The salient clinical features of Huntington’s disease are listed below:

• Chorea: Patients with Huntington’s disease present with are continuous, involuntary, jerky and dyskinetic movements. This is referred to as chorea. In case of Huntington’s disease, chorea is often generalized and involves the face, head, neck, tongue and extremities.
• Impaired memory and cognition: Progressive loss of memory is a key feature of Huntington’s disease [5]. Initially, there is a loss of short-term memory. Later on, cognitive functions such as speech, reasoning and comprehension are also impaired. [6][7] In most cases, severe dementia occurs by the age of 50 years.
• Altered behavior: A variety of behavioral abnormalities are also present in Huntington’s disease. Depression is the most common abnormality. As a result, suicidal tendency is often present in the patients suffering from this disease. Other disorders include personality changes, irritability, antisocial behavior, psychosis and obsessive-compulsive features [8].
• Gait abnormalities: Gait abnormalities start developing in the intermediate stage of the disease. The gait is irregular and unsteady. In the later stage, features similar to Parkinsonism (bradykinesia and rigidity) also develop.

• Difficulty Walking

  He had depression, poor cognitive function, choreiform movements, difficulty pronouncing words, and difficulty walking. His symptoms had worsened markedly over several months. [ncbi.nlm.nih.gov]

  Symptoms may appear at any age and include uncontrolled movements, clumsiness, balance problems, difficulty walking, talking, or swallowing. [icd9data.com]

  Physical symptoms: weight loss, involuntary movements (chorea), diminished coordination, difficulty walking, talking and swallowing Cognitive symptoms: difficulty with focus, planning, recall of information and making decisions; impaired insight Emotional [huntingtonsociety.ca]

  […] twitching movements, called chorea difficulty walking trouble swallowing and speaking confusion memory loss personality changes speech changes decline in cognitive abilities Early Onset This type of Huntington’s disease is less common. [healthline.com]

• Muscle Rigidity

  Juvenile HD (also called Westphal variant or akinetic-rigid HD) develops before the age of 20, progresses rapidly, and produces muscle rigidity in which the patient moves little, if at all (akinesia). [healthcommunities.com]

  Eventually, the symptoms progress into substantial movement problems like chorea, which involves uncontrolled, spasmodic movements; impaired coordination and balance; muscle rigidity; and difficulty speaking and/or swallowing. [youtube.com]

  Other movement problems include figidty movements, tics, difficulty swallowing, balance problems and falls, and muscle rigidity and/or tightness. Cognition problems generally occur slowly over time. [ucdmc.ucdavis.edu]

  Muscle rigidity and involuntary muscle contractions can be treated with diazepam. Depression and other psychiatric symptoms can be treated with antidepressants and mood-stabilizing drugs. [healthline.com]

• Bruxism

  Bruxism Bruxism is an involuntary clenching with excessive contraction of the jaw muscles. It typically causes lateral movements (or front to back) responsible for gnashing and can lead to tooth damage. [frontiersin.org]

  Michael Behr, Sebastian Hahnel, Andreas Faltermeier, Ralf Bürgers, Carola Kolbeck, Gerhard Handel and Peter Proff, The two main theories on dental bruxism, Annals of Anatomy - Anatomischer Anzeiger, 194, 2, (216), (2012). Carolien M. [doi.org]

• Muscle Twitch

  Initially, the movements often occur in the distal extremities such as fingers and toes, but also in small facial muscles. For bystanders these muscle twitches are often invisible or can be explained as nervousness. [ncbi.nlm.nih.gov]

• Abnormal Eye Movement

  Abnormal eye movements may be seen early in the disease. Other movement disorders, such as tics and myoclonus, may be seen in patients with HD. [emedicine.medscape.com]

  Characteristics and Symptoms of Huntington's Disease Personality changes, depression, anxiety, irritable or aggressive behavior, apathy, hallucinations, delusions or mood swings Unsteady gait, dance-like movements, rigidity, abnormal eye movements, problems [health.ucsd.edu]

  Chorea is initially mild but may be severe and cause uncontrollable limb movements. As the disease progresses, chorea is gradually replaced by dystonia and Parkinsonian features. Dysarthria, dysphagia and abnormal eye movements are common. [patient.info]

  […] rigidity or muscle contracture (dystonia) Slow or abnormal eye movements Impaired gait, posture and balance Difficulty with the physical production of speech or swallowing Impairments in voluntary movements — rather than the involuntary movements — may [mayoclinic.org]

• Mood Swings

  Signs and Symptoms Diagnosis Treatment Early symptoms of Huntington's disease (HD) include mood swings, depression and irritability. [ucsfhealth.org]

  Mood swings and unusual behavior are common early signs. Early signs and symptoms Early symptoms may not be recognized if HD has not previously occurred in the family. It can take a long time to reach a diagnosis. [medicalnewstoday.com]

  The most common symptoms of Huntington's disease include depression, irritability, mood swings, deficits in memory and concentration, dementia, difficulty in swallowing, jerky movements, and loss of coordination. [merriam-webster.com]

  Symptoms of Huntington's disease can include: difficulty concentrating and memory lapses depression stumbling and clumsiness involuntary jerking or fidgety movements of the limbs and body mood swings and personality changes problems swallowing, speaking [nhs.uk]

• Psychiatric Manifestation

  Huntington's disease (HD) is an autosomal dominant and progressive neurodegenerative syndrome characterized by motor, cognitive and psychiatric manifestations. [ncbi.nlm.nih.gov]

  Specific psychiatric manifestations among preclinical Huntington disease mutation carriers. [web.archive.org]

  The onset of the disease was defined as the time when motor clinical manifestations (i.e. choreic movements), or severe psychiatric symptoms changing the normal life state ( Brinkman et al ., 1997 ), first became noticeable. [dx.doi.org]

• Abnormal Behavior

  Behavior changes may occur before movement problems, and can include: Behavioral disturbances Hallucinations Irritability Moodiness Restlessness or fidgeting Paranoia Psychosis Abnormal and unusual movements include: Facial movements, including grimaces [nlm.nih.gov]

  Dopamine blockers and drugs such as amantadine and tetrabenazine can be used to help control involuntary movements and some of the abnormal behaviors associated with this disease. [pfizer.com]

  The abnormal behavior is one of impaired emotional expression. Can this be a symptom... [hddrugworks.org]

  We have previously demonstrated that partial suppression of both wild-type and mutant HTT in the striatum prevents behavioral and neuropathological abnormalities in rodent models of HD. [ncbi.nlm.nih.gov]

• Withdrawn

  The shoulders are shrugged, and the feet and legs kept in perpetual motion; the toes are turned in, and then everted; one foot is thrown across the other, and then suddenly withdrawn, and, in short, every conceivable attitude and expression is assumed [en.wikisource.org]

• Facial Grimacing

  On physical examination, he has random facial grimaces with intermittent protrusion of the tongue and irregular shoulder jerks with athethoid movement of the distal extremities. [iomcworld.org]

  Typical features include a bizarre, puppet-like gait, facial grimacing, inability to intentionally move the eyes quickly without blinking or head thrusting (oculomotor apraxia), and inability to sustain a motor act (motor impersistence), such as tongue [merckmanuals.com]

• Chorea

  chorea Chronic progressive non-hereditary chorea Dementia due to Huntington chorea Dementia due to Huntington chorea with altered behavior Dementia due to Huntingtons chorea w behavior changes Dementia due to Huntingtons disease Dementia from huntingtons [icd9data.com]

  566 had a diagnosis of other chorea and 12 had a diagnosis of drug induced chorea. [doi.org]

  This occurrence of rheumatic chorea in a family with Huntington's disease highlights the importance of the differential diagnosis for the different forms of chorea. [ncbi.nlm.nih.gov]

  […] nervous system characterized by unwanted choreatic movements, behavioral and psychiatric disturbances and dementia HD Huntington's chorea Huntington’s disease Huntington Chorea Huntington's disease HUNTINGTON DISEASE; HD Huntington disease Statements [wikidata.org]

• Involuntary Movements

  Chorea (involuntary movements) is a much less prominent feature and may be absent altogether. [huntingtonsociety.ca]

  Additional characteristics of HD include personality changes, weight loss (probably from a combination of difficulty eating, and calories burned by the involuntary movements), difficulty swallowing, and hard-to-understand speech. [hopkinsmedicine.org]

  We herein report a case of late-onset Huntington's disease (HD) that presented without any involuntary movement. [ncbi.nlm.nih.gov]

• Irritability

  In multivariate regression analyses, both suicidal ideation and suicidal behavior were associated with a depressed mood, and to a lesser extend to irritability. [ncbi.nlm.nih.gov]

  During the early stages of HD, irritability, depression, anxiety and aggression are common behavior symptoms. In the later stages, individuals tend to be less irritable and aggressive, as apathy and a lack of concern become more pronounced. [web.stanford.edu]

  Irritability: For severe anger and threatening behavior, experts agree that an atypical antipsychotic drug is the preferred approach. [alz.org]

• Ataxia

  The autosomal dominant spinocerebellar ataxias, commonly referred to as SCAs, are clinically and genetically heterogeneous neurodegenerative disorders. [ncbi.nlm.nih.gov]

  Lasek K et al. (2006) Morphological basis for the spectrum of clinical deficits in spinocerebellar ataxia 17 (SCA17). Brain 129 : 2341–2352 39. Manganelli F et al. (2006) Electrophysiologic characterization in spinocerebellar ataxia 17. [dx.doi.org]

• Personality Change

  Personality changes changes in behavior or interactions with other people that so no not fall into another diagnostic category. [hopkinsmedicine.org]

  During the interview, the patient's family revealed that he had a previous diagnosis of Huntington's disease; there was also a family history of personality changes preceding Huntington's chorea. [ncbi.nlm.nih.gov]

  Symptoms of the disease usually develop after age 40 and include rapid, jerky movements (twitches in the face and jerks of the arms) that cannot be controlled (chorea) and the gradual loss of mental abilities (dementia), leading to personality changes [stanfordhealthcare.org]

Diagnosis of Huntington’s disease can usually be made on clinical grounds; especially in the patients who present with the typical features of the disease, or those who have a genetically proven family history.
In other cases, certain investigations may be needed to establish the diagnosis with certainty.

• Magnetic Resonance Imaging (MRI) or Computerized Tomography (CT) scan demonstrate atrophy of the head of the caudate nucleus. This is evaluated by measurement of the bicaudate diameter which is the distance between the heads of the two caudate nuclei.
• DNA testing can also be used to confirm the diagnosis of Huntington’s disease.

There is no definitive treatment of Huntington’s disease. Palliative and symptomatic management is provided to the patient.

• Chorea is managed by administration of benzodiazepines (such as diazepam), valproic acid, dopamine depleting agents (such as reserpine) and neuroleptics.
• A novel drug tetrabenazine has also been shown to have a beneficial effect in the treatment of chorea in Huntington’s disease [9].
• Parkinson’s like symptoms of bradykinesia and rigidity are treated by levodopa or dopamine agonists [10].
• Antidepressants are given to the patients who suffer from depression and suicidal tendencies.
• Surgical treatments for Huntington’s disease are still under experimentation.

Once the disease develops, it is slowly progressive. The severity of the clinical features depends on the trinucleotide repeat length. Patients with 60 or more repeats often present early by the age of 20 years. In contrast, those with fewer than 40 repeats do not develop clinically apparent features [3]. 

On average, the patient lives for around 20 years after the onset of symptoms. Complications develop due to motor and cognitive abnormalities. Death most commonly results from pneumonia. Up to one third of the patients of Huntington’s disease die of this complication. Heart disease and suicide are the second and third most common causes of death in these patients [4].

Huntington’s disease almost always has positive family history since it is an autosomal dominant disease. It is caused by a mutation in the Huntingtin gene (HTT) on the short arm of chromosome 4 that codes the protein Huntingtin (Htt). A trinucleotide repeat sequence that is normally present in this gene is expanded in case of this disease. The abnormal protein thus produced is called mutated Huntingtin protein (mHtt) and is responsible for the underlying pathological mechanism of the disease.

The prevalence of Huntington’s disease varies greatly in different populations around the world. The prevalence is maximum in Western Europe (7 cases per 100,000 people) and much lower in Asia and Africa (one case per million people). A recent epidemiological study has calculated the average prevalence of Huntington’s disease in the UK during the past 20 years (1990 to 2010) to be 12.3 cases per 100,000 people [1]. Worldwide, the prevalence of this disease is around 5 to 10 cases per 100,000 people.

Huntington’s disease is equally prevalent in both sexes. The age of onset is variable; however, onset in the first decade and after the seventh decade is extremely rare. The average age of onset ranges from 35 to 44 years.

Huntingtin protein (Htt) is present in high concentrations in the brain. The exact function of this protein is not clear but it is believed to have an anti-apoptotic and neuroprotective role. Mutated Huntingtin protein (mHtt) is not able to perform these neuroprotective functions and accumulates in the neurons in the form of aggregates to form inclusion bodies within them [2]. Mutated Huntingtin protein causes cell death by effect on chaperone proteins, interaction with caspases, impairment of energy production within the cells and effects on gene expression.

Cell death resulting in atrophy is most prominent in the portion of basal ganglia referred to as the neostriatum (which consists of the caudate nucleus and putamen). Cell death also occurs to a lesser extent in substantia nigra, certain layers of the cerebral cortex (2, 5 & 6) and portions of the cerebellum, thalamus and hypothalamus. Basal ganglia play a role in the inhibition of a many neuronal circuits that are responsible for initiation of movements. If basal ganglia are damaged, this inhibitory effect is lost and as a result, involuntary movements such as those seen in Huntington’s disease result.

Since Huntington’s disease results from genetic abnormalities, there are no effective preventive measures against it.

Huntington’s disease is an autosomal dominant disorder caused by a mutation in the Huntingtin gene (HTT) on the short arm of chromosome 4. It is characterized by chorea, altered behavior, dementia and motor abnormalities. The disease is progressive and the patients survive for an average of 20 years after the onset of symptoms. There is no definite cure and the disease is treated symptomatically.

Huntington’s disease is a genetic disorder which is characterized by involuntary movements of the body, altered behavior, loss of memory and abnormalities of gait. There is no definite cure and the disease is treated symptomatically. The life expectancy after the onset of symptoms is around 20 years.

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