On Friday, the U.S. Food and Drug Administration approved the first-ever treatment for Huntington's disease—the crippling illness that killed folksinger Woody Guthrie and that plagues 30,000 Americans.

Tetrabenazine, known commercially as Xenazine, was originally developed in the 1950s to treat symptoms of psychosis. It's not a cure-all for sufferers of the disease. Rather, it addresses a primary symptom of Huntington's—which is seen in 90 percent of patients: involuntary, spastic movements. According to a 2006 study, researchers at the University of Rochester Medical Center were able to reduce these movements in 54 patients by an average of 25 percent.

Huntington's disease is a genetic disorder that can be diagnosed with a simple blood test. Typically, people who inherit one or more of these disrupted genes from their parents will live normally until their 30s or 40s, when brain cells in areas linked to functions such as movement begin to die off. In addition to the sudden, involuntary movements, sufferers also experience mental difficulties, depression and changes in their personality. Eventually, the illness results in death—in many cases by suicide because of the suffering form the disease.

The drug is not without side effects: It may heighten depression and cause the body to stiffen up. But, as Rochester neurologist Frederick Marshall notes in a press statement, while tetrabenazine won't cure Huntington's, it allows sufferers to enjoy a better quality of life—with some patients able to return to the activities they enjoy after spending years homebound.