[1] Royal Manchester Childrens Hosp, Willink Biochem Genet Unit, Manchester M27 1HA, Lancs, England
[2] Ctr Hosp Lyon Sud, Lab Fdn Gillet Merieux, F-69310 Pierre Benite, France
[3] Fac Med Lyon Sud, Inserm U189, Oullins, France
[4] Guys Hosp, Genet Ctr, London SE1 9RT, England