Figure 1

Haplotype bifurcation plots and extended haplotype homozygosity diagrams for CYP2C19 slow metabolizing allele (* 2 ) in West Africans. The core for the haplotypes in the first four diagrams is centred at the genomic position of the CYP2C19*2 variant (SNP positions rs4244285, rs4417205 and rs3758580) which is universally present and known to encode a functionally inactive protein. The upper part of each diagram shows a haplotype bifurcation plot representing the degree to which a haplotype is broken down by the emergence of new mutations in the gene. The lower graph shows relative homozygosity for each haplotype (depicted by the coloured lines, described in Figure 2) plotted against genomic position. High values observed some distance from the core indicate extended homozygosity and suggest recent positive evolutionary selection. Common core haplotypes and their frequencies are indicated in Figure 2. A. CYP2C19 haplotype structure in Gambians. The CYP2C19*2 containing haplotype AGT (haplotype 2) is relatively conserved in the bifurcation plot as demonstrated by the single thick line and by relatively few, thinner branches. There is some limited evidence of extended homozygosity. B. CYP2C19 haplotype structure in Yoruba. The CYP2C19*2 containing haplotypes AGT (haplotype 2) and GGC (haplotype 4) both show conservation in the bifurcation plots and extended haplotype homozygosity.