CACNA1A and spinocerebellar ataxia type 6: Pathogenic variants directly hitting the negative charges forming the Ca2+ selectivity filter are rare but have been reported for Cav1.2 (E1135K) associated with LQT8 and Cav2.1 associated with a Spinocerebellar Ataxia Type 6 (SCA6) phenotype (not illustrated; see below).