after controlling for nicotine dependence, (3) whether the genetic risk for nicotine dependence associated with the diplotypes of SNPs (rs16969968, rs588765) was moderated by comorbid psychiatric disorders, and (4) the statistical power to test the above hypotheses. The answers to questions of pleiotropy (the genetic effect of a single gene on multiple phenotypic traits) between nicotine dependence and other psychiatric disorders and of possible genetic risk moderation by comorbid disorders provide a critical step to further our understanding of common versus specific vulnerability for nicotine dependence and comorbid disorders.
