High Phenylalanine Levels Research Articles

5-Hydroxytryptophan during critical postnatal period improves cognitive performances and promotes dendritic spine maturation in genetic mouse model of phenylketonuria

Although phenylketonuria (PKU) is the most common genetic cause of mental retardation, the cellular mechanisms underlying impaired brain function are still unclear. Using PAHenu2 mice (ENU2), the genetic mouse model of PKU, we previously demonstrated that high phenylalanine levels interfere with brain tryptophan hydroxylase activity by reducing the availability of serotonin (5-hydroxytryptamine, 5-HT), crucial for maturation of neuronal connectivity in the prefrontal cortex (PFC), around the third postnatal week, a critical period for cortical maturation. 5-Hydroxytryptophan (5-HTP), the product of tryptophan hydroxylation, is known to be a better treatment to increase brain 5-HT levels. In this study we investigated the role of 5-HT during the early postnatal period in cognitive disturbances and in cortical dendritic alterations of PKU subjects by restoring temporarily (postnatal days 14–21) physiological brain levels of 5-HT in ENU2 through 5-HTP treatment. In adult ENU2 mice early 5-HTP treatment reverses cognitive deficits in spatial and object recognition tests accompanied by an increase in spine maturation of pyramidal neurons in layer V of the prelimbic/infralimbic area of the PFC, although locomotor deficits are not recovered by treatment. Taken together, our results support the hypothesis that mental retardation in PKU depends on reduced availability of brain 5-HT during critical developmental periods that interferes with cortical maturation and point to 5-HTP supplementation as a highly promising additional tool to heal PKU patients.

Pleiotropic physiological consequences of feedback-insensitive phenylalanine biosynthesis in Arabidopsis thaliana

A large proportion of plant carbon flow passes through the shikimate pathway to phenylalanine, which serves as a precursor for numerous secondary metabolites. To identify new regulatory mechanisms affecting phenylalanine metabolism, we isolated Arabidopsis thaliana mutants that are resistant to the phytotoxic amino acid m-tyrosine, a structural analog of phenylalanine. Map-based cloning identified adt2-1D, a dominant point mutation causing a predicted serine to alanine change in the regulatory domain of ADT2 (arogenate dehydratase 2). Relaxed feedback inhibition and increased expression of the mutant enzyme caused up to 160-fold higher accumulation of free phenylalanine in rosette leaves, as well as altered accumulation of several other primary and secondary metabolites. In particular, abundance of 2-phenylethylglucosinolate, which is normally almost undetectable in leaves of the A. thaliana Columbia-0 accession, is increased more than 30-fold. Other observed phenotypes of the adt2-1D mutant include abnormal leaf development, resistance to 5-methyltryptophan, reduced growth of the generalist lepidopteran herbivore Trichoplusia ni (cabbage looper) and increased salt tolerance.

Modelo de atención inicial de la fenilcetonuria y otras hiperfenilalaninemias en el Instituto Nacional de Pediatría

Hyperphenylalaninemias are a group of autosomal recessive diseases produced in 98% of the cases by impaired activity of phenylalanine hydroxilase (PAH). The phenotype ranges from classic phenylketonuria (OMIM 261600, CIE-10 E090) to mild hyperphenylalaninemia. A high blood level of phenylalanine produces chronic encephalopathy in children, characterized by vomit, refusal to eat, irritability, skin and hair hypopigmentation, eczema, myoclonus, seizures and delay in developmental milestones whose final consequence is usually severe and irreversible mental retardation. For almost 50 years it has been known that early treatment of these conditions attenuates brain damage and can prevent intellectual and motor disabilities. Hyperphenylalaninemia is the most common aminoacid metabolic disorder diagnosed at the Instituto Nacional de Pediatria (INP). This Institute has a long and well documented experience in this disease; it is a referral centre with a multidisciplinary team, advanced technology for the diagnosis and follow-up of patients. The objective of this paper is to show the workshop algorithms for patients suspected of hyperphenylalaninemia seen at the INP, from their first visit at the outpatient clinic to the final diagnosis, in order to provide timely management.

Experimental evidence that phenylalanine provokes oxidative stress in hippocampus and cerebral cortex of developing rats.

High levels of phenylalanine (Phe) are the biochemical hallmark of phenylketonuria (PKU), a neurometabolic disorder clinically characterized by severe mental retardation and other brain abnormalities, including cortical atrophy and microcephaly. Considering that the pathomechanisms leading to brain damage and particularly the marked cognitive impairment in this disease are poorly understood, in the present study we investigated the in vitro effect of Phe, at similar concentrations as to those found in brain of PKU patients, on important parameters of oxidative stress in the hippocampus and cerebral cortex of developing rats. We found that Phe induced in vitro lipid peroxidation (increase of TBA-RS values) and protein oxidative damage (sulfhydryl oxidation) in both cerebral structures. Furthermore, these effects were probably mediated by reactive oxygen species, since the lipid oxidative damage was totally prevented by the free radical scavengers alpha-tocopherol and melatonin, but not by L-NAME, a potent inhibitor of nitric oxide synthase. Accordingly, Phe did not induce nitric oxide synthesis, but significantly decreased the levels of reduced glutathione (GSH), the major brain antioxidant defense, in hippocampus and cerebral cortex supernatants. Phe also reduced the thiol groups of a commercial GSH solution in a cell-free medium. We also found that the major metabolites of Phe catabolism, phenylpyruvate, phenyllactate and phenylacetate also increased TBA-RS levels in cerebral cortex, but to a lesser degree. The data indicate that Phe elicits oxidative stress in the hippocampus, a structure mainly involved with learning/memory, and also in the cerebral cortex, which is severely damaged in PKU patients. It is therefore presumed that this pathomechanism may be involved at least in part in the severe cognitive deficit and in the characteristic cortical atrophy associated with dysmyelination and leukodystrophy observed in this disorder.

Prevention of Intellectual and Developmental Disabilities

The first plenary session of 132nd Annual Meeting of the American Association on Intellectual and Developmental Disabilities (AAIDD) reflected its support for basic and applied research to prevent or minimize the effects of conditions causing developmental disabilities, with Dr. Alan Guttmacher (2008), currently the acting director of the National Human Genome Research Institute, discussing the realized and potential benefits of genomics research on health and quality of life. This presentation dealt with an incredibly complex topic with clarity and sensitivity, and it was carefully neutral in tone and content with respect to intellectual and developmental disabilities. Nevertheless, a major implication regarding disabilities in general and developmental disabilities more specifically was quite clear. Current research in genomics, as well as in many other areas, is intended to improve understanding of the fundamental causes of disability to reduce risk, thereby lowering incidence of impairments and minimizing their severity. Should these goals be realized, the proportion of the population with disability would decrease, perhaps dramatically, and in some distant future significant impairments might even be eliminated altogether. As unachievable as that ultimate goal might appear to be, an assumption supporting many of the programs and much of the research agenda in the field of developmental disabilities is that we, as a society and as individuals, would be better off if physical, mental, and cognitive impairments ceased to exist. Yet, prevention encompasses many things and can be viewed from many perspectives, some of which have continued to challenge the universality of this assumption. There is a need for serious and open discussion of the many aspects of prevention within our field (and the disabilities field more generally) that entails explicit consideration of risks and benefits of specific programs and approaches to implementation. Although important distinctions can and should be made among primary prevention (avoiding the occurrence of a causal condition), secondary prevention (avoiding or minimizing the consequences of a causal condition after it occurs), and tertiary prevention (minimizing or improving outcomes after the consequences of a causal condition are evident), this dialogue needs to begin with consideration of the overarching goal of lowering the incidence and prevalence of impairments and reducing disability. In many respects, prevention was embraced long ago as a valued societal benefit, and this has had significant impacts in the case of intellectual and developmental disabilities. Certainly, the history of prevention in our own field has included some policies and actions that had devastating consequences for people with intellectual and developmental disabilities, and careful and constant vigilance will always be required to ensure that the rights, privileges, and dignity of every individual are respected and preserved. Nevertheless, many other aspects of the past continue to be broadly viewed as enormously beneficial, and several examples seem particularly illustrative. Until the late 19th century, congenital hypothyroidism (cretinism) caused many individuals in western Europe to have intellectual disability. For some alpine regions, it was so common an occurrence that local physicians thought it unremarkable (Merke, 1984). We now know that this condition is caused by dietary iodine deficiency, and this discovery, along with the availability of iodized salt, has virtually eliminated it as a public health concern in industrialized countries. (Nevertheless, congenital hypothyroidism remains one of the most common preventable causes of intellectual impairment in many underdeveloped regions of the world; Jain, Agarwal, Deorari, & Paul, 2008.) Prior to the 1950s, babies born with phenylketonuria (PKU), a relatively rare genetic disorder, were unimpaired at birth but invariably developed severe intellectual disabilities. This was caused by their inability to metabolize phenylalanine, a INTELLECTUAL AND DEVELOPMENTAL DISABILITIES VOLUME 47, NUMBER 4: 320–322 | AUGUST 2009

Evaluation of the proximal tubular function in individuals with primary renal hypouricemia: an NMR‐based metabonomic study

Primary renal hypouricemia (PRH) refers to a rare condition of increased renal urate clearance, caused by an isolated inborn error of membrane transport of urate in the renal proximal tubule. Several cases of exercise-induced acute renal failure and urolithiasis have been reported. This is the first study that assessed tubular function in PRH using NMR-based metabonomic urine analysis. The study groups consisted of 36 unrelated asymptomatic subjects with PRH, defined as serum uric acid levels (sUA) <2.5 mg/dL and fractional excretion of uric acid (FEUA) >10%, after exclusion of diseases and drugs that may affect urate homeostasis, and 39 sex and age-matched healthy individuals with normal sUA levels (>4.0 mmol/L) and FEUA<10%. Individuals with primary hypouricemia presented similar biochemical profiles to the controls without significant differences with regard to FE of electrolytes and renal threshold for phosphate excretion. Individuals with primary hypouricemia were differentiated from healthy individuals in the orthogonal signal correction/partial least-squares-discriminant analysis models of the NMR data with a statistically significant separation. The components that contributed to this separation were the lower levels of hippurate, creatinine, and trimethylaminoxide, and the higher levels of phenylalanine, alanine, glycine, glutamate, acetate, and of an unidentified metabolite (3.3 ppm) observed in hypouricemic subjects compared with controls. Primary hypouricemia, though considered an isolated renal tubular defect, is often associated with a more generalized proximal tubular disorder that mimics a partial Fanconi syndrome.

Phenylketonuria in Children and Mothers

Phenylketonuria (PKU) is an inborn metabolic error in which metabolism of phenylalanine into tyrosine is disrupted. If the diet of an infant with PKU is not restricted, blood phenylalanine levels are elevated, leading to irremediable brain damage and severe mental retardation. Children with PKU who are placed early and continuously on a low-phenylalanine diet develop normal levels of intelligence, and brain damage is largely prevented. However, if the diet of a mother with PKU is unrestricted during her pregnancy, high phenylalanine levels in her blood can cross the placental barrier and damage the developing fetus in multiple ways. These results demonstrate how genes and environmental factors combine to create prenatal environments that can have profound effects on the growth and development of offspring during infancy and childhood.

Effect of short- and long-term exposition to high phenylalanine blood levels on oxidative damage in phenylketonuric patients

Phenylketonuria is the most frequent disturbance of amino acid metabolism. Treatment for phenylketonuric patients consists of phenylalanine intake restriction. However, there are patients who do not adhere to treatment and/or are not submitted to neonatal screening. These individuals are more prone to develop brain damage due to long-lasting toxic effects of high levels of phenylalanine and/or its metabolites. Oxidative stress occurs in late-diagnosed phenylketonuric patients, probably contributing to the neurological damage in this disorder. In this work, we aimed to compare the influence of time exposition to high phenylalanine levels on oxidative stress parameters in phenylketonuric patients who did not adhere to protein restricted diet. We evaluated a large spectrum of oxidative stress parameters in plasma and erythrocytes from phenylketonuric patients with early and late diagnosis and of age-matched healthy controls. Erythrocyte glutathione peroxidase activity and glutathione levels, as well as plasma total antioxidant reactivity were significantly reduced in both groups of patients when compared to the control group. Furthermore, protein oxidative damage, measured by carbonyl formation and sulfhydryl oxidation, and lipid peroxidation, determined by malondialdehyde levels, were significantly increased only in patients exposed for a long time to high phenylalanine concentrations, compared to early diagnosed patients and controls. In conclusion, exposition to high phenylalanine concentrations for a short or long time results in a reduction of non-enzymatic and enzymatic antioxidant defenses, whereas protein and lipid oxidative damage only occurs in patients with late diagnosis.

Brain dysfunction in phenylketonuria: Is phenylalanine toxicity the only possible cause?

In phenylketonuria, mental retardation is prevented by a diet that severely restricts natural protein and is supplemented with a phenylalanine-free amino acid mixture. The result is an almost normal outcome, although some neuropsychological disturbances remain. The pathology underlying cognitive dysfunction in phenylketonuria is unknown, although it is clear that the high plasma concentrations of phenylalanine influence the blood-brain barrier transport of large neutral amino acids. The high plasma phenylalanine concentrations increase phenylalanine entry into brain and restrict the entry of other large neutral amino acids. In the literature, emphasis has been on high brain phenylalanine as the pathological substrate that causes mental retardation. Phenylalanine was found to interfere with different cerebral enzyme systems. However, apart from the neurotoxicity of phenylalanine, a deficiency of the other large neutral amino acids in brain may also be an important factor affecting cognitive function in phenylketonuria. Cerebral protein synthesis was found to be disturbed in a mouse model of phenylketonuria and could be caused by shortage of large neutral amino acids instead of high levels of phenylalanine. Therefore, in this review we emphasize the possibility of a different idea about the pathogenesis of mental dysfunction in phenylketonuria patients and the aim of treatment strategies. The aim of treatment in phenylketonuria might be to normalize cerebral concentrations of all large neutral amino acids rather than prevent high cerebral phenylalanine concentrations alone. In-depth studies are necessary to investigate the role of large neutral amino acid deficiencies in brain.

A case of two sisters births from mother with phenylketonuria lacking mental retardation

= Abstract = In this untreated classic phenylketonuria (PKU case mental retardation is severe; however there have been individuals- like the mother of this case- who have escaped mental retardation and all the other potential sequelae of phenylketonuria despite having high blood phenylalanine levels and very poor dietary control. It appears that they have nearly normal brain phenylalanine levels despite high blood phenylalanine (Phe levels. A number of studies have now demonstrated considerable variability in blood vs. brain phenylalanine levels in phenylketonuria patients. Outcome of phenylketonuria appears to be related to brain phenylalanine levels. We report a case of undiagnosed maternal phenylketonuria syndrome. A female infant had low birth weight (2400 g with microcephaly. We examined her family an dd iscovered that her mother was an undiag- nosed phenylketonuria patient with a borderline intelligence quotient ( IQ. The infant's sistersix years oldwas diagnosed with phenylketonuria at the age of four years was mentally retarded and had received an operation for cleft lip and palate. the sister had also had a low birth weight (2300 g. Her sister and mother were compound heterozygotes (mother: R243Q/Y325X; sister: Y325X/P407S. The infant and father were heterozygous carriers (baby: R243Q/-; father: P407S/-. (Korean J Pediatr 2008;51:546-550

Family conditions and dietary control in phenylketonuria

This investigation is an attempt to describe coping with phenylketonuria (PKU) in order to understand some aspects underlying good compliance. The coping concept was applied to PKU in two questionnaires. Self- and parental ratings were combined with assessments of phenylalanine levels and the severity of the disease. All Swedish patients with PKU born in 1980-91, a total of 53 children and youths with their parents, were invited to participate in the study and 41 (77%) of them did so. The patients turned out to have good compliance with the diet. The main result was that patients with separated or divorced parents were more likely to have higher phenylalanine levels and this association was not diminished by adjustment for the potential confounding factors. Patients' need for support must be judged individually according to different family conditions.

Genotype and natural history in unrelated individual with phenylketonuria and autistic behavior

We describe three unrelated individuals, two males (ages 35 and 9) and a female (age 8) presenting with late diagnosed phenylketonuria (PKU) and autistic behavior, all showing poor adhesion to the dietary treatment resulting in high plasmatic phenylalanine levels, particularly in the oldest subject. Clinical findings included hair hypopigmentation, microcephaly, severe mental retardation with absent development of verbal language and autistic symptoms in all three patients, whereas variable neurological signs such as seizures, spasticity, ataxia, aggressivity, and hyperactivity were individually found. Homozygosity for the IVS10nt11g/a (IVS10nt546) was found in all. This is the first report of molecular findings in subjects with PKU also presenting with autistic features. The authors discuss if this mutation is particularly involved in the association of autistic symptoms in untreated PKU individuals.

Three‐year audit of the hyperphenylalaninaemia/phenylketonuria spectrum in Victoria

To determine the prevalence, the types and severity of hyperphenylalaninaemia (including phenylketonuria (PKU)) in Victoria and to report on a new treatment modality of PKU. We reviewed the medical records of all patients diagnosed with high blood phenylalanine levels by newborn screening between November 2001 and October 2004. We identified 17 newborn babies with high levels of blood phenylalanine (total samples: 190,835). Dihydrobiopterin reductase deficiency was excluded in all babies. Five babies had persistent phenylalanine levels of 200-300, and do not receive any dietary or pharmaceutical therapy. One baby was diagnosed as having pyruvoyl tetrahydro-pterin synthase deficiency. Following reports of tetrahydrobiopterin (BH(4))-responsive PKU, we have performed a BH(4) load (20 mg/kg, 6R-5,6,7,8-tetrahydro-L-biopetrin dehydrochloride; Schricks Laboratories, Jona, Switzerland) in 10 newborn babies with PKU (one baby with a phenylalanine level of 2600 micromol/L was started on diet without prior load). Three babies had a significant response to BH(4) (>35% decrease in phenylalanine level). Protein restriction (1.2 g/kg/day) and introduction of phenylalanine-free formula, in addition to BH(4) treatment, were necessary in one patient. The other patients maintain good metabolic control with BH(4) treatment only (at approximately 11 mg/kg/day) and an intake of 2-3 g protein per day. Of the nine babies who are on a full PKU diet, three have high phenylalanine tolerance (consistently >40 mg/kg/day). There is a spectrum of severity of hyperphenylalaninaemia in the population. The detection of BH(4)-responsive PKU patients offers them a less restrictive dietary regimen and an improved quality of life, and may enable near normal life-style in adolescence.

Neonatal Screening by Tandem Mass Spectrometry

After completing this article, readers should be able to: 1. List the major categories of diseases detectable by expanded newborn screening. 2. Give examples of the benefits and limitations of screening by tandem mass spectrometry. 3. Describe the appropriate follow-up for an abnormal screening result. The screening of newborns for inherited metabolic disorders is a well-established public health activity, first implemented in the early 1960s for the presymptomatic identification of patients who have phenylketonuria (PKU). Since then, significant technological advances, most importantly the development of tandem mass spectrometry (MS/MS), have enabled the detection of an increasing number of metabolic disorders in newborn blood. This article reviews the basic technology of MS/MS and its application to newborn screening, with the aim of highlighting the benefits and pointing out some limitations of this powerful technology. Early screening for PKU used the bacterial inhibition assay of Guthrie, in which inhibition of bacterial growth on an agar medium, introduced by the addition of a phenylalanine analog, was overcome by the presence of dried blood discs containing high levels of phenylalanine (such as from a PKU patient). This approach later was adapted for the detection of leucine in patients who have maple syrup urine disease (MSUD), methionine in patients who have classic homocystinuria, and tyrosine in patients who have tyrosinemia. Over the years, other techniques have been implemented to screen for additional disorders, including congenital hypothyroidism, biotinidase deficiency, galactosemia, hemoglobinopathies, and congenital adrenal hyperplasia. The classic criteria used to determine whether a disorder is suitable for screening include: 1) the disorder is clinically and biochemically well defined, 2) it is associated with significant morbidity or mortality, 3) an effective treatment is available, and 4) there is a simple and safe screening test. (1) By the early 1990s, all states offered screening for at least PKU and congenital hypothyroidism, …

Administration-route and gender-independent long-term therapeutic correction of phenylketonuria (PKU) in a mouse model by recombinant adeno-associated virus 8 pseudotyped vector-mediated gene transfer

Phenylketonuria (PKU) is an inborn error of metabolism caused by deficiency of the hepatic enzyme phenylalanine hydroxylase (PAH) which leads to high blood phenylalanine (Phe) levels and consequent damage of the developing brain with severe mental retardation if left untreated in early infancy. The current dietary Phe restriction treatment has certain clinical limitations. To explore a long-term nondietary restriction treatment, a somatic gene transfer approach in a PKU mouse model (C57Bl/6-Pahenu2) was employed to examine its preclinical feasibility. A recombinant adeno-associated virus (rAAV) vector containing the murine Pah-cDNA was generated, pseudotyped with capsids from AAV serotype 8, and delivered into the liver of PKU mice via single intraportal or tail vein injections. The blood Phe concentrations decreased to normal levels (< or =100 microM or 1.7 mg/dl) 2 weeks after vector application, independent of the sex of the PKU animals and the route of application. In particular, the therapeutic long-term correction in females was also dramatic, which had previously been shown to be difficult to achieve. Therapeutic ranges of Phe were accompanied by the phenotypic reversion from brown to black hair. In treated mice, PAH enzyme activity in whole liver extracts reversed to normal and neither hepatic toxicity nor immunogenicity was observed. In contrast, a lentiviral vector expressing the murine Pah-cDNA, delivered via intraportal vein injection into PKU mice, did not result in therapeutic levels of blood Phe. This study demonstrates the complete correction of hyperphenylalaninemia in both males and females with a rAAV serotype 8 vector. More importantly, the feasibility of a single intravenous injection may pave the way to develop a clinical gene therapy procedure for PKU patients.

Pathologic and Immunohistochemical Findings in Hypothalamic and Mesencephalic Regions in the Pahenu2 Mouse Model for Phenylketonuria

The Pah(enu2) mouse, created through ethylnitrosurea mutagenesis, is a model for phenylketonuria. These mice have elevated serum phenylalanine levels, hypopigmentation, and behavior and movement abnormalities, and female mice exhibit a maternal phenylketonuria syndrome. We evaluated the brains of adult and juvenile Pah(enu2) mice for consistent, demonstrable lesions to elucidate various neuropathologic processes and to assess the efficacy of various treatment modalities such as AAV-mediated gene therapy. One aspect of the disease may involve the effect of hyperphenylalanemia on catecholamine function. High levels of phenylalanine inhibit enzymes that are important in the conversion of tyrosine and tryptophan to their respective neurotransmitter derivatives, including dopamine. Therefore, assessment of dopaminergic regions was of interest in this study. Histologic evaluation of juvenile and adult brains revealed an increased cellular density as early as 4 wk of age in the middle to posterior hypothalamus and substantia nigra. The infiltrating cells showed immunoreactivity for CD11b and had morphologic characteristics of macrophages. There was marked expression of inducible nitric oxide synthase in these dopaminergic regions that co-localized to CD11b-positive cells. The CD11b-positive cells and increased inducible nitric oxide synthase expression in these regions may function in a neuroregulatory manner to compensate for alterations in dopamine metabolism.

Phenylalanine ammonia-lyase modified with polyethylene glycol: Potential therapeutic agent for phenylketonuria

Phenylketonuria (PKU) is an autosomal recessive genetic disease caused by the defects in the phenylalanine hydroxylase (PAH) gene. Individuals homozygous for defective PAH alleles show elevated levels of systemic phenylalanine and should be under strict dietary control to reduce the risk of neuronal damage associated with high levels of plasma phenylalanine. Researchers predict that plant phenylalanine ammonia-lyase (PAL), which converts phenylalanine to nontoxic t-cinnamic acid, will be an effective therapeutic enzyme for the treatment of PKU. The problems of this potential enzyme therapy have been the low stability in the circulation and the antigenicity of the plant enzyme. Recombinant PAL originated from parsley (Petroselinum crispum) chemically conjugated with activated PEG2 [2,4-bis(O-methoxypolyethyleneglycol)-6-chloro-s-triazine] showed greatly enhanced stability in the circulation and was effective in reducing the plasma concentration of phenylalanine in the circulation of mice. PEG-PAL conjugate will be an effective therapeutic enzyme for the treatment of PKU.

Neuropsychological outcome of subjects participating in the PKU Adult Collaborative Study: A preliminary review

Adult subjects with classical phenylketonuria (PKU) who were diagnosed and treated neonatally participated in this long-term follow-up study. Twenty-four subjects received neuropsychological (NP) assessment and a subset received magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) to identify: (1) pattern of cognitive dysfunction; (2) effect of high blood phenylalanine (Phe) level at time of cognitive testing; and (3) treatment variables that may be associated with cognitive difficulties in adulthood. All subjects had average IQ except one subject in the borderline range. Diet was initiated by the 15th day of life. All subjects except one were on diet until age 6 years (mean years of treatment = 15). Blood Phe levels at cognitive testing ranged from 157 to 1713 micromol/L (mean = 1038); 11 subjects had levels < 1000 micromol/L and 13 subjects had levels >1000 micromol/L. Results suggest that adults with early-treated PKU demonstrate specific cognitive deficits, a number of which are associated with the frontal and temporal area of the brain. Deficits were noted in several domains including executive functioning, attention, verbal memory, expressive naming and verbal fluency. Self-report measures of depression and anxiety were generally in the normal/mild range. The group with a Phe level > 1000 micromol/L scored lower than the group with Phe level < 1000 micromol/L on measures of focused attention, verbal fluency, reaction time, verbal recognition memory, visual memory and naming. Tests of cognitive functioning were often correlated with measures of treatment during childhood rather than with Phe level at the time of cognitive testing. Subjects with abnormal MRI scored significantly lower on two cognitive tests (Trails A and CVLT Recognition Memory). We found no significant correlation between current brain Phe level obtained through MRS (n = 10) and neuropsychological functioning. Future longitudinal investigation with a larger sample size will assist in clarifying the aetiology of neuropsychological deficits and association with treatment history.

The association of serum lipids, lipoproteins and apolipoproteins with selected trace elements and minerals in phenylketonuric patients on diet

Objective: Classical phenylketonuria (PKU) is an inborn error of metabolism characterized by high Phenylalanine (Phe) levels in blood and treated with a special low Phe diet which can be defined as “nonatherogenic”. Since coronary heart disease (CHD) was reported to be a disease of zinc and copper imbalance, we aimed indirectly to evaluate the effect of the special diet on the size of LDL particles and to investigate whether some minerals and trace elements are involved in their lipoprotein metabolism. Methods: Eighty-six ( N=86) PKU patients were divided into two groups. Group A ( N=44) on a strict diet and group B ( N=42) who did not adhere to their treatment. Healthy children ( N=98) were the controls. Serum total cholesterol (t-Chol), triacylglycerol, High-density lipoprotein (HDL) and t-Chol in very-low-density lipoprotein (VLDL) and low-density lipoprotein (LDL) were measured with enzymatic methods, whereas Apolipoprotein AI (Apo AI), Apolipoprotein AII (Apo AII) and Apolipoprotein B (Apo B) were determined by nephelometric techniques. LDL/Apo B positively correlated with LDL size. Magnesium (Mg), calcium (Ca), copper (Cu) and zinc (Zn) measurements were performed by atomic absorption spectrometry. Results: t-Chol, LDL, VLDL, Apo B, the ratio t-Chol/HDL, Apo AI/Apo B and LDL/Apo B as well as copper levels and the ratio Zn/Cu in group A statistically significantly differed as compared to those of group B and Controls. Positive correlations were found between Mg and HDL and Apo AI in all the groups whereas the mineral correlated with t-Chol, Apo B and the ratio LDL/Apo B only in the group A of patients. Copper negatively correlated with triacylglycerol, LDL, and Apo B and positively with t-Chol in group A. Zinc showed negative relationships in HDL and Apo A in all the studied groups. The ratio Zn/Cu negatively correlated with triacylglycerol and LDL in all the groups and positively with the ratios Apo AI/Apo B and LDL/Apo B in group A. Conclusion: Some of the minerals and trace elements were correlated with the lipids and lipoproteins and were also involved in the size of LDL particles in PKU patients on strict diet. Larger and less atherogenic LDL particles were associated with a high Zn/Cu ratio.

Role of Nutrition in Pregnancy With Phenylketonuria and Birth Defects

The maternal phenylketonuria (PKU) syndrome is caused by high blood phenylalanine (Phe) levels during pregnancy, leading to a host of birth defects, especially microcephaly and congenital heart disease (CHD). For finding whether the maternal PKU syndrome could be prevented, an international collaborative study was organized to evaluate treatment with a Phe-restricted diet. Blood Phe levels, maternal weight gain, and nutrient intakes during pregnancy were evaluated as to their effect on the rate of microcephaly and CHD in the offspring. The study was a prospective, longitudinal effort aimed at lowering blood Phe during pregnancy. Women were enrolled at time of referral for pregnancy. Nutrient intake analysis, which serves as the basis for this report, was available from 251 pregnancies. Subjects were stratified by blood Phe control of < or =600 micromol/L by 8 weeks gestation or >600 micromol/L by 8 weeks gestation. Outcome of these pregnancies was correlated to blood Phe levels, weight gain, and nutrient intake. The study goal was to attain blood Phe levels of 120 to 360 micromol/L 3 months preconception; however, this goal was achieved by only a limited number of patients. Therefore, the data presented were based on blood Phe control < or =600 micromol/L or >600 micromol/L by 8 weeks of gestation. Blood Phe control of < or =600 micromol/L by 8 weeks of gestation was attained by 86 (34.3%) of the 251 women in this study, whereas the other 165 women had blood Phe control >600 micromol/L by 8 weeks of gestation. Of the 251 offspring, 166 were born with normal head circumference and 85 were born with microcephaly (<2 standard deviations below normal). Women with blood Phe >600 micromol/L at 8 weeks of gestation included 78 (92%) of the 85 infants with microcephaly compared with 8% in the group of women who had blood Phe levels < or =600 micromol/L. Weight gain during pregnancy was related to the rate of microcephaly. The highest occurrence of microcephaly (58%) was found in the pregnant women who gained <70% of recommended weight gain. Stepwise logistic regression analysis was used to determine factors associated with microcephaly. Significant factors included higher blood Phe levels when off diet, higher average Phe exposure during the pregnancy, low prepregnancy weight, poor weight gain during the pregnancy, and lower intake of protein and higher iron intake during the pregnancy. Infants with CHD were found only in the group of women who had blood Phe levels >600 micromol/L by 8 weeks of gestation. There was a higher rate of CHD in the offspring who were born to women who consumed <50% of the recommended intake of protein in the first trimester. The main source of protein for women with PKU is the medical food; therefore, when protein intake was low, vitamin and mineral intakes were also inadequate. The data indicate that blood Phe control and how soon it is attained during pregnancy with PKU is important. Normal pregnancy weight gain should be encouraged to reduce microcephaly. Adequate protein and vitamin intakes early in pregnancy may have a protective effect for the prevention of CHD, even if blood Phe is elevated. The rate of microcephaly and CHD may be reduced if nutrient intake is optimal while attempting to control blood Phe levels.