many years. Analyses of JHD cohorts are required to explore it frequency in populations with different backgrounds to avoid an underestimation of this rare phenotype. Moreover, data from selected populations may open new pathways in therapeutic approaches and may explain new potential correlations between HD presentations and environmental or biological factors.

Genetic aspects of Huntington's disease in Latin America. A systematic review

We aimed to present a systematic review on Huntington's disease (HD) in Latin America (LA). PubMed and LILACS were searched up to March 2015, reporting confirmed HD cases in LA. Case series, cross-sectional, case-control, and prospective studies were included. From 534 communications, 47 were eligible. Population-based studies were not found; minimal prevalence of 0.5-4/100,000 was estimated for Venezuela and Mexico. Geographical isolates were well characterized in Venezuela and in Peru. CAG repeats at HTT gene varied between 7-33 and 37-112 in normal and expanded alleles, respectively. Intermediate alleles were found in 4-10% of controls. Ages at onset and the expanded CAG repeats correlated with r from - 0.55 to -0.91. While haplotype patterns of Venezuelan and Brazilian chromosomes were similar to those observed in Europeans, haplotypes from Peruvian HD patients did not match the same pattern. The limited number of papers found suggests that HD is poorly diagnosed in LA. Minimal prevalence seemed to be halfway between those of Caucasians and Asians. Range of CAG repeats was similar to those of Europeans. Haplotype studies indicate that majority of HD patients might be of Caucasian descent; an Asian origin for some Peruvian patients was proposed.

Differential diagnosis of Huntington's disease: what the clinician should know

Huntington's disease (HD), an autosomal-dominant illness caused by an expansion of the CAG repeats on the short arm of chromosome 4, is clinically characterized by a combination of movement disorders, cognitive decline and behavioral changes. HD accounts for 90-99% of patients who present with this clinical picture. The remaining patients that are negative for the HD genetic mutation are said to have HD phenocopies. Autosomal-dominant diseases that can mimic HD are HD-like 2, C9orf72 mutations, spinocerebellar ataxia type 2, spinocerebellar ataxia type 17 (HD-like 4), benign hereditary chorea, neuroferritinopathy (neurodegeneration with brain iron accumulation type 3), dentatorubropallidoluysian atrophy and HD-like 1. There are also autosomal-recessive choreas that can be HD phenocopies: Friedreich's ataxia, neuroacanthocytosis, several forms of neurodegeneration with brain iron accumulation, ataxia telangiectasia, HD-like 3 and ataxia with oculomotor apraxia. Among X‑linked conditions, McLeod syndrome can mimic the clinical features of HD. Although less frequently, sporadic conditions, such as tardive dyskinesia and non-Wilsonian hepatolenticular degeneration, can also mimic HD.

Trinucleotide repeats and haplotypes at the huntingtin locus in an Indian sample overlaps with European haplogroup a

Huntington's disease (HD), an autosomal dominant neurodegenerative syndrome, has a world-wide distribution. An estimated 2.5-10/100,000 people of European ancestry are affected with HD, while the Asian populations have lower prevalence (0.6-3.8/100,000). The epidemiology of HD is not well described in India, and the distribution of the pathogenic CAG expansion, and the associated haplotype, in this population needs to be better understood. This study demonstrates a distribution of CAG repeats, at the HTT locus, comparable to the European population in both normal and HD affected chromosomes. Further, we provide an evidence for similarity of the HD halpotype in Indian sample to the European HD haplogroup.

Examination of Huntington's disease in a Chinese family

We report brain imaging and genetic diagnosis in a family from Wuhan, China, with a history of Huntington's disease. Among 17 family members across three generations, four patients (II2, II6, III5, and III9) show typical Huntington's disease, involuntary dance-like movements. Magnetic resonance imaging found lateral ventricular atrophy in three members (II2, II6, and III5). Moreover, genetic analysis identified abnormally amplified CAG sequence repeats (> 40) in two members (III5 and III9). Among borderline cases, with clinical symptoms and brain imaging features of Huntington's disease, two cases were identified (II2 and II6), but shown by mutation analysis for CAG expansions in the important transcript 15 gene, to be non-Huntington's disease. Our findings suggest that clinical diagnosis of Huntington's disease requires a combination of clinical symptoms, radiological changes, and genetic diagnosis.