Mutations in key genes can lay waste to the nervous system. Spinocerebellar ataxia type 1 (SCA1), for example, can start with a stagger at age 30 or 40. Patients eventually experience severe muscle deterioration, rendering them unable to talk, swallow, or even breathe. By studying large families predisposed to developing SCA1, Dr. Zoghbi and her colleagues identified the responsible altered gene. The culprit is a sort of genetic stutter that increases the size of the SCA1 gene. As a result, the product of the mutant gene—a protein called ataxin-1—forms large, sticky clumps that disable the neurons involved in controlling movement. Dr. Zoghbi is now searching for compounds that will clear ataxin-1 tangles.