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: 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; · 2.18 Impact Factor
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ABSTRACT: Fifty years after the implementation of universal newborn screening programs for phenylketonuria, the first disease identified through newborn screening and considered a success story of newborn screening, a cohort of adults with phenylketonuria treated from birth provides valuable information about effects of long-term treatment for inborn errors of metabolism in general, and phenylketonuria specifically. For phenylketonuria, newborn screening allows early implementation of the phenylalanine-restricted diet, eliminating the severe neurocognitive and neuromotor impairment associated with untreated phenylketonuria. However, executive function impairments and psychiatric problems are frequently reported even for those treated early and continuously with the phenylalanine-restricted diet alone. Moreover, a large percentage of adults with phenylketonuria are reported as lost to follow-up by metabolic clinics. While a group of experts identified by the National Institutes of Health convenes to update treatment guidelines for phenylketonuria, we explore individual patient, social, and economic factors preventing >70% of adult phenylketonuria patients in the United States from accessing treatment. As more conditions are identified through newborn screening, factors affecting access to treatment grow in importance, and we must continue to be vigilant in assessing and addressing factors that affect patient treatment outcomes and not just celebrate amelioration of the most severe manifestations of disease.Genet Med advance online publication 7 March 2013Genetics in Medicine (2013); doi:10.1038/gim.2013.10.Genetics in medicine: official journal of the American College of Medical Genetics 03/2013; · 3.92 Impact Factor