Objective: To describe a series of patients in Santiago Chile with genetically confirmed SCA15.

Background: Spinocerebellar ataxia (SCA) are genetic neurodegenerative diseases for which SCA subtype 15 (SCA15) is considered a rare variant.  In a 2025 review and meta-analysis including literature regarding Latin American epidemiology, only 50% of the reported SCA cases were confirmed with genetic tests and no SCA15 was reported.

Method: In a movement disorder specialized clinic in Santiago, Chile, 4 patients from the same family cluster were analyzed. Only a single individual had been genetically confirmed. Data from each individual was obtained through history and physical exam. Scale for the assessment and rating of ataxia (SARA), mini bestest, Activities-specific balance confidence (ABC) Patient reported outcome measure of ataxia (PROM) rating scales were obtained. Genogram was made through verbal reports from patients.

Results: 3 patients were female; At time of data collecting individuals were 33, 30, 61 and 70 years old, median symptom-onset-age was 19 years (range 18-35 years), median disease duration time was 24 years old (range 12-43), Median Diagnostic delay was of 4 years. The presenting symptom was cephalic tremor in 2 of them, dysarthria for one, and walking instability for the other. All of them presented ataxia, difficulty to perform tandem and dysarthria. 

Median for scores were SARA 14 (range 9.5-22), Mini BESTest 12 (range 5-19), ABC 47.8 (range 0.5-58.12), PROM 18.5 (range 15-35),

Conclusion: This case series depicts a familiar cluster for SCA15, first in Latin America described as far as the author’s understanding. Limited genetic testing access in the region diminishes diagnostic capacity, for which, it is presumable that this variant, as well as The others, is underdiagnosed.

Performed scores and scales results

Description of patients

Family tree genogram

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MDS Abstracts - https://www.mdsabstracts.org/abstract/a-case-series-of-spinocerebellar-ataxia-subtype-15-from-chile/