1 Centre for Cardiovascular Genetics, British Heart Foundation Laboratories, Institute of Cardiovascular Science, The Rayne Building, University College London, London WC1E 6JF, UK. Electronic address: steve.humphries@ucl.ac.uk.
2 Centre for Cardiovascular Genetics, British Heart Foundation Laboratories, Institute of Cardiovascular Science, The Rayne Building, University College London, London WC1E 6JF, UK.