Late-onset spinocerebellar ataxia-27B (SCA27B) is an autosomal dominant neurodegenerative disorder characterized by the onset of gait and appendicular ataxia in adulthood, usually around age 55 (range 30 to late eighties). About half of patients present with episodic features. The disorder is slowly progressive, and some patients may lose independent ambulation. Additional features include downbeat and horizontal nystagmus, diplopia, vertigo, and dysarthria. Brain imaging tends to show cerebellar atrophy (Pellerin et al., 2023). The disease or phenotype is late-onset spinocerebellar ataxia 27b (EFO_0022191). Also known as: SCA27B.