Huntington's disease

Huntington's disease (HD) is a brain illness that runs in families. A change in one gene slowly damages nerve cells deep in the brain. Over many years, this affects how a person moves, feels and thinks.¹ There is no cure yet, but treatment and good support can make daily life better.^1,6

HD touches the whole family. A parent's diagnosis raises hard questions for children and grandchildren about their own risk. This page explains the gene, the main symptoms, testing choices and where to find help.

What causes Huntington's disease?

Everyone has a gene called HTT. It makes a protein called huntingtin. Inside this gene, a short piece of DNA code, called "CAG," repeats a number of times in a row.^1,2

In HD, the CAG piece repeats too many times. This builds a faulty form of huntingtin that harms brain cells. The damage hits hardest in the striatum (a deep brain area that helps control movement, mood and planning).¹

The number of repeats matters:^1,2

The count can grow from one generation to the next. A higher count usually means symptoms start earlier.²

How the gene passes in families

HD follows a pattern called dominant inheritance. One copy of the changed gene is enough to cause it. Each child of a parent with HD has a 50% chance of getting the gene, like a coin toss.¹

The odds are the same for each child. One child having HD does not change the odds for a brother or sister.¹

Who gets HD, and when

Most people notice symptoms between ages 30 and 50.³ Adults with HD usually live about 15 to 20 years after symptoms begin.^2,6

Juvenile HD. In rare cases, HD starts in childhood or the teen years. Children with juvenile HD usually have more than 60 CAG repeats. Seizures happen in about a third to a half of them, and the illness moves faster.²

Late-onset HD. Some people first show signs after age 60. In studies, they make up about 4% to 12% of people with HD. Most have a smaller number of repeats (44 or fewer), and the illness may move more slowly.¹¹ Some have no known family history. Doctors can miss HD in older adults because they do not expect it at that age.¹¹

HD is more common in people of European descent, and less common among people of Japanese, Chinese and African descent.²

Symptoms: movement, mood and thinking

Changes can start years before a diagnosis. A large NIH-funded study found brain and behavior changes up to 15 years before doctors diagnosed HD.¹

Movement

• Chorea: sudden, jerky, dance-like movements a person cannot control
• Stiff or twisting muscles, clumsiness, and trouble with balance and walking
• Slurred speech and unusual eye movements
• Trouble chewing and swallowing, which gets worse over time¹

Falls become more likely as movement problems grow.⁶ See preventing falls.

Mood and behavior

For many families, these are the hardest changes. They can show up before the movement problems.

• Depression, irritability, anger and mood swings
• Apathy (losing interest and drive)
• Pulling away from family and friends
• Psychosis (seeing or believing things that are not real) in some people
• Thoughts of suicide¹

Sleep problems, tiredness and weight loss are common too.¹

Thinking

HD makes it harder to focus, plan, organize and make decisions. Learning new things gets harder. Driving may become unsafe. These problems grow over time and often become dementia.¹

The early thinking problems in HD center on focus, judgment and planning.¹ This is different from Alzheimer's disease, which usually starts with memory loss. Changes in judgment and behavior can also be confused with frontotemporal dementia or a mental illness, which is one reason family history matters.

How HD is diagnosed

A neurologist (brain doctor) looks at symptoms, family history and an exam of movement, thinking and mood.¹ A blood test that counts the CAG repeats is the most accurate way to confirm HD.¹ Brain scans like MRI may show shrinking in some areas, but they can look normal early on.¹

There are two very different kinds of gene tests:

Genetic counseling and the choice to test

Choosing whether to learn your gene status is a deeply personal choice. Some people want to know so they can plan. Others choose not to know. Both choices are valid.

The Huntington's Disease Society of America (HDSA) has a testing guide for doctors. It says a person should have genetic counseling before giving blood for a predictive test.⁴ The counselor talks through what a positive or negative result could mean for your life, work and family. HDSA also advises thinking about life, disability and long-term care insurance before testing.⁴ Results should be given in person, with a chance to ask questions and come back later.⁴

Why insurance timing matters. A federal law called GINA (2008) bars health insurers and most employers from using genetic test results against you.⁸ But it does not cover life insurance, disability insurance or long-term care insurance. It also does not cover employers with fewer than 15 workers or the U.S. military.⁸ Some states add their own protections.⁸ See genes and dementia for more.

Couples with HD in the family who plan to have children can also ask about testing during pregnancy.^1,6 A genetic counselor can explain these choices without pressure.

Treatment and care

No treatment can stop or reverse HD yet.¹ But many symptoms can be treated, and good care helps people stay active and safe longer.⁶

Daily care tips. Weight loss is common in HD.¹ Ask about a dietitian. Swallowing problems can cause choking. A speech therapist can test swallowing and suggest safer foods. See eating, drinking and swallowing. As HD moves forward, a person may need supervision and, later, care around the clock.⁶

Finding expert care. HDSA has 60 Centers of Excellence and 9 partner sites across 37 states and Washington, D.C.⁹ In and near Virginia, they include the University of Virginia, Virginia Commonwealth University, MedStar Georgetown University Hospital and Johns Hopkins.⁹ The HDSA helpline is 800-345-4372.³

Research and clinical trials

Scientists are testing ways to lower the faulty huntingtin protein or to switch off the changed gene.¹ Several of these are in clinical trials.

One experimental gene therapy, called AMT-130, is given once during brain surgery. In September 2026, its maker asked the FDA to approve it under a faster review path. The request is based on a small, early-stage study compared with outside records, not a large trial against placebo.¹² As of October 2026, it is not FDA-approved. The FDA's decision could take many months.¹²

If you are interested in research, ask an HD center about studies that fit you. See joining a dementia clinical trial.

Support for families

HD is often called a family disease. One parent may be ill while a grown child waits to learn their own risk. Some families care for more than one person with HD over the years.

• Disability benefits. Social Security lists both adult-onset and juvenile HD as Compassionate Allowances. This can speed up a disability claim.¹⁰ See Social Security disability for young-onset dementia.
• Plan ahead early. Make legal and health care plans while the person can still take part. See advance directives and power of attorney.
• Grief and stress. Families often grieve losses long before the end. See grieving someone still here and caregiver stress.
• Comfort later on. In later stages, hospice and palliative care can help with comfort at home or in a facility.

When to get help

See a doctor if you or a family member has new jerky movements, clumsiness, mood changes or trouble planning, especially with HD in the family.⁶ Ask for a referral to a neurologist or an HD center.

The risk of suicide is highest at two times: when early symptoms start, and later when a person loses independence.⁷ Depression, a past suicide attempt and thinking problems raise the risk.⁷ Ask about suicide directly and kindly. Asking does not plant the idea. A safety plan can help.

Education only. This page is general information written from the sources listed. It is not medical, legal or financial advice and does not replace a doctor, therapist or lawyer who knows your situation. How we write and check pages.