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, eventually rendering patients unable to talk, swallow, or even breathe. Dr. Zoghbi discovered that the culprit is a sort of genetic stutter that increases the size of the SCA1 gene. As a result, the gene’s protein product forms large, sticky clumps that disable the neurons involved in controlling movement. Researching compounds that will clear these tangles may also lead to treatments for other neurodegenerative diseases. From the Series:HHMI's Understanding Biomedical Research Series