Therapeutic strategies for Huntington’s disease

PURPOSE AND REVIEW: Huntington's disease is a fatal autosomal dominant neurodegenerative disorder caused by a trinucleotide expansion in the HTT gene, and current therapies focus on symptomatic treatment. This review explores therapeutic approaches that directly target the pathogenic mutation, disrupt HTT mRNA or its translation. RECENT FINDINGS: Zinc-finger transcription repressors and CRISPR-Cas9 therapies target HTT DNA, thereby preventing all downstream pathogenic mechanisms. These therapies, together with RNA interference (RNAi), require intraparenchymal delivery to the brain in viral vectors, with only a single delivery potentially required, though they may carry the risk of irreversible side-effects. Along with RNAi, antisense oligonucleotides (ASOs) target mRNA, but are delivered periodically and intrathecally. ASOs have safely decreased mutant huntingtin protein (mHTT) levels in the central nervous system of patients, and a phase 3 clinical trial is currently underway. Finally, orally available small molecules, acting on splicing or posttranslational modification, have recently been shown to decrease mHTT in animal models. SUMMARY: Huntingtin-lowering approaches act upstream of pathogenic mechanisms and therefore have a high a priori likelihood of modifying disease course. ASOs are already in late-stage clinical development, whereas other strategies are progressing rapidly toward human studies

Current Methods for the Treatment and Prevention of Drug-Induced Parkinsonism and Tardive Dyskinesia in the Elderly

Drug-induced parkinsonism (DIP) and tardive dyskinesia (TD) are iatrogenic consequences of antidopaminergic drugs. Both are particularly prevalent among the elderly and those with dementia. However, despite their prevalence, these disorders are often overlooked. Both entities share risk factors, physiopathological mechanisms and, to some degree, therapeutic approaches. Withdrawing the causal agent, reducing the dose or switching to a less potent antidopaminergic drug should be the first therapeutic options. Here we review both entities and emerging therapies including the recently approved drugs deutetrabenazine and valbenazine. We discuss relevant aspects for clinical practice such as new diagnostic techniques and the latest advances in the understanding of DIP and TD

El correo electrónico en la consulta de Parkinson: ¿soluciones a un clic? // Use of e-mail for Parkinson's disease consultations: Are answers just a clic away?

INTRODUCCION: La problemática de los trastornos del movimiento (TM) es compleja y la duración y frecuencia de las consultas presenciales puede estar limitada por problemas de espacio y tiempo. Analizamos el funcionamiento de un servicio de atención por correo electrónico institucional para médicos de Atención Primaria (MAP) y pacientes en la Unidad de Trastornos del Movimiento (UTM). METODOS: Se revisaron retrospectivamente los correos electrónicos enviados y recibidos en un periodo de 4 meses, un año tras su implantación. La dirección se proporcionaba en consulta y mediante sesiones informativas a los MAP del área. Se analizaron datos clínicos y demográficos de los pacientes, tipo de interlocutor, número de consultas, motivo y actuaciones derivadas de ellas. RESULTADOS: Del 1 de enero al 30 de abril de 2015 se recibieron 137 correos de 63 pacientes (43% varones; edad 71 ± 10,5 años) diagnosticados de enfermedad de Parkinson (76%), parkinsonismos atípicos (10%) y otros (14%), y se enviaron 116 respuestas. En 20 casos (32%) fueron redactados por el paciente, en 38 (60%) por sus familiares y en 5 (8%) por MAP. Los motivos de consulta fueron clínicos en 50 casos (80%): deterioro clínico (16; 32%), nuevos síntomas (14; 28%), efectos secundarios o dudas sobre medicación (20; 40%). Como consecuencia, se adelantó una cita programada en 9 casos (14%), mientras que el resto se solucionaron por correo electrónico. En 13 (20%), el motivo de consulta fue burocrático: relacionado con citas (11, 85%) y solicitud de informe (2, 15%). La satisfacción fue generalizada, sin constituir una sobrecarga asistencial excesiva para los facultativos responsables. CONCLUSIONES: La implantación de una consulta por correo electrónico es factible en UTM, facilita la comunicación médico-paciente y la continuidad asistencial con Atención Primaria. // INTRODUCTION: The clinical problems of patients with movement disorders (MD) are complex, and the duration and frequency of face-to-face consultations may be insufficient to meet their needs. We analysed the implementation of an e-mail-based query service for our MD unit's patients and their primary care physicians (PCPs). METHODS: We retrospectively reviewed all consecutive emails sent and received over a period of 4 months, one year after implementation of the e-mail inquiry system. All patients received the during consultations, and PCPs, during scheduled informative meetings. We recorded and later analysed the profile of the questioner, patients’ demographic and clinical data, number of queries, reason for consultation, and actions taken. RESULTS: From 1 January 2015 to 30 April 2015, the service received 137 emails from 63 patients (43% male, mean age 71 ± 10.5) diagnosed with Parkinson's disease (76%), atypical parkinsonism (10%), and others (14%); 116 responses were sent. Twenty (32%) emails were written by patients, 38 (60%) by their caregivers, and 5 (8%) by their PCPs. The reasons for consultation were clinical in 50 cases (80%): 16 (32%) described clinical deterioration, 14 (28%) onset of new symptoms, and 20 (40%) side effects or concerns about medications. In 13 cases (20%), the query was bureaucratic: 11 were related to appointments (85%) and 2 were requests for clinical reports (15%). In response, new appointments were scheduled in 9 cases (14%), while the rest of the questions were answered by email. Patients were satisfied overall and the additional care burden on specialists was not excessive. CONCLUSIONS: Implementing an e-mail-based consultation system is feasible in MD units. It facilitates both communication between neurologists and patients and continued care in the primary care setting

Expanding the Spectrum of Movement Disorders Associated With C9orf72 Hexanucleotide Expansions

Objective: Hexanucleotide repeat expansions (HREs) in C9orf72 are a major cause of frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). We aimed to determine the frequency and phenomenology of movement disorders (MD) in carriers of HRE in C9orf72 through a retrospective review of patients' medical records. Methods: We retrospectively reviewed the clinical records of patients carrying a C9orf72 HRE in the pathogenic range and compared the characteristics of patients with and without MD. Results: Seventeen of 40 patients with a C9orf72 HRE had a documented MD. In 6 of 17, MD were the presenting symptom, and in 2 of 17, MD were the sole manifestation of the disease. FTD was present in 13 of 17 patients, ALS in 5 of 17 patients, and 2 of 17 patients did not develop FTD or ALS. Thirteen of 17 patients had more than one MD. The most common MD were parkinsonism and tremor (resembling essential tremor syndrome), each one present in 11 of 17 patients. Distal, stimulus-sensitive upper limbs myoclonus was present in 6 of 17 patients and cervical dystonia in 5 of 17 patients. Chorea was present in 5 of 17 patients, 4 of whom showed marked orofacial dyskinesias. The most frequent MD combination was tremor and parkinsonism, observed in 8 of 17 patients, 5 of whom also had myoclonus. C9orf72 patients without MD had shorter follow-up times and higher proportion of ALS, although these results did not survive the correction for multiple comparisons. Conclusions: MD are frequent in C9orf72. They may precede signs of ALS or FTD, or even be present in isolation. Parkinsonism, tremor, and myoclonus are most commonly observed

Intellectual enrichment and genetic modifiers of cognition and brain volume in Huntington's disease.

An important step towards the development of treatments for cognitive impairment in ageing and neurodegenerative diseases is to identify genetic and environmental modifiers of cognitive function and understand the mechanism by which they exert an effect. In Huntington's disease, the most common autosomal dominant dementia, a small number of studies have identified intellectual enrichment, i.e. a cognitively stimulating lifestyle and genetic polymorphisms as potential modifiers of cognitive function. The aim of our study was to further investigate the relationship and interaction between genetic factors and intellectual enrichment on cognitive function and brain atrophy in Huntington's disease. For this purpose, we analysed data from Track-HD, a multi-centre longitudinal study in Huntington's disease gene carriers and focused on the role of intellectual enrichment (estimated at baseline) and the genes FAN1, MSH3, BDNF, COMT and MAPT in predicting cognitive decline and brain atrophy. We found that carrying the 3a allele in the MSH3 gene had a positive effect on global cognitive function and brain atrophy in multiple cortical regions, such that 3a allele carriers had a slower rate of cognitive decline and atrophy compared with non-carriers, in agreement with its role in somatic instability. No other genetic predictor had a significant effect on cognitive function and the effect of MSH3 was independent of intellectual enrichment. Intellectual enrichment also had a positive effect on cognitive function; participants with higher intellectual enrichment, i.e. those who were better educated, had higher verbal intelligence and performed an occupation that was intellectually engaging, had better cognitive function overall, in agreement with previous studies in Huntington's disease and other dementias. We also found that intellectual enrichment interacted with the BDNF gene, such that the positive effect of intellectual enrichment was greater in Met66 allele carriers than non-carriers. A similar relationship was also identified for changes in whole brain and caudate volume; the positive effect of intellectual enrichment was greater for Met66 allele carriers, rather than for non-carriers. In summary, our study provides additional evidence for the beneficial role of intellectual enrichment and carrying the 3a allele in MSH3 in cognitive function in Huntington's disease and their effect on brain structure

Dissecting the Phenotype and Genotype of PLA2G6-Related Parkinsonism.

BACKGROUND: Complex parkinsonism is the commonest phenotype in late-onset PLA2G6-associated neurodegeneration. OBJECTIVES: The aim of this study was to deeply characterize phenogenotypically PLA2G6-related parkinsonism in the largest cohort ever reported. METHODS: We report 14 new cases of PLA2G6-related parkinsonism and perform a systematic literature review. RESULTS: PLA2G6-related parkinsonism shows a fairly distinct phenotype based on 86 cases from 68 pedigrees. Young onset (median age, 23.0 years) with parkinsonism/dystonia, gait/balance, and/or psychiatric/cognitive symptoms were common presenting features. Dystonia occurred in 69.4%, pyramidal signs in 77.2%, myoclonus in 65.2%, and cerebellar signs in 44.6% of cases. Early bladder overactivity was present in 71.9% of cases. Cognitive impairment affected 76.1% of cases and psychiatric features 87.1%, the latter being an isolated presenting feature in 20.1%. Parkinsonism was levodopa responsive but complicated by early, often severe dyskinesias. Five patients benefited from deep brain stimulation. Brain magnetic resonance imaging findings included cerebral (49.3%) and/or cerebellar (43.2%) atrophy, but mineralization was evident in only 28.1%. Presynaptic dopaminergic terminal imaging was abnormal in all where performed. Fifty-four PLA2G6 mutations have hitherto been associated with parkinsonism, including four new variants reported in this article. These are mainly nontruncating, which may explain the phenotypic heterogeneity of childhood- and late-onset PLA2G6-associated neurodegeneration. In five deceased patients, median disease duration was 13.0 years. Brain pathology in three cases showed mixed Lewy and tau pathology. CONCLUSIONS: Biallelic PLA2G6 mutations cause early-onset parkinsonism associated with dystonia, pyramidal and cerebellar signs, myoclonus, and cognitive impairment. Early psychiatric manifestations and bladder overactivity are common. Cerebro/cerebellar atrophy are frequent magnetic resonance imaging features, whereas brain iron deposition is not. Early, severe dyskinesias are a tell-tale sign. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society

Intellectual enrichment and genetic modifiers of cognition and brain volume in Huntington's disease

An important step towards the development of treatments for cognitive impairment in ageing and neurodegenerative diseases is to identify genetic and environmental modifiers of cognitive function and understand the mechanism by which they exert an effect. In Huntington’s disease, the most common autosomal dominant dementia, a small number of studies have identified intellectual enrichment, i.e. a cognitively stimulating lifestyle and genetic polymorphisms as potential modifiers of cognitive function. The aim of our study was to further investigate the relationship and interaction between genetic factors and intellectual enrichment on cognitive function and brain atrophy in Huntington’s disease. For this purpose, we analysed data from Track-HD, a multi-centre longitudinal study in Huntington’s disease gene carriers and focused on the role of intellectual enrichment (estimated at baseline) and the genes FAN1, MSH3, BDNF, COMT and MAPT in predicting cognitive decline and brain atrophy. We found that carrying the 3a allele in the MSH3 gene had a positive effect on global cognitive function and brain atrophy in multiple cortical regions, such that 3a allele carriers had a slower rate of cognitive decline and atrophy compared with non-carriers, in agreement with its role in somatic instability. No other genetic predictor had a significant effect on cognitive function and the effect of MSH3 was independent of intellectual enrichment. Intellectual enrichment also had a positive effect on cognitive function; participants with higher intellectual enrichment, i.e. those who were better educated, had higher verbal intelligence and performed an occupation that was intellectually engaging, had better cognitive function overall, in agreement with previous studies in Huntington’s disease and other dementias. We also found that intellectual enrichment interacted with the BDNF gene, such that the positive effect of intellectual enrichment was greater in Met66 allele carriers than non-carriers. A similar relationship was also identified for changes in whole brain and caudate volume; the positive effect of intellectual enrichment was greater for Met66 allele carriers, rather than for non-carriers. In summary, our study provides additional evidence for the beneficial role of intellectual enrichment and carrying the 3a allele in MSH3 in cognitive function in Huntington’s disease and their effect on brain structure

Search for a vector-like quark T′ → tH via the diphoton decay mode of the Higgs boson in proton-proton collisions at s \sqrt{s} = 13 TeV

A search for the electroweak production of a vector-like quark T′, decaying to a top quark and a Higgs boson is presented. The search is based on a sample of proton-proton collision events recorded at the LHC at = 13 TeV, corresponding to an integrated luminosity of 138 fb−1. This is the first T′ search that exploits the Higgs boson decay to a pair of photons. For narrow isospin singlet T′ states with masses up to 1.1 TeV, the excellent diphoton invariant mass resolution of 1–2% results in an increased sensitivity compared to previous searches based on the same production mechanism. The electroweak production of a T′ quark with mass up to 960 GeV is excluded at 95% confidence level, assuming a coupling strength κT = 0.25 and a relative decay width Γ/MT′ < 5%