title: A preliminary investigation of the role of the phenylalanine:tyrosine ratio in children with early and continuously treated phenylketonuria: toward identification of "safe" levels.
abstract: Children with early and continuously treated phenylketonuria (ECT-PKU) remain at risk of developing executive function (EF) deficits. There is some evidence that a high phenylalanine to tyrosine ratio (phe:tyr) is more strongly associated with impaired EF development than high phenylalanine alone. This study examined EF in a sample of 11 adolescents against concurrent and historical levels of phenylalanine, phe:tyr, and tyrosine. Lifetime measures of phe:tyr were more strongly associated with EF than phenylalanine-only measures. Children with a lifetime phe:tyr less than 6 demonstrated normal EF, whereas children who had a lifetime phe:tyr above 6, on average, demonstrated clinically impaired EF.
authors.affiliation: Queensland University of Technology, School of Psychology and Counselling, and Institute of Health and Biomedical Innovation, Brisbane, Australia. r.sharman@qut.edu.au
authors.forename: Rachael
authors.initials: R
authors.lastname: Sharman
authors.forename: Karen
authors.initials: K
authors.lastname: Sullivan
authors.forename: Ross
authors.initials: R
authors.lastname: Young
authors.forename: Jim
authors.initials: J
authors.lastname: McGill
mesh_terms: D000293:Adolescent; D000704:Analysis of Variance; D002648:Child; D003072:Cognition Disorders / Q000209:etiology*; D056344:Executive Function / Q000502:physiology*; D006801:Humans; D009483:Neuropsychological Tests; D010649:Phenylalanine / Q000097:blood*; D010661:Phenylketonurias / Q000097:blood* / Q000150:complications / Q000178:diet therapy; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D014443:Tyrosine / Q000097:blood*
chemical_list: D014443:Tyrosine; D010649:Phenylalanine