SNPs or haplotypes with SC remained after Bonferroni correction for multiple testing. Also, we did not correct for our testing of two genetic models and three phenotypes, as they are highly related, which violates the assumption of independence for Bonferroni correction. Because of the aforementioned concerns, to some extent, we consider this study explorative, and more replication in Korean or other Asian samples is greatly needed. Second, although we defined the three smoking-related phenotypes on the basis of all the related information collected from each smoker, we are not fully convinced this is the best sample for investigation of this gene cluster and smoking behaviors, as this work was not designed originally as a genetic study on smoking, and the information collected from each smoker is limited. For example, SQ was assessed by CPD instead of ND determined by the FTND or DSM-IV criteria commonly used in other studies. Also, there was no SQ information (i.e., a 5-category ordinal trait based on CPD) for light or occasional smokers, although we do know they smoked only when they were in specific social circumstances such as during a party or gathering with their friends. Further, the SC status was based on individual
