Outcomes beyond phenylalanine: an international perspective.
ABSTRACT Control of blood phenylalanine (Phe) levels throughout the life of a person diagnosed with phenylketonuria (PKU) is the biochemical management strategy necessary to provide the best potential for optimal outcome. Psychosocial support mechanisms comprise the other aspects of PKU management that are necessary to overcome the hurdles of living with this chronic disease and to adhere to the rigors of its management. Additional psychosocial support may be required, in light of increasing evidence that control of blood Phe levels in PKU can still lead to subtle but measurable cognitive function deficits as well as a predisposition to certain psychiatric symptoms and disorders. An all encompassing PKU management strategy that goes beyond simply treating blood Phe levels can empower and enable people born with PKU to achieve similar life goals as those born without PKU. This review looks at PKU management strategies that go beyond treating Phe levels, specifically (1) the roles psychologists play in managing PKU from infancy through adulthood and how they help PKU families and caregivers deal with the disease and the burden of its management; (2) understanding the challenges of transitioning into adulthood as an individual with PKU and addressing unmet needs in this population; (3) how non-traditional practices can be utilized in PKU. The objective is to emphasize that management of PKU goes well beyond addressing the biochemical nature of this disease in order to achieve optimal patient outcomes.
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ABSTRACT: Background: In untreated patients, phenylketonuria (PKU) results in severe encephalopathy with mental retardation. A protein-restricted diet is recommended which can be relaxed in adolescence/adulthood.Methods: We contacted all 72 adult/adolescent PKU patients who had been treated in our center during early childhood. Some still regularly attended our outpatient clinics, while others were lost for follow-up, giving 51 patients in our study. We asked all patients to complete a dietary protocol as well as a questionnaire on quality of life. Blood and urine were analyzed and body impedance plethysmography and cerebral MRI were performed.Results: 42 % of the patients followed protein restriction supplemented with amino acid mixtures (AAM), others had a vegan diet with (8 %) or without (14 %) AAM; 36 % said they were eating normally and did not need any AAM. However, based on dietary protocols and blood urea levels, protein intake was restricted in this patient group. None of the patients examined had serious nutritional deficits. Phenylalanine levels were higher in patients not taking AAM. MRI of the brain was not different from those following protein restriction and taking AAM. The lesions score and mood correlated best with the cumulative phenylalanine values during the first 10 years of life.Conclusion: In summary, 50 % of adult/adolescent patients from our center did not take AAM at the start of our survey although they unknowingly followed self-imposed protein restriction. They had no overt nutritional deficits; however, long-term brain function may be compromised. Our study emphasizes the need for specialized metabolic care in PKU during adulthood.11/2013; DOI:10.1007/8904_2013_273
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ABSTRACT: Phenylketonuria (PKU) is a well-defined metabolic disorder arising from a mutation that disrupts phenylalanine metabolism and so produces a variety of neural changes indirectly. Severe cognitive impairment can be prevented by dietary treatment; however, residual symptoms may be reported. These residual symptoms appear to overlap a more prevalent childhood disorder: Attention Deficit/Hyperactivity Disorder (ADHD). However, the aetiology of ADHD is a vast contrast to PKU: it seems to arise from a complex combination of genes; and it has a substantial environmental component. We ask whether these two disorders result from two vastly different genotypes that converge on a specific core phenotype that includes similar dysfunctions of Gray's (Gray, 1982) Behavioural Inhibition System (BIS), coupled with other disorder-specific dysfunctions. If so, we believe comparison of the commonalities will allow greater understanding of the neuropsychology of both disorders. We review in detail the aetiology, treatment, neural pathology, cognitive deficits and electrophysiological abnormalities of PKU; and compare this with selected directly matching aspects of ADHD. The biochemical and neural pathologies of PKU and ADHD are quite distinct in their causes and detail; but they result in the disorder in the brain of large amino acid levels, dopamine and white matter that are very similar and could explain the overlap of symptoms within and between the PKU and ADHD spectra. The common deficits affect visual function, motor function, attention, working memory, planning, and inhibition. For each of PKU and ADHD separately, a subset of deficits has been attributed to a primary dysfunction of behavioural inhibition. In the case of ADHD (excluding the inattentive subtype) this has been proposed to involve a specific failure of the BIS; and we suggest that this is also true of PKU. This accounts for a substantial proportion of the parallels in the superficial symptoms of both disorders and we see this as linked to prefrontal, rather than more general, dysfunction of the BIS.Brain research bulletin 10/2013; DOI:10.1016/j.brainresbull.2013.10.003 · 2.97 Impact Factor
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ABSTRACT: Purpose:Sapropterin is an oral synthetic formulation of tetrahydrobiopterin prescribed as adjunctive therapy for phenylketonuria. The efficacy of sapropterin in reducing blood phenylalanine levels has been demonstrated in clinical studies of individuals with phenylketonuria older than 4 years of age. Its effect on neurocognitive functioning in younger children has not been examined.Methods:A 2-year interim analysis of blood phenylalanine levels, prescribed dietary phenylalanine intake, and neurocognitive functioning was performed in children who started receiving sapropterin at 0-6 years of age and responded with a ≥30% mean blood phenylalanine reduction. Children were evaluated at baseline and 2-year follow-up.Results:Sapropterin had a favorable safety profile and lowered blood phenylalanine levels with increased prescribed dietary phenylalanine intakes. Mean full-scale intelligence quotient was 103 ± 12 at baseline and 104 ± 10 at 2-year follow-up (P = 0.50, paired t-test, n = 25). For children younger than 30 months of age, the cognitive composite score from the Bayley Scales of Infant and Toddler Development, Third Edition, remained within the average range.Conclusion:Sapropterin had a favorable safety profile, was effective in lowering blood phenylalanine levels while clinically requiring dietary adjustment, resulting in increased phenylalanine intake, and preserved neurocognitive performance in children who started therapy between 0 and 6 years of age.Genet Med advance online publication 18 September 2014Genetics in Medicine (2014); doi:10.1038/gim.2014.109.Genetics in medicine: official journal of the American College of Medical Genetics 09/2014; DOI:10.1038/gim.2014.109 · 3.92 Impact Factor