variants identified to date, each genetic variant, or single-nucleotide polymorphism (SNP), accounts for a very small proportion of the variance in smoking behavior (<2%). Smoking behaviors are complex genetic traits, influenced by multiple genetic variants,7, 8 which likely interact with the individual's social context.9, 10, 11, 12 Polygenic risk scores, which aggregate common genetic risk variants, have been increasingly used to model the genetic architecture of complex traits.8, 13, 14, 15 In addition to circumventing the statistical stringency of multiple test corrections necessary for GWAS, this method may more accurately reflect the underlying genetic architecture of complex behaviors, such as cigarette use.
