[1] Guys Hosp, Dept Clin Genet, London SE1 9RT, England
[2] Kings Coll London, Dept Med & Mol Genet, London SE1 9RT, England
[3] Univ Manchester, St Marys Hosp, Manchester Acad Hlth Sci Ctr, Manchester M13 9WL, Lancs, England
[4] Inst Neurol, MRC, Ctr Neuromuscular Dis, London WC1N 3BG, England
[5] St Thomas Hosp, Evelina Childrens Hosp, Paediat Intens Care Unit, London SE1 7EH, England
[6] St Thomas Hosp, Evelina Childrens Hosp, Dept Paediat Neurol, London SE1 7EH, England
[7] Univ Cambridge, Addenbrookes Hosp, Cambridge Inst Med Res, Dept Med Genet, Cambridge CB2 0XY, England
[8] Gen Infirm, Leeds Teaching Hosp HNS, Dept Paediat Neurol, Leeds LS1 3EX, W Yorkshire, England
[9] St James Univ Hosp, Leeds Inst Mol Med, Genet Sect, Leeds LS9 7TF, W Yorkshire, England