Huntington's disease

Role of Sirtuins in Physiology and Diseases of the Central Nervous System

Silent information regulators, sirtuins (SIRTs), are a family of enzymes which take part in major posttranslational modifications of proteins and contribute to multiple cellular processes, including metabolic and energetic transformations, as well as regulation of the cell cycle. Recently, SIRTs have gained increased attention as the object of research because of their multidirectional activity and possible role in the complex pathomechanisms underlying human diseases. The aim of this study was to review a current literature evidence of SIRTs' role in the physiology and pathology of the central nervous system (CNS). SIRTs have been demonstrated to be crucial players in the crosstalk between neuroinflammation, neurodegeneration, and metabolic alterations. The elucidation of SIRTs' role in the background of various CNS diseases offers a chance to define relevant markers of their progression and promising candidates for novel therapeutic targets. Possible diagnostic and therapeutic implications from SIRTs-related investigations are discussed, as well as their future directions and associated challenges.

Management of information within Portuguese families with Huntington disease: a transgenerational process for putting the puzzle together

Huntington disease (HD) is a rare progressive neurological disease, with no cure, inherited in an autosomal dominant fashion, significantly impacting family relations, health and well-being. So far, no studies have reported how Portuguese families deal with information about HD, from a transgenerational perspective. This qualitative study aims to fill in that gap, and focuses on how families acquire knowledge about HD and management of information within the family and in their social relationships. The study adopted semi-structured interviews with 10 participants from HD families. Interviews were transcribed and analysed thematically. Findings suggested that management of information in the family started with the search for a diagnosis in an affected family member. Diagnosis led to a process of "making sense of HD in the family", which activated a transgenerational process to understand HD in the family context, marked by improved awareness and different ways family members manage it (closedness and openness). These results should be relevant for health-care professionals, bringing further insight into the process of acquiring knowledge about HD, and highlighting the relevance of continued efforts for enhanced pre- and post-test counselling and ongoing support to the HD families.

Laser Evoked Potentials in Early and Presymptomatic Huntington's Disease

Pain was rarely studied in Huntington's disease (HD). We presently aimed to extend our previous study on pain pathways functions by laser evoked potentials (LEPs) to a larger cohort of early unmedicated HD patients and a small group of presymptomatic HD (PHD) subjects. Forty-two early HD patients, 10 PHD patients, and 64 controls were submitted to LEPs by right-hand stimulation. Two series of 30 laser stimuli were delivered, and artifact-free responses were averaged. The N1, N2, and P2 latencies were significantly increased and the N2P2 amplitude significantly reduced in HD patients compared to controls. In the HD group, the LEPs abnormalities correlated with functional decline. PHD subjects showed a slight and insignificant increase in LEPs latencies, which was inversely correlated with the possible age of HD clinical onset. Data of the present study seem to suggest that the functional state of nociceptive pathways as assessed by LEPs may be a potential biomarker of disease onset and progression. The assessment of pain symptoms in premanifest and manifest HD may also open a new scenario in terms of subtle disturbances of pain processing, which may have a role in the global burden of the disease.

Speech in spinocerebellar ataxia

Spinocerebellar ataxias (SCAs) are a heterogeneous group of autosomal dominant cerebellar ataxias clinically characterized by progressive ataxia, dysarthria and a range of other concomitant neurological symptoms. Only a few studies include detailed characterization of speech symptoms in SCA. Speech symptoms in SCA resemble ataxic dysarthria but symptoms related to phonation may be more prominent. One study to date has shown an association between differences in speech and voice symptoms related to genotype. More studies of speech and voice phenotypes are motivated, to possibly aid in clinical diagnosis. In addition, instrumental speech analysis has been demonstrated to be a reliable measure that may be used to monitor disease progression or therapy outcomes in possible future pharmacological treatments. Intervention by speech and language pathologists should go beyond assessment. Clinical guidelines for management of speech, communication and swallowing need to be developed for individuals with progressive cerebellar ataxia.

The personal experience of parenting a child with juvenile Huntington's disease: perceptions across Europe

The study reported here presents a detailed description of what it is like to parent a child with juvenile Huntington's disease in families across four European countries. Its primary aim was to develop and extend findings from a previous UK study. The study recruited parents from four European countries: Holland, Italy, Poland and Sweden,. A secondary aim was to see the extent to which the findings from the UK study were repeated across Europe and the degree of commonality or divergence across the different countries. Fourteen parents who were the primary caregiver took part in a semistructured interview. These were analyzed using an established qualitative methodology, interpretative phenomenological analysis. Five analytic themes were derived from the analysis: the early signs of something wrong; parental understanding of juvenile Huntington's disease; living with the disease; other people's knowledge and understanding; and need for support. These are discussed in light of the considerable convergence between the experiences of families in the United Kingdom and elsewhere in Europe.

Targeting sirtuin-1 in Huntington's disease: rationale and current status

Huntington's disease (HD) is an autosomal dominant hereditary disease caused by a trinucleotide repeat mutation in the huntingtin gene that results in an increased number of glutamine residues in the N terminus of huntingtin protein. Mutant huntingtin leads to progressive impairment of motor function, cognitive dysfunction, and neuropsychiatric disturbance. There are no disease-modifying treatments available. During the past decade, sirtuin-1 (SIRT1) has been the focus of intense investigation and discussion because it regulates longevity in multiple organisms and has shown beneficial effects in a variety of models of neurodegenerative disorders. Studies in different animal models provide convincing evidence that SIRT1 protects neurons in mouse models of HD as well as in Caenorhabditis elegans, although controversial results were reported in a fly model. Indeed, many connections exist between the deacetylation function of SIRT1 and its role in neuroprotection. As a result, pharmacological interventions targeting SIRT1 might become promising strategies to combat HD. This review summarizes recent progress in SIRT1 research, with a focus on the specificity of this protein as a potential therapeutic target for HD, as well as existing challenges for developing SIRT1 modulators for clinical use.

Neuroprotective effects of PPAR-γ agonist rosiglitazone in N171-82Q mouse model of Huntington's disease

Huntington's disease (HD) is a devastating genetic neurodegenerative disease caused by CAG trinucleotide expansion in the exon-1 region of the huntingtin gene. Currently, no cure is available. It is becoming increasingly apparent that mutant Huntingtin (HTT) impairs metabolic homeostasis and causes transcriptional dysregulation. The peroxisome proliferator-activated receptor gamma (PPAR-γ) is a transcriptional factor that plays a key role in regulating genes involved in energy metabolism; recent studies demonstrated that PPAR-γ activation prevented mitochondrial depolarization in cells expressing mutant HTT and attenuated neurodegeneration in various models of neurodegenerative diseases. PPAR-γ-coactivator 1α (PGC-1 α) transcription activity is also impaired by mutant HTT. We now report that the PPAR-γ agonist, rosiglitazone (RSG), significantly attenuated mutant HTT-induced toxicity in striatal cells and that the protective effect of RSG is mediated by activation of PPAR-γ. Moreover, chronic administration of RSG (10 mg/kg/day, i.p) significantly improved motor function and attenuated hyperglycemia in N171-82Q HD mice. RSG administration rescued brain derived neurotrophic factor(BDNF) deficiency in the cerebral cortex, and prevented loss of orexin-A-immunopositive neurons in the hypothalamus of N171-82Q HD mice. RSG also prevented PGC-1α reduction and increased Sirt6 protein levels in HD mouse brain. Our results suggest that modifying the PPAR-γ pathway plays a beneficial role in rescuing motor function as well as glucose metabolic abnormalities in HD.

The Prevalence of Juvenile Huntington's Disease: A Review of the Literature and Meta-Analysis

Juvenile Huntington's disease (JHD) is usually defined as Huntington's disease with an onset ≤ 20 years. The proportion of JHD cases reported in studies of Huntington's disease (HD) varies. A review of the literature found 62 studies that reported the proportion of JHD cases amongst all HD cases. The proportion of JHD cases in these studies ranged from 1% to 15%, and in a meta-analysis the pooled proportion of JHD cases was 4.92% (95% confidence interval of 4.07% to 5.84%). Limiting the analysis to the 25 studies which used multiple methods of ascertainment resulted in a similar pooled proportion of 5.32%, (95% confidence interval 4.18% to 6.60%). A small difference was observed when the meta-analysis was restricted to studies from countries defined by the World Bank as high income, that used multiple methods of ascertainment, and that were conducted since 1980 (4.81%, 95% confidence interval 3.31% to 6.58%, n=11). This contrasts with the pooled result from three post 1980 studies using multiple methods of ascertainment from South Africa and Venezuela, defined by the World Bank as upper middle income, where the estimated mean proportion was 9.95%, (95% confidence interval 6.37% to 14.22%). These results, which are expected to be more robust than those from a single study alone, may be helpful in estimating the proportion of JHD cases in a given population. Key Words: Juvenile Huntington's disease, prevalence, epidemiology.