IL28B Haplotype Blocks. (a) Location and D' values for the SNPs genotyped in this study. Linkage disequilibrium blocks determined from our cohort data using Haploview. HapMap SNPs genotyped in multiple populations shown in the header map in each case. (b) Ethnic differences in linkage disequilibrium across the IL28B gene region. r2 values are for the currently available SNPs genotyped in different ethnic groups, with the designated SNPs compared to rs12980275.