complex on chromosome 6 and by 1993, ataxin 1 was identified as the causative gene. It was the first spinocerebellar ataxia-causing gene to be localized and identified. Signs and symptoms Ataxia refers to a lack of coordinated muscle movements that include gait abnormality and is the cerebellar sign that typifies all spinocerebellar ataxia (SCA) types, though individuals with SCA1 also develop pyramidal and bulbar signs as the disease progresses. The average age of onset is between 30 and 40 years of age, though exceptions exist. From the first symptoms, duration is typically between one and three decades, where earlier onset correlates with faster progression. Spinocerebellar ataxia 1, like other SCAs, often causes dysarthria, a motor disorder of speech often manifest as slurring of words; pathological nystagmus, a disorder in which eyes drift involuntarily affecting vision; and gait and balance issues. SCA1 is also commonly present with dysphagia, a swallowing disorder that can cause choking while eating and drinking; and hypermetric saccades, where the eye tends to move faster or further than intended as it tracks an object or moves from one focus to another. As the disease progresses, more severe neurologic symptoms can appear like dysmetria, where limb movements consistently overshoot the desired position; dysdiadochokinesia, where repeated body movements become uncoordinated; or hypotonia, where muscles atrophy. While new symptoms appear as SCA1 progresses, nystagmus may disappear as eye movements and saccades slow down. Fatality may ultimately be caused by loss of bulbar functions, but complications from symptoms, such as pneumonia from swallowing problems, or trauma from falls, can be fatal as well. The severity and exact phenotype of these symptoms may vary between types of SCA. SCA 1 dysarthria may vary in severity depending on the task and is often associated with more strained, strangled or harsh sounding vocalization than that of other disorders. Because of the significant variance between cases of SCA1, typical signs and symptoms may appear alongside more subtle or rare symptoms. Maculopathy has been reported in rare cases, and may be linked effects from the mutation on the ATXN1 locus on genes in neighboring loci. Task specific dystonias have been reported in individual cases, often in the form of writer's cramps or cervical dystonia. SCAs can also be detected before serious atrophy with electrophysiologic techniques, using electrodes on the scalp to detect changes in electric potential within the brain in response to sensations or movements. Individuals