spinocerebellar ataxia type 12 (Monarch Disease Ontology identifier MONDO_0011439) (SCA12) is a very rare subtype of type I autosomal dominant cerebellar ataxia (ADCA type I). It is characterized by the presence of action tremor associated with relatively mild cerebellar ataxia. Associated pyramidal and extrapyramidal signs and dementia have been reported. Also known as: SCA12.