Delayed phenylketonuria diagnosis: a challenging case in child psychiatry

ObjectivesPhenylalanine hydroxylase deficiency is an autosomal recessive inborn error of phenylalanine metabolism.What is new?Εven in cases with negative newborn screening for inborn errors of metabolism, the possibility of a metabolic disorder including PKU should be considered in any child presenting symptoms of developmental disorders. Late diagnosed PKU patients require a more specialized and individualized management than if they were early treatment cases.Case presentationWe discuss a case of a child with typical autistic symptomatology, in whom years later a diagnosis of phenylketonuria was set, even neonatal screening was negative. Τhe patient was placed on a phenylalanine-restricted diet. After a period of clinical improvement, severe behavioral problems with aggressiveness and anxiety were presented. Less restrictive diet ameliorated the symptomatology.ConclusionThis case highlights the major medical importance of adequate newborn screening policy, in order to avoid missed diagnosed cases. PKU may be presented as autism spectrum disorder. Dietary management needs individualized attentive monitoring.