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Engineered bacteria (synthetic biotics) represent a new class of therapeutics that leverage the tools of synthetic biology. Translational testing strategies are required to predict synthetic biotic function in the human body. Gut-on-a-chip microfluidics technology presents an opportunity to characterize strain function within a simulated human gastrointestinal tract. Here, we apply a human gut-chip model and a synthetic biotic designed for the treatment of phenylketonuria to demonstrate dose-dependent production of a strain-specific biomarker, to describe human tissue responses to the engineered strain, and to show reduced blood phenylalanine accumulation after administration of the engineered strain. Lastly, we show how in vitro gut-chip models can be used to construct mechanistic models of strain activity and recapitulate the behavior of the engineered strain in a non-human primate model. These data demonstrate that gut-chip models, together with mechanistic models, provide a framework to predict the function of candidate strains in vivo., Engineered live bacteria could represent a new class of therapeutic treatment for human disease. Here, the authors use a human gut-on-a-chip microfluidics system to characterize an engineered live bacterial therapeutic, designed for the treatment of phenylketonuria, and to construct mathematical models that predict therapeutic strain function in non-human primates.

Phenylketonuria (PKU) is the most common inborn error of amino acids metabolism. PKU management aims to keep as soon as possible blood phenylalanine (Phe), a non-acutely neurotoxic metabolite, within safe ranges through a dietary Phe restriction tailored to individual dietary Phe tolerance. Information on initial neonatal management of PKU, when Phe tolerance is still unknown, is scanty. We reviewed the metabolic data from 304 patients with PAH deficiency detected at newborn screening within the last 37 years. In keeping with the general neonatal management of intoxication-type inborn errors of metabolism, initial management consisted in a Phe wash-out through the exclusive administration of normocaloric Phe-free formulas until normalization of blood Phe. Based on genotype and Phe tolerance assessed at follow-up, 55 patients had classic PKU (18%), 50 mild PKU (17%), and 199 non-PKU hyperphenylalaninemia (HPA) (65%). The duration of Phe wash-out amounted to 7 ± 2 days in classic PKU, 4 ± 2 days in mild PKU, and

Phenylketonuria (PKU) and Hyperphenylalaninemia (HPA) are inborn errors of metabolism (IEM) due to mutations in the PAH gene resulting in increased blood phenylalanine (Phe) concentrations. Depending on the Phe levels, a lifelong dietary intervention may be needed. During the COVID-19 pandemic, finding new strategies to ensure follow-up and metabolic control for such patients became mandatory and telehealth was identified as the most eligible tool to provide care and assistance beyond barriers. The aim of this study was to evaluate how telehealth use may have impacted disease follow-ups. Seven hundred and fifty-five patients affected by PKU/HPA in follow-ups at the Clinical Department of Pediatrics (San Paolo Hospital, ASST Santi Paolo e Carlo, University of Milan, Italy) were included in this study. The data regarding the used telehealth model, type of performed consultations and patients’ perspectives were retrospectively collected and analyzed after a one-year experience of implemented follow-ups. The results demonstrated that telehealth seemed to be a useful tool to improve the adherence to treatment and that it could guarantee continuous assistance and care beyond the surrounding epidemiological status. Patients expressed great satisfaction with the offered services and requested that they were implemented in standards of care on a long-term basis. Our results suggested the implementation of telehealth in the management guidelines for PKU/HPA patients.

Blood phenylalanine (Phe) is used as the primary marker to evaluate metabolic control. Our study aimed to describe the metabolic control of patients with phenylketonuria (PKU) comparing three different treatment recommendations (European guidelines/US guidelines/Portuguese consensus). This was a retrospective, observational, single centre study in patients with PKU collecting data on blood Phe levels from 2017. Nutritional intake data and sapropterin (BH4) prescription were collected at the last appointment of 2017. The final sample studied included 87 patients (48% females) [13 hyperphenylalaninemia, 47 mild PKU, 27 classical PKU] with a median age of 18 y (range: 1–36 y). The median number of blood Phe measurements for patients was 21 (range: 6–89). In patients aged &lt, 12 y, the median blood Phe level was 300 μmol/L (range 168–480) and 474 μmol/L (range 156–1194) for patients ≥ 12 y. Overall, a median of 83% of blood Phe levels were within the European PKU guidelines target range. In patients aged ≥ 12 years, there was a higher median % of blood Phe levels within the European PKU guidelines target range (≥12 y: 84% vs. &lt, 12 y: 56%). In children &lt, 12 y with classical PKU (n = 2), only 34% of blood Phe levels were within target range for all 3 guidelines and 49% with mild PKU (n = 11). Girls had better control than boys (89% vs. 66% median Phe levels within European Guidelines). Although it is clear that 50% or more patients were unable to achieve acceptable metabolic control on current treatment options, a globally agreed upper Phe target associated with optimal outcomes for age groups is necessary. More studies need to examine how clinics with dissimilar resources, different therapeutic Phe targets and frequency of monitoring relate to metabolic control.

Objective Although past studies have documented motor control impairments in individuals with early-treated phenylketonuria (ETPKU), much less is known regarding motor learning in ETPKU. The goal of the present study was to advance our understanding on this front. Method We isolated and examined motor kinematics associated with the learning of a rapid aimed limb movement in a sample of 40 individuals (13-34 years of age) with ETPKU and a matched comparison group of 40 individuals without phenylketonuria (PKU). Indices of motor learning included overall movement duration as well as the relative proportion of movement time devoted to ballistic and corrective submovements. (Note that practice of motor movements in nonclinical populations is associated with, not only improvements in overall speed, but also reduction in the proportion of movement time devoted to corrective submovements relative to an initial ballistic submovement.) Results: A group-by-time interaction was found. With practice, the non-PKU group showed a significant reduction in the proportion of movement time devoted to the corrected (as compared to the ballistic) submovement. A similar change was not observed for the ETPKU group. In addition, within the ETPKU group, the rate of improvement in total movement duration was correlated with recent blood phenylalanine levels (an indicator of treatment adherence). Conclusions Motor learning is adversely affected in individuals with ETPKU. Further investigation into the behavioral and neural mechanisms of motor learning in ETPKU will advance our understanding of the etiologic basis for this disruption as well as how it relates to the broader neurocognitive profile of ETPKU. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Protein substitutes developed for phenylketonuria (PKU) are a synthetic source of protein commonly based on L-amino acids. They are essential in the treatment of phenylketonuria (PKU) and other amino acid disorders, allowing the antagonistic amino acid to be removed but with the safe provision of all other amino acids necessary for maintaining normal physiological function. They were first formulated by a chemist and used experimentally on a 2-year-old girl with PKU and their nutritional formulations and design have improved over time. Since 2008, a bioactive macropeptide has been used as a base for protein substitutes in PKU, with potential benefits of improved bone and gut health, nitrogen retention, and blood phenylalanine control. In 2018, animal studies showed that physiomimic technology coating the amino acids with a polymer allows a slow release of amino acids with an improved physiological profile. History has shown that in PKU, the protein substitute’s efficacy is determined by its nutritional profile, amino acid composition, dose, timing, distribution, and an adequate energy intake. Protein substitutes are often given little importance, yet their pharmacological actions and clinical benefit are pivotal when managing PKU.

BACKGROUND: In patients with phenylketonuria, stability of blood phenylalanine and tyrosine concentrations might influence brain chemistry and therefore patient outcome. This study prospectively investigated the effects of tetrahydrobiopterin (BH4), as a chaperone of phenylalanine hydroxylase on diurnal and day-to-day variations of blood phenylalanine and tyrosine concentrations.METHODS: Blood phenylalanine and tyrosine were measured in dried blood spots (DBS) four times daily for 2 days (fasting, before lunch, before dinner, evening) and once daily (fasting) for 6 days in a randomized cross-over design with a period with BH4 and a period without BH4. The sequence was randomized. Eleven proven BH4 responsive PKU patients participated, 5 of them used protein substitutes during BH4 treatment. Natural protein intake and protein substitute dosing was adjusted during the period without BH4 in order to keep DBS phenylalanine levels within target range. Patients filled out a 3-day food diary during both study periods. Variations of DBS phenylalanine and Tyr were expressed in standard deviations (SD) and coefficient of variation (CV).RESULTS: BH4 treatment did not significantly influence day-to-day phenylalanine and tyrosine variations nor diurnal phenylalanine variations, but decreased diurnal tyrosine variations (median SD 17.6 μmol/l, median CV 21.3%, p = 0.01) compared to diet only (median SD 34.2 μmol/l, median CV 43.2%). Consequently, during BH4 treatment diurnal phenylalanine/tyrosine ratio variation was smaller, while fasting tyrosine levels tended to be higher.CONCLUSION: BH4 did not impact phenylalanine variation but decreased diurnal tyrosine and phenylalanine/tyrosine ratio variations, possibly explained by less use of protein substitute and increased tyrosine synthesis.

Background According to studies of phenylketonuria (PKU), the Brazilian population’s metabolic control shows unsatisfactory indexes from childhood. Research on patients’ perceived difficulties or barriers to adherence to treatment can help us to comprehend how these outcomes are associated. The present study aimed to: (1) describe the development of an inventory for identifying the most frequent and relevant perceived barriers to PKU treatment from the perspective of patients, caregivers, and healthcare professionals; (2) evaluate certain psychometric characteristics of the new measure; and, (3) explore potential predictors (sociodemographic and medical characteristics) that may contribute to increasing the number of perceived barriers and examine whether the number of barriers is associated with the degree of adherence shown by the patient. Results Participants in the study were 23 patients with PKU (M age = 18.0 years; SD = 7.3; range 6 to 34 years; 69% early-treated) in classical (n = 11) and mild (n = 12) form, and 11 caregivers. The inventory, developed to ascertain perceived barriers to treatment, was completed by patients (≥ 13 years) and caregivers of patients aged 6 to 17 years. Analyses were conducted to investigate whether barrier inventory scores were associated with adherence to treatment as measured by phenylalanine levels in patients’ medical records. Scores on the inventory differed across the patient age groups: adolescents had lower scores (i.e. reported fewer barriers) compared with those of adults (U = 8.000, p = 0.008); patients with better recent metabolic control also reported fewer perceived barriers than did patients with poor adherence (U = 20.000, p = 0.009); and the number of perceived barriers was positively associated with recent blood phenylalanine concentration (Kendall’s taub = 0.41; p = 0.001). Conclusions These results suggest that the inventory has merit in assessing perceived barriers and support the need for further research on barriers perceived by PKU patients.

Homozygous siblings with different treatment histories represent an excellent model to study both the phenotypic manifestation of mutations and the efficacy of therapy. We compared phenylketonuria (PKU) manifestations in two different gender siblings who were homozygous carriers of a rare phenylalanine hydroxylase (PAH) mutation, p.R155H, subjected to different treatments. PKU caused by mild mutations may be easily underdiagnosed if the diagnosis is based solely on the phenylalanine (Phe) blood concentration. One of the described patients is an example of this diagnostic error. For reducing diagnostic errors, we suggest the use of more elaborate methods in screening practice, in particular mass spectrometric analysis of blood metabolites, the efficiency of which is demonstrated in the present study.

ObjectiveFamilies of children with phenylketonuria (PKU) report child emotional and behavioral problems, parenting stress, and parenting difficulties, which are associated with worse health-related quality of life. This study aimed to examine acceptability and feasibility of a brief, group-based parenting program (Healthy Living Triple P) for families of children with PKU.MethodsAn uncontrolled nonrandomized trial design was used. Families of children aged 2–12 years (N = 17) completed questionnaire measures assessing child behavior and impact of PKU on quality of life (primary outcomes), and parenting behavior, self-efficacy and stress, and children’s behavioral and emotional adjustment (secondary outcomes). Routinely collected blood phenylalanine (Phe) levels were obtained from the treating team. Parents selected two child behaviors as targets for change. The intervention comprised two, 2-hr group sessions delivered face-to-face or online. Assessment was repeated at 4-week postintervention (T2) and 4-month follow-up (T3).ResultsAttrition was low and parent satisfaction with the intervention (face-to-face and online) was high. All families achieved success with one or both child behavior goals, and 75% of families achieved 100% success with both behavior goals by T3; however, there was no change in health-related quality of life. There were moderate improvements in parent-reported ineffective parenting (total score, d = 0.87, 95% CI −1.01 to 2.75) and laxness (d = 0.59, 95% CI −1.27 to 2.46), but no effects on parenting stress or children’s adjustment. Phe levels improved by 6month post-intervention for children with elevated preintervention levels.ConclusionsResults support intervention acceptability and feasibility. A randomized controlled trial is warranted to establish intervention efficacy.

Importance Sapropterin hydrochloride, a natural coenzyme (6R-tetrahydrobiopterin) of phenylalanine hydroxylase, was first approved as a treatment for tetrahydrobiopterin deficiency in 1992 in Japan, and was then approved as a treatment for a tetrahydrobiopterin-responsive hyperphenylalaninemia in 2007 and 2008, in the USA and Japan, respectively. Guidelines are required on the proper use of sapropterin hydrochloride for tetrahydrobiopterin-responsive hyperphenylalaninemia. Observations It is recommended that tetrahydrobiopterin-responsive hyperphenylalaninemia should be diagnosed in all cases of hyperphenylalaninemia, including phenylketonuria, by tetrahydrobiopterin administration tests rather than by phenotype or blood phenylalanine levels. Conclusions and relevance If tetrahydrobiopterin-responsive hyperphenylalaninemia is diagnosed, all ages can be treated with sapropterin hydrochloride. Although there are reports that sapropterin hydrochloride is effective and safe for the prevention of maternal phenylketonuria, further investigation is required.

Analysis of blood phenylalanine is central to the monitoring of patients with phenylketonuria (PKU) and age-related phenylalanine target treatment-ranges (0–12 years; 120–360 μmol/L, and >12 years; 120–600 μmol/L) are recommended in order to prevent adverse neurological outcomes. These target treatment-ranges are based upon plasma phenylalanine concentrations. However, patients are routinely monitored using dried bloodspot (DBS) specimens due to the convenience of collection. Significant differences exist between phenylalanine concentrations in plasma and DBS, with phenylalanine concentrations in DBS specimens analyzed by flow-injection analysis tandem mass spectrometry reported to be 18% to 28% lower than paired plasma concentrations analyzed using ion-exchange chromatography. DBS specimens with phenylalanine concentrations of 360 and 600 μmol/L, at the critical upper-target treatment-range thresholds would be plasma equivalents of 461 and 768 μmol/L, respectively, when a reported difference of 28% is taken into account. Furthermore, analytical test imprecision and bias in conjunction with pre-analytical factors such as volume and quality of blood applied to filter paper collection devices to produce DBS specimens affect the final test results. Reporting of inaccurate patient results when comparing DBS results to target treatment-ranges based on plasma concentrations, together with inter-laboratory imprecision could have a significant impact on patient management resulting in inappropriate dietary change and potentially adverse patient outcomes. This review is intended to provide perspective on the issues related to the measurement of phenylalanine in blood specimens and to provide direction for the future needs of PKU patients to ensure reliable monitoring of metabolic control using the target treatment-ranges.

We developed European guidelines to optimise phenylketonuria (PKU) care. To develop the guidelines, we did a literature search, critical appraisal, and evidence grading according to the Scottish Intercollegiate Guidelines Network method. We used the Delphi method when little or no evidence was available. From the 70 recommendations formulated, in this Review we describe ten that we deem as having the highest priority. Diet is the cornerstone of treatment, although some patients can benefit from tetrahydrobiopterin (BH4). Untreated blood phenylalanine concentrations determine management of people with PKU. No intervention is required if the blood phenylalanine concentration is less than 360 mu mol/L. Treatment is recommended up to the age of 12 years if the phenylalanine blood concentration is between 360 mu mol/L and 600 mu mol/L, and lifelong treatment is recommended if the concentration is more than 600 mu mol/L. For women trying to conceive and during pregnancy (maternal PKU), untreated phenylalanine blood concentrations of more than 360 mu mol/L need to be reduced. Treatment target concentrations are as follows: 120-360 mu mol/L for individuals aged 0-12 years and for maternal PKU, and 120-600 mu mol/L for non-pregnant individuals older than 12 years. Minimum requirements for the management and follow-up of patients with PKU are scheduled according to age, adherence to treatment, and clinical status. Nutritional, clinical, and biochemical follow-up is necessary for all patients, regardless of therapy.

Tyrosinemia type 1 (TT1) treatment with 2-(2-nitro-4-trifluormethyl-benzyl)-1,3-cyclohexanedione (NTBC) and a phenylalanine-tyrosine restricted diet is associated with low phenylalanine concentrations. Phenylalanine supplementation is prescribed without comprehensive consideration about its effect on metabolic control. We investigated the effect of phenylalanine supplementation on bloodspot phenylalanine, tyrosine, NTBC and succinylacetone. Eleven TT1 patients received 0, 20 and 40 mg/kg/day phenylalanine supplementation with the phenylalanine-tyrosine free L-amino acid supplements. Bloodspots were collected before breakfast, midday and evening meal. Differences between study periods, sample times and days within a study period were studied using (generalized) linear mixed model analyses. Twenty and 40 mg/kg/day phenylalanine supplementation prevented daytime phenylalanine decreases (p = 0.05) and most low phenylalanine concentrations, while tyrosine concentrations increased (p &lt, 0.001). Furthermore, NTBC and succinylacetone concentrations did not differ between study periods. To conclude, 20 mg/kg/day phenylalanine supplementation can prevent most low phenylalanine concentrations without increasing tyrosine to concentrations above the target range or influencing NTBC and succinylacetone concentrations, while 40 mg/kg/day increased tyrosine concentrations to values above the targeted range. Additionally, this study showed that the effect of phenylalanine supplementation, and a possible phenylalanine deficiency, should be assessed using pre-midday meal blood samples that could be combined with an overnight fasted sample when in doubt.

Blood phenylalanine (Phe) values from the dried blood spots of all Estonian phenylketonuria (PKU) patients have been deposited into a unified electronic laboratory database for eight years, providing an opportunity to assess the adherence of the patients to dietary recommendations over time and to observe patient practices both individually and collectively. Our results demonstrate generally good adherence to clinical and dietary recommendations during the first six years of life, as the percentage of patients with median Phe values fitting under the national recommendation levels were 95%, 84% and 70% in age groups 0–1, 1–2 and 2–6 years, respectively. Conversely, significant deviations occur in the group of 6 to 12 year-olds, mildly decreasing in adolescence and increasing in adulthood (43%, 53% and 57%, respectively). Wide individual differences occurred in all groups, especially in patients with a classical PKU phenotype caused by PAH variants that fully abolish phenylalanine hydroxylase activity. Surprisingly, some of the best dietary adherence was seen in the late-diagnosed PKU patients with poor cognitive functioning. As a rule, the median of Phe values crosses the recommended thresholds in approximately one third to one half of the patients of each age group after the first two years of life. Keywords: Phenylketonuria, Blood phenylalanine value, Adherence to treatment, Electronic laboratory records

Purpose: Phenylketonuria PKU is an inherited metabolic disease caused by low levels of the enzyme phenylalanine hydroxylase. Treatment includes dietary restriction of phenylalanine Phe and supplementation with tetrahydrobiopterin and large neutral amino acids LNAAs . The purpose of this study is to evaluate the effect of LNAA therapy on blood Phe levels in patients undergoing treatment for at least 6 months.Methods: Blood Phe levels in 34 patients with classical PKU receiving LNAA supplementation for longer than 6 months were compared before the treatment and during the first 3 years of treatment.Results: The mean age of patients was 20.7±6.6 years, and the mean age at the beginning of LNAA therapy was 16.0±6.1 years. The median duration of LNAA use was 32 months minimum-maximum: 8-171 months . The mean blood Phe level before the use of LNAA supplementation was 23.1±5.9 mg/dL, whereas the first blood Phe level 1 month after the start of LNAA therapy was 18.9±5.5 mg/dL p=0.000 . The mean blood Phe levels in the first n=34 , second n=33 , and third year n=28 after the beginning of LNAA supplementation were 21.1±5.0 mg/dL, 21.2±6.4 mg/dL, and 21.3±5.8 mg/dL, respectively. There was no significant variation between these and pre-treatment values p>0.05 .Conclusion: There were no significant decreases in the blood Phe levels of patients receiving LNAA supplementation observed in this study. This may be due to poor dietary compliance. Nevertheless, since LNAA supplementation reduces the passage of Phe through the blood-brain barrier, it is still recommended in all adolescent and adult patients with PKU not complying with diet therapy, even if blood values do not change

We present Boston Children's Hospital's clinic model for pegvaliase therapy in adults with phenylketonuria (PKU) and clinical outcomes in 46 patients over the first 1.5 years of commercial therapy. Approximately 70% (18/26) of patients starting pegvaliase achieved blood phenylalanine (Phe)

Background Phenylketonuria (PKU) treatment consists of life-long protein restriction and Phe-free medical foods for adequate nutritional intake and growth. A relationship between body composition and blood phenylalanine (Phe) concentrations in subjects with PKU has been proposed but this has not been consistently reported. Methods Dietary intake, lean body mass (LBM) and fat mass (FM) were measured in 30 pediatric subjects with PKU compared to 30 age, and sex matched controls. The relationship between body composition and blood Phe was analyzed within the PKU cohort from clinically collected dried blood spot Phe concentrations. Results Male subjects with PKU had less LBM% and more FM% than controls (p = .024). There was no difference in LBM% and FM% among female subjects. Age (p = .02) and FM% (p = .02) were positively correlated to dried blood spot Phe. Synthetic protein intake (g/kg body weight) was negatively correlated with dried blood spot Phe (p = .04). Natural protein intake was not related to blood spot Phe. Conclusions Children with PKU face additional dietary challenges maintaining healthy growth and body composition while keeping Phe levels low. We observed higher FM% and lower LBM% in male subjects with PKU. Correlations do not prove cause and effect but suggest a relationship between increased blood Phe, lower synthetic protein intake and increased FM%. Future studies may explore if lower blood Phe concentrations is associated with a lower FM% and higher LBM%; particularly among adult patients now managed on pegvaliase (Palynziq®) who consume normal amounts of natural protein or among younger patients who consume glycomacropeptide (GMP).

In phenylketonuria, casein glycomacropeptide (CGMP) requires modification with the addition of some essential and semi essential amino acids to ensure suitability as a protein substitute. The optimal amount and ratio of additional amino acids is undefined. Aim A longitudinal, parallel, controlled study over 12 months evaluating a CGMP (CGMP-AA2) formulation compared with phenylalanine-free L-amino acid supplements (L-AA) on blood Phe, Tyr, Phe:Tyr ratio, biochemical nutritional status and growth in children with PKU. The CGMP-AA2 contained 36 mg Phe per 20 g protein equivalent. Methods Children with PKU, with a median age of 9.2 y (5-16y) were divided into 2 groups: 29 were given CGMP-AA2, 19 remained on Phe-free L-AA. The CGMP-AA2 formula gradually replaced L-AA, providing blood Phe concentrations were maintained within target range. Median blood Phe, Tyr, Phe:Tyr ratio and anthropometry, were compared within and between the two groups at baseline, 26 and 52 weeks. Nutritional biochemistry was studied at baseline and 26 weeks only. Results At the end of 52 weeks only 48% of subjects were able to completely use CGMP-AA2 as their single source of protein substitute. At 52 weeks CGMP-AA2 provided a median of 75% (30–100) of the total protein substitute with the remainder being given as L-AA. Within the CGMP-AA2 group, blood Phe increased significantly between baseline and 52 weeks: [baseline to 26 weeks; baseline Phe 270 μmol/L (170–430); 26 weeks, Phe 300 μmol/L (125–485) p = 0.06; baseline to 52 weeks: baseline, Phe 270 μmol/L (170–430), 52 weeks Phe 300 μmol/L (200–490), p

BioMarin Pharmaceutical is developing pegvaliase (PALYNZIQ™) as a treatment for phenylketonuria, a genetic disorder caused by deficiency of phenylalanine hydroxylase which leads to neurotoxic accumulation of phenylalanine. Data from the phase III PRISM clinical trial program indicate treatment with pegvaliase is associated with sustained reductions in blood phenylalanine levels and sustained improvements in neurological sequelae in patients with phenylketonuria. Based on these positive results pegvaliase was recently approved in the US for adults with phenylketonuria who have uncontrolled blood phenylalanine concentrations on current treatment. This article summarizes the milestones in the development of pegvaliase leading to this first approval.

SSIEM and Springer 2007 BH4-responsive hyperphenylalaninaemia (HPA) is a recently described variant of phenylalanine hydroxylase (PAH) deficiency caused by specific mutations in the PAH gene. Diagnosis is performed by the tetrahydrobiopterin (BH4) loading test (20 mg/kg body weight) and the overall prevalence of BH4-responsiveness within patients with phenylketonuria (PKU) for blood phenylalanine reduction of 20%, 30%, 40% and 50% was found to be 48%, 38%, 31% and 24%, respectively, 8 h after the administration, and 55%, 46%, 41% and 33%, respectively, 24 h after the administration. Using the standard 30% cut-off, BH4-responsiveness was similar regardless of the two modalities in patients with mild hyperphenylalaninaemia (79–83% responders), mild PKU (49–60% responders), and classical PKU (7–10% responders). About 46% of all HPA patients

ResumenLas hiperfenilalaninemias se definen por un nivel sanguíneo de fenilalanina sobre 2mg/dl. La principal causa es una mutación en el gen que codifica la fenilalanina hidroxilasa que cataliza la reacción que transforma la fenilalanina en tirosina. Las hiperfenilalaninemias se clasifican en benignas o leves, y las fenilcetonurias en leves, moderadas y clásicas. Debido a que su detección más allá del periodo neonatal causa retardo mental severo, desde 1992 en Chile su detección, junto con la del hipotirodismo congénito, es parte del Programa Nacional de Pesquisa Neonatal. Este artículo pretende responder las preguntas más comunes que se puede hacer el pediatra cuando enfrenta a un paciente con hiperfenilalaninemias.AbstractHyperphenylalaninaemias are defined by a blood phenylalanine over 2mg/dl. The main cause is due to a mutation in the gene that codes the phenylalanine hydroxylase that catalyses the reaction that converts phenylalanine into tyrosine. The hyperphenylalaninaemias are classified into benign or mild hyperphenylalaninaemias, or mild, moderate or classic phenylketonurias. Due to its delayed detection outside the neonatal period it causes severe mental retardation. Its detection along with congenital hypothyroidism has been part of the National Neonatal Screening Program since 1992 in Chile. This article aims to answer the most common questions asked by the paediatrician when faced with a patient with hyperphenylalaninaemias.

The Phenylketonuria (PKU) Demographics, Outcomes and Safety (PKUDOS) registry is designed to provide longitudinal safety and efficacy data on subjects with PKU who are (or have been) treated with sapropterin dihydrochloride. The PKUDOS population consists of 1189 subjects with PKU: N = 504 who were continuously exposed to sapropterin from date of registry enrollment, N = 211 who had intermittent exposure to the drug, and N = 474 with some other duration of exposure. Subjects continuously exposed to sapropterin showed an average 34% decrease in blood phenylalanine (Phe)--from 591 ± 382 μmol/L at baseline to 392 ± 239 μmol/L (p = 0.0009) after 5 years. This drop in blood Phe was associated with an increase in dietary Phe tolerance [from 1000 ± 959 mg/day (pre-sapropterin baseline) to 1539 ± 840 mg/day after 6 years]. Drug-related adverse events (AEs) were reported in 6% of subjects, were mostly considered non-serious, and were identified in the gastrointestinal, respiratory, and nervous systems. Serious drug-related AEs were reported in ≤ 1% of subjects. Similar safety and efficacy data were observed for children

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 indicate that these symptoms are potentially reversible when blood Phe levels are reduced.

We analyzed long-term sustainability of improved blood Phenylalanine (Phe) control and changes to dietary Phe tolerance in 11 patients (1 month to 16 years), with various forms of primary PAH deficiency (classic, moderate, severe phenylketonuria [PKU], mild hyperphenylalaninemia [HPA]), who were treated with 15-20mg/kg/d Sapropterin-dihydrochloride during a period of 13-44 months. 7/11 patients had a sustainable, significant reduction of baseline blood Phe concentrations and 6 of them also had an increase in mg/kg/day Phe tolerance. In 2 patients with mild HPA, blood Phe concentrations remained in the physiologic range even after a 22 and 36% increase in mg/kg/day Phe tolerance and an achieved Phe intake at 105% and 268% of the dietary reference intake (DRI) for protein. 2 of these responders had classic PKU. 1 patient with mild HPA who started treatment at 2 months of life, had a significant and sustainable reduction in pretreatment blood Phe concentrations, but no increase in the mg/kg/day Phe tolerance. An increase in Phe tolerance could only be demonstrated when expressing the patient's daily Phe tolerance with the DRI for protein showing an increase from 58% at baseline to 78% of normal DRI at the end of the observation. Long-term follow-up of patients with an initial response to treatment with Sapropterin is essential to determine clinically meaningful outcomes. Phenylalanine tolerance should be expressed in mg/kg/day and/or % of normal DRI to differentiate medical therapy related from physiologic growth related increase in daily Phe intake.

We assessed the relationship between anxiety and long-term metabolic control in adolescents with phenylketonuria (PKU). We used a standardized psychological test to measure anxiety level and analyzed lifelong blood phenylalanine stability in a selected group of 25 PKU teenagers with treatment adherence problems. We demonstrated significant correlations of anxiety with variability of blood phenylalanine concentrations and with severity of hyperphenylalaninemia. Avoiding blood phenylalanine fluctuations in childhood can probably reduce anxiety in PKU adolescents.

Phenylketonuria (PKU) is an inborn error in phenylalanine metabolism due to deficiency of the enzyme, phenylalanine hydroxylase (PAH). Treatment includes restriction of dietary phenylalanine, and in some individuals, supplementation with the PAH cofactor, tetrahydrobiopterin (sapropterin dihydrochloride). A survey was conducted among patients with PKU who had been prescribed sapropterin to assess reasons for continuing or discontinuing the drug. The primary reason that sapropterin responders discontinued the drug was because of side effects, followed by insufficient reduction of blood phenylalanine and insurance issues. Conversely, those who remained on therapy cited increased tolerance for dietary protein as the main reason for continuation, along with lower blood phenylalanine concentrations and feeling better. This study suggests that adherence to sapropterin therapy is mainly dependent upon the increase in dietary protein allowed when on the drug.

The objective of this research was to collect data on the prevalence of phenylketonuria in Jordan, to assess the nutritional status and physical growth of a sample of PKU patients in Jordan using anthropometric measurements and evaluation of the adequacy of their diets. Twenty five patients were divided, according to their age, into four groups: 4-6 months age (n = 6), 8-12 months age (n = 5), 2 years old (n = 7) and 4 years old (n = 7). Height, weight, triceps and subscapular skinfold thicknesses were measured. Dietary intake was taken using three-day food records, and blood phenylalanine (Phe) concentration was determined. The results indicated that 48% of the whole sample had poor physical growth; about (66%) of patients in group 1, (40%) of patients in group 2, (28%) of patients in group 3 and (57%) of patients in group 4 were underweight. Significant positive correlations (p < 0.05) were found between protein intake and each of head circumference (r = 0.434) weight (0.420) and height (r = 0.502) of patients. The protein intakes were 77% and 88% of the recommended levels for groups 1 and 2 respectively. Other low dietary intakes included energy (in groups 1 and 4), fat (in groups 1 and 3) and selenium (in group 1). All patients had controlled blood Phe levels except those in group 4 (4 years age) who had a concentration of 358mol/L. It is concluded that there is need for counseling the community about the relationship between PKU and consanguineous marriages and for stressing the importance of monitoring the dietary management of PKU patients.

Fluctuations in blood phenylalanine concentrations may be an important determinant of intellectual outcome in patients with early and continuously treated phenylketonuria (PKU). This review evaluates the studies on phenylalanine fluctuations, factors affecting fluctuations, and if stabilizing phenylalanine concentrations affects outcomes, particularly neurocognitive outcome. Electronic literature searches of Embase and PubMed were performed for English-language publications, and the bibliographies of identified publications were also searched. In patients with PKU, phenylalanine concentrations are highest in the morning. Factors that can affect phenylalanine fluctuations include age, diet, timing and dosing of protein substitute and energy intake, dietary adherence, phenylalanine hydroxylase genotype, changes in dietary phenylalanine intake and protein metabolism, illness, and growth rate. Even distribution of phenylalanine-free protein substitute intake throughout 24 h may reduce blood phenylalanine fluctuations. Patients responsive to and treated with 6R-tetrahydrobiopterin seem to have less fluctuation in their blood phenylalanine concentrations than controls. An increase in blood phenylalanine concentration may result in increased brain and cerebrospinal fluid phenylalanine concentrations within hours. Although some evidence suggests that stabilization of blood phenylalanine concentrations may have benefits in patients with PKU, more studies are needed to distinguish the effects of blood phenylalanine fluctuations from those of poor metabolic control. (C) 2013 The Authors. Published by Elsevier Inc. All rights reserved.

We are reporting a retrospective review of blood phenylalanine (Phe) concentrations in 33 patients with classical phenylketonuria (PKU) born between 1991 and 2009 and continuously followed up in our clinic in 2009. As an indicator of blood Phe control, we analysed the percentage of blood Phe concentrations within and outside of the treatment range for each individual for treatment periods between 1 month and 12 months, 1 to 6 years, and 6 to 12 years of age. Despite early diagnosis and medical management in a centralized care model, only approximately 40% of patients had 60% and more of their blood Phe concentrations within the treatment range during their lifetime treatment periods. There was no statistical difference for the percentage of blood Phe concentrations within the treatment range, the mean Phe concentrations or the SD between the various treatment periods. We found a correlation between Phe tolerance and percentage of blood Phe concentrations within the treatment range. Patients born between 1991 and 1999 had poorer control than those born later. A frequent quality assurance audit is recommended to assess treatment outcomes in clinics providing care to children with PKU.