[1] Great Ormond St Hosp Sick Children, Dubowitz Neuromuscular Ctr, London WC1N 31EH, England
[2] Inst Child Hlth, London WC1N 31EH, England
[3] St Thomas Hosp, Evelina Childrens Hosp, Dept Paediat Neurol, London SE1 7EH, England
[4] Robert Jones & Agnes Hunt Orthopaed Hosp NHS Trus, Ctr Inherited Neuromuscular Disorders, Oswestry SY10 7AG, Shrops, England