1. From the Respiratory Muscle Laboratory, Royal Brompton Hospital, London, United Kingdom (NSH and MIP); the Centre for Cardiovascular Genetics, Royal Free and UCL Medical School, Rayne Institute, London, United Kingdom (KWL and SEH); the UCL Institute for Human Health and Performance, London, United Kingdom (AK and HM); the National Heart and Lung Institute, Imperial College, London, United Kingdo