[1] Evelina Childrens Hosp, London, England
[2] Guys & St Thomas NHS Fdn Trust, Dept Paediat Neurol, London, England
[3] Guys & St Thomas NHS Fdn Trust, Diagnost Genet Lab, London, England
[4] UCL Inst Child Hlth, Dubowitz Neuromuscular Ctr, London, England
[5] Royal London Hosp, Dept Neurol, London E1 1BB, England