Hereditary episodic ataxias.

Hereditary episodic ataxia (EA) syndromes are rare monogenic disorders that are phenotypically and genetically heterogeneous. The number of identified EA phenotypes is expanding. So far, mutations have been identified in four genes, all coding for membrane proteins including ion channels and transporters. The study of EA has illuminated previously unrecognized but important roles of ion channels and transporters in cerebellar function. This review summarizes recent advances and focuses on practical approaches in the diagnosis and treatment of episodic ataxia.