Objective: The objective of this study is to find a useful clinical marker that reflect progression of spinocerebellar ataxia type 31 (SCA31).

Background: SCA31 is a uniquely Japanese autosomal dominant spinocerebellar degeneration. Interestingly, SCA31 is one of the most common SCAs in Japanese. The main clinical feature is a slowly progressive purely cerebellar syndrome, with an average of onset at 60 years. Previous study demonstrated that clinical progression of this disease is 0.8 points/year in SARA (Nakamura K. et al., Cerebellum, 2017). We embarked a basic study for developing a disease-modifying therapy against SCA31. In parallel to this, we started prospective clinical study to find clinical parameter(s) that would predict efficacy in future clinical trial.

Method: A clinical study was designed to test all SCA31 patients every 48 weeks with SARA, ICARS, 9-hole peg test (9-PHT), 6-minute walk (6MWT), 10-m fast walk (10mW), and 25-foot walk time (T25W). Blood, urine, and spinal fluid samples and head MRI were also collected. 48-week measurements were completed in 15 patients at the time of abstract submission, and 24 patients are expected to complete this study by the presentation.

Results: There was a highly significant correlation between SARA and ICARS at baseline and the number of years of disease, 9-PHT, 6MWT, and T25W measurements.

The annual change in SARA was +0.97 points, while 9-PHT, 6MWT, and 10mW were significantly correlated after 48 weeks (P<0.05). Serum and CSF fluid markers were tested in an un-biased fashion, and one of the markers in CSF were found to correlate with the clinical severity.

Conclusion: In addition to SARA and ICARS, 9-PHT, 6MWT, and 10mW may be useful indicators to evaluate the progression of SCA31, and for assessing efficacy of SCA31 upon clinical trial.

References: 1) Nakamura K. et al., Natural history of spinocerebellar ataxia Type 31: a 4-year prospective study. Cerebellum. 2017 Apr;16(2):518-524. doi: 10.1007/s12311-016-0833-6.
2) Sato N. and Amino T. et al. Spinocerebellar ataxia type 31 is associated with “inserted” penta-nucleotide repeats containing (TGGAA)n. Am J Hum Genet. 2009 Nov;85(5):544-57. doi: 10.1016/j.ajhg.2009.09.019.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/clinical-progression-and-biomarkers-in-spinocerebellar-ataxia-type-31-a-form-unique-to-and-common-in-japanese/