Episodic Ataxias: Clinical and Genetic Features

Abstract

Episodic ataxia (EA) is a clinically heterogeneous group of disorders that are characterized by recurrent spells of truncal ataxia and incoordination lasting minutes to hours. Most have an autosomal dominant inheritance pattern. To date, 8 subtypes have been defined according to clinical and genetic characteristics, and five genes are known to be linked to EAs. Both EA1 and EA2, which are caused by mutations in KCNA1 and CACNA1A, account for the majority of EA, but many patients with no identified mutations still exhibit EA-like clinical features. Furthermore, genetically confirmed EAs have mostly been identified in Caucasian families. In this article, we review the current knowledge on the clinical and genetic characteristics of EAs. Additionally, we summarize the phenotypic features of the genetically confirmed EA2 families in Korea.

Keywords: CACNA1A; Episodic ataxia; KCNA1.

Figure 1.

Mutations of the α1 subunit of the P/Q-type voltage-gated calcium channel in Korean patients with episodic ataxia type 2. The protein contains four homologous domains (I–IV), each with six transmembrane segments (S1–S6). The numbers in the symbol correspond to the mutations listed in Table 3.