Doc: Huntington’s a progressive loss of function
Dear Dr. Roach: My sister was diagnosed with Huntington’s disease. What are the symptoms she might be experiencing?
Dear R.G.: I am very sorry to hear about your sister. Huntington’s disease is a terrible disease with no cure.
Huntington’s disease is an inherited condition causing progressive loss of neurological function. It is caused by an abnormality in the huntingtin gene called “CAG repeats”: the more repeats, the earlier symptoms tend to occur. This leads to an abnormality of a protein called huntingtin, which is especially present in some parts of the brain. It is a rare disorder, seen in only about 3 people per 100,000 worldwide.
Symptoms can start anytime from childhood to a person’s 70s, but onset is most common in middle age. There are three types of symptoms: neurological, psychiatric and dementia. Neurological symptoms include a type of abnormal movement called “chorea.” These are involuntary rapid movements, usually of the face, trunk or limbs. People with HD occasionally are unaware of them and may (or may not) notice changes in their walking. There are subtle signs that a trained neurologist can find on physical exam. There are new treatments (tetrabenazine and deutetrabenazine) available for the abnormal movements.
Psychiatric symptoms happen in roughly half of people with HD. Depression and irritability can affect people’s social lives years before any motor symptoms become apparent. Suicide is a significant risk, at the time of diagnosis or as the disease progresses.
Dementia is universal in those with advanced HD. But, the decline in function may occur early or late in the course of the illness.
I don’t know where your sister is in the course of her disease. Early on, people generally are able to continue with their lives, as HD is a slowly progressive disease. Most people live 10-20 years after diagnosis, some much longer. As the disease progresses, though, people slowly lose the ability to live without assistance. The last stage of HD may last for years, and most people eventually will require around-the-clock care.
The majority of people with HD will have a family history of the disease, but that may not be the case in an adopted child, if the affected parent died before HD became apparent, or in the case of a new genetic mutation. Genetic testing is now 99 percent sensitive and 100 percent specific for HD: All family members (this includes you) should consider having the test and should meet with a genetic counselor prior to proceeding. Testing should not be undertaken lightly for asymptomatic family members. Many people choose not to be tested.
There is no approved treatment to cure or slow down the HD’s progression. Symptoms can be treated with a combination of medication, physical and occupational therapies and home care. It’s critical to discuss advance directives when the person with HD has full capability of expressing his or her wishes.
A new, promising treatment for HD is in clinical trials. It is called IONIS-HTTRx, and it has been shown to reduce huntingtin protein in the brain fluid. Hopefully it will be shown to affect the course of the disease.
There are several places for good information and support groups. One is the Huntington’s Disease Society of America (hdsa.org); another is the Huntington Society of Canada (huntingtonsociety.ca).
Email questions to ToYourGoodHealth@med.cornell.edu.