PSP-Phenotype in SCA8: Case Report and Systemic Review

Area of Science:

• Neurogenetics
• Neurology
• Molecular Biology

Background:

• Spinocerebellar ataxia type 8 (SCA8) is an autosomal dominant neurodegenerative disorder.
• It is caused by expanded CTA/CTG repeats in the ATXN8OS gene.
• The clinical presentation often includes cerebellar ataxia, but parkinsonism has also been observed without clear explanation.

Observation:

• The ATXN8OS gene was analyzed in Japanese patients with ataxia and Parkinson's disease.
• 123 patients with SCA8 were systematically reassessed.
• Two patients with progressive supranuclear palsy (PSP) were found to have ATXN8OS gene mutations.

Findings:

• Patients with parkinsonism showed significantly shorter CTA/CTG repeat expansions in ATXN8OS compared to those with predominant ataxia.
• An inverse relationship was observed between repeat size and age at onset across all SCA8 patients.
• Imaging results differentiated patients with and without parkinsonism.

Implications:

• These findings may aid genetic counseling for SCA8.
• Understanding the pathomechanism of SCA8 can be improved.
• The clinical phenotype of SCA8 may be extended to include parkinsonism more broadly.