The influence of initial symptoms on phenotypes in spinocerebellar ataxia type 3.

Background: Spinocerebellar ataxia type 3 (SCA3) is a rare, inherited form of ataxia that leads to progressive neurodegeneration. The initial symptoms could affect clinical phenotypes in neurodegenerative diseases, such as Parkinson's disease and amyotrophic lateral sclerosis. However, the contribution of initial symptoms to the phenotypes of SCA3 has been scarcely investigated.

Methods: In the present study, 143 SCA3 patients from China were recruited and divided into two groups of gait-onset and non-gait-onset. For determining the influences of initial symptoms on age at onset (AAO), the severity and progression of ataxia, and the possible factors affecting the initial symptoms, multivariable linear regression, and multivariate logistic regression were performed.

Results: We found that the frequency of gait-onset was 87.41%, and the frequency of non-gait-onset was 12.59% (diplopia: 7.69%, dysarthria: 4.20%, dystonia: 0.70%). Compared to the non-gait-onset group, the gait-onset group had significantly more severe ataxia (p = 0.046), while the initial symptoms had no effect on AAO (p = 0.109) and progression of ataxia (p = 0.265). We failed to find the existence of any factors affecting initial symptoms.

Conclusion: These findings collectively suggested that initial symptoms influenced phenotypes in SCA3 and that neurodegeneration in different parts of brain may induce different disease severity in SCA3.