Neuroradiological Findings of an Adolescent with Early Treated Phenylketonuria: Is Phenylalanine Restriction Enough?

Mayara Thays Beckhauser,Laura Vilarinho,Mirella Maccarini Peruchi,Sofia Esteves,Kátia Lin ,Gisele Rozone De Luca ,Jaime Lin

doi:10.4081/cp.2011.e25

Abstract

Phenylketonuria is caused by mutations in the enzyme phenylalanine hydroxylase gene, that can result in abnormal concentrations of phenylalanine on blood, resulting in metabolites that can cause brain damage. The treatment is based on dietary restriction of phenylalanine, and noncompliance with treatment may result in damage of the brain function. Brain abnormalities can be seen on magnetic resonance imaging of these individuals. Studies indicate that the appearance of abnormalities in white matter reflects high levels of phenylalanine on the blood. This case will show the clinical and neuroradiological aspects of a teenager with constant control of phenylalanine levels. Despite the continuous monitoring and early treatment, the magnetic resonance imaging identified impressive abnormalities in the white matter. This leads us to one question: is the restriction of phenylalanine sufficient to prevent changes in the white matter in patients with phenylketonuria?

Highlights

Phenylketonuria (PKU) is an inborn error of metabolism, characterized by mutations of the phenylalanine hydroxylase (PAH) gene
In Latin America, its prevalence varies between one case per 50.000 and one per 25.000 with a higher prevalence in Southern Latin America.[2]
Little is known about clinical aspects and outcomes of early treated adolescents with PKU

Summary

Introduction

Phenylketonuria (PKU) is an inborn error of metabolism, characterized by mutations of the phenylalanine hydroxylase (PAH) gene. Loss of PAH activity results in increased concentrations of Phenylalanine (Phe) in the blood and toxic concentrations in the brain.[1]. Compliance with the diet is often poor, especially when the patients reach adolescence.[1]. Due to those inconsistencies, little is known about clinical aspects and outcomes of early treated adolescents with PKU. Non-adherence to treatment and persistent exposure to high levels of Phe among these older patients, result in impairments of brain function characterized by deficits in executive functioning,[6] processing speed[7] and fine motor control.[8]. We present the clinical and neuroradiological aspects of an adolescent patient, who despite all difficulties, followed successfully a lifelong restrictive dietotherapy for PKU

Case Report

Findings

Discussion