In all cases examined, mice that harbor loss-of-function mutations in the Cacna1a gene have been found to exhibit characteristic signs of EA2, rather than those of the other allelic disorders, FHM1 or SCA6 (Fletcher et al., 1996; Mori et al., 2000; Zwingman et al., 2001). Here, CACNA1A is linked to episodic ataxia type 2.