My older brother called from California to tell me that he may have Huntington's disease. I know it runs in families. What are the symptoms of this disease, and is there some way to know whether I will get it too?
Huntington's disease is an inherited progressive disorder of the brain that is first manifest on average around age 40, but symptoms can begin in rare instances in childhood or as late as in the 80s.
The three major symptoms are abnormal function of the nerves controlling muscles, deterioration of intellectual function (dementia) and emotional difficulties. All develop slowly and worsen gradually.
About a third of patients with Huntington's disease suffer from depression, and obsessive-compulsive disorder is fairly common. These psychiatric problems may precede the other symptoms by many years and can be quite troublesome.
The most obvious and characteristic symptoms are repetitive, involuntary movements that eventually become almost constant. These jerky, twisting movements of the eyes, hands, fingers and limbs are referred to as chorea. Over times the afflicted individual develops severe, disabling lack of coordination due to loss of control of voluntary movements.
These disturbances of muscle function are accompanied by a relentless loss of intellectual ability.
Huntington's disease is inherited as an autosomal, dominant trait; that is, there is a 50-50 chance that any child of either an affected mother or father will inherit the disorder.
From a practical viewpoint, a readily available genetic test makes it possible to diagnose the disease with absolute certainty, and to identify those who are destined to develop it later in life. Many people with a proven family history of Huntington's disease are reluctant to undergo genetic testing because of an understandable concern about the effect this information may have on their health insurance, as well as fears ++ about the impact of learning that they will eventually be afflicted with a devastating disease for which there is no treatment.
It is worthwhile to note, however, that those who have learned that they have inherited the disorder have generally weathered this knowledge without major psychiatric fallout, and those who have found out that they are unaffected are obviously greatly relieved.
Dr. Margolis is professor of medicine and biological chemistry at the Johns Hopkins School of Medicine.