1. ; Research Unit for Molecular Medicine; Aarhus University Hospital and Faculty of Health Sciences; Aarhus Denmark
2. ; Department of Child Health; Royal Victoria Infirmary; Newcastle-upon-Tyne UK
3. ; Research Unit for Molecular Medicine, Skejby Sygehus; Aarhus University Hospital; DK-8200 Aarhus N Denmark. E-mail
4. ; Paediatric Department; North Tees General Hospital; Stockton UK
5. ; Institute of Human Genetics; Aarhus University; Aarhus Denmark
6. ; Chemical Pathology/Neonatal Screening and Metabolic Disease Service; Sheffield Children's Hospital; Sheffield UK