HapMap haplotypic information was downloaded and organized locally (HapMap Public Release #22, 2007). A haplotypic block was defined as the complete set of r2 marker-marker measures associated to a specific marker independently of the use of a pre defined minimum threshold for the r2 measure. Once defined, these sets are informative for the determination of specific chromosomal regions under strong linkage disequilibrium. Each haplotypic block was characterized by their summary statistics and further explored for the identification of local patterns of strong association and the possible correlation between weak linkage disequilibrium regions and the accuracy of imputation derived association statistics.
