News Release

Poor adherence to control measures for older children with phenylketonuria

N. B. Please note that if you are outside North America the embargo date for all Lancet press material is 0001hours UK time 5 July 2002

Peer-Reviewed Publication

The Lancet_DELETED

Authors of a research letter in this week's issue of THE LANCET highlight how older children are less likely to adhere to recommended guidelines to control phenylketonuria (PKU), a metabolic disorder which can cause severe cognitive impairment.

PKU is one of the most frequent inherited metabolic disorders, with a prevalence of about one in 14,000 babies in populations of European descent. The disorder (caused by mutations within the gene for the enzyme phenylalanine hydroxylase), results in a failure to convert phenylalanine to tyrosine in the liver. The accumulation of phenylalanine prevents normal postnatal brain development and leads to severe learning difficulties. Screening at birth to identify individuals with the disorder, and regulation of blood concetrations of phenylalanine by a low-protein diet in affected children can result in normal cognitive functioning in adulthood.

John Walter from the Royal Manchester Childrens Hospital, UK, and colleagues assessed data from 4 PKU centres (three in the UK and one from Australia) to estimate the adherence to PKU control among younger and older children. Children younger than 10 years had substantially fewer phenylalanine concentrations above the recommended limit for PKU control compared with children older than 15 years (30% compared with 80%, respectively). Similar results were observed for the frequency of blood testing; more than 80% of children younger than 10 years had the recommended frequency of blood testing, compared with less than half of children aged 15 years or older.

John Walter comments: "Our findings indicate that adolescents and young adults generally do not comply with recommendations for the monitoring and control of phenylalanine concentrations. If phenylketonuria is proven to be dangerous in adults as it is in infants, maintenance of good dietary control beyond childhood will become increasingly important, and more acceptable modes of treatment than available will need to be developed. Even in young patients, maintenance of good biochemical control can be difficult. Our results should serve as a benchmark for the quality of control that can be realised in practice."

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Contact: Dr John H Walter, Willink Biochemical Genetic Unit, Royal Manchester Children's Hospital, Manchester M27 4HA, UK; T) +44 (0)161 727 2137; F) +44 (0)161 727 2137; E) jhwalter@doctors.org.uk


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