Huntington disease

Huntington disease (HD) is a progressive neurodegenerative condition caused by a CAG repeat expansion in HTT. It is inherited in an autosomal dominant pattern and can affect movement, cognition, behavior, mood, speech, and swallowing. The order, combination, and rate of change vary substantially.1

Urgent safety

Suicidal thoughts, intent, or behavior, severe agitation or psychosis, or an immediate risk to the person or others requires emergency or crisis assessment. Ask directly about safety and use local emergency services or crisis resources when risk is immediate.2

Seek urgent medical assessment for choking, breathing difficulty, inability to clear secretions, acute dehydration or weight loss, or a fall with possible injury. Sudden neurologic or behavioral change should not automatically be attributed to HD.

Clinical pattern and diagnosis

Possible manifestations include:

• chorea, dystonia, bradykinesia, rigidity, impaired balance, and falls;
• slowed processing, reduced initiation, impaired planning, attention, judgment, or cognitive flexibility;
• depression, anxiety, irritability, apathy, impulsivity, obsessive or psychotic symptoms;
• dysarthria, communication change, dysphagia, weight loss, and sleep disturbance.

Diagnosis in a symptomatic person combines clinical assessment, family history, and molecular testing for the HTT CAG repeat expansion. Repeat ranges and penetrance are nuanced, particularly in intermediate and reduced-penetrance ranges. Repeat length has a population-level relationship with age at onset, but it cannot precisely predict one person's onset, symptoms, or course.1

Juvenile-onset HD begins before age 20 and more often features rigidity, bradykinesia, dystonia, decline in school performance, and seizures than the typical adult choreic presentation. It remains variable. Developmental, educational, and communication plans should be based on the young person's demonstrated skills, not an assumption that literacy or learning is absent.1

Genetics and testing

Each child of a person with a heterozygous HD-causing expansion has a 50% chance of inheriting an expanded allele, but the clinical meaning depends on the allele and laboratory interpretation. Predictive testing of an asymptomatic adult is voluntary and should occur through a formal genetic-counseling protocol that addresses informed choice, mental health, privacy, family impact, and follow-up.1

Predictive testing of an asymptomatic minor for adult-onset risk is generally deferred to preserve future autonomy. A child or adolescent with symptoms suggestive of juvenile HD needs specialist diagnostic evaluation; that is different from predictive testing. Prenatal and preimplantation testing are possible after a familial expansion is identified and require genetics and reproductive counseling.1

Treatment and follow-up

There is no established cure or disease-modifying treatment. Care is multidisciplinary and symptom-directed. Medication may target selected movement or psychiatric symptoms, but a treatment that reduces chorea can worsen sedation, swallowing, balance, mood, or parkinsonism. Prescribing and medication changes require a clinician familiar with HD, current symptoms, and the person's priorities.2

Physical, occupational, nutrition, mental-health, social-work, palliative, and speech-language support should be offered according to current need. Exercise, mobility equipment, environmental changes, behavioral approaches, and supervision levels require individualized assessment. They should not be assigned from diagnosis or disease stage alone.

Swallowing, cognition, and communication

Swallowing review should consider coughing or choking, wet or changed voice, prolonged meals, food remaining in the mouth, weight loss, hydration, recurrent chest symptoms, impulsive eating, movement, positioning, and cognition. Texture, pacing, assistance, and exercises require direct assessment. Nutrition goals should reflect safety, comfort, health, and the person's preferences.2

Allow extra time for processing and initiation, reduce dual-task demands, make one request at a time, and check understanding without taking over. Communication difficulty does not by itself establish incapacity. Use supported decision-making and retain the person's own voice in care planning for as long as possible.

AAC may supplement speech before it becomes unreliable. Preserve existing language and literacy. Options may include written choices, alphabet or topic boards, schedules, stored phrases, text-to-speech, and speech-generating devices. Trial direct touch, adapted pointing, switches, partner-assisted scanning, or eye gaze based on real performance; chorea, dystonia, ocular-motor control, attention, fatigue, and positioning can change access. Train partners, include personally meaningful vocabulary and urgent messages, and keep a low-tech backup.3 For evaluation, trials, funding, and implementation, use the AAC device acquisition guide.

Coding

• ICD-10-CM G10: Huntington's disease.

Use the documented diagnosis and current local coding rules. The code does not describe symptom severity, juvenile onset, communication needs, or decision-making capacity.4

Sources

1. Brás, Dawson, Kay, Caron, and Hayden. Huntington Disease, GeneReviews — current genetics, diagnosis, repeat interpretation, inheritance, predictive testing, and juvenile presentation (last update February 12, 2026).
2. Bachoud-Lévi et al. International Guidelines for the Treatment of Huntington's Disease — multidisciplinary symptom management and treatment tradeoffs (2019; PMID 31333565).
3. American Speech-Language-Hearing Association: Augmentative and Alternative Communication — individualized, multimodal AAC assessment without cognitive or age prerequisites.
4. ICD-10-CM G10 — Huntington's disease — code descriptor; confirm against the current official CMS ICD-10-CM files for the care year.

Review boundary

This page cannot diagnose HD, interpret a genetic result, determine capacity, or remotely assess psychiatric, swallowing, nutrition, or fall risk. Emergencies require immediate local assessment. Genetic testing, medication, diet, exercise, mobility, communication, and care-planning decisions require direct review with appropriately qualified clinicians and the person's informed participation.