We screened the NIMH Genetics Initiative African-American control population for their self-report of maximal CPD smoked (questionnaire subsection M3B). Using a 20 CPD cut-off for inclusion in the CHRNA5 re-sequencing project yielded 250 African-American heavy smokers. The African-American cocaine (N=487) and opiate (N=325) addicted populations from the NIDA Genetics Initiative were obtained from the RUCDR. These de-identified genomic DNA (gDNA) samples were used to determine the frequency of the exon 2 deletion in a larger, independent African-American population. Ethnicity was by self-report.
