In summary, multiple associations have been found between nicotine dependence and nicotinic receptor subunit genes. The strongest and most robust association is seen with a nonsynonymous SNP in the nicotinic receptor gene CHRNA5, rs16969968. This SNP is also associated with lung cancer and COPD, both smoking-related disorders. The current scientific question is whether there is an association between these smoking-related disorders and rs16969968, independent of nicotine dependence.
