NRG3 and Anxiety: By using a Finnish twin family sample, we have previously identified linkage of SI at the ERBB4 locus,14 and association between ND and ERBB4.13 Turner et al.15 have recently shown the involvement of Nrg3 and Erbb4 in the anxiety effects of NW in a behavioral mouse model, and association between NRG3 SNPs with smoking cessation success in a clinical trial.