Phenylketonuria Treated from Earliest Infancy

Abstract

It has been suggested that an assessment of the effects of the dietary treatment of phenylketonuria might best be made by observing the developmental pattern of affected children treated from the neonatal period.¹The purpose of this paper is to report the developmental patterns of three patients, aged 3½ years, 2⅓ years, and 1 year, respectively, who have received a phenylalanine-deficient diet continuously since early infancy.* The dietary program was one that has been outlined in detail by Armstrong and Tyler.⁵A phenylalanine-free diet consisting of a commercial protein hydrolysate with fat and carbohydrate supplements was given for three weeks. On such a diet the serum phenylalanine level returned from abnormally high to normal levels. After the initial three-week period, 2 gm. of natural protein in the form of cow's milk (2oz.) were added to the diet. At about 6 months of age, the natural protein was