Jamaican βS haplotypes. Haplotypes designated as 'Benin' type are shown in part A; non-Benin type haplotypes are shown in part B. RFLP markers used to distinguish individual βS haplotypes have shaded marker labels and are outlined by the white border. Haplotypes are arrayed along the Y-axis with SNPs on the X-axis. At each SNP position, the major allele of each SNP is represented in blue and the minor allele in orange. For reference, the 70 kb region of the HBB cluster is indicated at the top of the figure.