Juvenile Huntington disease in the Netherlands

Clinical Review of Juvenile Huntington's Disease

 Juvenile Huntington's disease (JHD) is rare. In the first decade of life speech difficulties, rigidity, and dystonia are common clinical motor symptoms, whereas onset in the second decade motor symptoms may sometimes resemble adult-onset Huntington's disease (AOHD). Cognitive decline is mostly detected by declining school performances. Behavioral symptoms in general do not differ from AOHD but may be confused with autism spectrum disorder or attention deficit hyperactivity disorder and lead to misdiagnosis and/or diagnostic delay. JHD specific features are epilepsy, ataxia, spasticity, pain, itching, and possibly liver steatosis. Disease progression of JHD is faster compared to AOHD and the disease duration is shorter, particularly in case of higher CAG repeat lengths. The diagnosis is based on clinical judgement in combination with a positive family history and/or DNA analysis after careful consideration. Repeat length in JHD is usually > 55 and caused by anticipation, usually via paternal transmission. There are no pharmacological and multidisciplinary guidelines for JHD treatment. Future perspectives for earlier diagnosis are better diagnostic markers such as qualitative MRI and neurofilament light in serum.

Pediatric-Onset Epilepsy and Developmental Epileptic Encephalopathies Followed by Early-Onset Parkinsonism

Genetic early-onset Parkinsonism is unique due to frequent co-occurrence of hyperkinetic movement disorder(s) (MD), or additional neurological of systemic findings, including epilepsy in up to 10-15% of cases. Based on both the classification of Parkinsonism in children proposed by Leuzzi and coworkers and the 2017 ILAE epilepsies classification, we performed a literature review in PubMed. A few discrete presentations can be identified: Parkinsonism as a late manifestation of complex neurodevelopmental disorders, characterized by developmental and epileptic encephalopathies (DE-EE), with multiple, refractory seizure types and severely abnormal EEG characteristics, with or without preceding hyperkinetic MD; Parkinsonism in the context of syndromic conditions with unspecific reduced seizure threshold in infancy and childhood; neurodegenerative conditions with brain iron accumulation, in which childhood DE-EE is followed by neurodegeneration; and finally, monogenic juvenile Parkinsonism, in which a subset of patients with intellectual disability or developmental delay (ID/DD) develop hypokinetic MD between 10 and 30 years of age, following unspecific, usually well-controlled, childhood epilepsy. This emerging group of genetic conditions leading to epilepsy or DE-EE in childhood followed by juvenile Parkinsonism highlights the need for careful long-term follow-up, especially in the context of ID/DD, in order to readily identify individuals at increased risk of later Parkinsonism.

Juvenile-Onset Huntington's Disease in Peru: A Case Series of 32 Patients

Background

Juvenile-onset Huntington's Disease (JoHD) or Huntington's disease (HD) with age of onset ≤20 years, is a rare clinical entity that often differs phenotypically from adult HD and represents only 1-15% of total HD cases.

Objective

To characterize the genetic and clinical characteristics of 32 JoHD patients seen in a Peruvian Neurogenetics clinic from 2000-2018.

Methods

This study is a retrospective clinical and genetic review. The clinical database in Lima, Peru was searched for HD patients seen in clinic between 2000 and 2018. Inclusion criteria were: (1) genetically confirmed disease; and (2) HD age of onset ≤20 years, according to the documented medical history.

Results

Among 475 patients with genetically confirmed HD in the database, 32 patients (6.7%) had symptom onset at ≤20 years. Among JoHD patients with a known transmitting parent (30 of 32), paternal transmission accounted for 77% of cases. Anticipation was higher with paternal transmission compared to maternal transmission (27.5 ± 11.5 vs. 11.3 ± 7.1 years). Overall expanded CAG repeat length ranged from 44 to 110, with a mean length of 65.6 ± 15.4, and 14 (44%) cases had repeat length under 60. Of the 32 patients included in the study, 25 had detailed clinical symptomatology available, and many patients had unique clinical features such as prominent sleep disturbance (60% of patients), or parkinsonism (73%).

Conclusions

This large case series of JoHD patients characterizes the Peruvian JoHD population, reports on unique familial relationships in JoHD, and highlights the varied symptomatic presentation of this rare disease.

Recent approaches on Huntington's disease (Review)

Huntington's disease (HD) is a neurodegenerative disorder characterized by severe motor, cognitive and psychiatric symptoms. Patients of all ages can present with a dysfunction of the nervous system, which leads to the progressive loss of movement control and disabilities in speech, swallowing, communications, etc. The molecular basis of the disease is well-known, as HD is related to a mutated gene, a trinucleotide expansion, which encodes to the huntingtin protein. This protein is linked to neurogenesis and the loss of its function leads to neurodegenerative disorders. Although the genetic cause of the disorder has been known for decades, no effective treatment is yet available to prevent onset or to eliminate the progression of symptoms. Thus, the present review focused on the development of novel methods for the timely and accurate diagnosis of HD in an aim to aid the development of therapies which may reduce the severity of the symptoms and control their progression. The majority of the therapies include gene-silencing mechanisms of the mutated huntingtin gene aiming to suppress its expression, and the use of various substances as drugs with highly promising results. In the present review, the latest approaches on the diagnosis of HD are discussed along with the need for genetic counseling and an up-to-date presentation of the applied treatments.

Juvenile-Onset Huntington Disease Pathophysiology and Neurodevelopment: A Review

Huntington disease is an autosomal dominant inherited brain disorder that typically becomes manifest in adulthood. Juvenile-onset Huntington disease refers to approximately 5% of patients with symptom onset before the age of 21 years. The causal factor is a pathologically expanded CAG repeat in the Huntingtin gene. Age at onset is inversely correlated with CAG repeat length. Juvenile-onset patients have distinct symptoms and signs with more severe pathology of involved brain structures in comparison with disease onset in adulthood. The aim of this review is to compare clinical and pathological features in juvenile- and adult-onset Huntington disease and to explore which processes potentially contribute to the observed differences. A specific focus is placed on molecular mechanisms of mutant huntingtin in early neurodevelopment and the interaction of a neurodegenerative disease and postnatal brain maturation. The importance of a better understanding of pathophysiological differences between juvenile- and adult-onset Huntington disease lies in development and implementation of new therapeutic strategies. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Clinical Presentation and Features of Juvenile-Onset Huntington's Disease: A Systematic Review

BACKGROUND

Juvenile-onset Huntington's disease (JHD) is defined by onset at the age of 20 or younger and represents approximately 5% of all HD cases. Patients with JHD present with a broad range of symptoms and signs that only overlap partially with adult-onset HD. A greater awareness and understanding of the presentation of JHD would improve the diagnosis and treatment of this condition.

OBJECTIVE

To undertake a systematic review of the literature relating to the clinical features at first presentation of JHD.

METHODS

We searched MEDLINE and EMBASE for all studies describing presenting features of JHD patients, performed quality control, and collated and analysed the data.

RESULTS

We screened 2917 records for eligibility, and included 79 studies (n = 285 individuals) in the analysis. All were case reports and case series, synthesising data from 25 different countries. Thirty-four different clinical features at presentation were identified. Four groups of symptoms or signs were present in more than 15% of cases: behavioural disturbance, falls/gait disturbance, cognitive impairment and parkinsonian features. Where data were available, the median age of onset was 9 years, 52% were female, the mutant HTT allele was transmitted paternally in 80% of cases, and the median CAG repeat length was 64.

CONCLUSIONS

JHD can present with a wide variety of symptoms and signs, with non-motor characteristics being observed most frequently. Greater recognition of these presentations will facilitate early diagnosis and management. Tailored rating scales to score motor, non-motor, and functional impairments specifically in JHD are required to standardise research studies, and are under development.

Brain structure in juvenile-onset Huntington disease

OBJECTIVE

To assess brain morphometry in a sample of patients with juvenile-onset Huntington disease (JOHD) and several mouse models of Huntington disease (HD) that likely represent the human JOHD phenotype.

METHODS

Despite sharing the mutation in the Huntingtin gene, adult-onset HD characteristically presents as a hyperkinetic motor disorder, while JOHD typically presents as a hypokinetic motor disease. The University of Iowa Kids-JHD program enrolls individuals 5 to 25 years of age who have already received the clinical diagnosis. A total of 19 children with juvenile HD (JHD) (mean CAG = 72) were studied. Patients with JHD were compared to healthy controls (n = 234) using a cross-sectional study design. Volumetric data from structural MRI was compared between groups. In addition, we used the same procedure to evaluate brain morphology of R6/2, zQ175, HdhQ250 HD mice models.

RESULTS

Participants with JHD had substantially reduced intracranial volumes. After controlling for the small intracranial volume size, the volumes of subcortical regions (caudate, putamen, globus pallidus, and thalamus) and of cortical white matter were significantly decreased in patients with JHD. However, the cerebellum was proportionately enlarged in the JHD sample. The cerebral cortex was largely unaffected. Likewise, HD mice had a lower volume of striatum and a higher volume of cerebellum, mirroring the human MRI results.

CONCLUSIONS

The primary pathology of JOHD extends beyond changes in the striatal volume. Brain morphology in both mice and human patients with JHD shows proportional cerebellar enlargement. This pattern of brain changes may explain the unique picture of hypokinetic motor symptoms in JHD, which is not seen in the hyperkinetic chorea-like phenotype of adult-onset HD.

Therapeutic effects of stem cells in rodent models of Huntington's disease: Review and electrophysiological findings

The principal symptoms of Huntington's disease (HD), chorea, cognitive deficits, and psychiatric symptoms are associated with the massive loss of striatal and cortical projection neurons. As current drug therapies only partially alleviate symptoms, finding alternative treatments has become peremptory. Cell replacement using stem cells is a rapidly expanding field that offers such an alternative. In this review, we examine recent studies that use mesenchymal cells, as well as pluripotent, cell-derived products in animal models of HD. Additionally, we provide further electrophysiological characterization of a human neural stem cell line, ESI-017, which has already demonstrated disease-modifying properties in two mouse models of HD. Overall, the field of regenerative medicine represents a viable and promising avenue for the treatment of neurodegenerative disorders including HD.

Risk factors for the onset and progression of Huntington disease

Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder characterized by chorea, behavioural and psychiatric manifestations, and dementia, caused by a CAG triplet repeat expansion in the huntingtin gene. Systematic review of the literature was conducted to determine the risk factors for the onset and progression of HD. Multiple databases were searched, using terms specific to Huntington disease and to studies of aetiology, risk, prevention and genetics, limited to studies on human subjects published in English or French between 1950 and 2010. Two reviewers independently screened the abstracts and identified potentially relevant articles for full-text review using predetermined inclusion criteria. Three major categories of risk factors for onset of HD were identified: CAG repeat length in the huntingtin gene, CAG instability, and genetic modifiers. Of these, CAG repeat length in the huntingtin gene is the most important risk factor. For the progression of HD: genetic, demographic, past medical/clinical and environmental risk factors have been studied. Of these factors, genetic factors appear to play the most important role in the progression of HD. Among the potential risk factors, CAG repeat length in the mutant allele was found to be a relatively consistent and significant risk factor for the progression of HD, especially in motor, cognitive, and other neurological symptom deterioration. In addition, there were many consistent results in the literature indicating that a higher number of CAG repeats was associated with shorter survival, faster institutionalization, and earlier percutaneous endoscopic gastrostomy.

Huntington disease: a single-gene degenerative disorder of the striatum

Huntington disease (HD) is an autosomal dominant, neurodegenerative disorder with a primary etiology of striatal pathology. The Huntingtin gene (HTT) has a unique feature of a DNA trinucleotide (triplet) repeat, with repeat length ranging from 10 to 35 in the normal population. Repeat lengths between 36 and 39 cause HD at reduced penetrance (some will get the disease, others won't) and when expanded to 40 or more repeats (mHTT), causes HD at full penetrance (every person with this length or beyond will definitely develop the disease). The symptoms of HD may be motor, cognitive, and psychiatric, and are consistent with the pathophysiology of frontostriatal circuitry malfunction. Expressed ubiquitously and throughout the entire life cycle (development through adulthood), mHTT causes initial dysfunction and eventual death of a specific cell population within the striatum. Although all areas of the brain are eventually affected, the primary pathology of the disease is regionally specific. As a single-gene disorder, HD has the distinction of having the potential of treatment that is aimed directly at the known pathogenic mechanism by gene silencing, providing hope for neuroprotection and ultimately, prevention.

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.

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.

Use of Caenorhabditis elegans as a model to study Alzheimer's disease and other neurodegenerative diseases

Advances in research and technology has increased our quality of life, allowed us to combat diseases, and achieve increased longevity. Unfortunately, increased longevity is accompanied by a rise in the incidences of age-related diseases such as Alzheimer’s disease (AD). AD is the sixth leading cause of death, and one of the leading causes of dementia amongst the aged population in the USA. It is a progressive neurodegenerative disorder, characterized by the prevalence of extracellular Aβ plaques and intracellular neurofibrillary tangles, derived from the proteolysis of the amyloid precursor protein (APP) and the hyperphosphorylation of microtubule-associated protein tau, respectively. Despite years of extensive research, the molecular mechanisms that underlie the pathology of AD remain unclear. Model organisms, such as the nematode, Caenorhabditis elegans, present a complementary approach to addressing these questions. C. elegans has many advantages as a model system to study AD and other neurodegenerative diseases. Like their mammalian counterparts, they have complex biochemical pathways, most of which are conserved. Genes in which mutations are correlated with AD have counterparts in C. elegans, including an APP-related gene, apl-1, a tau homolog, ptl-1, and presenilin homologs, such as sel-12 and hop-1. Since the neuronal connectivity in C. elegans has already been established, C. elegans is also advantageous in modeling learning and memory impairments seen during AD. This article addresses the insights C. elegans provide in studying AD and other neurodegenerative diseases. Additionally, we explore the advantages and drawbacks associated with using this model.

Mind the gap: models in multiple species needed for therapeutic development in Huntington's disease

Unraveling the pathophysiology and testing candidate therapeutics in neurodegenerative disorders is, necessarily, highly dependent on model systems. Because Huntington's disease (HD) is caused by a single (expanded CAG tract) mutation in the huntingtin (HTT) gene, a richness of model systems, particularly mice, have been engineered to both dissect disease mechanisms and test potential therapeutics. Even so, as with other neurodegenerative diseases, very little success has been achieved in translating HD mouse model drug testing results to the clinic. Because of the considerable costs-human, opportunity, and financial-there is a pressing need to improve the use of existing HD models and also to develop models in higher species beyond rodent, such as sheep, minipig, and nonhuman primate, to bridge the translational gap from preclinical to clinical testing of candidate therapeutics.

Tremor in neurodegenerative ataxias, Huntington disease and tic disorder

INTRODUCTION

Tremor is the most prevalent movement disorder, defined as rhythmic oscillations of a body part, caused by alternating or synchronic contractions of agonistic or antagonistic muscles. The aim of the study was to assess prevalence and to characterize parameters of tremor accompanying de-generative ataxias, Huntington disease (HD) and tic disorders in comparison with a control group.

MATERIAL AND METHODS

Forty-three patients with degenerative ataxias, 28 with HD and 26 with tic disorders together with 51 healthy controls were included in the study. For each participant, clinical and instrumental assessment (accelerometer, electromyography [EMG], graphic tablet) of hand tremor was performed. Frequency and severity of tremor were assessed in three positions: at rest (rest tremor), with hands extended (postural tremor), during the 'finger-to-nose' test and during Archimedes spiral drawing (kinetic tremor). Based on the mass load test, the type of tremor was determined as essential tremor type or enhanced physiological tremor type.

RESULTS

The incidence of tremor in the accelerometry in patients with degenerative ataxia (50%) significantly differs from controls (10%) (p = 0.001). The dominant tremor was postural, low-intense, with 7-Hz frequency, essential tremor (23%) or other tremor type (23%), while enhanced physiological tremor was the least frequent (2%). Tremor in patients with HD and tic disorders was found in 10% and 20% of patients, respectively, similarly to the control group. Tremor was mild, postural and of essential tremor type, less frequently of enhanced physiological tremor type. No correlation between severity of tremor and severity of disease was found.

CONCLUSIONS

The prevalence of tremor is considerably higher among patients with degenerative ataxias compared with HD, tic disorder and the control group. The most common type of tremor accompanying ataxias, HD and tic disorders is essential tremor type.

Managing juvenile Huntington's disease

Huntington's disease (HD) is a well-recognized progressive neurodegenerative disorder that follows an autosomal dominant pattern of inheritance. Onset is insidious and can occur at almost any age, but most commonly the diagnosis is made between the ages of 35 and 55 years. Onset ≤20 years of age is classified as juvenile HD (JHD). This age-based definition is arbitrary but remains convenient. There is overlap between the clinical pathological and genetic features seen in JHD and more traditional adult-onset HD. Nonetheless, the frequent predominance of bradykinesia and dystonia early in the course of the illness, more frequent occurrence of epilepsy and myoclonus, more widespread pathology, and larger genetic lesion means that the distinction is still relevant. In addition, the relative rarity of JHD means that the clinician managing the patient is often doing so for the first time. Management is, at best, symptomatic and supportive with few or no evidence-based guidelines. In this article, the authors will review what is known of the condition and present some suggestions based on their experience.

Huntington's disease in children

Huntington's disease (HD) is a dominantly inherited, fatal neurodegenerative disease. This incurable illness is characterized by a triad of a movement disorder, cognitive decline and psychiatric manifestations. Although most patients with HD have disease onset in the adult years, a small but significant proportion present with pediatric HD. It has been long known that patients with early-onset HD commonly exhibit prominent parkinsonism, known as the Westphal variant of HD. However, even among patients with pediatric HD there are differential clinical features depending on the age of onset, with younger patients frequently presenting diagnostic challenges. In his chapter, the characteristics of patients with childhood- and adolescence-onset HD are discussed, focusing on the differential clinical features that can aid the clinical reach a correct diagnosis, the indications and rational use of genetic testing and the currently available options for symptomatic treatment.

Seizures in juvenile Huntington's disease: frequency and characterization in a multicenter cohort

Little is known about the epilepsy that often occurs in the juvenile form of Huntington's disease (HD), but is absent from the adult-onset form. The primary aim of this study was to characterize the seizures in juvenile HD (JHD) subjects with regard to frequency, semiology, defining EEG characteristics, and response to antiepileptic agents. A multicenter, retrospective cohort was identified by database query and/or chart review. Data on age of HD onset, primary HD manifestations, number of CAG repeats, the presence or absence of seizures, seizure type(s), antiepileptic drugs used, subjects' response to antiepileptic drugs (AEDs), and EEG results were assembled, where available. Ninety subjects with genetically confirmed JHD were included. Seizures were present in 38% of subjects and were more likely to occur with younger ages of HD onset. Generalized tonic-clonic seizures were the most common seizure type, followed by tonic, myoclonic, and staring spells. Multiple seizure types commonly occurred within the same individual. Data on EEG findings and AED usage are presented. Seizure risk in JHD increases with younger age of HD onset. Our ability to draw firm conclusions about defining EEG characteristics and response to AEDs was limited by the retrospective nature of the study. Future prospective studies are required.

Huntington's Disease and Striatal Signaling

Huntington’s Disease (HD) is the most frequent neurodegenerative disease caused by an expansion of polyglutamines (CAG). The main clinical manifestations of HD are chorea, cognitive impairment, and psychiatric disorders. The transmission of HD is autosomal dominant with a complete penetrance. HD has a single genetic cause, a well-defined neuropathology, and informative pre-manifest genetic testing of the disease is available. Striatal atrophy begins as early as 15 years before disease onset and continues throughout the period of manifest illness. Therefore, patients could theoretically benefit from therapy at early stages of the disease. One important characteristic of HD is the striatal vulnerability to neurodegeneration, despite similar expression of the protein in other brain areas. Aggregation of the mutated Huntingtin (HTT), impaired axonal transport, excitotoxicity, transcriptional dysregulation as well as mitochondrial dysfunction, and energy deficits, are all part of the cellular events that underlie neuronal dysfunction and striatal death. Among these non-exclusive mechanisms, an alteration of striatal signaling is thought to orchestrate the downstream events involved in the cascade of striatal dysfunction.

Motor abnormalities in premanifest persons with Huntington's disease: the PREDICT-HD study

The PREDICT-HD study seeks to identify clinical and biological markers of Huntington's disease in premanifest individuals who have undergone predictive genetic testing. We compared baseline motor data between gene-expansion carriers (cases) and nongene-expansion carriers (controls) using t-tests and Chi-square. Cases were categorized as near, mid, or far from diagnosis using a CAG-based formula. Striatal volumes were calculated using volumetric magnetic resonance imaging measurements. Multiple linear regression associated total motor score, motor domains, and individual motor items with estimated diagnosis and striatal volumes. Elevated total motor scores at baseline were associated with higher genetic probability of disease diagnosis in the near future (partial R(2) 0.14, P < 0.0001) and smaller striatal volumes (partial R(2) 0.15, P < 0.0001). Nearly all motor domain scores showed greater abnormality with increasing proximity to diagnosis, although bradykinesia and chorea were most highly associated with diagnostic immediacy. Among individual motor items, worse scores on finger tapping, tandem gait, Luria, saccade initiation, and chorea show unique association with diagnosis probability. Even in this premanifest population, subtle motor abnormalities were associated with a higher probability of disease diagnosis and smaller striatal volumes. Longitudinal assessment will help inform whether motor items will be useful measures in preventive clinical trials.

Tremor in childhood

Tremor in childhood is not commonly described in the literature; but it is also likely underappreciated. The etiology of childhood tremor encompasses a wide variety of pathologic processes. Tremor may occur in isolation, or in association with other neurologic findings or systemic disorders. This article aims to provide an overview of tremorogenic mechanisms with respect to neuroanatomy and neurophysiology, particularly as they relate to children. Classification of tremors, diagnostic entities in childhood, and treatment will also be discussed. With improved recognition and characterization of childhood tremors, we may gain a better understanding of the pathophysiology of the disease and determine more age-appropriate treatment strategies.

The current clinical management of Huntington's disease

Huntington's disease is a neurodegenerative condition, characterized by movement disorders, cognitive decline, and psychiatric disturbance. We review the pharmacological management of the various movement disorders associated with the disease, the cognitive decline and the commonly encountered behavioral disturbances. We discuss the nonclassical features of the disease, important in the management of these patients. Nonpharmacological support including genetic counseling and therapy and the importance of palliative care are also addressed. Finally, experimental approaches that may soon impact upon clinical practice are discussed.

Juvenile Huntington disease exacerbated by methylphenidate: case report

The authors describe the case of an 8-year-old boy, otherwise healthy, who presented with symptoms consistent with attention-deficit hyperactivity disorder (ADHD) and was started on a trial of methylphenidate. Within 4 weeks, he experienced a rapid decline in fine motor skills, with dysarthria, intention tremor, motor impersistence, and diffusely increased tone. Symptoms persisted despite cessation of methylphenidate. At that time, a paternal history of Huntington disease was disclosed. Molecular analysis revealed an expansion in CAG repeats to 75 copies, within the range characteristic of juvenile Huntington disease. This report raises the possibility that use of dopaminergic agonists in patients with a family history of Huntington disease may lead to clinical exacerbation of motor symptoms and/or unwitting diagnosis in an unprepared family.

Huntington’s disease

Although available treatments for Huntington's disease (HD) are imperfect, thoughtful application can positively impact quality of life. Dopamine antagonists can provide control of the troublesome hyperkinetic movements. These agents can also diminish the frequency of hallucinations and delusions when symptoms of psychosis occur. Classical neuroleptics have the widest utilization, although atypical antipsychotics are being increasingly used. Suppression of choreiform movements has also been reported with amantadine and tetrabenazine, which is not currently approved in the United States but under investigation. Alteration in mood can be successfully managed with a variety of antidepressant medications. Superior tolerability and value in the management of a variety of behavioral disturbances have lead to extensive use of serotonin reuptake inhibitors. Modest disturbance of mood can sometimes be addressed with anticonvulsant medications. Considered a manifestation of advanced disease, dementia is less commonly addressed therapeutically. However, gathering experience suggests improved cognitive function can occur with cholinesterase inhibitor therapy. Frequently overlooked is the value of rehabilitation services in the management of diverse symptoms. Although the value of a dysphagia evaluation is apparent, the benefit to be derived from physical and occupational therapy involvement cannot be overstated. Current therapeutic trials will undoubtedly provide additional therapies to moderate symptoms, but once the mechanism(s) of selective striatal projection neuron degeneration are delineated, a revolution in the management of HD will occur.

Clinical characteristics of childhood-onset (juvenile) Huntington disease: report of 12 patients and review of the literature

Whereas adult-onset Huntington disease is a well-characterized clinical entity, childhood-onset cases have not received as much attention. In this report, the clinical, demographic, and genetic characteristics in 12 patients with childhood-onset Huntington disease are presented and compared with data in the literature. The patients were divided into two groups based on age at onset of symptoms (< 10 or > or = 10 years old). The majority of patients had onset of symptoms before 10 years of age and most at or below 5 years of age. The delay in diagnosis was longer in those with earlier onset of symptoms. Inheritance was paternal in all patients with onset beyond 10 years of age. We found a preponderance of male patients in the younger age at onset group and of female patients in the older age at onset group. The most frequent heralding symptom was cognitive decline in the group with earlier onset and oropharyngeal dysfunction in the later-onset group. Seizures occurred only in the younger age at onset group. Chorea was not a presenting sign but developed later in the course of the disease and, with dystonia, was more prevalent in the early age at onset group, whereas rigidity and bradykinesia were more prevalent in the older age at onset group. Patients in both groups developed gait, cognitive, and behavioral disorders at some point during the course of the disease. Furthermore, a slow and steady decline in IQ was observed on serial neuropsychologic testing in patients from both groups. Imaging studies were normal early and most commonly revealed neostriatal atrophy later in the course of the disease. In this report, we describe the characteristics of 12 patients with childhood-onset Huntington disease and review those previously reported, expanding our knowledge about the features of childhood-onset Huntington disease, underlining the differences with patients with adult-onset Huntington disease, and suggesting a differential phenotype within patients with childhood-onset Huntington disease depending on the age at onset.

Dose-dependent improvement of myoclonic hyperkinesia due to Valproic acid in eight Huntington's Disease patients: a case series

Background

Chorea in Huntington's Disease (HD) is usually treated with antidopaminergic neuroleptics like haloperidol, olanzapine and tiaprid or dopamine depleting drugs like tetrabenazine. Some patients with hyperkinesia, however, react to treatment with antidopaminergic drugs by developing extrapyramidal side effects. In earlier studies valproic acid showed no beneficial effect on involuntary choreatic movements. Myoclonus is rare in HD and is often overseen or misdiagnosed as chorea.

Methods

In this report, we present eight patients whose main symptom is myoclonic hyperkinesia. All patients were treated with valproic acid and scored by using the Unified Huntington's Disease Rating Scale (UHDRS) motor score before and after treatment. In addition to this, two patients agreed to be videotaped.

Results

In seven patients myoclonus and, therefore the UHDRS motor score improved in a dose dependent manner. In three of these patients antidopaminergic medication could be reduced.

Conclusion

In the rare subgroup of HD patients suffering from myoclonic hyperkinesia, valproic acid is a possible alternative treatment.

Huntington's disease of early onset or juvenile Huntington's disease

The presentation of juvenile Huntington's disease can cause diagnostic difficulties. The genetics and pathogenesis of the condition are discussed. The diagnosis will depend on the symptoms raising suspicions and the exclusion of other disorders, especially by genetic studies.

XL PCR for the detection of large trinucleotide expansions in juvenile Huntington's disease

Juvenile Huntington's disease (HD) becomes clinically manifest before 20 years of age. The diagnosis of HD is based on family history, characteristic clinical findings, and the detection of an expansion of a CAG polyglutamine tract in the Huntingtin gene. Juvenile HD is characterized by paternal anticipation and large CAG expansions that may be missed using routine molecular analysis. We have developed an easy, rapid, and reliable modified PCR method using XL (Extra Long) PCR that allowed us to diagnose one of the youngest children reported with juvenile HD. Without this innovation we would not have been able to demonstrate the large CAG expansion. This assay could become part of a standard protocol for HD testing in molecular diagnostic laboratories.

Unusual early-onset Huntingtons disease

Huntington's disease is an autosomal dominant progressive neurodegenerative disorder characterized by involuntary movements, cognitive decline, and behavioral disorders leading to functional disability. In contrast to patients with adult onset, in which chorea is the major motor abnormality, children often present with spasticity, rigidity, and significant intellectual decline associated with a more rapidly progressive course. An unusual early-onset Huntington's disease case of an 11-year-old boy with severe hypokinetic/rigid syndrome appearing at the age of 2.5 years is presented. Clinical diagnosis was confirmed by polymerase chain reaction study of the expanded IT-15 allele with a compatible size of 102 cytosine-adenosine-guanosine repeats L-Dopa mildly ameliorated rigidity, bradykinesia, and dystonia. We conclude that Huntington's disease should be included in the differential diagnoses of regressive syndromes of early childhood.

Juvenile parkinsonism

Juvenile parkinsonism (JP) is a clinically and etiologically heterogeneous entity. Unlike in the adult form, secondary causes, hereditary and metabolic conditions, are the predominant causes of JP. Idiopathic Parkinson's disease is very rare in this age group. In most cases of JP, parkinsonism is accompanied by other neurologic features, such as dystonia, cognitive impairment, seizures, oculomotor and visual dysfunction, and ataxia. Systemic findings, such as liver dysfunction or hepatosplenomegaly, may be present depending on the cause. This review article describes the clinical characteristics, classification, genetic basis, pathophysiology, biochemistry, pathology, and treatment of JP.

Hereditary causes of chorea in childhood

Chorea and athetosis are rare presenting symptoms in childhood. Chorea can be a presenting symptom in a number of hereditary diseases, including neurodegenerative diseases, paroxysmal diseases, and metabolic diseases. In these situations, family history, associated symptoms, and other physical findings will often enable a correct diagnosis. Benign childhood chorea is probably a genetically heterogeneous group of disorders, generally without other symptoms. Clinical aspects of these disorders are reviewed here.

Chorea and its disorders

Chorea (Greek for "dance") refers to irregular, rapid, flowing, non-stereotyped and random involuntary movements that often possess a writhing quality, referred to as choreoathetosis. When mild, it may be difficult to differentiate from restlessness. The movements can be strikingly asymmetric, as in hemichorea, or generalized. When chorea is proximal and of large amplitude, it is called ballism. Chorea is worsened by stress and anxiety and subsides during sleep. Movements can interfere with the completion of many daily activities, making fastening a button a substantial effort. Chorea often is incorporated into a purposeful activity in an attempt to disguise it. Motor impersistence is a common associated feature, demonstrated by varying intensity of grip strength (milkmaid's grasp) or by an inability to sustain eye closure or tongue protrusion.