Search

Previous research supports the notion that children with early‐treated classical phenylketonuria (PKU) have specific cognitive deficits in executive function skills. These deficits may relate to depressed levels of dopamine, due to defective tyrosine synthesis. We investigated whether deficits reported for preschoolers with early‐treated PKU are manifested also among school‐age children with PKU, and whether cognitive performance among the latter group is related to phenylalanine level at time of testing. Seventeen children with PKU and 17 age‐, sex‐, and IQ‐matched controls were tested individually on measures of executive functions. The results demonstrate that executive function deficits reported for preschoolers with PKU were not manifested in the school‐age PKU children included in this study. The authors discuss the implications of these findings for theories of the development of executive function skills.

The progress of nine maple syrup urine disease patients (eight classical, one possible variant) was reviewed to look for similarities in developmental patterns. A consistent developmental profile of stronger Verbal than Performance IQ and lower than familially expected IQ was seen. Younger age at diagnosis was associated with a milder neonatal course. Those who were asymptomatic or suffered mild complications in the newborn period have higher IQs than children experiencing moderate or severe complications. Children with asymptomatic or mild neonatal course also required less special education services. Overall, a picture of ubiquitous motor, visual-analytic and learning deficits is seen.

Sir. —Phenylketonuria (PKU) is an inborn error of metabolism characterized by the inability to hydroxylate phenylalanine (PHE) to tyrosine (TYR). The condition is diagnosed by documentation of elevated serum PHE levels, and typically leads to moderate to severe mental retardation in its untreated form. Individuals with PKU who undergo early dietary PHE restriction usually achieve a full-scale IQ in the normal range. 1 Serum PHE levels of 120 to 480 μmol/L are the typical target values in treatment and constitute good dietary control. Current clinical recommendations and research findings support the need to maintain dietary control throughout childhood. 2-4 For various reasons, monitoring of serum TYR levels is not routine in many metabolic clinics. In our clinic, approximately 38% of patients with PKU who are younger than age 19 years have below-normal serum TYR concentrations (48 μmol/L). This is not clearly correlated with the kind of medical food or diet

Treatment for phenylketonuria (PKU) involves using low phenylalanine-free or phenylalanine-free formulas and supplementation with sufficient phenylalanine for normal growth and development. Eighteen infants with phenylketonuria who received breast milk as their primary phenylalanine source were compared with ten other infants with PKU who received their phenylalanine primarily from infant formulas. There were no significant differences between breast-fed and formula-fed infants for serum phenylalanine, serum tyrosine, length, weight, head circumference, haematocrit, haemoglobin, serum iron, total iron binding capacity, percentage iron saturation, ferritin, plasma zinc and total calorie intake. Breast-fed infants did show lower mean corpuscular volume at 3 months and 6 months of age. Breast-fed infants had lower phenylalanine intake at 2, 4, 5 and 6 months of age. Breast-fed infants at 1, 2, 3, 4, 5 and 6 months of age had lower protein intake. Breast feeding may be continued in the newly diagnosed phenylketonuric infant without any apparent adverse nutritional consequences.

• Ten children with classic phenylketonuria (PKU) participated in a controlled study of a phenylalanine-free formula recently released in the United States (PKU-2). Control data were obtained in the clinic while the children were receiving their baseline formula. The children were given the study formula and returned to the clinic for follow-up after they had been receiving the new formula for 4, 8, and 12 months. Serum phenylalanine and tyrosine concentrations, other hematologic measurements, urine analysis, growth, electroencephalogram, and physical findings remained similar to baseline values throughout the study. Nutrient intakes were comparable with the exception of a decrease in several micronutrients relative to baseline levels. We found that PKU-2 is appropriate for children with PKU who are over 3 years of age and may prove beneficial for the overweight child with PKU. ( AJDC 1987;141:1327-1329)