Results from this study indicate that the previously reported association between the *1B allele and faster in vivo nicotine metabolism, mainly in subjects of European descent [27], is also primarily due to insufficient accounting for polymorphisms linked to rs1137115 (51A/G) rather than the impact of the *1B 3′ UTR conversion itself. When the analysis performed in that previous report is repeated, a significant difference is also found. However, this difference is overwhelmingly driven by the difference between the *1B and *1A(51A) alleles alone. Comparing only the *1B and *1D haplotypes, which are similar at all genotyped polymorphisms except the 3′ UTR [24], a statistically significant difference is not found. Another study, in African Canadians, also failed to confirm an association between *1B and faster metabolism[31]. This is likely due to a higher frequency of the *1D haplotype among African North Americans than among European North Americans ([31]and our unpublished observation).
