With the current interest in phenylketonuria surveys and case-finding programs, many questions are being asked about the use of the low-phenylalanine basal mix and the low-phenylalanine diet. It is the purpose of this paper to present the experiences and observations of the research team studying metabolic errors at the Children's Hospital Research Foundation, Cincinnati, Ohio.
Investigators generally agree that the administration of low-phenylalanine diets to phenylketonuric children is of most advantage if begun very early in life, preferably within the first six months.1,2 However, in the light of reports of some improvement in older children,3,4 and owing to lack of other therapy, 10 phenylketonuric children between the ages of 9 months and 7 years were placed on low-phenylalanine diets. The group included three pairs of affected siblings. Mental ability ranged from near normal in two cases to severely affected.
Serum phenylalanine concentrations, urinary amino acid, phenolic acid, and