1 Wellcome-Medical Research Council Cambridge Stem Cell Institute, Department of Haematology, University of Cambridge, Jeffrey Cheah Biomedical Centre, Puddicombe Way, Cambridge, United Kingdom.
2 Wellcome Sanger Institute, Wellcome Genome Campus, Cambridge, United Kingdom.
3 Instituto de Investigación Sanitaria del Principado de Asturias, Oviedo, Spain; and.
4 Department of Haematology, Cambridge University Hospitals National Health Service Trust, Cambridge, United Kingdom.