To demonstrate the more powerful method, we re-analyzed an existing dataset, which confirmed the association of the DOPA decarboxylase (DDC) gene on chromosome 7p11 with measures of nicotine dependence.
These findings confirm a previous report of association of DDC with ND, localize the causative variants to the 3' end of the coding region and extend the association to multiple population groups.
In summary, our findings provide the first evidence for the involvement of DDC in the susceptibility to ND and, further, reveal the racial specificity of its impact.