The pair-wise D’ values of 22 SNPs for the three genes in a total of 77 kb of nucleotide sequence were determined using the Haploview program (Barrett and others 2005). On the basis of the block definition proposed by Gabriel et al. (2002), we found four blocks within the gene cluster in the AA, EA, and pooled samples (Figure 1). One block of 4.0 kb containing rs12441088 and rs3813567 in CHRNB4 was observed for the three samples; three other blocks differed across the AA and EA samples, indicating the presence of different genetic architectures.
