Genome-wide association analyses suggested a novel mechanism for smoking behavior regulated by IL15

Mol Psychiatry. 2009 Jul;14(7):668-80. doi: 10.1038/mp.2009.3. Epub 2009 Feb 3.


Cigarette smoking is the leading preventable cause of death in the United States. Although smoking behavior has a significant genetic determination, the specific genes and associated mechanisms underlying the smoking behavior are largely unknown. Here, we carried out a genome-wide association study on smoking behavior in 840 Caucasians, including 417 males and 423 females, in which we examined approximately 380,000 single nucleotide polymorphisms (SNPs). We found that a cluster of nine SNPs upstream from the IL15 gene were associated with smoking status in males, with the most significant SNP, rs4956302, achieving a P-value (8.80 x 10(-8)) of genome-wide significance. Another SNP, rs17354547 that is highly conserved across multiple species achieved a P-value of 5.65 x 10(-5). These two SNPs, together with two additional SNPs (rs1402812 and rs4956396) were selected from the above nine SNPs for replication in an African-American sample containing 1251 subjects, including 412 males and 839 females. The SNP rs17354547 was replicated successfully in the male subgroup of the replication sample; it was associated with smoking quantity (SQ), the Heaviness of Smoking Index (HSI) and the Fagerstrom Test for Nicotine Dependence (FTND), with P-values of 0.031, 0.0046 and 0.019, respectively. In addition, a haplotype formed by rs17354547, rs1402812 and rs4956396 was also associated with SQ, HSI and FTND, achieving P-values of 0.039, 0.0093 and 0.0093, respectively. To further confirm our findings, we carried out an in silico replication study of the nine SNPs in a Framingham Heart Study sample containing 7623 Caucasians from 1731 families, among which, 3491 subjects were males and 4132 were females. Again, the male-specific association with smoking status was observed, for which seven of the nine SNPs achieved significant P-values (P<0.05) and two achieved marginally significant P-values (P<0.10) in males. Several of the nine SNPs, including the highly conserved one across species, rs17354547, are located at potential transcription factor binding sites, suggesting transcription regulation as a possible function for these SNPs. Through this function, the SNPs may modulate the gene expression of IL15, a key cytokine regulating immune function. As the immune system has long been recognized to influence drug addiction behavior, our association findings suggest a novel mechanism for smoking addiction involving immune modulation through the IL15 pathway.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Female
  • Gene Frequency
  • Genetic Predisposition to Disease
  • Genome-Wide Association Study*
  • Genotype
  • Humans
  • Interleukin-15 / genetics*
  • Male
  • Middle Aged
  • Polymorphism, Single Nucleotide / genetics*
  • Retrospective Studies
  • Sex Factors
  • Smoking / genetics*


  • Interleukin-15

Grant support