Loss-of function or dominant negative mutations in the KCNQ2 gene are found in epilepsy and bipolar disorder (Singh et al., 1998; Cooper et al., 2000; Mulley et al., 2003), and inhibition of M-channel activity has been linked to schizophrenia (Fedorenko et al., 2008), suggesting that neuronal hyperexcitability resulting from impaired M-channel function may be a common denominator in a number of neurological and psychiatric illnesses in which GSK-3 activity is dysfunctional (Li et al., 2002). The gene discussed is KCNQ2; the disease is bipolar disorder.