FGF14 and late-onset spinocerebellar ataxia 27b: A dominantly inherited GAA repeat expansion in intron 1 of the fibroblast growth factor 14 (FGF14) gene has recently been identified as the cause of GAA-FGF14 disease/spinocerebellar ataxia 27B (SCA27B),1,2 a late-onset slowly progressive cerebellar syndrome that is frequently associated with episodic symptoms and downbeat nystagmus (DBN).1