1. UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery and Great Ormond Street; MRC Centre for Neuromuscular Diseases and Dubowitz Neuromuscular Centre; PO Box 114 London UK WC1B 3BN
2. Freeman Hospital; Department of Cardiology; Freeman Road Newcastle Upon Tyne UK NE7 DN
3. King's College Hospital; Cardiac Care Group; Hambleden Wing, Denmark Hill London UK SE5 9RS