During 1967-1983, the Maternal and Child Health Division of the Public Health Services funded a collaborative study of 211 newborn infants identified on newborn screening as having phenylketonuria (PKU). Subsequently, financial support was provided by the National Institute of Child Health and Human Development (NICHD). The infants were treated with a phenylalanine (Phe)-restricted diet to age 6 years and then randomized either to continue the diet or to discontinue dietary treatment altogether. One hundred and twenty-five of the 211 children were then followed until 10 years of age. In 1998, NICHD scheduled a Consensus Development Conference on Phenylketonuria and initiated a study to follow up the participants from the original Collaborative Study to evaluate their present medical, nutritional, psychological, and socioeconomic status. Fourteen of the original clinics (1967-1983) participated in the Follow-up Study effort. Each clinic director was provided with a list of PKU subjects who had completed the original study (1967-1983), and was asked to evaluate as many as possible using a uniform protocol and data collection forms. In a subset of cases, magnetic resonance imaging and spectroscopy (MRI/MRS) were performed to study brain Phe concentrations. The medical evaluations revealed that the subjects who maintained a phenylalanine-restricted diet reported fewer problems than the diet discontinuers, who had an increased rate of eczema, asthma, mental disorders, headache, hyperactivity and hypoactivity. Psychological data showed that lower intellectual and achievement test scores were associated with dietary discontinuation and with higher childhood and adult blood Phe concentrations. Abnormal MRI results were associated with higher brain Phe concentrations. Early dietary discontinuation for subjects with PKU is associated with poorer outcomes not only in intellectual ability, but also in achievement test scores and increased rates of medical and behavioural problems.
"Untreated PKU is characterized by neurological and behavioral problems, such as severe mental retardation, epilepsy, developmental delays, and anxiety disorders  . Outcome is clearly related to blood Phe concentrations  . Since the introduction of the neonatal screening for PKU in 1974 in The Netherlands, early diagnosis and treatment are feasible and have reduced most of the neurological problems . "
"studies, higher blood Phe levels have been correlated with ADHD symptoms  and executive functioning impairment . While less data are available for continuously treated adults with PKU, those who discontinue treatment have lower intellectual ability and achievement test scores than those who continue to maintain metabolic control . These findings, in aggregate, suggest the possibility that ADHD symptoms and impaired executive functioning may be caused by potentially reversible brain dysfunction that results from disruption in monoamine synthesis by high blood Phe levels rather than irreversible 'toxic' brain damage from high blood Phe levels during early life. "
[Show abstract][Hide abstract] ABSTRACT: Symptoms of attention deficit hyperactivity disorder (ADHD), particularly inattention, and impairments in executive functioning have been reported in early and continuously treated children, adolescents, and adults with phenylketonuria (PKU). In addition, higher blood phenylalanine (Phe) levels have been correlated with the presence of ADHD symptoms and executive functioning impairment. The placebo-controlled PKU-ASCEND study evaluated the effects of sapropterin therapy on PKU-associated symptoms of ADHD and executive and global functioning in individuals who had a therapeutic blood Phe response to sapropterin therapy. The presence of ADHD inattentive symptoms and executive functioning deficits was confirmed in this large cohort of 206 children and adults with PKU, of whom 118 responded to sapropterin therapy. In the 38 individuals with sapropterin-responsive PKU and ADHD symptoms at baseline, sapropterin therapy resulted in a significant improvement in ADHD inattentive symptoms in the first 4 weeks of treatment, and improvements were maintained throughout the 26 weeks of treatment. Sapropterin was well-tolerated with a favorable safety profile. The improvements in ADHD inattentive symptoms and aspects of executive functioning in response to sapropterin therapy noted in a large cohort of individuals with PKU indicates that these symptoms are potentially reversible when blood Phe levels are reduced.
"In addition, those
who discontinued diet were found to have high incidence of recurrent headaches (31%),
neurological abnormalities (24%), hyperactivity (14%), and lethargy (19%), whereas none of
these problems were reported by those who continued diet. Mental problems such as phobias
and depression were also more frequently reported in those who discontinued versus those who
continued diet.22 "
[Show abstract][Hide abstract] 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; 15(8). DOI:10.1038/gim.2013.10 · 7.33 Impact Factor
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