Huntington's Disease Cohort Research Articles

Changes in 24(S)-Hydroxycholesterol Are Associated with Cognitive Performance in Early Huntington's Disease: Data from the TRACK and ENROLL HD Cohorts.

There is evidence for dysregulated cholesterol homeostasis in Huntington's disease (HD). The brain-specific cholesterol metabolite 24(S)-hydroxycholesterol (24(S)-OHC) is decreased in manifest HD. 24(S)-OHC is an endogenous positive allosteric modulator (PAM) of the N-methyl-D-aspartate (NMDA) receptor, suggesting lower 24(S)-OHC may contribute to NMDA receptor hypofunction in HD. We hypothesized changes in 24(S)-OHC would be associated with cognitive impairment in early HD. To determine the interactions between oxysterols (24(S)-OHC, 25-OHC, and 27-OHC) at the NMDA receptor, the plasma levels of these oxysterols, and how these levels relate to cognitive performance. An in vitro competition assay was used to evaluate interactions at the NMDA receptor, liquid chromatography coupled tandem mass spectrometry (LC-MS/MS) was used to measure plasma 24(S)-OHC, 25-OHC, and 27-OHC levels, and correlation analyses investigated their relationship to performance on cognitive endpoints in TRACK and ENROLL-HD (NCT01574053). In vitro, 25-OHC and 27-OHC attenuated the PAM activity of 24(S)-OHC on the NMDA receptor. Lower plasma 24(S)-OHC levels and 24(S)/25-OHC ratios were detected in participants with early HD. Moderate and consistent associations were detected between plasma 24(S)/25-OHC ratio and performance on Stroop color naming, symbol digit modality, Trails A/B, and emotion recognition. Little association was observed between the ratio and psychiatric or motor endpoints, suggesting specificity for the relationship to cognitive performance. Our findings support growing evidence for dysregulated CNS cholesterol homeostasis in HD, demonstrate a relationship between changes in oxysterols and cognitive performance in HD, and propose that NMDA receptor hypofunction may contribute to cognitive impairment in HD.

The frequency and clinical impact of synonymous HTT loss-of-interruption and duplication-of-interruption variants in a diverse HD cohort

PurposeTo determine the frequency and clinical impact of loss-of-interruption (LOI) and duplication-of-interruption modifier variants of the HTT CAG and CCG repeat in a cohort of individuals with Huntington disease (HD). MethodsWe screened symptomatic HD participants from the UBC HD Biobank and 5 research sites for sequence variants. After variant identification, we examined the clinical impact and frequency in the reduced penetrance range. ResultsParticipants with CAG-CCG LOI and CCG LOI variants have a similar magnitude of earlier onset of HD, by 12.5 years. The sequence variants exhibit ancestry-specific differences. Participants with the CAG-CCG LOI variant also have a faster progression of Total Motor Score by 1.9 units per year. Symptomatic participants with the CAG-CCG LOI variant show enrichment in the reduced penetrance range. The CAG-CCG LOI variant explains the onset of 2 symptomatic HD participants with diagnostic repeats below the pathogenetic range. ConclusionOur findings have significant clinical implications for participants with the CAG-CCG LOI variant who receive inaccurate diagnoses near diagnostic cutoff ranges. Improved diagnostic testing approaches and clinical management are needed for these individuals. We present the largest and most diverse HTT CAG and CCG sequence variant cohort and emphasize their importance in clinical presentation in HD.

The characteristic and prognostic role of blood inflammatory markers in patients with Huntington's disease from China.

This study aims to elucidate the role of peripheral inflammation in Huntington's disease (HD) by examining the correlation of peripheral inflammatory markers with clinical manifestations and disease prognosis. This investigation involved 92 HD patients and 92 matched healthy controls (HCs). We quantified various peripheral inflammatory markers and calculated their derived metrics including neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), lymphocyte-to-monocyte ratio (LMR), and systemic immune-inflammation index (SII). Clinical assessments spanning cognitive, motor, and disease severity were administered. Comparative analysis of inflammatory markers and clinical correlations between HD and controls was performed. Kaplan-Meier survival analysis and Cox regression model were used to assess the effect of inflammatory markers on survival. The study revealed that HD patients had significantly reduced lymphocyte counts, and LMR. Conversely, NLR, PLR, and SII were elevated compared to HCs. Lymphocyte levels inversely correlated with the age of onset and monocyte levels inversely correlated with the UHDRS-total functional capacity (TFC) scores. After adjusting for age, sex, and CAG repeat length, lymphocyte count, NLR, PLR, and SII were significantly correlated with the progression rate of TFC scores. Elevated levels of white blood cells and monocytes were associated with an increased risk of disability and mortality in the HD cohort. Our findings indicate that HD patients display a distinct peripheral inflammatory profile with increased NLR, PLR, and SII levels compared to HCs. The peripheral inflammation appears to be linked with accelerated disease progression and decreased survival in HD.

Optimizing Screening for Intrastriatal Interventions in Huntington's Disease Using Predictive Models.

Intrastriatal delivery of potential therapeutics in Huntington's disease (HD) requires sufficient caudate and putamen volumes. Currently, volumetric magnetic resonance imaging is rarely done in clinical practice, and these data are not available in large research cohorts such as Enroll-HD. The objective of this study was to investigate whether predictive models can accurately classify HD patients who exceed caudate and putamen volume thresholds required for intrastriatal therapeutic interventions. We obtained and merged data for 1374 individuals across three HD cohorts: IMAGE-HD, PREDICT-HD, and TRACK-HD/TRACK-ON. We imputed missing data for clinical variables with >72% non-missing values and used the model-building algorithm BORUTA to identify the 10 most important variables. A random forest algorithm was applied to build a predictive model for putamen volume >2500 mm3 and caudate volume >2000 mm3 bilaterally. Using the same 10 predictors, we constructed a logistic regression model with predictors significant at P < 0.05. The random forest model with 1000 trees and minimal terminal node size of 5 resulted in 83% area under the curve (AUC). The logistic regression model retaining age, CAG repeat size, and symbol digit modalities test-correct had 85.1% AUC. A probability cutoff of 0.8 resulted in 5.4% false positive and 66.7% false negative rates. Using easily obtainable clinical data and machine learning-identified initial predictor variables, random forest, and logistic regression models can successfully identify people with sufficient striatal volumes for inclusion cutoffs. Adopting these models in prescreening could accelerate clinical trial enrollment in HD and other neurodegenerative disorders when volume cutoffs are necessary enrollment criteria. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Factors influencing cognitive function in patients with Huntington's disease from China: A cross-sectional clinical study.

Huntington's disease (HD) is an autosomal dominant inherited neurodegenerative disorder caused by CAG repeats expansion. Cognitive decline contributes to the loss of daily activity in manifest HD. We aimed to examine the cognition status in a Chinese HD cohort and explore factors influencing the diverse cognitive domains. A total of 205 participants were recruited in the study with the assessment by neuropsychological batteries, including the mini-mental state examination (MMSE), Stroop test, symbol digit modalities test (SDMT), trail making test (TMT), verbal fluency test (VFT), and Hopkins verbal learning test-revised, as well as motor and psychiatric assessment. Pearson correlation and multiple linear regression models were applied to investigate the correlation. Only 41.46% of patients had normal global function first come to our center. There was a significantly difference in MMSE, Stroop test, SDMT, TMT, and VFT across each stage of HD patients (p<.05). Apathy of PBA-s was correlated to MMSE, animal VFT and Stroop-interference tests performance. Severity of motor symptoms, functional capacity, age, and age of motor symptom onset were correlated to all neuropsychological scores, whereas education attainment and diagnostic delay were correlated to most neuropsychological scores except TMT. Severity of motor symptoms, functional capacity, and education attainment showed independent predicting effect (p<.05) in diverse cognitive domains. Cognitive impairment was very common in Chinese HD patients at the first visit and worse in the patients in advanced phase. The severity of motor symptoms and functional capacity were correlated to the diverse cognitive domains.

Cerebrospinal Fluid Flow in Patients with Huntington's Disease.

Investigations of cerebrospinal fluid (CSF) flow aberrations in Huntington's disease (HD) are of growing interest, as impaired CSF flow may contribute to mutant Huntington retention and observed heterogeneous responsiveness to intrathecally administered therapies. We assessed net cerebral aqueduct CSF flow and velocity in 29 HD participants (17 premanifest and 12 manifest) and 51 age- and sex matched non-HD control participants using 3-Tesla magnetic resonance imaging methods. Regression models were applied to test hypotheses regarding: (i) net CSF flow and cohort, (ii) net CSF flow and disease severity (CAP-score), and (iii) CSF volume after correcting for age and sex. Group-wise analyses support a decrease in net CSF flow in HD (mean 0.14 ± 0.27 mL/min) relative to control (mean 0.32 ± 0.20 mL/min) participants (p = 0.02), with lowest flow in the manifest HD cohort (mean 0.04 ± 0.25 mL/min). This finding was explained by hyperdynamic CSF movement, manifesting as higher caudal systolic CSF flow velocity and higher diastolic cranial CSF flow velocity across the cardiac cycle, in HD (caudal flow: 0.17 ± 0.07 mL/s, cranial flow: 0.14 ± 0.08 mL/s) compared to control (caudal flow: 0.13 ± 0.06 mL/s, cranial flow: 0.11 ± 0.04 mL/s) participants. A positive correlation between cranial diastolic flow and disease severity was observed (p = 0.02). Findings support aqueductal CSF flow dynamics changing with disease severity in HD. These accelerated changes are consistent with changes observed over the typical adult lifespan, and may have relevance to mutant Huntington retention and intrathecally administered therapeutics responsiveness. ANN NEUROL 2023;94:885-894.

PolyQ length-dependent metabolic alterations and DNA damage drive human astrocyte dysfunction in Huntington's disease.

Huntington's Disease (HD) is a neurodegenerative disease caused by a polyglutamine (polyQ) expansion in the Huntingtin gene. Astrocyte dysfunction is known to contribute to HD pathology, however our understanding of the molecular pathways involved is limited. Transcriptomic analysis of patient-derived PSC (pluripotent stem cells) astrocyte lines revealed that astrocytes with similar polyQ lengths shared a large number of differentially expressed genes (DEGs). Notably, weighted correlation network analysis (WGCNA) modules from iPSC derived astrocytes showed significant overlap with WGCNA modules from two post-mortem HD cohorts. Further experiments revealed two key elements of astrocyte dysfunction. Firstly, expression of genes linked to astrocyte reactivity, as well as metabolic changes were polyQ length-dependent. Hypermetabolism was observed in shorter polyQ length astrocytes compared to controls, whereas metabolic activity and release of metabolites were significantly reduced in astrocytes with increasing polyQ lengths. Secondly, all HD astrocytes showed increased DNA damage, DNA damage response and upregulation of mismatch repair genes and proteins. Together our study shows for the first time polyQ-dependent phenotypes and functional changes in HD astrocytes providing evidence that increased DNA damage and DNA damage response could contribute to HD astrocyte dysfunction.

Loss of CAA interruption and intergenerational CAG instability in Chinese patients with Huntington's disease.

Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder caused by CAG expansions in huntingtin (HTT) gene, involving motor, cognitive, and neuropsychiatric symptoms. However, genetic modifiers and CAG repeat instability may lead to variations of clinical manifestations, making diagnosis of HD difficult. In this study, we recruited 229 HD individuals from 164 families carrying expanded CAG repeats of HTT, and analyzed loss of CAA interruption (LOI) on the expanded allele and CAG instability during germline transmission. Sanger sequencing and TA cloning were used to determine CAG repeat length and identify LOI variants. Detailed clinical features and genetic testing results were collected. We identified 6 individuals with LOI variants from 3 families, and all probands presented with earlier motor onset age than predicted onset age. In addition, we also presented 2 families with extreme CAG instability during germline transmission. One family showed an expansion from 35 to 66 CAG repeats, while the other family showed both CAG expansion and contraction in lineal three generations. In conclusion, we present the first document of Asian HD population with LOI variant, and we suggest that for symptomatic individuals with intermediate or reducedpenetrance allele or negative family history, HTT gene sequencing should be considered in the clinical practice. KEY MESSAGES : We screened the loss of CAA interruption (LOI) variant in a Chinese HD cohort and presented the first document of Asian patients with Huntington's disease carrying LOI variant. We identified 6 individuals with LOI variants from 3 families, and all probands presented with earlier motor onset age than predicted onset age. We presented 2 families with extreme CAG instability during germline transmission. One family showed an expansion from 35 to 66 CAG repeats, while the other family showed both CAG expansion and contraction in lineal three generations. We suggest that for symptomatic individuals with intermediate or reduced penetrance allele or negative family history, HTT gene sequencing should be considered in the clinical practice.

Health care resource utilization and costs among individuals with vs without Huntington disease in a US population.

BACKGROUND: Quantifying the extent of health care resource utilization (HCRU) and costs associated with Huntington disease (HD) is vital for providers, decisionmakers, and payers to understand unmet treatment needs and to ensure limited resources can be used to benefit the maximum number of people with HD. OBJECTIVE: To quantify HCRU and costs for people with HD, overall and by disease stage, and compare these with non-HD controls. METHODS: This was a retrospective cohort study using administrative claims data from the IBM MarketScan Commercial, Multi-State Medicaid, and Medicare Supplemental Databases from January 1, 2009, to December 31, 2018. People with an HD claim between January 1, 2010, and December 31, 2017, were selected for this analysis and matched with non-HD controls for comparison. The HD cohort and the non-HD controls were exact matched on their follow-up duration and propensity score matched 1:4 to create the final analytical cohort. Index date was the first HD diagnosis for the HD cohort (proxy index date assigned to controls), and all individuals were required to have continuous enrollment for 12 or more months pre-index (baseline) and 3 or more months post-index. Proportions of all-cause HCRU (ie, outpatient visits, inpatient visits, emergency department visits, pharmacy fills, radiology visits, and physical/occupational therapy visits) in the 6-months post-index and HCRU counts and costs per patient per month (PPPM) over the entire follow-up were calculated for each cohort. RESULTS: A total of 2,473 individuals with HD and 9,522 matched non-HD controls were identified. HCRU in 6 months post-index was significantly greater in people with HD compared with non-HD controls for all health care service categories; P < 0.0001. The mean number of HCRU PPPM for all measured healthcare services was significantly higher in people with HD compared with non-HD controls (P < 0.001). Mean total costs (2018 USD PPPM) for the HD cohort ($2,260 [SD = $4,682]) were twice the total costs in the non-HD cohort ($1,056 [SD = $3,078]) (P < 0.0001) and were highest across all disease stages. CONCLUSIONS: This study provides current comprehensive HCRU and cost estimates in individuals with HD relative to those without the disease, thus demonstrating the high economic burden imposed by HD. DISCLOSURES: Dr Ta: Employment with Genentech (at time of study) and stock options with Roche; Dr To: Employment and stock options/dividends with Genentech; Dr Patel: Employment and stock options with Roche/Genentech; Dr Fuller: Employment with CHDI Management/CHDI Foundation; Mr Surinach: Employment with Genesis Research (which receives consulting fees from Genentech/Roche); Dr Abbass: Employment and stock options with Genentech; Dr Exuzides: Employment and stock options with Roche/Genentech; and Ms Luo: Employment with CHDI Management/CHDI Foundation. This study was funded by Genentech Inc. The authors thank Greg Rowe of Chrysalis Medical Communications for providing medical writing support, which was funded by F. Hoffmann-La Roche Ltd, in accordance with Good Publication Practice (GPP3) guidelines (http://www.ismpp.org/gpp3).

No optical coherence tomography changes in premanifest Huntington's disease mutation carriers far from disease onset

BackgroundSpectral‐domain optical coherence tomography (OCT) may detect retinal changes as a biomarker in neurodegenerative diseases like manifest Huntington's disease (HD). We investigate macular retinal layer thicknesses in a premanifest HD (pre‐HD) cohort and healthy controls (HC).MethodsPre‐HD mutation carriers underwent standardized ratings and a preset macular OCT scan. Thickness values were determined for each sector of all macular retinal layers, the mean of all sectors and the mean of the inner ring (IR, 3 mm) after segmentation (Heyex segmentation batch). HC were retrospectively included from an existing database. The IR thickness of the ganglion cell layer (GCL), retinal nerve fiber layer (RNFL), GCL + inner plexiform layer (GCIPL), and total retina were included in the exploratory correlation analyses with paraclinical ratings and compared to HC.ResultsThe analyses comprised n = 24 pre‐HD participants (n = 10 male, n = 14 female) and n = 38 HC (n = 14 male, n = 24 female). Retinal layer parameters did not correlate with paraclinical ratings. Expected correlations between established HD biomarkers were robust. The IR thicknesses of the GCL, GCIPL, and total retina did not differ between pre‐HD and HC. The IR thickness of the RNFL was significantly higher in pre‐HD participants (pre‐HD: 23.22 μm (standard deviation 2.91), HC: 21.26 μm (1.90), p = .002).DiscussionIn this cross‐sectional cohort of genetically determined pre‐HD participants, neurodegenerative features were not detected with retinal layer segmentation. Since our pre‐HD collective was more than 16 years before disease onset, OCT may not be sensitive enough to detect early changes.

Hippocampal and striatal volumes correlate with spatial memory impairment in Huntington's disease.

Spatial memory impairments are observed in people with Huntington's disease (HD), however, the domain of spatial memory has received little focus when characterizing the cognitive phenotype of HD. Spatial memory is traditionally thought to be a hippocampal-dependent function, while the neuropathology of HD centers on the striatum. Alongside spatial memory deficits in HD, recent neurocognitive theories suggest that a larger brain network is involved, including the striatum. We examined the relationship between hippocampal and striatal volumes and spatial memory in 36 HD gene expansion carriers, including premanifest (n=24) and early manifest HD (n=12), and 32 matched healthy controls. We assessed spatial memory with Paired Associates Learning, Rey-Osterrieth Complex Figure Test, and the Virtual House task, which assesses three components of spatial memory: navigation, object location, and plan drawing. Caudate nucleus, putamen, and hippocampal volumes were manually segmented on T1-weighted MR images. As expected, caudate nucleus and putamen volumes were significantly smaller in the HD group compared to controls, with manifest HD having more severe atrophy than the premanifest HD group. Hippocampal volumes did not differ significantly between HD and control groups. Nonetheless, on average, the HD group performed significantly worse than controls across all spatial memory tasks. The spatial memory components of object location and recall of figural and topographical drawings were associated with striatal and hippocampal volumes in the HD cohort. We provide a case to include spatial memory impairments in the cognitive phenotype of HD, and extend the neurocognitive picture of HD beyond its primary pathology within the striatum.

Neuropsychiatric comorbidities in Huntington's and Parkinson's Disease: A United States claims database analysis.

ObjectiveHuntington’s disease is a rare, genetic, neurodegenerative disease characterized by a triad of cognitive, behavioral, and motor symptoms. The condition gradually results in increasing disability, loss of independence, and ultimately death. Our objective was to use United States claims data (which offer valuable insight into the natural history of disease) to compare the prevalent comorbidities of people with Huntington’s disease against matched controls with Parkinson’s disease or with no major neurodegenerative diseases (general population controls). We also assess medication use in people with Huntington’s disease.MethodsThis was a retrospective, observational study using data from the IBM MarketScan® Databases. Cases and controls were matched 1:1, and comorbidities were analyzed in each group during 2017. Medications were also assessed in the Huntington’s disease cohort. Eligible cases had ≥ 2 diagnostic codes for Huntington’s disease; controls had ≥ 2 codes for Parkinson’s disease (with no record of Huntington’s disease), or, for general population controls, no record of Huntington’s disease, Parkinson’s disease, amyotrophic lateral sclerosis, or dementia.ResultsA total of 587 matched individuals were assessed in each cohort. Depression and anxiety were more common in Huntington’s disease versus Parkinson’s disease (odds ratios: 1.51 and 1.16, respectively). Other conditions more common in Huntington’s disease included dementia, communication/speech problems, dysphagia, and falls. The use of antidepressant (59.9%) and antipsychotic (39.5%) medications was frequent among Huntington’s disease cases.InterpretationThese data highlight the prevalence of psychiatric, cognitive, communication, swallowing, and mobility problems in people with Huntington’s disease, underscoring the need for holistic expert care of these individuals.

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.

Late Onset Huntington Disease: Phenotypic and Genotypic Characteristics of 10 Cases in Argentina.

Huntington's disease (HD) is a neurodegenerative disorder that includes motor, psychiatric and cognitive manifestations with typical onset of symptoms is in the forties. A percentage of patients (4.4% - 11.5%) may be exceptions to this and manifest symptoms later (>60 years old). Diagnosis of Late onset HD (LoHD) can be a challenge, due to the low suspicion of the disease at this age. To review the genotype and phenotype of LoHD in an Argentinian cohort. We reviewed the medical records and genetic testing of a total of 95 individuals with clinical and molecular diagnosis of Huntington's disease, based on 2 institution's registry. Among our HD cohort, 10 patients (10.52%) had LoHD, with variable results regarding family history. The average of repetitions of the expanded allele was 40 (range 38-44). All cases had mild motor symptoms at onset. Late onset HD can be a diagnostic challenge, due to its slow progression, unawareness of manifestations among patients and in many cases, mild symptomatology that does not warrant medical attention.

Cerebrospinal fluid sCD27 levels indicate active T cell-mediated inflammation in premanifest Huntington's disease.

IntroductionHuntington’s disease (HD) is a neurodegenerative disorder, but evidence also suggests neuroinflammation in the pathogenesis. The immune mechanisms involved and the timing of their activation need further clarification.MethodsA clinically well-characterized HD cohort and gene negative controls were enrolled. YKL-40 reflecting innate immunity and sCD27, a marker of adaptive immunity, were measured across disease stages. Comparisons were made with markers of neurodegeneration: neurofilament light (NFL), total-tau (T-tau), and phospho-tau (P-tau).Results52 cross-sectional cerebrospinal fluid samples and 23 follow-up samples were analyzed. sCD27 was elevated in manifest HD and premanifest gene expansion carriers, whereas controls mostly had undetectable levels. YKL-40 showed a trend toward increase in manifest HD. sCD27 correlated with YKL-40 which in turn was closely associated to all included markers of neurodegeneration. YKL-40, NFL, and both forms of tau could all independently predict HD symptoms, but only NFL levels differed between groups after age-adjustment.ConclusionIncreased sCD27 in premanifest HD is a sign of T cell-mediated neuroinflammation. This finding is novel since other reports almost exclusively have found early involvement of innate immunity. Validation of sCD27 in a larger HD cohort is needed. The role of adaptive immunity in HD needs further clarification, as it may hasten disease progression.

Comparison of mid-age-onset and late-onset Huntington's disease in Finnish patients.

The phenotype of juvenile Huntington's disease (HD) differs clearly from that of adult-onset HD, but information about differences between mid-age-onset HD and late-onset HD (LOHD) is scarce. A national cohort of 206 patients with adult-onset HD was identified using national registries and patient records. LOHD was defined as age ≥60years at HD diagnosis. Genetic disease burden was assessed using CAG age product (CAP) score. LOHD comprised 25% of the adult-onset HD cohort giving a point prevalence of 2.38/100,000 in the Finnish population at least 60years of age. The proportion of LOHD out of new HD diagnoses increased from 21% in 1991-2000 to 33% in 2001-2010. At the time of diagnosis, patients with LOHD had 10.4 units (95% CI 4.8-15.9; p=0.0003) higher CAP scores, more severe motor impairment and slightly more severe functional impairment than that in patients with mid-age-onset HD. There was no difference in the rate of disease progression or survival between LOHD and mid-age-onset patients. The lifespans of deceased patients were shorter in mid-age-onset HD (p<0.001) and LOHD (p=0.002) than their life expectancies. Causes of death differed between the two patient groups (p=0.025). LOHD comprises a quarter of Finnish HD patients and the proportion appears to be increasing. Our results did not reveal differences in the phenotype between mid-age-onset HD and LOHD, but prospective studies are needed.

What do we know about Late Onset Huntington's Disease?

Background: Although the typical age of onset for Huntington’s disease (HD) is in the fourth decade, between 4.4–11.5% of individuals with HD have a late onset (over 60 years of age). Diagnosis of Late onset HD (LoHD) can be missed, due to the perceived low likelihood of HD in the over 60-year-olds.Objective: To review the epidemiology, genotype and phenotype of LoHD.Methods: We systematically searched MEDLINE, EMBASE and Web of Science (inception-November 2016). Web of Science was then used to search for papers citing identified studies. Content experts were consulted for any additional studies. We included all studies reporting the clinical phenotype of LoHD for more than one participant.Results: 20 studies were identified from a potential list of 1243. Among Caucasian HD cohorts, 4.4–11.5% of individuals have LoHD, and this proportion may be increasing. Proportion of LoHD without a positive family history ranges from 3–68%. 94.4% of reported cases of LoHD had CAG repeat lengths of ≤44. Motor manifestations are the commonest initial presentation, although 29.2% presented with non-motor manifestations as the first clinical feature in one case series. Individuals with LoHD may have slower progression of illness. Cognitive impairment rather than chorea may be the major source of disability in this group.Conclusions: LoHD represents a substantial proportion of new diagnoses of HD and has some unique features. Further characterization of this population will aid clinicians in diagnosis.

Chapter 18 - Motor outcome measures in Huntington disease clinical trials

Deficits in motor function are a hallmark of Huntington disease (HD). The Unified Huntington's Disease Rating Scale Total Motor Score (UHDRS-TMS) is a categoric clinical rating scale assessing multiple domains of motor disability in HD. The UHDRS-TMS or subsets of its items have served as primary or secondary endpoints in numerous clinical trials. In spite of a well-established video-based annual online certification system, intra- and interrater variability, subjective error, and rater-induced placebo effects remain a concern. In addition, the UHDRS-TMS was designed to primarily assess motor symptoms in manifest HD. Recently, advancement of technology resulted in the introduction of the objective Q-Motor (i.e., Quantitative-Motor) assessments in biomarker studies and clinical trials in HD. Q-Motor measures detected motor signs in blinded cross-sectional and longitudinal analyses of manifest, prodromal, and premanifest HD cohorts up to two decades before clinical diagnosis. In a multicenter clinical trial in HD, Q-Motor measures were more sensitive than the UHDRS-TMS and exhibited no placebo effects. Thus, Q-Motor measures are currently explored in several multicenter trials targeting both symptomatic and disease-modifying mechanisms. They may supplement the UHDRS-TMS, increase the sensitivity and reliability in proof-of-concept studies, and open the door for phenotype assessments in clinical trials in prodromal and premanifest HD.

Systems Genetic Analyses Highlight a TGFβ-FOXO3 Dependent Striatal Astrocyte Network Conserved across Species and Associated with Stress, Sleep, and Huntington's Disease.

Recent systems-based analyses have demonstrated that sleep and stress traits emerge from shared genetic and transcriptional networks, and clinical work has elucidated the emergence of sleep dysfunction and stress susceptibility as early symptoms of Huntington's disease. Understanding the biological bases of these early non-motor symptoms may reveal therapeutic targets that prevent disease onset or slow disease progression, but the molecular mechanisms underlying this complex clinical presentation remain largely unknown. In the present work, we specifically examine the relationship between these psychiatric traits and Huntington's disease (HD) by identifying striatal transcriptional networks shared by HD, stress, and sleep phenotypes. First, we utilize a systems-based approach to examine a large publicly available human transcriptomic dataset for HD (GSE3790 from GEO) in a novel way. We use weighted gene coexpression network analysis and differential connectivity analyses to identify transcriptional networks dysregulated in HD, and we use an unbiased ranking scheme that leverages both gene- and network-level information to identify a novel astrocyte-specific network as most relevant to HD caudate. We validate this result in an independent HD cohort. Next, we computationally predict FOXO3 as a regulator of this network, and use multiple publicly available in vitro and in vivo experimental datasets to validate that this astrocyte HD network is downstream of a signaling pathway important in adult neurogenesis (TGFβ-FOXO3). We also map this HD-relevant caudate subnetwork to striatal transcriptional networks in a large (n = 100) chronically stressed (B6xA/J)F2 mouse population that has been extensively phenotyped (328 stress- and sleep-related measurements), and we show that this striatal astrocyte network is correlated to sleep and stress traits, many of which are known to be altered in HD cohorts. We identify causal regulators of this network through Bayesian network analysis, and we highlight their relevance to motor, mood, and sleep traits through multiple in silico approaches, including an examination of their protein binding partners. Finally, we show that these causal regulators may be therapeutically viable for HD because their downstream network was partially modulated by deep brain stimulation of the subthalamic nucleus, a medical intervention thought to confer some therapeutic benefit to HD patients. In conclusion, we show that an astrocyte transcriptional network is primarily associated to HD in the caudate and provide evidence for its relationship to molecular mechanisms of neural stem cell homeostasis. Furthermore, we present a unified systems-based framework for identifying gene networks that are associated with complex non-motor traits that manifest in the earliest phases of HD. By analyzing and integrating multiple independent datasets, we identify a point of molecular convergence between sleep, stress, and HD that reflects their phenotypic comorbidity and reveals a molecular pathway involved in HD progression.

Change in PDE10 across early Huntington disease assessed by [18F]MNI-659 and PET imaging.

To evaluate whether striatal [(18)F]MNI-659 PET imaging of phosphodiesterase 10A (PDE10) serves as a sensitive and reliable biomarker of striatal neurodegeneration in a longitudinal cohort of participants with early Huntington disease (HD). A cohort of participants with HD, including both participants premanifest or manifest with motor signs, underwent clinical assessments, genetic determination, and 2 [(18)F]MNI-659 PET imaging sessions approximately 1 year apart. Eleven healthy control (HC) participants underwent clinical assessments and [(18)F]MNI-659 PET imaging once. Striatal binding potentials (BPnd) were estimated for brain regions of interest, specifically within the basal ganglia, and compared between baseline and follow-up imaging. Clinical measures of HD severity were assessed at each visit. Eight participants with HD (6 manifest; 2 premanifest) participated. Of those with manifest HD, all had relatively early stage disease (stage 1, n = 2; stage 2, n = 4) and a Unified Huntington's Disease Rating Scale total motor score <45. As expected, the HD cohort as a whole had a reduction in the basal ganglia BPnd to approximately 50% of that seen in HC. On follow-up scans, [(18)F]MNI-659 uptake declined in the putamen and caudate nucleus in all 8 participants. The mean annualized rates of decline in signal in the caudate, putamen, and globus pallidus and the putamen were 16.6%, 6.9%, and 5.8%, respectively. In HC, the annualized reduction in signal in striatal regions was less than 1%. Longitudinal data in this small cohort of participants with early HD support [(18)F]MNI-659 PET imaging of PDE10 as a useful biomarker to track HD disease progression.