Late-diagnosed phenylketonuria in an eight-year-old boy with dyslexia and attention-deficit hyperactivity disorder

Abstract

Phenylketonuria, previously a common cause of severe intellectual disability, is a metabolic disorder now promptly diagnosed and effectively treated thanks to newborn screening programs. Here, we report a male patient presenting with dyslexia and attention-deficit hyperactivity disorder, who was diagnosed with mild phenylketonuria at eight years of age. Earlier recognition and treatment before the establishment of irreversible brain damage would have resulted in better neurobehavioural outcomes. Classical phenylketonuria and milder phenotypes of phenylalanine hydroxylase deficiency need to be considered in the differential diagnosis of all cognitive and behavioural problems of unknown cause.

Geç Tanı Klasik Fenilketonüri Olgularımız ve Geç Tanı Nedenleri

“…Although rare, clinical symptoms of classical PKU without treatment can be encountered in children and adolescents, the inevitable end of these patients is developmental delay and intellectual disability. In addition, various behavioral disorders such as microcephaly, convulsions, ataxia, autistic symptoms, self-mutilation, aggression and psychosis can be observed in these patients (1,6) In mild types of PKU, intelligence development may be close to normal, however, mild school problems and learning difficulties, mild behavioral disorders and poor social communication can be observed (1). In our cases, there were those who continued their lives with a near-normal intelligence level and had children, as well as those who had a much more severe clinic.…”

Comparison of Fluorometric İmmunoassay and Tandem Mass Spectrometry Methods Used in the Diagnosis of Phenylalanine Metabolism Disorders in Turkish Children

“…PMD may appear in a wide variety of clinical situations ranging from mild hyperphenylalaninemia (HPA) to classic PKU (5). Considering data from newborn screening programs (NSP), it is observed that the prevalence of PAH deficiency varies in different regions (for example, it is 1 in 1.000.000 births in Finland, it is 1 in 4200 births in Turkey) (5,6).…”

Inborn Errors of Metabolism as Mimickers of Pediatric Neuropsychiatric Disorders: Phenylketonuria as an Example

“…Our patient falls somewhere in the middle of this spectrum with relatively mild complaints and many more similar patients may be undiagnosed or misdiagnosed if they were not detected by newborn screening. Therefore, we recommend determination of blood phenylalanine level in all patients with cognitive or behavioural problem of unknown cause, such as autism spectrum disorders, attention-deficit hyperactivity disorder and learning difficulties, especially if there was not an efficient PKU screening program when and where this patient was born [7].…”

“…He was not investigated for possible organic causes of his complaints and he probably would never have come to our attention had his newborn brother not screened positive for PKU. Family history of this newborn infant prompted us to investigate PKU in his older brother [7].…”