Case report: A Chinese patient with spinocerebellar ataxia finally confirmed as Gerstmann-Sträussler-Scheinker syndrome with P102L mutation oleh Lin Chen, Yin Xu, Ming-juan Fang, Yong-guang Shi, Jie Zhang, Liang-liang Zhang, Yu Wang, Yong-zhu Han, Ji-yuan Hu, Ren-min Yang, Xu-en Yu