AbstractHuntington disease (HD) is an autosomal dominant neurodegenerative disorder characterized by motor, behavioral, and cognitive manifestations. It is caused by an expansion of a trinucleotide ...repeat in the huntingtin gene ( HTT) on chromosome 4. Although disease onset is currently clinically defined by motor signs, the presence of non-motor symptoms prior to motor diagnosis is increasingly recognized. Complex multimodal symptoms adversely affect quality of life and longevity of patients. Thoughtful interdisciplinary symptomatic care can make a major positive impact for patients and families. A variety of symptomatic treatments are currently available, and new symptomatic and potentially disease modifying therapies are being actively developed. Functional and quality of life outcome measures can be used to assess efficacy of clinical interventions. These outcomes along with clinical data and novel longitudinal biomarkers are increasingly utilized in clinical trials, particularly those testing disease-modifying therapeutics. Recent advances in novel therapeutic strategies, including targeting mutant huntingtin (HTT) and the HTT gene, promise another wave of disease-modifying trials in the near future. Better appreciation of heterogeneous clinical phenomenology and immediate tractable treatment goals coupled with advances in new therapeutics heralds a golden age of HD treatment that will positively impact quality of life and longevity of HD patients and inform advances in other inherited and neurodegenerative neurological disorders.
One of the roadblocks to developing effective therapeutics for Huntington disease (HD) is the lack of animal models that develop progressive clinical traits comparable to those seen in patients. Here ...we report a longitudinal study that encompasses cognitive and motor assessment, and neuroimaging of a group of transgenic HD and control monkeys from infancy to adulthood. Along with progressive cognitive and motor impairment, neuroimaging revealed a progressive reduction in striatal volume. Magnetic resonance spectroscopy at 48 months of age revealed a decrease of N-acetylaspartate (NAA), further suggesting neuronal damage/loss in the striatum. Postmortem neuropathological analyses revealed significant neuronal loss in the striatum. Our results indicate that HD monkeys share similar disease patterns with HD patients, making them potentially suitable as a preclinical HD animal model.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Purpose of Review
Expanding therapeutic targets from proteins to RNAs opens up new possibilities for neurodegenerative disorders therapeutics development. Recently, a disease-modifying antisense ...oligonucleotide (ASO) agent was approved for spinal muscular atrophy, suggesting ASOs will fulfill their early promise and become a significant new therapeutic category for neurodegenerative disorders.
Recent Findings
ASOs are in human subjects testing for Huntington disease, monogenic forms of amyotrophic lateral sclerosis, Alzheimer disease, myotonic dystrophy, Leber congenital amaurosis, Usher syndrome, and retinitis pigmentosum, with many more in preclinical development. Current ASO strategies encompass RNA processing modulation, and RNA target breakdown. Broad ASO mechanism categories are protein restoring versus protein lowering. Individual ASO mechanisms of action range from mutation-specific to impacting many proteins.
Summary
Current ASOs show great promise in neurodegenerative disorders. Specific ASO designs and mechanisms may be more tenable in this disease area. Preclinical development is already leveraging early knowledge from these initial clinical trials to develop novel ASO cocktails, new ASO chemical modifications, and new ASO RNA and protein targets.
Exposure of rats to the pesticide and complex I inhibitor rotenone reproduces features of Parkinson's disease, including selective nigrostriatal dopaminergic degeneration and alpha-synuclein-positive ...cytoplasmic inclusions (Betarbet et al., 2000; Sherer et al., 2003). Here, we examined mechanisms of rotenone toxicity using three model systems. In SK-N-MC human neuroblastoma cells, rotenone (10 nm to 1 microm) caused dose-dependent ATP depletion, oxidative damage, and death. To determine the molecular site of action of rotenone, cells were transfected with the rotenone-insensitive single-subunit NADH dehydrogenase of Saccharomyces cerevisiae (NDI1), which incorporates into the mammalian ETC and acts as a "replacement" for endogenous complex I. In response to rotenone, NDI1-transfected cells did not show mitochondrial impairment, oxidative damage, or death, demonstrating that these effects of rotenone were caused by specific interactions at complex I. Although rotenone caused modest ATP depletion, equivalent ATP loss induced by 2-deoxyglucose was without toxicity, arguing that bioenergetic defects were not responsible for cell death. In contrast, reducing oxidative damage with antioxidants, or by NDI1 transfection, blocked cell death. To determine the relevance of rotenone-induced oxidative damage to dopaminergic neuronal death, we used a chronic midbrain slice culture model. In this system, rotenone caused oxidative damage and dopaminergic neuronal loss, effects blocked by alpha-tocopherol. Finally, brains from rotenone-treated animals demonstrated oxidative damage, most notably in midbrain and olfactory bulb, dopaminergic regions affected by Parkinson's disease. These results, using three models of increasing complexity, demonstrate the involvement of oxidative damage in rotenone toxicity and support the evaluation of antioxidant therapies for Parkinson's disease.
A two-year longitudinal study composed of morphometric MRI measures and cognitive behavioral evaluation was performed on a transgenic Huntington's disease (HD) monkey. rHD1, a transgenic HD monkey ...expressing exon 1 of the human gene encoding huntingtin (HTT) with 29 CAG repeats regulated by a human polyubiquitin C promoter was used together with four age-matched wild-type control monkeys. This is the first study on a primate model of human HD based on longitudinal clinical measurements.
Changes in striatal and hippocampal volumes in rHD1 were observed with progressive impairment in motor functions and cognitive decline, including deficits in learning stimulus-reward associations, recognition memory and spatial memory. The results demonstrate a progressive cognitive decline and morphometric changes in the striatum and hippocampus in a transgenic HD monkey.
This is the first study on a primate model of human HD based on longitudinal clinical measurements. While this study is based a single HD monkey, an ongoing longitudinal study with additional HD monkeys will be important for the confirmation of our findings. A nonhuman primate model of HD could complement other animal models of HD to better understand the pathogenesis of HD and future development of diagnostics and therapeutics through longitudinal assessment.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We conducted a genome-wide association study of essential tremor, a common movement disorder characterized mainly by a postural and kinetic tremor of the upper extremities. Twin and family history ...studies show a high heritability for essential tremor. The molecular genetic determinants of essential tremor are unknown. We included 2807 patients and 6441 controls of European descent in our two-stage genome-wide association study. The 59 most significantly disease-associated markers of the discovery stage were genotyped in the replication stage. After Bonferroni correction two markers, one (rs10937625) located in the serine/threonine kinase STK32B and one (rs17590046) in the transcriptional coactivator PPARGC1A were associated with essential tremor. Three markers (rs12764057, rs10822974, rs7903491) in the cell-adhesion molecule CTNNA3 were significant in the combined analysis of both stages. The expression of STK32B was increased in the cerebellar cortex of patients and expression quantitative trait loci database mining showed association between the protective minor allele of rs10937625 and reduced expression in cerebellar cortex. We found no expression differences related to disease status or marker genotype for the other two genes. Replication of two lead single nucleotide polymorphisms of previous small genome-wide association studies (rs3794087 in SLC1A2, rs9652490 in LINGO1) did not confirm the association with essential tremor.
IMPORTANCE: Tetrabenazine is efficacious for chorea control; however, tolerability concerns exist. Deutetrabenazine, a novel molecule that reduces chorea, was well tolerated in a double-blind, ...placebo-controlled study. OBJECTIVES: To evaluate the safety and explore the efficacy of conversion from tetrabenazine to deutetrabenazine in patients with chorea associated with Huntington disease (HD). DESIGN, SETTING, AND PARTICIPANTS: In this ongoing, open-label, single-arm study that started on December 21, 2013, 37 patients at 13 Huntington Study Group sites in the United States and Australia who were taking stable doses of tetrabenazine that provided a therapeutic benefit were switched overnight to deutetrabenazine therapy. After week 1, the deutetrabenazine dose was titrated on a weekly basis for optimal chorea control. INTERVENTIONS: Deutetrabenazine administration at a dosage thought to provide comparable systemic exposure to the active metabolites of the prior, stable tetrabenazine regimen. MAIN OUTCOMES AND MEASURES: Safety measures included adverse events (AEs), clinical laboratory tests, vital signs, electrocardiograms, and validated scales. Changes in the Unified Huntington’s Disease Rating Scale total maximal chorea score and total motor score were efficacy end points. RESULTS: Of the 53 patients with HD screened for the study, 37 ambulatory patients with manifest HD (mean SD age, 52.4 11.5 years; 22 59% male and 15 41% female; 36 white 97.3%) were enrolled. Deutetrabenazine was generally well tolerated, with low rates of neuropsychiatric AEs. Safety scales did not reveal subclinical toxicity with deutetrabenazine treatment. Rates of dose reduction or suspension attributable to AEs were also low. Chorea control, as measured by the total maximal chorea score, was maintained at week 1 and significantly improved at week 8 (mean SD change from baseline, 2.1 3.2; P < .001). CONCLUSIONS AND RELEVANCE: In patients with chorea, overnight conversion to deutetrabenazine therapy provided a favorable safety profile and effectively maintained chorea control.
IMPORTANCE: Essential tremor (ET) is one of the most common movement disorders, affecting 5% of the general population older than 65 years. Common variants are thought to contribute toward ...susceptibility to ET, but no variants have been robustly identified. OBJECTIVE: To identify common genetic factors associated with risk of ET. DESIGN, SETTING, AND PARTICIPANTS: Case-control genome-wide association study. Inverse-variance meta-analysis was used to combine cohorts. Multicenter samples collected from European populations were collected from January 2010 to September 2019 as part of an ongoing study. Included patients were clinically diagnosed with or reported having ET. Control individuals were not diagnosed with or reported to have ET. Of 485 250 individuals, data for 483 054 passed data quality control and were used. MAIN OUTCOMES AND MEASURES: Genotypes of common variants associated with risk of ET. RESULTS: Of the 483 054 individuals included, there were 7177 with ET (3693 51.46% female; mean SD age, 62.66 15.12 years), and 475 877 control individuals (253 785 53.33% female; mean SD age, 56.40 17.6 years). Five independent genome-wide significant loci and were identified and were associated with approximately 18% of ET heritability. Functional analyses found significant enrichment in the cerebellar hemisphere, cerebellum, and axonogenesis pathways. Genetic correlation (r), which measures the degree of genetic overlap, revealed significant common variant overlap with Parkinson disease (r, 0.28; P = 2.38 × 10−8) and depression (r, 0.12; P = 9.78 × 10−4). A separate fine-mapping of transcriptome-wide association hits identified genes such as BACE2, LRRN2, DHRS13, and LINC00323 in disease-relevant brain regions, such as the cerebellum. CONCLUSIONS AND RELEVANCE: The results of this genome-wide association study suggest that a portion of ET heritability can be explained by common genetic variation and can help identify new common genetic risk factors for ET.
Transducer-based evaluation of tremor Haubenberger, Dietrich; Abbruzzese, Giovanni; Bain, Peter G. ...
Movement disorders,
September 2016, Letnik:
31, Številka:
9
Journal Article
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