Epidemiology of Huntington's Disease in the United States Medicare and Medicaid Populations.

INTRODUCTION: Huntington's disease (HD) is a rare, genetic, and ultimately fatal neurodegenerative disease, with a devastating impact on individuals and families across generations. Few estimates of HD epidemiology in the United States (US) exist. METHODS: This study employed a retrospective cross-sectional design to examine the epidemiology of HD in the US Medicare and Medicaid beneficiary populations using 2016-2017 claims data from the Medicare 100% Research Identifiable Files (RIFs) and 2014 claims data from the Medicaid Analytic eXtract (MAX) files for 17 states. Medicare beneficiaries ≥65 years with a diagnosis of HD (≥1 claim with ICD-10-CM code G10) in 2017 and Medicaid beneficiaries <65 years with a diagnosis of HD (≥1 claim with ICD-9-CM code 333.4) in 2014 were identified. The study outcomes included the 2017 prevalence proportion and incidence rate of HD in the Medicare population and the 2014 prevalence proportion of HD in the Medicaid population. RESULTS: In the Medicare population, 1,941 prevalent and 819 incident cases of HD were identified in 2017, corresponding to a prevalence proportion of 13.1 per 100,000 persons and incidence rate of 6.1 per 100,000 person-years. In the Medicaid population, 353 prevalent cases of HD were identified in 2014, corresponding to a prevalence proportion of 15.2 per 100,000 persons. CONCLUSION: This study suggests that prevalence and incidence of HD in the US may be higher than previously estimated. This has important implications in raising awareness of HD among providers and payers and ensuring availability of and access to services for HD patients and care partners in the Medicare and Medicaid populations.

Healthcare utilization and cost burden of Huntington's disease among Medicare beneficiaries in the United States.

AIMS: To examine healthcare utilization and costs in a US Medicare population diagnosed with Huntington's disease (HD). METHODS: This was a retrospective matched cohort study using Medicare fee-for-service (FFS) claims data using 2013-2017 Research Identifiable Files. Medicare beneficiaries diagnosed with HD based on the presence of at least one medical claim with an International Classification of Diseases, Ninth or Tenth Revision, Clinical Modification (ICD-9/10-CM) diagnosis code for HD (ICD-9-CM: 333.4; ICD-10-CM: G10) during the identification period (2014-2016). Beneficiaries without HD were drawn from a 5% random sample of Medicare beneficiaries and 1:1 matched to those with HD for comparison. All-cause and HD-related (any utilization related to HD diagnosis or symptoms associated with HD) healthcare utilization and costs were reported. RESULTS: We identified 3,688 matched pairs of beneficiaries with and without HD. Of those with HD, 1,922 (52.1%) were late-stage, 916 (24.8%) were middle-stage, and 850 (23.1%) were early-stage. Mean [SD] annual total healthcare costs were higher for HD beneficiaries than beneficiaries without HD ($41,631 [57,393] vs. $17,222 [31,218], p < .001) and were primarily driven by outpatient pharmacy costs ($19,182 [45,469] vs. $4,318 [11,553], p < .001). In the stratified analysis, total healthcare costs were highest among beneficiaries with late-stage HD (mean [SD] cost: $20,475 [$41,122] for early-stage vs. $29,733 [$44,977] for middle-stage vs. $56,657 [$64,185] for late-stage; p < .001). LIMITATIONS: Results are not generalizable to beneficiaries enrolled in other non-FFS Medicare plans. Administrative claims are intended for billing purposes, not research, and may not capture all symptoms, comorbidities, and other adverse events. CONCLUSIONS: This original, comprehensive analysis of healthcare utilization and economic burden among Medicare beneficiaries with HD found that healthcare needs and associated costs are substantially higher among Medicare beneficiaries who are diagnosed with HD compared to beneficiaries without HD.

Macrocyclic BACE inhibitors: Optimization of a micromolar hit to nanomolar leads.

We have identified macrocyclic inhibitors of the aspartic protease BACE, implicated in the etiology of Alzheimer's disease. An X-ray structure of screening hit 1 in the BACE active site revealed a hairpin conformation suggesting that constrained macrocyclic derivatives may also bind there. Several of the analogs we prepared were >100x more potent than 1, such as 7 (5 nM K(i)).

Huntingtin modulates transcription, occupies gene promoters in vivo, and binds directly to DNA in a polyglutamine-dependent manner.

Transcriptional dysregulation is a central pathogenic mechanism in Huntington's disease, a fatal neurodegenerative disorder associated with polyglutamine (polyQ) expansion in the huntingtin (Htt) protein. In this study, we show that mutant Htt alters the normal expression of specific mRNA species at least partly by disrupting the binding activities of many transcription factors which govern the expression of the dysregulated mRNA species. Chromatin immunoprecipitation (ChIP) demonstrates Htt occupation of gene promoters in vivo in a polyQ-dependent manner, and furthermore, ChIP-on-chip and ChIP subcloning reveal that wild-type and mutant Htt exhibit differential genomic distributions. Exon 1 Htt binds DNA directly in the absence of other proteins and alters DNA conformation. PolyQ expansion increases Htt-DNA interactions, with binding to recognition elements of transcription factors whose function is altered in HD. Together, these findings suggest mutant Htt modulates gene expression through abnormal interactions with genomic DNA, altering DNA conformation and transcription factor binding.

Quality of Care for Huntington's Disease in the United States: Findings from a National Survey of Patients and Caregivers.

BACKGROUND: Little is known about the quality of care for people living with Huntington's disease (HD) in the United States. OBJECTIVE: To document the current HD care experience and identify gaps in care provision in the United States. METHODS: Web-based surveys for persons self-identifying as being affected by HD (PAHD, which included individuals with, or at risk for HD) or as caregivers/family members, were developed and refined with targeted input from focus groups comprised of caregivers and family members. The surveys were disseminated via social media and patient advocacy partners from April-May 2017. RESULTS: Total valid responses numbered 797, including 585 caregiver/family respondents and 212 PAHD responses. Respondents reported care provision from HD specialty centers, primary care, movement disorder clinics, and other settings. One in five respondents reported that the person with HD was not currently receiving medical or community care. Respondents generally reported a good level of care, with HD specialists providing the highest rated healthcare experience. Caregiver/family respondents reported helping with a range of activities including budget/finances (60.5%), housekeeping (57.1%) and daily help (53.2%). Most respondents (97.9%) reported searching online, including general information about HD (86.4%), using HD social media channels (61.3%) and looking up clinical trials (59.8%). Respondents emphasized a need for support in financial planning and accessing care, and also for more HD education in the medical community. CONCLUSIONS: There is need for more support for HD patients and families. People desire more credible, accessible information. Improving resources available to patients and families should be a goal for HD organizations, along with measurement of patient outcomes.

A comparative analysis of brain and plasma Abeta levels in eight common non-transgenic mouse strains: validation of a specific immunoassay for total rodent Abeta.

Transgenic mouse models of Alzheimer's disease (AD) are being utilized as models for elucidating AD etiology and potential therapeutic approaches. However, two major drawbacks of these models are: (1) transgenic animals often over-express amyloid beta (Abeta) to high levels compared to that seen in sporadic human AD and (2) the current intellectual property issues surrounding a number of these models make them difficult to utilize in a commercial setting. Our goal was to identify an appropriate non-transgenic mouse strain, devoid of these patent restrictions and test whether amyloid-modulating compounds will lower total brain and plasma Abeta. Plasma and brain samples were collected from eight commonly used mouse strains (C57BL/6, SJL, CF-1, DBA/2, CD-1, 129, FVB and B6D2F1; Charles River Labs) and total Abetalevels were validated and quantified with a rodent-specific monoclonal Abetaantibody. Plasma Abeta in SJL mice was the highest of the eight strains tested (213 pM +/- 21 pM), but was not significantly different than the seven other strains. Total brain Abeta in SJL mice was also the greatest of the mouse strains tested (356 pM +/- 73 pM). SJL, C57BL/6 and CF-1 mice had total brain Abeta levels that were significantly greater than Abeta levels in B6D2F1 mice (242 +/- 20 pM). In vivo efficacy of an Abeta lowering agent was observed in CF-1 mice upon oral administration of the gamma-secretase inhibitors, DAPT and LY-411575. The absolute levels of rodent brain Abeta detected and the efficacy of the gamma-secretase treatment were dependent upon the antibodies used, as well as the extraction methodology. The measurement of total brain Abeta lowering in a common mouse strain could help accelerate drug discovery programs for Alzheimer's disease without relying on costly transgenic animals that overexpress APP in a manner that may not be predictive of the effects of these compounds in human AD.

Stewarding Hope: The Evolving Landscape of Huntington's Disease Science Communications.

For individuals faced with Huntington's disease (HD), there is no lack of access to information about the newest HD research topics and care trends thanks to social media and online news feeds. Unfortunately, making sense of this volume of information presents a modern challenge to families who are eager to follow every whisper of hope. Scientists with research news to share should be mindful of the dialog in which they are participating and of the hopes that they may be raising as they seek awareness for their work. To help families navigate these waters, patient advocacy organizations must remain a vigilant counterbalance by providing access to expertise and context to information that stewards the hope of HD families responsibly.

Survey of the Huntington's Disease Patient and Caregiver Community Reveals Most Impactful Symptoms and Treatment Needs.

BACKGROUND: In preparation for a meeting with the U.S. Food and Drug Administration (FDA) on Patient-Focused Drug Development in Huntington's disease, the Huntington's Disease Society of America (HDSA) created and distributed two comprehensive surveys on the symptom experience and treatment approaches for Huntington's disease. OBJECTIVE: The objective of these surveys was to identify the specific symptoms that most impact the daily lives of individuals with Huntington's disease/Juvenile Huntington's disease (HD/JHD) and their caregivers and to solicit input on the types of treatments desired by HD affected families. The data were shared with the FDA to offer background and insight in preparation for the patient-focused meeting, as well as to ensure representation by the community in a manner that would complement those who attended in person. METHODS: Two distinct surveys were created using SurveyMonkey to capture patient and caregiver perspectives on HD symptoms and current treatments. HDSA distributed the surveys to the HD community in August and September 2014 and collected responses through January 2015. RESULTS: More than 3,600 responses to the two surveys were received. The data showed that both caregivers and individuals with HD were severely impacted by the cognitive and behavioral symptoms of HD with HD patients reporting problems with executive functioning and cognitive decline as most impactful to them. However, 30 percent of caregivers reported that chorea was the most impactful symptom compared to 17 percent of people with HD. Across all the symptom categories, patients reported a lower occurrence of symptoms than were reported by their caregivers. CONCLUSIONS: With only one drug approved for treatment of a symptom of Huntington's disease and no disease modifying treatments available, there is a critical need for new medicines to treat the cognitive, psychiatric and motor symptoms associated with HD. While the surveys did not capture risk/benefit data, the data collected do provide new insights around the different perspectives of patients and caregivers. We believe that industry development of treatments would be well-informed by incorporating the patient community, which is more knowledgeable and engaged than given credit, in consideration of treatment regimens, risk-benefit and priorities for therapeutic development.

Characterization of HTT inclusion size, location, and timing in the zQ175 mouse model of Huntington's disease: an in vivo high-content imaging study.

Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder caused by a CAG trinucleotide repeat expansion in the huntingtin gene. Major pathological hallmarks of HD include inclusions of mutant huntingtin (mHTT) protein, loss of neurons predominantly in the caudate nucleus, and atrophy of multiple brain regions. However, the early sequence of histological events that manifest in region- and cell-specific manner has not been well characterized. Here we use a high-content histological approach to precisely monitor changes in HTT expression and characterize deposition dynamics of mHTT protein inclusion bodies in the recently characterized zQ175 knock-in mouse line. We carried out an automated multi-parameter quantitative analysis of individual cortical and striatal cells in tissue slices from mice aged 2-12 months and confirmed biochemical reports of an age-associated increase in mHTT inclusions in this model. We also found distinct regional and subregional dynamics for inclusion number, size and distribution with subcellular resolution. We used viral-mediated suppression of total HTT in the striatum of zQ175 mice as an example of a therapeutically-relevant but heterogeneously transducing strategy to demonstrate successful application of this platform to quantitatively assess target engagement and outcome on a cellular basis.

Analysis of cellular, transgenic and human models of Huntington's disease reveals tyrosine hydroxylase alterations and substantia nigra neuropathology.

Huntington's disease (HD) is a progressive, autosomal dominant neurodegenerative disorder that is pathologically characterized by a striatal-specific degeneration. Aberrant dopamine neurotransmission has been proposed as a mechanism underlying the movement disorder of HD. We report that the enzymatic activity of tyrosine hydroxylase (TH), the rate-limiting enzyme for dopamine biosynthesis, is decreased in a transgenic mouse model of HD. In addition, mutant huntingtin was found to disrupt transcription of TH and dopamine beta-hydroxylase (DbetaH) promoter reporter constructs. In situ hybridization revealed extensive loss of TH mRNA and decreased dopaminergic cell size in human HD substantia nigra. TH-immunoreactive protein was reduced in human grade 4 HD substantia nigra by 32% compared to age-matched controls. These findings implicate abnormalities in dopamine neurotransmission in HD and may provide new insights into targets for pharmacotherapy.

Chromatin immunoprecipitation technique for study of transcriptional dysregulation in intact mouse brain.

Transcriptional dysregulation has emerged as an important pathologic mechanism underlying the pathogenesis of Huntington's disease (HD). The control of transcription depends on appropriate binding of transcription factor proteins to specific promoter regions of genes. Chromatin immunoprecipitation (ChIP) is a technique that has been used to study the association of transcription factors with DNA. To address the hypothesis that there is altered transcription factor-DNA association in HD, we have recently adapted the ChIP technique to the study of transgenic mouse brain. Here, we describe our method of performing ChIP in intact mouse brain. We have optimized conditions for formaldehyde crosslinking, antibody immunoprecipitation, and quantitative real-time polymerase chain reaction detection. Using ChIP, one can measure the association of transcription factors with specific genes and determine if this association is altered in transgenic HD mouse models. ChIP applied to whole-mouse brain can thus offer a window into mechanisms of transcriptional dysregulation.

Striatal synaptosomes from Hdh140Q/140Q knock-in mice have altered protein levels, novel sites of methionine oxidation, and excess glutamate release after stimulation.

BACKGROUND: Synaptic connections are disrupted in patients with Huntington's disease (HD). Synaptosomes from postmortem brain are ideal for synaptic function studies because they are enriched in pre- and post-synaptic proteins important in vesicle fusion, vesicle release, and neurotransmitter receptor activation. OBJECTIVE: To examine striatal synaptosomes from 3, 6 and 12 month old WT and Hdh140Q/140Q knock-in mice for levels of synaptic proteins, methionine oxidation, and glutamate release. METHODS: We used Western blot analysis, glutamate release assays, and liquid chromatography tandem mass spectrometry (LC-MS/MS). RESULTS: Striatal synaptosomes of 6 month old Hdh140Q/140Q mice had less DARPP32, syntaxin 1 and calmodulin compared to WT. Striatal synaptosomes of 12 month old Hdh140Q/140Q mice had lower levels of DARPP32, alpha actinin, HAP40, Na+/K+-ATPase, PSD95, SNAP-25, TrkA and VAMP1, VGlut1 and VGlut2, increased levels of VAMP2, and modifications in actin and calmodulin compared to WT. More glutamate released from vesicles of depolarized striatal synaptosomes of 6 month old Hdh140Q/140Q than from age matched WT mice but there was no difference in glutamate release in synaptosomes of 3 and 12 month old WT and Hdh140Q/140Q mice. LC-MS/MS of 6 month old Hdh140Q/140Q mice striatal synaptosomes revealed that about 4% of total proteins detected (>600 detected) had novel sites of methionine oxidation including proteins involved with vesicle fusion, trafficking, and neurotransmitter function (synaptophysin, synapsin 2, syntaxin 1, calmodulin, cytoplasmic actin 2, neurofilament, and tubulin). Altered protein levels and novel methionine oxidations were also seen in cortical synaptosomes of 12 month old Hdh140Q/140Q mice. CONCLUSIONS: Findings provide support for early synaptic dysfunction in Hdh140Q/140Q knock-in mice arising from altered protein levels, oxidative damage, and impaired glutamate neurotransmission and suggest that study of synaptosomes could be of value for evaluating HD therapies.

Carisbamate, a novel neuromodulator, inhibits voltage-gated sodium channels and action potential firing of rat hippocampal neurons.

Carisbamate (RWJ-333369; (S)-2-O-carbamoyl-1-o-chlorophenyl-ethanol) is a novel investigational antiepileptic drug that exhibits a broad-spectrum of activity in a number of animal models of seizure and drug refractory epilepsy. In an effort to understand the molecular mechanism by which carisbamate produces its antiepileptic actions, we studied its effects on the function of voltage-gated, rat brain sodium and potassium channels and on the repetitive firing of action potentials in cultured rat hippocampal neurons. In whole-cell patch clamp recording, carisbamate resulted in a concentration-, voltage- and use-dependent inhibition of rat Nav1.2, with an IC(50) value of 68 microM at -67 mV. In rat hippocampal neurons, carisbamate similarly blocked voltage-gated sodium channels, with an IC(50) value of 89 microM at -67 mV, and inhibited repetitive firing of action potentials in a concentration-dependent manner (by 46% at 30 microM and 87% at 100 microM, respectively). Carisbamate had no effect on the steady-state membrane potential or voltage-gated potassium channels (K(v)) in these neurons. These inhibitory effects of carisbamate occurred at therapeutically relevant concentrations in vivo, raising the possibility that block of voltage-gated sodium channels by carisbamate contributes to its antiepileptic activity.

Histones associated with downregulated genes are hypo-acetylated in Huntington's disease models.

Transcriptional dysregulation plays a major role in the pathology of Huntington's disease (HD). However, the mechanisms causing selective downregulation of genes remain unknown. Histones regulate chromatin structure and thereby control gene expression; recent studies have demonstrated a therapeutic role for histone deacetylase (HDAC) inhibitors in polyglutamine diseases. This study demonstrates that despite no change in overall acetylated histone levels, histone H3 is hypo-acetylated at promoters of downregulated genes in R6/2 mice, ST14a and STHdh cells, as demonstrated by in vivo chromatin immunoprecipitation. In addition, HDAC inhibitor treatment increases association of acetylated histones with downregulated genes and corrects mRNA abnormalities. In contrast, there is a decrease in mRNA levels in wild-type cells following treatment with a histone acetyltransferase inhibitor. Although changes in histone acetylation correlate with decreased gene expression, histone hypo-acetylation may be a late event, as no hypo-acetylation is observed in 4-week-old R6/2 mice. Nevertheless, treatment with HDAC inhibitors corrects mRNA abnormalities through modification of histone proteins and may prove to be of therapeutic value in HD.

Decreased association of the transcription factor Sp1 with genes downregulated in Huntington's disease.

Huntington's disease (HD) is a neurodegenerative disease caused by expansion of a polyglutamine tract within the huntingtin protein. Transcriptional dysregulation has been implicated in HD pathogenesis; recent evidence suggests a defect in Sp1-mediated transcription. We used chromatin immunoprecipitation (ChIP) assays followed by real-time PCR to quantify the association of Sp1 with individual genes. We find that, despite normal protein levels and normal to increased overall nuclear binding activity, Sp1 has decreased binding to specific promoters of susceptible genes in transgenic HD mouse brain, in striatal HD cells, and in human HD brain. Genes whose mRNA levels are decreased in HD have abnormal Sp1-DNA binding, whereas genes with unchanged mRNA levels have normal levels of Sp1 association. Moreover, the altered binding seen with Sp1 is not found with another transcription factor, NF-Y. These findings suggest that mutant huntingtin dissociates Sp1 from target promoters, inhibiting transcription of specific genes.

Mutant huntingtin increases nuclear corepressor function and enhances ligand-dependent nuclear hormone receptor activation.

There is increasing evidence that transcriptional dysregulation is important in Huntington's disease pathogenesis. The transcriptional protein, nuclear corepressor (NCoR), acts to repress transcription of nuclear hormone receptors, such as the thyroid hormone receptor (TR) and retinoic acid receptor, in the absence of their appropriate ligand. NCoR has been shown to bind to the mutated huntingtin protein in a yeast two-hybrid screen. This aberrant interaction may have profound effects on both the function of the NCoR protein and on its control of nuclear hormone receptor-mediated transcription. To test this hypothesis, reporter gene assays were performed in inducible PC12 cell lines expressing exon 1 of the human huntingtin protein (Htt) with either a 25 or 103 polyglutamine (Q) repeat. Expression of mutant 103Q protein appears to enhance the ability of NCoR to repress TR-mediated transcription in the absence of ligand. Western analyses indicated that the expression of the mutant 103Q Htt protein did not change the endogenous NCoR levels in the HD103Q PC12 cells when compared to uninduced cells. Interestingly, using GST pull-down assays we found that a mutant Htt exon 1 construct with 53 polyglutamine (HD53Q) did not bind to NCoR in a polyglutamine-dependent fashion. These findings suggest that an aberrant NCoR-Htt interaction does not exist in vitro. Expression of the mutant 103Q protein was also found to enhance ligand-dependent activation of TR and retinoic acid receptor. In vitro binding data shows that TR binds to HD53Q in the presence of ligand. Taken together these data suggest that Htt may function as a transcriptional coactivator of nuclear hormone receptors.