title: [Delayed diagnosis of phenylketonuria as the cause of mental retardation in an adolescent].
abstract: BACKGROUND
  The hyperphenylalaninemias (HFA) form a diverse group of recessive autosomic disorders. They are caused by defects in the hepatic system for hydroxylation of the amino acid phenylalamine to tyrosine. The estimated incidence is approximately 10 cases per 100,000 live births. Children with this metabolic disorder may present with varied neurological symptoms. Control of plasma levels, so that they are more normal as soon as possible after birth, significantly prevents mental retardation and other neuropsychological dysfunction. For this reason HFA has been included in neonatal screening. However, some patients are not detected on screening. When they are adults, these patients pose problems of diagnosis for neurologists who attend adults.
  
  
  METHODS
  We describe an adolescent with mental and linguistic retardation, in whom neonatal screening to rule out metabolic defects was normal. At the age of 15, the phenylalanine in blood and urine were found to be raised. On cerebral magnetic resonance changes typical of pheynylketonuria (PKU) were seen.
  
  
  CONCLUSIONS
  The HFA should be considered as causes of cerebral dysfunction in adults, since in spite of neonatal screening, false negatives may occur. We describe a clinical case and consider different forms of hyperphenylaleninemias. Their diagnosis and treatment.
authors.affiliation: Sección de Neurología, Hospital Universitario Virgen de la Arrixaca, El Palmar, Murcia, España.
authors.forename: R
authors.initials: R
authors.lastname: Villaverde
authors.forename: J B
authors.initials: JB
authors.lastname: Escribano
authors.forename: P
authors.initials: P
authors.lastname: Salmerón
authors.forename: D
authors.initials: D
authors.lastname: Tortosa
authors.forename: J
authors.initials: J
authors.lastname: Meca
authors.forename: A
authors.initials: A
authors.lastname: Fernández-Barreiro
mesh_terms: D000293:Adolescent; D001921:Brain / Q000473:pathology; D006801:Humans; D008607:Intellectual Disability / Q000175:diagnosis / Q000209:etiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D010651:Phenylalanine Hydroxylase / Q000097:blood; D010661:Phenylketonurias / Q000150:complications* / Q000175:diagnosis* / Q000178:diet therapy; D013997:Time Factors; D014057:Tomography, X-Ray Computed
chemical_list: D010651:Phenylalanine Hydroxylase
vernacular_title: Diagnóstico tardío de fenilcetonuria como causa de retraso mental en un adolescente.