[1] Princess Anne Hosp, Wessex Clin Genet Serv, Southampton, Hants, England
[2] Salisbury Hlth Care NHS Trust, Wessex Reg Genet Lab, Salisbury, Wilts, England
[3] Univ Udine, Dept Pediat, Sch Med, I-33100 Udine, Italy
[4] Univ Naples Federico II, Dept Pediat, Naples, Italy
[5] Inst Child Hlth, Dept Child Hlth, Bristol, Avon, England