Imagine you’re skiing down a sloping mountain, trying to maneuver through the twists and turns. It’s an exhilarating experience, but what if your coordination starts to falter? That’s what happens with spinocerebellar ataxia type 3 (SCA3), a genetic disorder affecting movement control. In this study, researchers set out to uncover the natural history of SCA3 in Mainland China. They found that the disease progresses at a rate of 1.49 points per year on the Scale for the Assessment and Rating of Ataxia (SARA). Other outcomes, such as the Inventory of Non-Ataxia Signs (INAS) and the SCA Functional Index (SCAFI), also showed progression but differing rates. Factors like the length of the expanded allele of ATXN3 and baseline scores influenced the pace of decline. These findings shed light on SCA3’s progression patterns, which can help determine sample sizes for future clinical trials. It’s like having a map of the mountain slope, enabling researchers to strategize their approach and develop targeted interventions. To explore more about this fascinating research and its implications, check out the full article!

ObjectiveThe natural history of spinocerebellar ataxia type 3 (SCA3) has been reported in several populations and shows heterogeneity in progression rate and affecting factors. However, it remains unexplored in the population of Mainland China. This study aimed to identify the disease progression rate and its potential affecting factors in patients with SCA3 in Mainland China.Participants and MethodsWe enrolled patients with genetically confirmed SCA3 in Mainland China. Patients were seen at three visits, i.e., baseline, 1 year, and 2 years. The primary outcome was the Scale for the Assessment and Rating of Ataxia (SARA), and the secondary outcomes were the Inventory of Non-Ataxia Signs (INAS) as well as the SCA Functional Index (SCAFI).ResultsBetween 1 October 2015, and 30 September 2016, we enrolled 263 patients with SCA3. We analyzed 247 patients with at least one follow-up visit. The annual progression rate of SARA was 1.49 points per year (SE 0.08, 95% confidence interval [CI] 1.33–1.65, p < 0.0001). The annual progression rates of INAS and SCAFI were 0.56 points per year (SE 0.05, 95% CI 0.47–0.66, p < 0.001) and −0.30 points per year (SE 0.01, 95% CI −0.33∼-0.28, p < 0.001), respectively. Faster progression in SARA was associated with longer length of the expanded allele of ATXN3 (p < 0.0001); faster progression in INAS was associated with lower INAS at baseline (p < 0.0001); faster decline in SCAFI was associated with shorter length of the normal allele of ATXN3 (p = 0.036) and higher SCAFI at baseline (p < 0.0001).ConclusionOur results provide quantitative data on the disease progression of patients with SCA3 in Mainland China and its corresponding affecting factors, which could facilitate the sample size calculation and patient stratification in future clinical trials.Trial RegistrationThis study was registered with Chictr.org on 15 September 2015, number ChiCTR-OOC-15007124.

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