Spinocerebellar ataxia type 14 (SCA14) is a rare form of autosomal dominant cerebellar ataxia caused by mutations in PRKCG. We herein report a case of SCA14 presenting with writer's cramp that predated the onset of progressive ataxia by four years. A 47-year-old Japanese woman had an 11-year history of writer's cramps, followed by unsteadiness. Whole-exome sequencing revealed a heterozygous mutation in PRKCG (p.C142S), leading to an SCA14 diagnosis. Therefore, writer's cramp might be a characteristic extracerebellar sign of SCA14 and can precede the onset of cerebellar ataxia.
Keywords: Dystonia; exome sequencing; spinocerebellar ataxias; writer's cramp.