1. William Harvey Research Institute, Queen Mary University of London 1 , London, EC1M 6BQ , UK
2. European Bioinformatics Institute (EMBL-EBI), Wellcome Trust Genome Campus 2 , Hinxton, Cambridge, CB10 1SD , UK
3. National Human Genome Research Institute, National Institutes of Health 3 , Bethesda, MD 20892 , USA