1 Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Cambridge, CB10 1SA, UK, 2Broad Institute of MIT and Harvard, Cambridge, MA 02141, USA, 3Beijing Institute of Genomics, Chinese Academy of Science, Beijing 100029, China, 4Department of Computer Science, University of California Los Angeles, Los Angeles, CA 90095, 5Department of Biology, Boston College, Chestnut Hill, MA 02467, 6Center for Statistical Genetics, Department of Biostatistics, University of Michigan, Ann Arbor, MI 48109, USA and 7http://1000genomes.org (At 2009-06-08)