A cerebellar ataxia patient harboring 229 pure GAA repeat units in FGF14 presenting with grip myotonia

Spinocerebellar ataxia 27 B (SCA27B) is caused by the expansion of GAA repeats in the intron of the fibroblast growth factor 14 ( FGF14 ) on chromosome 13 and is inherited dominantly. An 80‐year‐old male visited the hospital complaining of ataxic gait and harboring 229 pure GAA repeat units in the FGF14 . Almost all the clinical features were similar to that of SCA27B. However, the patient initially presented with episodic grip myotonia, which has not been previously reported.