1. ; PKU Programme; Hospital for Sick Children; Toronto, Ontario Canada
2. ; PKU Program, Division of Medical Genetics; Children's Hospital of Los Angeles; Los Angeles California USA
3. ; Department of Pediatrics; University of Texas Medical Branch, Galveston; Texas USA
4. Children's Hospital of Reutlingen; Germany
5. Biochemical Genetics, Children's Hospital; Boston, Massachusetts USA
6. ; Mental Retardation and Developmental Disabilities Branch; National Institute of Child Health and Human Development; Bethesda, Maryland USA