CHRNA7 and nervous system disorder: α7 and α4β2 nAChRs also contribute to other non-neurological diseases, including a correlation of both subtypes with nicotine addiction and nicotine-induced behaviors (Buisson and Bertrand, 2002; Balfour, 2004) and the overexpression of α7 nAChRs associated with small-cell lung carcinomas (Sciamanna et al., 1997).