associated with smoking persistence (Hamidovic et al. 2011). Both SNPs are located in regions that have been associated with smoking and nicotine dependence in European Americans (Liu et al. 2010; Saccone et al. 2009; TAG 2010), suggesting that there may be distinct variants which modulate smoking behavior phenotypes in African-Americans. Smoking during pregnancy is a phenotype influenced by many factors, including genetic susceptibility to the addictive properties of nicotine. Data from 2,474 European women, who smoked regularly before becoming pregnant, showed that the risk allele of the rs1051730 SNP in the CHRNA5-CHRNA3-CHRNB4 gene cluster is associated with continuing to smoke during pregnancy (Freathy et al. 2009). Thorgeirsson and Stefansson (2010) replicated these findings, finding the rs1051730 risk variant is also associated with continued smoking during pregnancy in their sample of 1,891 women.
