An important question is whether CHRN genes are also associated with nicotine dependence in African-ancestry populations. We recently examined the CHRNA5-CHRNA3-CHRNB4 region on chromosome 15q25 using an expanded United States sample (N=2772) (Saccone et al., 2009b). The expanded sample included a new African-American (AA) sample (N=710) and a new European-American (EA) sample (N=454), in addition to 1608 European-Americans previously studied together with 319 European-descent Australians (Saccone et al., 2009a, Saccone et al., 2007). The analysis of chromosome 15q25.1 in the expanded U.S. sample demonstrated that the non-synonymous CHRNA5 SNP rs16969968 is significantly associated with nicotine dependence in AAs as well as in EAs (Saccone et al., 2009b). Additional, distinct variants in that region appear associated in at least one of these populations.
