Q How has the discovery of the gene for Huntington's disease changed treatment options and research?
DR. ANNIE KILLORAN RESPONDS:
A The drugs we use to treat Huntington's disease (HD) are not new, but they can help manage some symptoms. Unwanted movements can be managed with neuroleptic drugs such as haloperidol. Unfortunately, these drugs can't slow the underlying disease process. This can only be done by “neuroprotective” drugs, which inhibit cell death and deter disease progression. These drugs don't exist yet for HD, but research has advanced since discovering the HD gene in 1993.
By identifying the gene that causes HD, scientists have been able to study genetically engineered animal models of the disease, which helps us understand the disease process and identify targets for new drugs. We have learned the defective HD gene produces an abnormal protein called huntingtin that damages the brain. Now, we are testing drugs that block this protein or stop it from being produced in the first place. We need to do these tests in animal models of HD before we can do clinical trials in humans.
The discovery of the HD gene has also helped to make genetic testing widely available. Each child of an HD parent has a 50-50 chance of inheriting the HD gene. Adults at risk for HD can learn of their gene status years before they develop any signs of the disease. Many people feel this can help them plan better for the future.
By participating in studies, people who test positive for the gene mutation but who don't have signs of the disease can help researchers find biomarkers–such as those we might measure in the blood—that indicate the presence of a disease. We hope to use these biomarkers to tell us how well a neuroprotective treatment is working, long before the patient starts showing any of signs of HD.