An Overview of Huntington's Disease

Huntington’s disease (HD) is a progressive neurodegenerative disease that is passed on genetically from parents to children.

Classic symptoms include uncontrollable movements in the face, trunk, arms, and legs, as well as problems thinking clearly, and mood changes, like anxiety, depression, and irritability.

There is a blood test that can confirm the presence of HD. While HD cannot be cured or slowed down, certain symptoms can be managed with medication.

The symptoms of Huntington's disease slowly get worse over time and tend to vary based on the disease stage:

Early Stage HD

Early symptoms of HD include difficulty learning new things or making decisions, problems with driving, irritability, mood swings, involuntary movement or twitching, coordination, and short-term memory problems.

Middle Stage HD

As HD progresses into the middle stage, the person has trouble with swallowing, speaking, walking, memory and concentrating on tasks. Weight loss is common.

The classic writhing movements (called chorea) of HD may become very pronounced and interfere significantly with daily functioning. The person may also develop some obsessive behaviors.

Late Stage HD

Late-stage HD symptoms consist of the inability to walk or talk, and require full care from a caregiver. Instead of chorea, a person may have rigidity, slowed movements (called bradykinesia), and dystonia. People who have late-stage HD are at high risk for choking.

With Huntington's disease, a faulty gene (called the HTT gene) creates a mutant huntingtin protein, which leads to the death of nerve cells in a person's brain.

Nearly all cases of HD are hereditary, and the disease is inherited in an autosomal dominant pattern. This means if your father or mother has HD, you have a 50% chance of having the HD gene.

If you inherit the faulty or altered HTT gene, you will most likely develop HD. That said, some people do not inherit as faulty of a gene, so they may not develop HD; however, their children are still at risk.

If you do not inherit the faulty HTT gene, you will not develop HD. The exception is rare cases where a de novo mutation occurs in the HD gene. In these instances, the disease cannot be traced to someone else in the family.

The diagnosis of HD begins with a medical history and is confirmed with a blood test to look for the HTT gene.

Medical History

In addition to inquiring about possible symptoms of HD, your doctor will want to obtain a detailed family history. Sometimes old medical records or autopsy reports are needed to complete this search. 

Genetic Blood Test

If you are experiencing symptoms of HD or have a family member with HD, your doctor can order a genetic test to look for the HTT gene.

Prior to undergoing the test, it's important to speak to a genetic counselor—someone who can help you understand the potential test results. For instance, if the test is positive, your counselor can explain what that means for you and your children's future health.

There is no cure for Huntington’s disease, but medication and non-pharmacological therapies can be used to ease certain symptoms and improve a person's quality of life.

Medications

The symptoms of involuntary movements (chorea) can be treated with Xenazine (tetrabenazine), the only drug approved by the U.S. Food and Drug Administration for Huntington's disease.

While an effective drug, there are potential adverse effects associated with Xenazine, such as:

• Restlessness (called akathisia)
• Depression
• Dizziness
• Fatigue
• Parkinsonism (movement features seen in Parkinson's disease).

Other medications can also be used to treat HD's cognitive, behavioral, and emotional symptoms. For example, benzodiazepines may be used to treat anxiety and chorea in HD, while atypical antipsychotics such as Zyprexa (olanzapine) may be used to treat chorea accompanied by psychosis, aggression, or impulsivity.

Complementary Therapies

Exercising—through formal methods like physical therapy and occupational therapy, and informal ways such as walking and remaining active—may also help relieve symptoms. Besides exercise, other complementary therapies that may be beneficial include music therapy, dance, or video-game-playing. 

It's normal to have many concerns if you or your loved one has been diagnosed with, or tested positive for, Huntington's disease. Knowing that there are many resources and support networks, such as the Huntington's Disease Society of America, available can be helpful as you learn what to expect and how to cope.