Huntington’s disease is a progressive neurodegenerative disorder that affects movement, cognition and behavior. It is inherited and ultimately fatal. Current treatments focus on managing symptoms, while research is underway to explore potential disease‑modifying interventions. The condition often takes a significant emotional and physical toll on both patients and families as its progression leads to increasing dependence over time. Awareness of the disease has grown in recent years, driving advocacy, clinical trials and funding for research. By highlighting early detection and supportive care, healthcare providers can help improve quality of life while scientists continue to study new treatment options. 

Huntington’s disease is caused by a mutation in the huntingtin (HTT) gene, which leads to the production of an altered form of the huntingtin protein. Over time, this protein damages brain cells—especially in parts of the basal ganglia and cerebral cortex—resulting in worsening motor, cognitive and psychiatric symptoms.  

The disease is inherited in an autosomal dominant pattern: if one parent carries the mutation, each child has a 50% chance of inheriting it. In most cases, people with a pathogenic mutation eventually develop symptoms, although the age of onset varies. The size of the CAG repeat expansion in the HTT gene, along with other genetic and environmental factors, can influence when and how the disease develops. In some families, the condition may appear at an earlier age in subsequent generations, a phenomenon called anticipation. 

Huntington’s disease is considered a rare disease: 

• In populations of European descent, prevalence estimates range between 4 to 15 per 100,000 individuals. 

• In the United States, about 41,000 individuals are symptomatic, and more than 200,000 people are estimated to be at risk (i.e. carrying the mutation but not yet symptomatic). 

• In the UK, estimates suggest around 6,000 to 10,000 people are affected. 

Prevalence varies geographically: the disease is less common among populations of Asian or African descent and more common in certain regions due to founder effects. 

The disease progresses gradually over many years, often beginning before visible symptoms appear. At the molecular level, Huntington’s disease is caused by an abnormal expansion of the CAG (cytosine-adenine-guanine) repeat sequence in the HTT gene. In unaffected individuals, the repeat length is usually around 20; in people with Huntington’s disease, it is typically 40 or more. Larger expansions are associated with earlier onset and faster progression. 

The altered protein disrupts normal cell functions and contributes to neuronal damage, especially in the striatum and later in other brain regions such as the cortex and hippocampus. These changes underlie the motor, cognitive, and psychiatric symptoms of the disease.

Huntington’s disease only occurs in people who inherit a specific mutation in the HTT gene (CAG repeat expansion).  

Risk factors and modifiers:

• Inheritance: If one parent carries the mutation, each child has a 50% chance of inheriting it. 

• Repeat length: Longer CAG repeat expansions generally lead to earlier onset. 

• Somatic expansion: The repeat length can further increase in brain cells over time, accelerating progression. 

• Modifier genes and environment: Other genetic and environmental factors (e.g. lifestyle, oxidative stress, inflammation) may also influence onset and progression. 

Symptoms usually begin in adulthood (ages 30–50), although juvenile onset (before age 20) is possible. 

Huntington’s disease features a triad of motor, cognitive and psychiatric symptoms: 

Motor symptoms 

• Chorea: involuntary, jerky, dancelike movements of the limbs, face, trunk 

• Dystonia, rigidity, bradykinesia (slowness) 

• Impaired voluntary movements: difficulty initiating or controlling movement 

• Gait and balance problems, falls 

• Slurred speech (dysarthria), difficulty swallowing (dysphagia) 

• Weight loss and muscle wasting (even in presence of adequate or increased intake) 

Cognitive symptoms 

• Difficulty with planning, multitasking, or judgment 

• Memory and concentration problems 

• Psychiatric/behavioral symptoms 

• Depression, irritability, apathy, anxiety 

• Obsessive or compulsive behaviors 

• Personality or mood changes 

• Psychosis in some cases 

Not every person will experience all these symptoms, and the severity and order of onset vary widely.

As Huntington’s disease advances, serious complications may include: 

• Aspiration pneumonia (a leading cause of death) 

• Injuries from falls 

• Malnutrition and weight loss 

• Severe swallowing difficulties 

• Advanced cognitive decline / dementia 

• Psychiatric complications (including depression and suicide) 

• Respiratory complications 

• Seizures (more common in juvenile-onset cases) 

Diagnosis of Huntington’s disease involves a combination of clinical evaluation, family history, imaging and genetic testing. 

Clinical evaluation: A neurologist will assess for characteristic motor signs (e.g. chorea), cognitive changes, and psychiatric symptoms. 

Family history: Family history of Huntington’s disease can be an important clue. 

Genetic testing: A blood test that measures the number of CAG repeats in the HTT gene can confirm the diagnosis. Predictive (presymptomatic) testing is possible for at-risk individuals even before symptoms appear but requires careful consideration of psychological, ethical and familial implications. 

Imaging and other assessments: Brain MRI or CT may show characteristic brain changes, but imaging is not diagnostic on its own. Other tests (neuropsychological testing, metabolic screens) may help rule out other causes of chorea or neurodegeneration. 

Genetic counseling is strongly recommended both before and after genetic testing, to help patients and families understand the implications. 

Currently, there is no cure for Huntington’s disease. Available treatments focus on managing symptoms and improving quality of life. Advances in gene therapy are changing the therapeutic landscape. 

Symptomatic and supportive treatments 

• Medications such as tetrabenazine and deutetrabenazine may reduce chorea. Antipsychotics and antidepressants may address psychiatric symptoms. 

• Physical, occupational, and speech therapy may help with mobility, daily activities, swallowing and communication. 

• Nutrition support and feeding interventions may be needed in advanced cases. 

• Palliative care and multidisciplinary support play an important role as the disease progresses. 

Research and investigational therapies 

Experimental approaches, including gene therapy, antisense oligonucleotides, and RNA-based treatments, are being studied in clinical trials. For example, AMT-130, a gene therapy under investigation, uses a viral vector to deliver molecules designed to reduce mutant huntingtin protein. Early trial results have shown signals suggesting possible slowing of disease progression, but studies remain small and ongoing. These therapies are not yet approved and should be considered investigational. 

On average: 

• Once motor symptoms appear, life expectancy is typically 15 to 20 years. 

• Juvenile-onset cases tend to progress more rapidly with shorter life expectancy. 

• The size of the CAG repeat length and other genetic and environmental factors influence the course of the disease. 

• Common causes of death include pneumonia, heart disease and suicide. 

• Over time, many individuals require increasing support and eventually full-time care. 

Huntington’s disease is a rare, inherited neurodegenerative condition that causes progressive decline in movement, cognition, and behavior. Current care focuses on managing symptoms and supporting patients and families. Research into new therapies, including gene therapy, is ongoing. These investigational treatments offer hope for the future, but further studies are needed to determine their safety and effectiveness. Early diagnosis, multidisciplinary care, symptom management, and ongoing support for patients and families remain central to helping people with Huntington’s disease maintain quality of life. 

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