have been shown to provide better coverage of common variation 17. An important note is that the calculated coverage by the selection of tagSNPs is currently based on coverage of all common SNPs genotyped in HapMap, not of the remaining unknown genetic variation. Therefore, coverage achieved is likely to be overestimated, and may not necessarily be sufficient for fine mapping and studying specific regions of interest. Data from the ENCODE project, aimed at identifying all genetic variation in 10 selected genomic regions for 48 HapMap individuals, however, showed that HapMap phase II data generally provide a high coverage of all common genetic variation 18. The 1000 Genomes Project, aimed at uncovering genomic variation in 1000 individuals around the world through resequencing (http://www.1000genomes.org), should enable a more accurate evaluation of coverage.
