This is consistent with the observation that the severe Purkinje neuron dysfunction observed in these SCA models cannot be recapitulated by targeted pharmacologic blockade of BK in wild-type neurons (30) but is readily apparent with intracellular Ca2+ chelation (31), which lowers intracellular free [Ca2+] needed for BK channel activation (32). This evidence concerns the gene KNG1 and autosomal dominant cerebellar ataxia.