Prevalence of Non-psychiatric Comorbidities in Pre-symptomatic and Symptomatic Huntington's Disease Gene Carriers in Poland

Modifiable factors associated with Huntington's disease progression in presymptomatic participants

OBJECTIVE

Huntington's disease (HD) is a neurodegenerative disorder characterized by progressive motor, cognitive, and psychiatric symptoms. Our aim here was to identify factors that can be modified to slow disease progression even before the first symptoms appear.

METHODS

We included 2636 presymptomatic individuals (comparison with family controls) drawn from the prospective observational cohort Enroll-HD, with more than 35 CAG repeats and at least two assessments of disease progression measured with the composite Huntington's disease rating Scale (cUHDRS). The association between sociodemographic factors, health behaviors, health history, and cUHDRS trajectory was assessed with a mixed-effects random forest using partial dependence plots and Shapley additive explanation method.

RESULTS

Participants were followed by an average of 3.4 (SD = 1.97) years. We confirmed the negative impact of age and a high number of CAG repeats. We found that a high level of education, a body mass index (BMI) <23 kg/m2 before the age of 40 and >23 kg/m2 thereafter, alcohol consumption of <15 units per week, current coffee consumption and no smoking were linked to slow disease progression, as did no previous exposure to antidepressants or anxiolytic, no psychiatric history or comorbidities, and being female. Other comorbidities or marital status showed no major association with HD evolution.

INTERPRETATION

Reducing modifiable risk factors for HD is one way to support the presymptomatic population. A high level of education, low-to-moderate alcohol consumption, no smoking, and BMI control are likely to slow disease progression in this population.

Deregulated Transcriptome as a Platform for Adrenal Huntington's Disease-Related Pathology

Huntington's disease (HD) is a neurodegenerative disorder that affects mainly the central nervous system (CNS) by inducing progressive deterioration in both its structure and function. In recent years, there has been growing interest in the impact of HD on peripheral tissue function. Herein, we used the R6/2 mouse model of HD to investigate the influence of the disease on adrenal gland functioning. A transcriptomic analysis conducted using a well-established quantitative method, an Affymetrix array, revealed changes in gene expression in the R6/2 model compared to genetic background controls. For the first time, we identified disruptions in cholesterol and sterol metabolism, blood coagulation, and xenobiotic metabolism in HD adrenal glands. This study showed that the disrupted expression of these genes may contribute to the underlying mechanisms of Huntington's disease. Our findings may contribute to developing a better understanding of Huntington's disease progression and aid in the development of novel diagnostic or therapeutic approaches.

A minimal region of the HSP90AB1 promoter is suitable for ubiquitous expression in different somatic tissues with applicability for gene therapy

Huntington's disease (HD) is a multi-tissue failure disorder for which there is no cure. We have previously shown an effective therapeutic approach limited mainly to the central nervous system, based on a synthetic zinc finger (ZF) transcription repressor gene therapy, but it would be important to target other tissues as well. In this study, we identify a novel minimal HSP90AB1 promoter region that can efficiently control expression not only in the CNS but also in other affected HD tissues. This promoter-enhancer is effective in driving expression of ZF therapeutic molecules in both HD skeletal muscles and the heart, in the symptomatic R6/1 mouse model. Moreover, for the first time we show that ZF molecules repressing mutant HTT reverse transcriptional pathological remodelling in HD hearts. We conclude that this HSP90AB1 minimal promoter may be used to target multiple HD organs with therapeutic genes. The new promoter has the potential to be added to the portfolio of gene therapy promoters, for use where ubiquitous expression is needed.

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).

Metabolism in Huntington's disease: a major contributor to pathology

Huntington's disease (HD) is a progressively debilitating neurodegenerative disease exhibiting autosomal-dominant inheritance. It is caused by an unstable expansion in the CAG repeat tract of HD gene, which transforms the disease-specific Huntingtin protein (HTT) to a mutant form (mHTT). The profound neuronal death in cortico-striatal circuits led to its identification and characterisation as a neurodegenerative disease. However, equally disturbing are the concomitant whole-body manifestations affecting nearly every organ of the diseased individuals, at varying extents. Altered central and peripheral metabolism of energy, proteins, nucleic acids, lipids and carbohydrates encompass the gross pathology of the disease. Intense fluctuation of body weight, glucose homeostasis and organ-specific subcellular abnormalities are being increasingly recognised in HD. Many of these metabolic abnormalities exist years before the neuropathological manifestations such as chorea, cognitive decline and behavioural abnormalities develop, and prove to be reliable predictors of the disease progression. In this review, we provide a consolidated overview of the central and peripheral metabolic abnormalities associated with HD, as evidenced from clinical and experimental studies. Additionally, we have discussed the potential of metabolic biomolecules to translate into efficient biomarkers for the disease onset as well as progression. Finally, we provide a brief outlook on the efficacy of existing therapies targeting metabolic remediation. While it is clear that components of altered metabolic pathways can mark many aspects of the disease, it is only conceivable that combinatorial therapies aiming for neuronal protection in consort with metabolic upliftment will prove to be more efficient than the existing symptomatic treatment options.

Identification of the Transcriptional Biomarkers Panel Linked to Pathological Remodelling of the Eye Tissues in Various HD Mouse Models

Ocular abnormalities are becoming associated with a spectrum of pathological events in various neurodegenerative diseases. Huntington's disease (HD) is just such an example of a fatal neurological disorder, where mutated genes (CAG trinucleotide expansions in the Huntingtin gene) have widespread expression, leading to the production of mutant Huntingtin (mHTT) protein. It is well known that mutant HTT protein is prone to form toxic aggregates, which are a typical pathological feature, along with global transcriptome alterations. In this study, we employed well-established quantitative methods such as Affymetrix arrays and quantitative PCR (qPCR) to identify a set of transcriptional biomarkers that will track HD progression in three well-established mouse models: R6/2, R6/1, and HdhQ150. Our array analysis revealed significantly deregulated networks that are related to visual processes and muscle contractions. Furthermore, our targeted quantitative analysis identified a panel of biomarkers with some being dysregulated even at the presymptomatic stage of the disease, e.g., Opn1mw, Opn1sw, and Pfkfb2. Some of the deregulated genes identified in this study have been linked to other genetic ocular disorders such as: GNAT2, a source of achromatopsia, and REEP6, linked to Retinitis pigmentosa. It may thus be a useful platform for preclinical evaluations of therapeutic interventions.

Structural Abnormalities of the Optic Nerve and Retina in Huntington's Disease Pre-Clinical and Clinical Settings

Huntington's disease (HD) is a fatal neurodegenerative disorder caused by a polyglutamine expansion in the huntingtin protein. HD-related pathological remodelling has been reported in HD mouse models and HD carriers. In this study, we studied structural abnormalities in the optic nerve by employing Spectral Domain Optical Coherence Tomography (SD-OCT) in pre-symptomatic HD carriers of Caucasian origin. Transmission Electron Microscopy (TEM) was used to investigate ultrastructural changes in the optic nerve of the well-established R6/2 mouse model at the symptomatic stage of the disease. We found that pre-symptomatic HD carriers displayed a significant reduction in the retinal nerve fibre layer (RNFL) thickness, including specific quadrants: superior, inferior and temporal, but not nasal. There were no other significant irregularities in the GCC layer, at the macula level and in the optic disc morphology. The ultrastructural analysis of the optic nerve in R6/2 mice revealed a significant thinning of the myelin sheaths, with a lamellar separation of the myelin, and a presence of myelonoid bodies. We also found a significant reduction in the thickness of myelin sheaths in peripheral nerves within the choroids area. Those ultrastructural abnormalities were also observed in HD photoreceptor cells that contained severely damaged membrane disks, with evident vacuolisation and swelling. Moreover, the outer segment of retinal layers showed a progressive disintegration. Our study explored structural changes of the optic nerve in pre- and clinical settings and opens new avenues for the potential development of biomarkers that would be of great interest in HD gene therapies.

Geographic Barriers Drive Disparities in Specialty Center Access for Older Adults with Huntington's Disease

BACKGROUND

Huntington's Disease Society of America Centers of Excellence (HDSA COEs) are primary hubs for Huntington's disease (HD) research opportunities and accessing new treatments. Data on the extent to which HDSA COEs are accessible to individuals with HD, particularly those older or disabled, are lacking.

OBJECTIVE

To describe persons with HD in the U.S. Medicare program and characterize this population by proximity to an HDSA COE.

METHODS

We conducted a cross-sectional study of Medicare beneficiaries ages ≥65 with HD in 2017. We analyzed data on benefit entitlement, demographics, and comorbidities. QGis software and Google Maps Interface were employed to estimate the distance from each patient to the nearest HDSA COE, and the proportion of individuals residing within 100 miles of these COEs at the state level.

RESULTS

Among 9,056 Medicare beneficiaries with HD, 54.5% were female, 83.0% were white; 48.5% were ≥65 years, but 64.9% originally qualified for Medicare due to disability. Common comorbidities were dementia (32.4%) and depression (35.9%), and these were more common in HD vs. non-HD patients. Overall, 5,144 (57.1%) lived within 100 miles of a COE. Race/ethnicity, sex, age, and poverty markers were not associated with below-average proximity to HDSA COEs. The proportion of patients living within 100 miles of a center varied from < 10% (16 states) to > 90% (7 states). Most underserved states were in the Mountain and West Central divisions.

CONCLUSION

Older Medicare beneficiaries with HD are frequently disabled and have a distinct comorbidity profile. Geographical, rather than sociodemographic factors, define the HD population with limited access to HDSA COEs.

Hereditary Chorea Associated With and Aggravated by Systemic Lupus Erythematosus

Chorea is caused by a number of conditions, including genetic, metabolic derangements, infections, drugs, toxins, tumors, and disorders of the immune and inflammatory system of the body. Huntington's disease (HD) is the most common genetic cause of chorea. Systemic lupus erythematosus (SLE) is an autoimmune condition. Common symptoms include oral ulcers, joint pain, malar or discoid rashes, photosensitivity, and blood dyscrasias. It can involve the heart, lungs, kidneys, and brain. SLE can cause neuropsychiatric manifestations like psychosis, seizures, headache, confusion, and stroke. Chorea is a known symptom of SLE. HD is now recognized to involve more than one system and is associated with a number of comorbid conditions. We report the first case of hereditary choreiform disorder associated with and aggravated by SLE. This is also the first case report of probable Huntington disease from Balochistan, Pakistan. We report a 19-year-old girl with choreiform disorder and a family history of chorea. Choreiform disorder was present in her paternal grandmother and uncles. She presented with fever, cough, and aggravation of choreiform movements of upper and lower limbs for 10 days. She also complained of pain in the small joints of her hands and feet, oral ulcers, hair loss, and aggravation of choreiform movements for two and half months. Probable differential diagnoses of HD, Wilson's disease, and other types of hereditary chorea, aggravated by infections, SLE, or Covid-19, were made. Her initial lab results revealed pancytopenia, increased D-dimers and serum ferritin, positive antinuclear antibodies (ANA), and anti-double-stranded DNA (anti-dsDNA). Her C3 and C4 complement factors were low. The rest of the lab test results, including polymerase chain reaction (PCR) coronavirus disease (COVID-19), blood culture, and malaria, were negative. Thus, a diagnosis of hereditary chorea associated with and aggravated by SLE was made. Hereditary choreiform disorders can be associated with and aggravated by autoimmune conditions like SLE. Thus, it is recommended to be vigilant and have a low threshold for diagnosing co-existing autoimmune conditions like SLE in patients with hereditary choreiform disorder.

Deciphering the key mechanisms leading to alteration of lipid metabolism in Drosophila model of Huntington's disease

Huntington's disease (HD) is an inherited, progressively debilitating disorder marked by prominent degeneration in striatal and cortical brain regions. HD is caused by (CAG)_n repeat expansion in huntingtin (HTT) gene that translates into a mutant form of the ubiquitously present Huntingtin (HTT) protein. Extensive metabolic dysfunction coexisting with overt neuropathies has been evidenced in clinical and experimental settings of HD. Body weight loss despite normal to high caloric intake remains a critical determinant of the disease progression and a challenge for therapeutic interventions. In the present study, we intended to monitor the cellular and molecular perturbations in Drosophila, caused by pan-neuronal expression of mHTT (mutant Huntingtin) protein. We found aberrant transcription profile of key lipolytic and lipogenic genes in whole-body of the fly with disease progression. Interestingly, fatbody undergoes extensive alteration of vital cellular processes and eventually surrenders to increased apoptotic cell death in terminal stage of the disease. Extensive mitochondrial dysfunction from early disease stage along with calcium derangement at terminal stage were observed in fatbody, which contribute to its deteriorating integrity. All the mechanisms were monitored progressively, at different disease stages, and many alterations were documented in the early stage itself. Our study hence provides insight into the mechanisms through which neuronal expression of mHTT might be inflicting the profound systemic effects, specifically on lipid metabolism, and may open new therapeutic avenues for alleviation of the multidimensional disease.