• SCA 1, 2, 3, 6, and FA with mutations in the pathogenic range confirmed from genetic testing

• SCA: aged 18-75 years

• FA: aged 12-30, diagnosed between ages 5-25

• community dwelling

• physically/cognitively capable of consenting/assenting and complying with the protocol based on investigator's judgement

• able to walk independently 10 yards without an assistive device

• able to sit or stand unassisted for 30 seconds

• no other neurological or musculoskeletal disorder that could affect mobility

• no other history of head injury, vestibular function, stroke, or other disorders that could affect mobility

• willing and able to participate in a 2-year study

• consent to be video recorded while performing study assessments