This research investigates how cognitive-affective aspects evolve during the course of SCA3/MJD. Due to COVID-19 pandemics, this study protocol was adapted for online-only consultations. Evaluations happening after March 2020 have been done by videocall with patients, and no neurological evaluation was thus performed on these patients. A scale on Activities of Daily Living was added to the online protocol to replace SARA, SCAFI and CCFS scales.

By the end of this study, the evaluated population will be composed of 144 participants: 36 ataxic SCA3/MJD carriers, 72 at 50% risk of carrying the SCA3/MJD mutation and 36 healthy controls. Ataxic subjects are invited to participate if they have an established molecular diagnosis of SCA3/MJD and have a SARA score greater than 2.5 points. At risk subjects are composed by the offspring of molecularly diagnosed SCA3/MJD subjects that have a SARA<3. Healthy controls belonging either to families living with the disease or to the general population are invited to participate according to how well they match with ataxic subjects included in the study. Subjects are invited to participate in the study and, after constentment procedures, cognitive-affective assessments and a scale on Activities of Daily Living (ADL) are performed on a videocall. At risk subjects collect a blood sample for double bilnd determination of their carrier status. Before March 2020, all procedures were performed in person and, instead of ADL, SARA, SCAFI and CCFS were obtained.

Inclusion Criteria:

• Symptomatic:
• older than 18 year old;
• molecular diagnosis of SCA3/MJD;
• SARA>2.5.
• At 50% risk:
• older than 18 year old;
• have a parent with molecular diagnosis of SCA3/MJD;
• SARA<3.
• Healthy Controls
• older than 18 year old;
• no genetic relationship with a SCA3/MJD carrier.

Exclusion Criteria:

• Non agreement in signing the informed consent;
• Healthy Controls: having any history of genetic disorders in their families or any psychiatric or neurologic disorder.

Individuals with molecular diagnosis of SCA3/MJD will be recruited from the Medical Genetics Service database of Hospital de Clínicas de Porto Alegre, Brazil, by telephone calls or by invitation in the outpatient clinic. First degree relatives of these subjects at 50% risk of carrying the mutation will also be invited to participate. Healthy controls will be invited from the general population.

Data sharing will be done via direct contact with the Principal Investigator in order to preserve individual participants identities.

Data will become available after final statistical analysis and data publishing via direct contact with principal investigator.

Investigators and researchers of the area