Conversion Of Phenylalanine Research Articles

Nutrition in phenylketonuria

Phenylketonuria (PKU) is a genetic metabolic disease resulting from a deficiency in the enzyme phenylalanine hydroxylase. This defect prevents the conversion of phenylalanine to tyrosine, and as a result, the level of phenylalanine in the body increases abnormally. The accumulation of this amino acid may cause brain damage and grows development in these patients.The primary approach to treating the disease involves dietary management that restricts protein and phenylalanine intake, often alongside Tetrahydrobiopterin (BH4) supplementation. Medical foods specifically formulated for these patients are utilized to supply the necessary energy, protein, and tyrosine. Other treatment options, including the use of large neutral amino acids (LNAAs) and the enzyme Phenylalanine ammonia lyase (PAL), can be utilized to manage symptoms in adult patients. Advancements in gene therapy aimed at correcting defective genes in patients may help restore phenylalanine metabolism, though further research in this area is necessary. Effective personal management of phenylketonuria necessitates enhanced knowledge and collaboration among healthcare professionals to achieve optimal treatment outcomes for patients. This article emphasis the nutritional management of individuals with phenylketonuria across various stages of their lives.

Toxic Determination of Cry11 Mutated Proteins Obtained Using Rational Design and Its Computational Analysis.

Cry11 proteins are toxic to Aedes aegypti, the vector of dengue, chikungunya, and Zika viruses. Cry11Aa and Cry11Bb are protoxins, which when activated present their active-toxin form in two fragments between 30 and 35 kDa respectively. Previous studies conducted with Cry11Aa and Cry11Bb genes using DNA shuffling generated variant 8, which presented a deletion in the first 73 amino acids and one at position 572 and 9 substitutions including L553F and L556W. In this study, variant 8 mutants were constructed using site-directed mutagenesis, resulting in conversion of phenylalanine (F) and tryptophan (W) to leucine (L) at positions 553 and 556, respectively, producing the mutants 8F553L, 8W556L, and 8F553L/8W556L. Additionally, two mutants, A92D and C157R, derived from Cry11Bb were also generated. The proteins were expressed in the non-crystal strain BMB171 of Bacillus thuringiensis and subjected to median-lethal concentration (LC50) tests on first-instar larvae of A. aegypti. LC50 analysis showed that the 8F553L, 8W556L, 8F553L/8W556L, and C157R variants lost their toxic activity (>500 ng·mL-1), whereas the A92D protein presented a loss of toxicity of 11.4 times that of Cry11Bb. Cytotoxicity assays performed using variant 8, 8W556L and the controls Cry11Aa, Cry11Bb, and Cry-negative BMB171 on the colorectal cancer cell line SW480 reported 30-50% of cellular viability except for BMB171. Molecular dynamic simulations performed to identify whether the mutations at positions 553 and 556 were related to the stability and rigidity of the functional tertiary structure (domain III) of the Cry11Aa protein and variant 8 showed the importance of these mutations in specific regions for the toxic activity of Cry11 against A. aegypti. This generates pertinent knowledge for the design of Cry11 proteins and their biotechnological applications in vector-borne disease control and cancer cell lines.

Expert opinion of an Italian working group on the assessment of cognitive, psychological, and neurological outcomes in pediatric, adolescent, and adult patients with phenylketonuria

Phenylketonuria (PKU) is an inherited metabolic disease characterized by a defective conversion of phenylalanine (Phe) to tyrosine, potentially leading to Phe accumulation in the brain. Dietary restriction since birth has led to normal cognitive development. However, PKU patients can still develop cognitive or behavioral abnormalities and subtle neurological deficits. Despite the increasing evidence in the field, the assessment of neurocognitive, psychopathological, and neurological follow-up of PKU patients at different ages is still debated. The high interindividual variability in the cognitive outcome of PKU patients makes the specificity of the neurocognitive and behavioral assessment extremely challenging. In the present paper, a multidisciplinary panel of Italian PKU experts discussed different tools available for cognitive, psychopathological, and neurological assessment at different ages based on the existing literature and daily clinical practice. This study aims to provide evidence and a real-life-based framework for a specific clinical assessment of pediatric, adolescent, and adult patients affected by PKU.

Biotransformation of the Proteogenic Amino Acids Phenylalanine, Tyrosine and Tryptophan by Yarrowia Species: An Application to the Preparative Synthesis of Natural Phenylacetic Acid

The biotransformation of the aromatic amino acids phenylalanine, tyrosine and tryptophan originates a number of bioactive compounds. Yeasts are the most used microorganisms for the transformation of (L)-phenylalanine into the flavour phenylethanol. Here, we reported a study on the biotransformation of the proteogenic aminoacids phenylalanine, tyrosine and tryptophan by yeast strains belonging to Yarrowia genus. We found that the latter microorganisms, in high aerobic conditions, metabolise the aromatic amino acids (L)-phenylalanine and (L)-tyrosine with the almost exclusive formation of phenylacetic acid and 4-hydroxyphenylacetic acid, respectively. Differently, the biotransformation of (L)-tryptophan with Y. lipolytica, gave anthranilic acid as the main product. As stated by the European and USA legislations concerning natural flavour production, phenylacetic acid obtained by microbial conversion of phenylalanine of natural origin can be commercialised as a natural flavour. Accordingly, our findings were exploited in a new process, based on the Yarrowia strains-mediated biotransformation of natural (L)-phenylalanine, that allows the large-scale preparation of the high-value, natural flavour, phenylacetic acid.

Recruitment of distinct UDP-glycosyltransferase families demonstrates dynamic evolution of chemical defense within Eucalyptus L'Hér.

The economic and ecologically important genus Eucalyptus is rich in structurally diverse specialized metabolites. While some specialized metabolite classes are highly prevalent across the genus, the cyanogenic glucoside prunasin is only produced by c. 3% of species. To investigate the evolutionary mechanisms behind prunasin biosynthesis in Eucalyptus, we compared de novo assembled transcriptomes, together with online resources between cyanogenic and acyanogenic species. Identified genes were characterized invivo and invitro. Pathway characterization of cyanogenic Eucalyptus camphora and Eucalyptus yarraensis showed for the first time that the final glucosylation step from mandelonitrile to prunasin is catalyzed by a novel UDP-glucosyltransferase UGT87. This step is typically catalyzed by a member of the UGT85 family, including in Eucalyptus cladocalyx. The upstream conversion of phenylalanine to mandelonitrile is catalyzed by three cytochrome P450 (CYP) enzymes from the CYP79, CYP706, and CYP71 families, as previously shown. Analysis of acyanogenic Eucalyptus species revealed the loss of different ortholog prunasin biosynthetic genes. The recruitment of UGTs from different families for prunasin biosynthesis in Eucalyptus demonstrates important pathway heterogeneities and unprecedented dynamic pathway evolution of chemical defense within a single genus. Overall, this study provides relevant insights into the tremendous adaptability of these long-lived trees.

Piperonylic acid alters growth, mineral content accumulation and reactive oxygen species-scavenging capacity in chia seedlings.

p-Coumaric acid synthesis in plants involves the conversion of phenylalanine to trans-cinnamic acid via phenylalanine ammonia-lyase (PAL), which is then hydroxylated at the para-position under the action of trans-cinnamic acid 4-hydroxylase. Alternatively, some PAL enzymes accept tyrosine as an alternative substrate and convert tyrosine directly to p-coumaric acid without the intermediary of trans-cinnamic acid. In recent years, the contrasting roles of p-coumaric acid in regulating the growth and development of plants have been well-documented. To understand the contribution of trans-cinnamic acid 4-hydroxylase activity in p-coumaric acid-mediated plant growth, mineral content accumulation and the regulation of reactive oxygen species (ROS), we investigated the effect of piperonylic acid (a trans-cinnamic acid 4-hydroxylase inhibitor) on plant growth, essential macroelements, osmolyte content, ROS-induced oxidative damage, antioxidant enzyme activities and phytohormone levels in chia seedlings. Piperonylic acid restricted chia seedling growth by reducing shoot length, fresh weight, leaf area measurements and p-coumaric acid content. Apart from sodium, piperonylic acid significantly reduced the accumulation of other essential macroelements (such as K, P, Ca and Mg) relative to the untreated control. Enhanced proline, superoxide, hydrogen peroxide and malondialdehyde contents were observed. The inhibition of trans-cinnamic acid 4-hydroxylase activity significantly increased the enzymatic activities of ROS-scavenging enzymes such as superoxide dismutase, ascorbate peroxidase, catalase and guaiacol peroxidase. In addition, piperonylic acid caused a reduction in indole-3-acetic acid and salicylic acid content. In conclusion, the reduction in chia seedling growth in response to piperonylic acid may be attributed to a reduction in p-coumaric acid content coupled with elevated ROS-induced oxidative damage, and restricted mineral and phytohormone (indole-3-acetic acid and salicylic) levels.

Succession of endophytic bacterial community and its contribution to cinnamon oil production during cinnamon shade-drying process

Cinnamon oil is a blend of secondary metabolites and is widely used as spice. Endophytic bacteria are always related to the secondary metabolites production. However, the potential of endophytic bacteria communities for cinnamon oil production during cinnamon shade-drying process is still not clear. In this study, we investigated the composition and metabolic function of endophytic bacterial community during 80-day shade-drying process. The temporal dynamics of essential oil content and its dominant constituents were analyzed. The succession of endophytic bacterial community from d0 to d80 was identified. The influence of endophytic bacterial community evolution on cinnamon oil is significant positive. Predictive functional analysis indicated that shade-drying process was rich in Saccharopolyspora that produce enzymes for the conversion of phenylalanine to cinnamaldehyde. These findings enhance our understanding of the functional bacterial genera and functional genes involved in the production of cinnamon oil during cinnamon shade-drying process.

Neural correlates of working memory and its association with metabolic parameters in early-treated adults with phenylketonuria

BackgroundPhenylketonuria (PKU) is an inborn error of metabolism affecting the conversion of phenylalanine (Phe) into tyrosine. Previous research has found cognitive and functional brain alterations in individuals with PKU even if treated early. However, little is known about working memory processing and its association with task performance and metabolic parameters. The aim of the present study was to examine neural correlates of working memory and its association with metabolic parameters in early-treated adults with PKU. MethodsThis cross-sectional study included 20 early-treated adults with PKU (mean age: 31.4 years ± 9.0) and 40 healthy controls with comparable age, sex, and education (mean age: 29.8 years ± 8.2). All participants underwent functional magnetic resonance imaging (fMRI) of working memory to evaluate the fronto-parietal working memory network. Fasting blood samples were collected from the individuals with PKU to acquire a concurrent plasma amino acid profile, and retrospective Phe concentrations were obtained to estimate an index of dietary control. ResultsOn a cognitive level, early-treated adults with PKU displayed significantly lower accuracy but comparable reaction time in the working memory task compared to the control group. Whole-brain analyses did not reveal differences in working memory-related neural activation between the groups. Exploratory region-of-interest (ROI) analyses indicated reduced neural activation in the left and right middle frontal gyri and the right superior frontal gyrus in the PKU group compared to the control group. However, none of the ROI analyses survived correction for multiple comparisons. Neural activation was related to concurrent Phe, tyrosine, and tryptophan concentrations but not to retrospective Phe concentrations. ConclusionIn early-treated adults with PKU, cognitive performance and neural activation are slightly altered, a result that is partly related to metabolic parameters. This study offers a rare insight into the complex interplay between metabolic parameters, neural activation, and cognitive performance in a sample of individuals with PKU.

Food Regime for Phenylketonuria: Presenting Complications and Possible Solutions.

In the category of rare inherited genetic disorders, phenylketonuria is a prominent example. Here, the defective phenylalanine hydroxylase enzyme fails to catalyze conversion of phenylalanine to tyrosine. This leads to not only excess deposition of phenylalanine leading to phenylalanine toxicity but also precludes the production of important glutamatergic and cholinergic neurotransmitters, leading to epileptic disorders, microcephaly, low intelligence quotient etc. For long, specialized food products are considered as preferred solution to prevent disease outcome. Different medical diets are developed for managing phenylketonuria includes amino acid mixtures, protein hydrolysates, cofactor-based therapy, large neutral amino acids and glycomacropeptides. However, despite the advent of alternate forms of diet products, the central form of treatment has still been free amino acid mixture. The formulated diet is by and large expensive and in-depth evaluation of several factors which contribute to the expense of medicated diet is requisite to create effective yet affordable avenues for management of disease. For this, we have discussed the role of various factors involved in increasing price of medicated diet and presented possible solutions to it. We have also extensively reviewed prevalence of disease, commercial diet for PKU patients, and their associated limitations. Overall, this is the first attempt to present a holistic view of balance between the overall impact of diet associated therapy and weighing it against the associated finances incurred.

Italian national consensus statement on management and pharmacological treatment of phenylketonuria

BackgroundPhenylketonuria (PKU) is a rare inherited metabolic disorder caused by defects in the phenylalanine-hydroxylase gene (PAH), the enzyme catalyzing the conversion of phenylalanine to tyrosine. PAH impairment causes phenylalanine accumulation in the blood and brain, with a broad spectrum of pathophysiological and neurological consequences for patients. Prevalence of disease varies, with peaks in some regions and countries, including Italy. A recent expert survey described the real-life of clinical practice for PKU in Italy, revealing inhomogeneities in disease management, particularly concerning approach to pharmacotherapy with sapropterin hydrochloride, analogous of the natural PAH co-factor, allowing disease control in a subset of patients. Therefore, the purpose of this paper is to continue the work initiated with the expert survey paper, to provide national guidances aiming to harmonize and optimize patient care at a national level.ParticipantsThe Consensus Group, convened by 10 Steering Committee members, consisted of a multidisciplinary crowd of 46 experts in the management of PKU in Italy.Consensus processThe Steering Committee met in a series of virtual meeting in order to discuss on clinical focuses to be developed and analyzed in guidance statements, on the basis of expert practice based evidence, large systematic literature review previously performed in the expert survey paper, and evidence based consensus published. Statements were re-discussed and refined during consensus conferences in the widest audience of experts, and finally submitted to the whole consensus group for a modified-Delphi voting.ResultsSeventy three statements, divided in two main clinical areas, PKU management and Pharmacotherapy, achieved large consensus in a multidisciplinary group of expert in different aspects of disease. Importantly, these statements involve guidances for the use of sapropterin dihydrochloride, still not sufficiently implemented in Italy, and a set of good practice to approach the use of novel enzyme replacement treatment pegvaliase.ConclusionsThis evidence-based consensus provides a minimum set of guidances for disease management to be implemented in all PKU centers. Moreover, these guidances represent the first statement for sapropterin dihydrochloride use, implementation and standardization in Italy, and a guide for approaching pegvaliase treatment at a national level on a consistent basis.

Determination of L-Phenylalanine in Human Plasma Samples with New Fluorometric Method.

The measurement of phenylalanine in biological fluids for the diagnosis of phenylketonuria (PKU) in newborns and the monitoring/therapeutic drug monitoring of individuals with PKU are especially important. Owing to the importance of PKU monitoring in clinical medicine, a new fluorometric method was developed for the determination of L-phenylalanine in serum samples. This method is based on the relationship between phenylalanine ammonia-lyase (PAL) and o-phthalaldehyde (OPA). PAL catalyzes the conversion of phenylalanine to ammonia and trans-cinnamic acid. The formed ammonia reacts with OPA in the presence of sodium sulfite, giving a fluorescent product. The presence of sulfide in an alkaline environment prevents OPA from reacting with other amino acids while allowing it to react only with ammonia. Method characterization and optimization studies, such as the effects of pH, temperature, and interferents, were carried out. The amount of L-phenylalanine in a human serum sample was successfully determined by using the fluorescence emission intensity of the fluorescent product formed as a result of the reaction between OPA and ammonia. The linear range of the method is between 10μM and 10mM. The obtained result showed good agreement with the results of the biochemistry analysis laboratory. Recoveries of 95.41% and 73.39% were obtained for phenylalanine and ammonia, respectively. This PAL-OPA-based fluorometric method for phenylalanine is practical, easy to operate, low cost, highly sensitive, and selective and can also be used for the simultaneous determination of ammonia in human serum samples.

A phosphoproteomic approach reveals that PKD3 controls PKA-mediated glucose and tyrosine metabolism.

Members of the protein kinase D (PKD) family (PKD1, 2, and 3) integrate hormonal and nutritional inputs to regulate complex cellular metabolism. Despite the fact that a number of functions have been annotated to particular PKDs, their molecular targets are relatively poorly explored. PKD3 promotes insulin sensitivity and suppresses lipogenesis in the liver of animals fed a high-fat diet. However, its substrates are largely unknown. Here we applied proteomic approaches to determine PKD3 targets. We identified more than 300 putative targets of PKD3. Furthermore, biochemical analysis revealed that PKD3 regulates cAMP-dependent PKA activity, a master regulator of the hepatic response to glucagon and fasting. PKA regulates glucose, lipid, and amino acid metabolism in the liver, by targeting key enzymes in the respective processes. Among them the PKA targets phenylalanine hydroxylase (PAH) catalyzes the conversion of phenylalanine to tyrosine. Consistently, we showed that PKD3 is activated by glucagon and promotes glucose and tyrosine levels in hepatocytes. Therefore, our data indicate that PKD3 might play a role in the hepatic response to glucagon.

Subcortical band heterotopia in a patient with phenylketonuria: Co-Existence or consequence?

Phenylketonuria (PKU) is an autosomal recessive metabolic disorder caused by deficient activity of phenylalanine hydroxylase, an enzyme that catalyzes the conversion of phenylalanine (PHE) to tyrosine. Tyrosine is further converted into catecholamines, melanin and thyroid hormones. Without dietary restriction, PHE accumulates in blood and tissue and causes secondary deficit of the above-mentioned metabolites, commonly leading to cerebral white matter (WM) abnormalities, microcephaly, neurological and cognitive deficits, behavioral problems, and epilepsy.

Energy metabolism profile of the effects of amino acid treatment on hepatocytes: Phenylalanine and phenylpyruvate inhibit glycolysis of hepatocytes.

Amino acids are not only the building blocks of proteins, but also can be metabolized to energy substances or function as signaling molecules. The aim of this study was to profile whether amino acid treatment (essential amino acids and alanine) affects the energy metabolism (glycolysis, mitochondrial respiration) of cultured hepatocytes. AML12 hepatocytes were treated with 5 mM of each amino acid for 1 h and the energy metabolism was then measured by using an extracellular flux analyzer. The results showed that phenylalanine and lysine decreased the extracellular acidification rate (ECAR), an indirect indicator of glycolysis, whereas isoleucine and histidine increased the ECAR. Amino acids did not affect the oxygen consumption rate, an indirect indicator of mitochondrial respiration. The glycolysis stress test revealed that treatment of the hepatocytes with phenylalanine inhibited glycolysis when the concentration of the substrate for glycolysis was sufficient in cultured media. We also investigated the effect of metabolites derived from conversion of phenylalanine on glycolysis in hepatocytes and found that phenylpyruvate inhibited glycolysis, whereas tyrosine and phenylethylamine did not affect glycolysis. The findings from the present study complement basic knowledge of the effects of amino acid treatment on energy metabolism in cultured hepatocytes and indicate that phenylalanine and phenylpyruvate inhibit glycolysis.

Development of low phenylalanine flour for phenylketonuric patient

Phenylketonuria is an autosomal recessive genetic disorder due to the mutation in the phenylalanine hydroxylase (PAH) gene which results in the lower level of phenylalanine hydroxylase enzyme, hence the conversion of phenylalanine (Phe) to tyrosine does not take place and excess Phe takes an alternate pathway to produce phenylketones. This manuscript describes the attempts made toward the development of a gelatin-based multipurpose flour with other low-cost ingredients as the available food products for PKU patients in the market are very expensive and affordability becomes an issue for the patients. The flour is easily bakeable, friable, extrudable, and can be mixed with an adequate amount of water to make new products. The Phe content of the sample was 251.8 mg/100 g of flour which was well within the limits, as recommended by the WHO. The experimentally developed biscuits from the flour has low Phe content and is suitable for PKU patients. Some of the applications for proposed low phenylalanine flour for phenylketonuric patient could be as a diet supplement for the patient suffering from PKU. The key advantage of this multipurpose flour is the low cost of the flour having high nutritional value. The flour can be used for baking, extrusion, and frying purpose. The functional and sensory properties of the biscuit formulated from the flour, are in par with commercially available biscuits indicating its suitability for commercialization. Furthermore, work on improving the flour quality and other functional properties of the flour can be studied. Practical applications The present article focuses on the importance of diet supplement for the patient suffering from PKU. The important advantage of multipurpose flour is the low cost of the ingredients and high nutritional value. The functional and sensory properties were in par with commercially available biscuit indicating its suitability for consumption. Further work on improving the flour quality and other functional properties of the flour can also be studied.

A Biochemical Method for Tyrosine Determination in Phenylketonuria Using a Colorimetric Enzymatic Approach

Phenylketonuria is a serious genetic disease caused by a deficiency of phenylalanine metabolism, an essential amino acid found in daily nutrition. This disorder is caused by the lack of a specific enzyme called phenylalanine hydroxylase which mediates the conversion of phenylalanine to tyrosine). Thus, after ingestion of phenyl alanine-rich proteins, the amino acid concentration increases considerably in the blood due to proteolysis. Genetic deffects of enzymes responsible for phenylalanine metabolic conversion were intensively studied. Among them the defect of gene encoding phenylalanine hydroxylase has a higher notoriety. This genetic defect is translated in an inactive enzyme constructs that impair the aminoacid hydroxylation. This physiological stage is also called hyperphenylalaninemia where slightly high levels of phenylalanine are noticed in the blood or urine. Consequently, the amino acid is converted to phenylpyruvic acid by transamination, the later displaying a particularly toxic effect against brain tissues. The aim of this study was to quantify tyrosine in the blood of patients suffering of phenylketonuria by an alternative enzymatic method. The tyrosinase used in this assay was extracted from commercial mushrooms (Agaricus bisporus) following the Haghbeen protocol with some modifications. Two chromatographic steps (molecular exclusion chromatography and ionic exchange chromatography) were used during the enzyme purification process. High purity samples were concentrated using ultrafiltration. The tyrosinase was screened by a classical enzymatic microplate assay having DOPA as a substrate. Finally the pure enzyme was used in order to quantify tyrosine from different standard solutions. The level of tyrosine from deproteinized serum samples was determined using a similar enzymatic strategy.

Metabolic analysis of phenolic profiles reveals the enhancements of anthocyanins and procyanidins in postharvest peach as affected by hot air and ultraviolet C

Abstract Anthocyanins are one of the most critical components in peach fruit and are responsible for their visual appearance and nutritional value. In this study, hot air (HA) and UV-C treatments were applied to induce colour development. Peach fruit were treated with HA (40 °C, 4 h) or UV-C (1.5 kJ m−2, 20 min for each side) and then stored at 1 °C for 35 d plus another 3 d at 20 °C. The results showed that anthocyanins, procyanidins (PAs) and cyanidin-3-glucoside (Cya-3-G) increased in response to HA and UV-C during the storage period. LC–MS/MS analysis indicated that most of the individual phenols increased in response to the two treatments. However, l -phenylalanine significantly decreased. HA and UV-C significantly upregulated the enzyme activity and gene expression of phenylalanine ammonialyase to promote the conversion of phenylalanine into downstream compounds. The activities of leucoanthocyanidin reductase and anthocyanidin reductase were enhanced by HA and UV-C, which led to the accumulation of PAs. Besides, the activities of dihydroflavonol reductase, anthocyanidin synthase and UDP-glucose: flavonoid 3-o-glucosyltransferase increased in response to the two treatments, with increased contents of Cya-3-G, leucopelargonidin and pelargonidin-3-G occurring in treated fruit. In summary, HA and UV-C promoted the synthesis of anthocyanins and PAs by enhancing the activities and expressions of enzymes involved in phenylpropanoid metabolism.

Simplified Diet for nutrition management of phenylketonuria: A survey of U.S. metabolic dietitians.

BackgroundPhenylketonuria (PKU) is an inherited metabolic disorder affecting the conversion of phenylalanine (Phe) to tyrosine. Medical nutrition therapy, consisting of a Phe‐restricted diet with medical formula, is the primary treatment for PKU. The Simplified Diet is an approach to PKU nutrition management that allows certain fruits, vegetables, and low‐protein foods to be eaten without measuring or tracking, referred to as free/uncounted foods. There is no consensus on how to implement this approach in metabolic centers in the United States (U.S.), and clinical practice varies.AimThis study describes the clinical experience of metabolic dietitians in U.S.‐based metabolic centers related to the use and implementation of the Simplified Diet.MethodsA survey was developed and sent out to metabolic dietitians to query current clinical practices related to the Simplified Diet. Descriptive statistics were used to analyze responses.ResultsSixty‐three dietitians managing ≥5 patients with PKU in U.S.‐based metabolic centers responded to the survey. Ninety‐eight percent of survey respondents reported using some version of the Simplified Diet in clinical practice. The survey identified areas of strong agreement, including introduction of the Simplified Diet at 6 to 12 months of age. The survey also identified areas of widespread variability, including specific Phe or protein thresholds for free/uncounted foods, and whether or not to set daily quantity limits on these foods.ConclusionsSignificant variability related to implementation of the Simplified Diet exists across U.S.‐based metabolic centers. This practice variability may contribute to differences in the patient experience across centers and may indicate a need for development of clinical guidelines.

Sustained Correction of a Murine Model of Phenylketonuria following a Single Intravenous Administration of AAVHSC15-PAH

Phenylketonuria is an inborn error of metabolism caused by loss of function of the liver-expressed enzyme phenylalanine hydroxylase and is characterized by elevated systemic phenylalanine levels that are neurotoxic. Current therapies do not address the underlying genetic disease or restore the natural metabolic pathway resulting in the conversion of phenylalanine to tyrosine. A family of hepatotropic clade F adeno-associated viruses (AAVs) was isolated from human CD34+ hematopoietic stem cells (HSCs) and one (AAVHSC15) was utilized to deliver a vector to correct the phenylketonuria phenotype in Pahenu2 mice. The AAVHSC15 vector containing a codon-optimized form of the human phenylalanine hydroxylase cDNA was administered as a single intravenous dose to Pahenu2 mice maintained on a phenylalanine-containing normal chow diet. Optimization of the transgene resulted in a vector that produced a sustained reduction in serum phenylalanine and normalized tyrosine levels for the lifespan of Pahenu2 mice. Brain levels of phenylalanine and the downstream serotonin metabolite 5-hydroxyindoleacetic acid were restored. In addition, the coat color of treated mice darkened following treatment, indicating restoration of the phenylalanine metabolic pathway. Taken together, these data support the potential of an AAVHSC15-based gene therapy as an investigational therapeutic for phenylketonuria patients.

First-in-human study of a liver-directed AAV gene therapy (FLT190) in Fabry disease

Phenylketonuria is an inborn error of metabolism caused by loss of function of the liver-expressed enzyme phenylalanine hydroxylase and is characterized by elevated systemic phenylalanine levels that are neurotoxic. Current therapies do not address the underlying genetic disease or restore the natural metabolic pathway resulting in the conversion of phenylalanine to tyrosine. A family of hepatotropic clade F adeno-associated viruses (AAVs) was isolated from human CD34+ hematopoietic stem cells (HSCs) and one (AAVHSC15) was utilized to deliver a vector to correct the phenylketonuria phenotype in Pahenu2 mice. The AAVHSC15 vector containing a codon-optimized form of the human phenylalanine hydroxylase cDNA was administered as a single intravenous dose to Pahenu2 mice maintained on a phenylalanine-containing normal chow diet. Optimization of the transgene resulted in a vector that produced a sustained reduction in serum phenylalanine and normalized tyrosine levels for the lifespan of Pahenu2 mice. Brain levels of phenylalanine and the downstream serotonin metabolite 5-hydroxyindoleacetic acid were restored. In addition, the coat color of treated mice darkened following treatment, indicating restoration of the phenylalanine metabolic pathway. Taken together, these data support the potential of an AAVHSC15-based gene therapy as an investigational therapeutic for phenylketonuria patients.