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[Intellectual development after relaxing the diet at the age of 5 years in typical phenylketonuria]
1Clinique de Médecine des Enfants, Hôpital des Enfants-Malades, Paris.
Insights
Phenylketonuria (PKU) patients treated until age 5 showed stable IQs but poorer school performance. Optimal intellectual progress depends on early diet control, maternal intelligence, and ongoing monitoring post-treatment relaxation.
Area of Science:
- Metabolic disorders
- Neurodevelopmental disorders
- Genetics
Context:
- Phenylketonuria (PKU) is a genetic disorder requiring early dietary intervention.
- Long-term outcomes after relaxing PKU treatment at age 5 are not well-established.
- Controlled trials on PKU management post-childhood are limited.
Purpose:
- To evaluate the intellectual and academic outcomes of children with typical PKU after dietary treatment was relaxed at age 5.
- To determine the correlation between dietary control, plasma phenylalanine levels, and cognitive performance.
- To assess the long-term impact of early PKU management on intellectual development.
Summary:
- A study followed 27 children with PKU treated from infancy, with dietary restrictions relaxed at age 5.
- IQ scores remained stable post-relaxation, but school performance was poorer than the general population, with an 8-point IQ deficit compared to siblings.
- No correlation was found between plasma phenylalanine levels and IQ post-age 5, suggesting early control is key.
Impact:
- Highlights the importance of strict dietary control in early childhood for PKU patients.
- Suggests that continued dietary treatment into adolescence may not be beneficial for intellectual outcomes.
- Emphasizes the need for ongoing monitoring and consideration of maternal intelligence for optimal development in PKU individuals.
Background:
No satisfactory controlled trial has yet been completed on typical phenylketonuria (PKU) patients whose treatment was relaxed at the age of 5 years.
Methods:
27 children having typical PKU were treated before the age of 3 months. The intake of phenylalanine and protein was carefully regulated during the first 5 years of life, after which the treatment was relaxed. All children were evaluated after at least 6 years on the relaxed diet. Their IQ scores and school performance were related to the degree of dietary control and plasma phenylalanine values.
Results:
The IQ scores at 5 years of age were 100 +/- 10.8. Continued evaluation showed that IQ scores remained unchanged. Poor school performance was twice as frequent as in general population; the deficit in the IQ score of this group was 8 points below that of normal sibs. There was no correlation between plasma phenylalanine and the IQ score after the age of 5 years. The positive control decreased with aged.
Conclusions:
Children with typical PKU have an IQ deficit relative to their normal sibs just before relaxing treatment. Good dietary control until 5 years of age, maternal intelligence and continuing evaluation during relaxing diet are the best conditions for optimal intellectual progress. There is no evidence that continued treatment during adolescence is beneficial.