Juvenile Huntington's Disease Research Articles

A-49Early Identification of Neurocognitive Deficits and Symptom Manifestation Associated with Juvenile Huntington's Disease (JHD) in a Preschooler: A Pediatric Case Study

A-49Early Identification of Neurocognitive Deficits and Symptom Manifestation Associated with Juvenile Huntington's Disease (JHD) in a Preschooler: A Pediatric Case Study

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.

The pathogenic exon 1 HTT protein is produced by incomplete splicing in Huntington\u2019s disease patients

We have previously shown that exon 1 of the huntingtin gene does not always splice to exon 2 resulting in the production of a small polyadenylated mRNA (HTTexon1) that encodes the highly pathogenic exon 1 HTT protein. The level of this read-through product is proportional to CAG repeat length and is present in all knock-in mouse models of Huntington’s disease (HD) with CAG lengths of 50 and above and in the YAC128 and BACHD mouse models, both of which express a copy of the human HTT gene. We have now developed specific protocols for the quantitative analysis of the transcript levels of HTTexon1 in human tissue and applied these to a series of fibroblast lines and post-mortem brain samples from individuals with either adult-onset or juvenile-onset HD. We found that the HTTexon1 mRNA is present in fibroblasts from juvenile HD patients and can also be readily detected in the sensory motor cortex, hippocampus and cerebellum of post-mortem brains from HD individuals, particularly in those with early onset disease. This finding will have important implications for strategies to lower mutant HTT levels in patients and the design of future therapeutics.

A Case of Previously Unsuspected Huntington Disease Diagnosed at Autopsy

Huntington disease (HD) is a neurodegenerative disorder with a worldwide prevalence of four to ten per 100 000. It is characterized by choreiform movements, behavioral/psychiatric disturbances, and eventual cognitive decline. Symptoms usually present between 30 and 50 years of age and the diagnosis is based on the combination of clinical symptoms, family history, and genetic testing. A variation of HD, juvenile Huntington disease (JHD), presents earlier, with more severe symptoms and with a worse prognosis. Symptoms are different in JHD, with personality changes and learning difficulties being the predominant presenting features. Seizures are common in JHD, and chorea is uncommon; movement disorders at presentation of JHD are predominantly nonchoreiform. The inheritance pattern for both HD and JHD is autosomal dominant and the disease is caused by an elongation of the CAG repeat in the huntingtin gene. There are many published case reports of Huntington disease that were confirmed at autopsy, but to our knowledge, there are no reports in the literature where the diagnosis of Huntington disease was first made at autopsy. We present a case of a 28-year-old African-American male who was in a state of neglect due to a lifetime of abuse, cognitive difficulties, and seizures, whose cause of death was pneumonia. The gross autopsy findings included bilateral caudate nucleus atrophy and lateral ventricular dilation. Microscopically, severe bilateral neuronal loss and gliosis of the caudate and putamen nuclei were seen. Genetic testing for the number of CAG repeats confirmed the diagnosis and was consistent with JHD.

Juvenile Huntington’s Disease: Diagnostic and Treatment Considerations for the Psychiatrist

Juvenile Huntington's disease (JHD) is a neurodegenerative disease with onset prior to the age of 21. While it accounts for a relatively small proportion of Huntington's disease (HD) diagnoses, its impact is significant on the quality of life for those affected. Clinicians may be unaware that HD can present in childhood and adolescence, delaying diagnosis. HD develops due to an expanded CAG repeat in the huntington gene. Rigidity, dystonia, and seizures are more common in JHD. Cognitive changes such as executive function impairments and decline in school performance are common. The burden of psychiatric symptoms is considerable and includes depression, anxiety, impulsivity, and aggression. While novel approaches to treatment interventions are investigated, current care is limited to targeting symptoms rather than disease modification. Prompt diagnosis and symptomatic treatment can maximize quality of life for these patients.

Children with Mild CAG Repeat Expansion in HTT Gene Showing Psychiatric but not Neurological Presentation: Is It One More Shade of Huntington Disease?

Objective: Huntington disease (HD) generally manifests in adulthood. Large mutations with CAG repeat expansion in HTT gene may rarely cause juvenile Huntington disease (JHD) in early childhood or adolescence with atypical clinical features, i.e., atypical parkinsonism, if compared to adult patients. Our objective is to characterize the rare occurrence of clinical manifestations in children carrying mutations in the low-mild size, generally causing adult HD with typical choreic movements. Methods: We are following up a subgroup of young subjects with HD mutation who manifested with disabling psychiatric condition since early childhood or adolescence. We are collecting data by the observational studies Registry and ENROLL-HD since 2004. Among 60 JHD patients we are currently following-up, we selected people who carry a mutation in the mild range of CAG expansions (i.e., expected to manifest in adulthood), psychiatric manifestations and no neurological signs or movement disorders suggestive of HD. All patients were genetically (i.e., CAG size analysis) and clinically (i.e., total motor score within the Unified HD Rating Scale) characterized. Results: We found four subjects who showed the characteristics for this analysis. All four subjects presented a CAG expansion size <45 repeats. Two patients manifested a schizophrenia-like disturbance during their adolescence, with the later appearance of motor signs after age 20. In the other two cases, patients presented symptoms of autistic spectrum disorder, since infancy. One of them showed also a schizophrenia-like disturbance and, later, HD onset with motor signs after 20. A 45 year old patient is currently manifesting an autistic disorder in absence of others neurological signs. Conclusion: The description of JHD includes sometimes children with psychiatric manifestations associated with adult motor onset. We advise to pay careful attention to such rare conditions that might represent either psychiatric conditions erroneously classified as JHD or prodromic adult HD cases.

Altered membrane properties and firing patterns of external globus pallidus neurons in the R6/2 mouse model of Huntington's disease.

In mouse models of Huntington's disease (HD), striatal neuron properties are significantly altered. These alterations predict changes in striatal output regions. However, little is known about alterations in those regions. The present study examines changes in passive and active membrane properties of neurons in the external globus pallidus (GPe), the first relay station of the indirect pathway, in the R6/2 mouse model of juvenile HD at presymptomatic (1 month) and symptomatic (2 month) stages. In GPe, two principal types of neurons can be distinguished based on firing properties and the presence (type A) or absence (type B) of Ih currents. In symptomatic animals (2 month), cell membrane capacitance and input resistance of type A neurons were increased compared with controls. In addition, action potential afterhyperpolarization amplitude was reduced. Although the spontaneous firing rate of GPe neurons was not different between control and R6/2 mice, the number of spikes evoked by depolarizing current pulses was significantly reduced in symptomatic R6/2 animals. In addition, these changes were accompanied by altered firing patterns evidenced by increased interspike interval variation and increased number of bursts. Blockade of GABAA receptors facilitated bursting activity in R6/2 mice but not in control littermates. Thus, alterations in firing patterns could be caused by changes in intrinsic membrane conductances and modulated by synaptic inputs. © 2016 Wiley Periodicals, Inc.

Huntington's Disease: Relationship Between Phenotype and Genotype.

Huntington's disease (HD) is an autosomal dominant inherited neurodegenerative disease with the typical manifestations of involuntary movements, psychiatric and behavior disorders, and cognitive impairment. It is caused by the dynamic mutation in CAG triplet repeat number in exon 1 of huntingtin (HTT) gene. The symptoms of HD especially the age at onset are related to the genetic characteristics, both the CAG triplet repeat and the modified factors. Here, we reviewed the recent advancement on the genotype-phenotype relationship of HD, mainly focus on the characteristics of different expanded CAG repeat number, genetic modifiers, and CCG repeat number in the 3' end of CAG triplet repeat and their effects on the phenotype. We also reviewed the special forms of HD (juvenile HD, atypical onset HD, and homozygous HD) and their phenotype-genotype correlations. The review will aid clinicians to predict the onset age and disease course of HD, give the genetic counseling, and accelerate research into the HD mechanism.

Juvenile Huntington disease in Argentina.

We analyzed demographic, clinical and genetic characteristics of juvenile Huntington disease (JHD) and it frequency in an Argentinean cohort. Age at onset was defined as the age at which behavioral, cognitive, psychiatric or motor abnormalities suggestive of JHD were first reported. Clinical and genetic data were similar to other international series, however, in this context we identified the highest JHD frequency reported so far (19.72%; 14/71). Age at onset of JHD is challenging and still under discussion. Our findings reinforce the hypothesis that clinical manifestations, other than the typical movement disorder, may anticipate age at onset of even many years. Analyses of JHD cohorts are required to explore it frequency in populations with different backgrounds to avoid an underestimation of this rare phenotype. Moreover, data from selected populations may open new pathways in therapeutic approaches and may explain new potential correlations between HD presentations and environmental or biological factors.

Developing stem cell therapies for juvenile and adult-onset Huntington's disease.

Stem cell therapies have been explored as a new avenue for the treatment of neurologic disease and damage within the CNS in part due to their native ability to mimic repair mechanisms in the brain. Mesenchymal stem cells have been of particular clinical interest due to their ability to release beneficial neurotrophic factors and their ability to foster a neuroprotective microenviroment. While early stem cell transplantation therapies have been fraught with technical and political concerns as well as limited clinical benefits, mesenchymal stem cell therapies have been shown to be clinically beneficial and derivable from nonembryonic, adult sources. The focus of this review will be on emerging and extant stem cell therapies for juvenile and adult-onset Huntington’s disease.

Optimising occupational performance through sensory modulation interventions: Case reports of two young adults diagnosed with juvenile Huntington's disease

Statement of context People with juvenile Huntington's disease often experience difficulty engaging in occupations due to neuropsychiatric sequelae, such as impulse control difficulties, agitation and aggression. Occupational therapy using sensory modulation intervention strategies may be utilised to assuage behavioural symptoms in this population. Critical reflection on practice Through case reports, this practice analysis explores changes in occupational performance for two young adults diagnosed with juvenile Huntington's disease who received sensory modulation treatment. Implications for practice These inspiring reports could encourage occupational therapists to consider sensory modulation intervention to decrease psychiatric disturbance, thus optimising performance capacity among this rare population.

Making (anti-) sense out of huntingtin levels in Huntington disease.

BackgroundHuntington disease (HD) is an autosomal dominant neurodegenerative disorder, characterized by motor, psychiatric and cognitive symptoms. HD is caused by a CAG repeat expansion in the first exon of the HTT gene, resulting in an expanded polyglutamine tract at the N-terminus of the huntingtin protein. Typical disease onset is around mid-life (adult-onset HD) whereas onset below 21 years is classified as juvenile HD. While much research has been done on the underlying HD disease mechanisms, little is known about regulation and expression levels of huntingtin RNA and protein.ResultsIn this study we used 15 human post-mortem HD brain samples to investigate the expression of wild-type and mutant huntingtin mRNA and protein. In adult-onset HD brain samples, there was a small but significantly lower expression of mutant huntingtin mRNA compared to wild-type huntingtin mRNA, while wild-type and mutant huntingtin protein expression levels did not differ significantly. Juvenile HD subjects did show a lower expression of mutant huntingtin protein compared to wild-type huntingtin protein. Our results in HD brain and fibroblasts suggest that protein aggregation does not affect levels of huntingtin RNA and protein. Additionally, we did not find any evidence for a reduced expression of huntingtin antisense in fibroblasts derived from a homozygous HD patient.ConclusionsWe found small differences in allelic huntingtin mRNA levels in adult-onset HD brain, with significantly lower mutant huntingtin mRNA levels. Wild-type and mutant huntingtin protein were not significantly different in adult-onset HD brain samples. Conversely, in juvenile HD brain samples mutant huntingtin protein levels were lower compared with wild-type huntingtin, showing subtle differences between juvenile HD and adult-onset HD. Since most HD model systems harbor juvenile repeat expansions, our results suggest caution with the interpretation of huntingtin mRNA and protein studies using HD cell and animal models with such long repeats. Furthermore, our huntingtin antisense results in homozygous HD cells do not support reduced huntingtin antisense expression due to an expanded CAG repeat.

Therapeutic Options in Treatment of Juvenile Huntington Disease: Difference to Adult Patients

Therapeutic Options in Treatment of Juvenile Huntington Disease: Difference to Adult Patients

Clinical diagnosis and management in early Huntington's disease: a review.

This review focuses on clinical diagnosis and both pharmacological and nonpharmacological therapeutic options in early stages of the autosomal dominant inherited neurodegenerative Huntington’s disease (HD). The available literature has been reviewed for motor, cognitive, and psychiatric alterations, which are the three major symptom domains of this devastating progressive disease. From a clinical point of view, one has to be aware that the HD phenotype can vary highly across individuals and during the course of the disease. Also, symptoms in juvenile HD can differ substantially from those with adult-onset of HD. Although there is no cure of HD and management is limited, motor and psychiatric symptoms often respond to pharmacotherapy, and nonpharmacological approaches as well as supportive care are essential. International treatment recommendations based on study results, critical statements, and expert opinions have been included. This review is restricted to symptomatic and supportive approaches since all attempts to establish a cure for the disease or modifying therapies have failed so far.

Novel BAC Mouse Model of Huntington's Disease with 225 CAG Repeats Exhibits an Early Widespread and Stable Degenerative Phenotype

Unusually large CAG repeat expansions (>60) in exon one of Huntingtin (HTT) are invariably associated with a juvenile-onset form of Huntington's disease (HD), characterized by a more extensive and rapidly progressing neuropathology than the more prevalent adult-onset form. However, existing mouse models of HD that express the full-length Htt gene with CAG repeat lengths associated with juvenile HD (ranging between ~75 to ~150 repeats in published models) exhibit selective neurodegenerative phenotypes more consistent with adult-onset HD. Objective: To determine if a very large CAG repeat (>200) in full-length Htt elicits neurodegenerative phenotypes consistent with juvenile HD. Using a …bacterial artificial chromosome (BAC) system, we generated mice expressing full-length mouse Htt with ~225 CAG repeats under control of the mouse Htt promoter. Mice were characterized using behavioral, neuropathological, biochemical and brain imaging methods. BAC-225Q mice exhibit phenotypes consistent with a subset of features seen in juvenile-onset HD: very early motor behavior abnormalities, reduced body weight, widespread and progressive increase in Htt aggregates, gliosis, and neurodegeneration. Early striatal pathology was observed, including reactive gliosis and loss of dopamine receptors, prior to detectable volume loss. HD-related blood markers of impaired energy metabolism and systemic inflammation were also increased. Aside from an age-dependent progression of diffuse nuclear aggregates at 6 months of age to abundant neuropil aggregates at 12 months of age, other pathological and motor phenotypes showed little to no progression. The HD phenotypes present in animals 3 to 12 months of age make the BAC-225Q mice a unique and stable model of full-length mutant Htt associated phenotypes, including body weight loss, behavioral impairment and HD-like neurodegenerative phenotypes characteristic of juvenile-onset HD and/or late-stage adult-onset HD.

Echogenicity of basal ganglia structures in different Huntington's disease phenotypes.

In Huntington's disease (HD), a neurodegenerative-inherited disease, chorea as the typical kind of movement disorder is described. Beside chorea, however, all other kinds of movement disturbances, such as bradykinesia, dystonia, tremor or myoclonus can occur. Aim of the current study was to investigate alterations in the echogenicity of basal ganglia structures in different Huntington's disease phenotypes. 47 patients with manifest and genetically confirmed HD were recruited. All participants underwent a thorough neurological examination. According to a previously described method, classification into predominantly choreatic, mixed or bradykinetic-rigid motor phenotypes was performed depending on subscores of the Unified Huntington's Disease Rating Scale. In addition, findings in juvenile HD were compared to adult HD. Transcranial sonography was performed by investigators blinded to clinical classification. There were no significant differences in basal ganglia echogenicities between the three phenotypes. Size of echogenic area of substantia nigra (SN) correlated positively with CAG repeat and bradykinesia subscore, and negatively with age of onset and chorea subscore. Comparing juvenile and adult HD subtypes, SN hyperechogenicity was significantly more often detectable in the juvenile form (100 vs. 29.3 %, p = 0.002). Regarding echogenicity of caudate or lentiform nuclei, no significant differences were detected. HD patients with the juvenile variant exhibit marked hyperechogenicity of substantia nigra. No significant differences in basal ganglia echogenicities between predominantly choreatic, mixed or bradykinetic-rigid motor phenotypes were detected.

J36 Juvenile Huntington Disease In Voronezh Families

Juvenile Huntington disease (JHD) amounts 10% of all Huntington disease (HD) cases and characterised by the manifests before 20, with a predominance akinesia and rigidity and progressive course of the disease. Although HD has an autosomal dominant pattern of inheritance, JHD in most cases is paternal inheritance with anticipation and the expansion of CAG trinucleotide repeats >60 in the IT15 gene located on chromosome 4p16.3; however, atypical cases exist, and maternal inheritance is possible. We present 6 (4 women and 2 men) JHD cases confirmed by DNA, where the number of CAG repeats varied from 60 till 66. All the patients had MRI which showed varying degrees of severity substitution hydrocephalus. Family nature of the disease was found in four cases (three maternal and one paternal inheritance). Two cases were not familial, but it is known that the mother did not have HD, and the father of one patient died at 46, and the other does not have information about his father. Four patients had akinetic-rigid form with onset between 12–19, three of them with cognitive decline. Two patients had a hyperkinetic form and cognitive decline. Diagnosis in 4 familial cases did not cause problems, although three of them had atypical maternal inheritance. Two isolated JHD cases were supposed 3 and 10 years after its onset that may indicate underestimation of JHD in practice. JHD probability should be kept in mind, even in cases with no family history, progressive akinetic-rigidy, choreic movements and cognitive decline DNA research on HD should be included.

I07 Abnormalities In Weight And Bmi In Children With Juvenile Huntington's Disease

Background Abnormalities in weight and BMI have been shown not only in preHD adults, but also preHD children suggesting that metabolic abnormalities may affect body composition with primary effects in skeletal muscle. Growth measures have never been reported in children with Juvenile Huntington’s disease (JHD). Methods Growth measures for 18 JHD subjects were obtained through medical chart review, documented either prior to diagnosis or soon after. These measures were compared to a large sample (n = 274) of healthy developing children, as well as the Centre for Disease Control (CDC) growth norms. Results After controlling for effects of sex and age, the JHD subjects had no significant differences in height. However, they were an average of 10% lower than normal controls in weight and BMI. Using CDC norms, the JHD subjects had the same pattern of normal height but decrement in weight. Length of CAG repeat was significantly correlated to measures of weight with longer CAG repeats being associated with more severe weight reduction. A subset of 4 subjects had measures that pre-dated onset of any symptom and were therefore preJHD. These subjects also had a significant decrement in BMI compared to CDC norms. Conclusion Children with JHD have normal height, but significantly reduced weight and BMI, indicating a specific deficit in skeletal muscle growth. As the preJHD subjects were also low in BMI, this suggests that these changes are due directly to the effect of the mutated gene on development, rather than symptom manifestation of the disease itself.

B03 Making (anti-) Sense Out Of Huntingtin Levels In Huntington Disease

<h3></h3> Huntington disease (HD) is an autosomal dominant neurodegenerative disorder, characterised by motor, psychiatric and cognitive symptoms. HD is caused by a CAG repeat expansion in the first exon of the HTT gene, resulting in an expanded polyglutamine tract at the N-terminus of the huntingtin protein. Typical disease onset is around mid-life (adult-onset HD) whereas onset below 21 years is classified as juvenile HD. While much research has been done on the underlying HD disease mechanisms, little is known about regulation and expression levels of huntingtin RNA and protein. In this study we used a unique collection of human post-mortem HD brain tissue and fibroblast cells to investigate huntingtin mRNA and protein expression, as well as huntingtin antisense isoforms. In adult-onset HD brain samples, there was only a small but significant lower expression of mutant huntingtin mRNA compared to wild-type huntingtin mRNA, while protein expression levels were equal. Juvenile HD subjects did show a lower protein expression of mutant huntingtin compared to wild-type huntingtin protein. Additionally, in brain tissue we did not find any evidence for a reduced expression of huntingtin antisense, as we showed HTTAS_v1 expression in a homozygous HD patient. Finally, we have identified a novel huntingtin antisense isoform and named it HTTAS_v2.2. Our study shows an intricate mechanism of huntingtin RNA and protein regulation of expression with slightly less mutant huntingtin mRNA, but equal wild-type and mutant huntingtin protein levels in adult-onset HD, indicating subtle differences in huntingtin protein expression between adult-onset and juvenile HD.

J35 Clinical Forms Of Huntington's Disease In The Patients From Republic Of Bashkortostan

<h3>Background</h3> Motor disturbances in Huntington’s disease (HD) can be subdivided into hyperkinetic (choreatic) or hypokinetic-rigid form. Patients with juvenile HD (JHD) also have bradykinesia and dystonia at an early stage of the illness. In different populations the clinical characteristics of patients with HD are similar, but may be a difference in the incidence of clinical forms. <h3>Aim</h3> Our aim was to analyse motor disturbances in patients with HD from Republic of Bashkortostan of various ethnic origins. <h3>Materials and methods</h3> The population of Bashkortostan is 4.07 million people. The population of Bashkirs is 1.2 million (29.5%) according to the 2010 census. Two other big ethnic groups are Russians (36.0%) and Tatars (25.4%). The prevalence of HD in Bashkortostan is 3.6 per 100.000 that compared to other populations. <h3>Results</h3> The majority of patients with HD had the hyperkinetic form of the disease. All groups (patients with HD from Bashkir, Russian, Tatar ethnic groups) showed no differences in the motor age of onset (p &gt; 0.02). Cases of JHD were observed in two families: Russian and Tatar ethnicities. Cases of HD with hypokinetic-rigid form were often observed in Bashkir families with HD (motor age of onset ranged from 27 to 32 years of life, number of CAG-repeats in HTT-gene varied from 43–47). <h3>Conclusion</h3> Analysis of the clinical features of HD and DNA-diagnostics will help to early diagnosis and effective genetic counselling in the families with HD.