[1] UCL, Inst Child Hlth, Clin & Mol Genet Unit, London WC1N 1EH, England
[2] Great Ormond St Hosp Sick Children, Dept Audiol Med, London WC1N 3JH, England
[3] UCL, Ear Inst, London WC1N 1EH, England
[4] Queen Alexandra Hosp, Dept Audiol Med, Portsmouth, Hants, England
[5] Royal Natl Throat Nose & Ear Hosp, Nuffield Hearing & Speech Ctr, London WC1X 8DA, England
[6] Great Ormond St Hosp Sick Children, Dept Haematol & Oncol, London WC1N 3JH, England
[7] Royal London Hosp, Dept Paediat Haematol & Oncol, London E1 1BB, England
[8] Great Ormond St Hosp Sick Children, N Thames E Reg Clin Mol Genet Lab, London WC1N 3JH, England
[9] Natl Hosp Neurol & Neurosurg, MRC, Ctr Neuromuscular Dis, London WC1N 3BG, England