Publications by authors named "Harvey Levy"

77 Publications

Robert Guthrie and the Trials and Tribulations of Newborn Screening.

Authors:
Harvey L Levy

Int J Neonatal Screen 2021 Jan 19;7(1). Epub 2021 Jan 19.

Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA 02115, USA.

Routine newborn screening for many disorders is now so ingrained in newborn care that there is no question about whether it should be done. However, acceptance of newborn screening was not guaranteed when Robert Guthrie introduced it for phenylketonuria (PKU). This article describes the professional and personal story of Guthrie, a physician and microbiologist, who veered from cancer research to a commitment to prevent intellectual disability from PKU. It recounts how Guthrie was able to overcome strong opposition to mandatory screening from prominent physicians and medical societies, so that newborn screening for PKU would be routinely performed throughout the developed world, and would eventually form the basis for the (much more) comprehensive screening conducted today.
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http://dx.doi.org/10.3390/ijns7010005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7838808PMC
January 2021

Pancreatic involvement in patients with inborn errors of metabolism.

Orphanet J Rare Dis 2021 Jan 20;16(1):37. Epub 2021 Jan 20.

Department of Pediatrics, College of Medicine, Chungnam National University, Daejeon, Korea.

Background: Repeated inflammation of the pancreas can cause pancreatitis or diabetes. It is well recognized that the organic acidemias may be complicated by pancreatitis but less recognized are other metabolic disorders in which pancreatitis can occur. This study shows that long-term follow-up of patients with various metabolic disorders in Korea revealed several with episodes of isolated pancreatitis or diabetes concomitantly with pancreatitis.

Results And Discussion: In this study, two patients with methylmalonic aciduria (MMA), two with propionic acidemia (PPA), one with fatty acid oxidation disorder (FAOD), and one with hyperornithinemia, gyrate atrophy, and juvenile onset diabetes mellitus (DM) were clinically followed for up to 10 - 21 years. Two Korean siblings with MMA showed recurrent pancreatitis from the age of 15 and 19, respectively. The frequency of admission due to pancreatitis was up to 11 times. One patient with MMA developed diabetes mellitus at the age of 20. The other patient with MMA developed recurrent pancreatitis at 4 years and diabetes at 8 years of age. One of the patients with PPA presented with diabetic ketoacidosis. The other PPA patient died of cardiac arrest at age 10. The patient with FAOD presented with pancreatitis at 10 years and died at the age of 15 years due to cardiac arrest. A 35-year-old woman with hyperornithinemia/gyrate atrophy was diagnosed with juvenile onset diabetes at the age of 7 years. No pancreatitis occurred during the follow-up period.

Conclusions: We conclude that various metabolic disorders can trigger acute or chronic pancreatitis. Proper and prompt multidisciplinary management of metabolic derangement is crucial for preventing pancreatic damage. Further clinical and investigational studies are required to elucidate the pathogenesis of pancreatitis and diabetes mellitus in patients with inborn errors in metabolism.
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http://dx.doi.org/10.1186/s13023-021-01685-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7819202PMC
January 2021

Ethical and Psychosocial Implications of Genomic Newborn Screening.

Authors:
Harvey L Levy

Int J Neonatal Screen 2021 Jan 9;7(1). Epub 2021 Jan 9.

Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA 02115, USA.

The potential for genomic screening of the newborn, specifically adding genomic screening to current newborn screening (NBS), raises very significant ethical issues. Regardless of whether NBS of this type would include entire genomes or only the coding region of the genome (exome screening) or even sequencing specific genes, the ethical issues raised would be enormous. These issues include the limitations of bioinformatic interpretation of identified variants in terms of pathogenicity and accurate prognosis, the potential for substantial uncertainty about appropriate diagnosis, therapy, and follow-up, the possibility of much anxiety among providers and parents, the potential for unnecessary treatment and "medicalizing" normal children, the possibility of adding large medical costs for otherwise unnecessary follow-up and testing, the potential for negatively impacting medical and life insurance, and the almost impossible task of obtaining truly-informed consent. Moreover, the potentially-negative consequences of adding genomic sequencing to NBS might jeopardize all of NBS which has been and continues to be so beneficial for thousands of children and their families throughout the world.
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http://dx.doi.org/10.3390/ijns7010002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7838903PMC
January 2021

The Genetic Landscape and Epidemiology of Phenylketonuria.

Am J Hum Genet 2020 08 14;107(2):234-250. Epub 2020 Jul 14.

Division of Child Neurology and Metabolic Medicine, Centre for Child and Adolescent Medicine, Clinic I, University Hospital Heidelberg, 69120 Heidelberg, Germany; Division of Metabolism, University Children's Hospital, 8032 Zürich, Switzerland. Electronic address:

Phenylketonuria (PKU), caused by variants in the phenylalanine hydroxylase (PAH) gene, is the most common autosomal-recessive Mendelian phenotype of amino acid metabolism. We estimated that globally 0.45 million individuals have PKU, with global prevalence 1:23,930 live births (range 1:4,500 [Italy]-1:125,000 [Japan]). Comparing genotypes and metabolic phenotypes from 16,092 affected subjects revealed differences in disease severity in 51 countries from 17 world regions, with the global phenotype distribution of 62% classic PKU, 22% mild PKU, and 16% mild hyperphenylalaninemia. A gradient in genotype and phenotype distribution exists across Europe, from classic PKU in the east to mild PKU in the southwest and mild hyperphenylalaninemia in the south. The c.1241A>G (p.Tyr414Cys)-associated genotype can be traced from Northern to Western Europe, from Sweden via Norway, to Denmark, to the Netherlands. The frequency of classic PKU increases from Europe (56%) via Middle East (71%) to Australia (80%). Of 758 PAH variants, c.1222C>T (p.Arg408Trp) (22.2%), c.1066-11G>A (IVS10-11G>A) (6.4%), and c.782G>A (p.Arg261Gln) (5.5%) were most common and responsible for two prevalent genotypes: p.[Arg408Trp];[Arg408Trp] (11.4%) and c.[1066-11G>A];[1066-11G>A] (2.6%). Most genotypes (73%) were compound heterozygous, 27% were homozygous, and 55% of 3,659 different genotypes occurred in only a single individual. PAH variants were scored using an allelic phenotype value and correlated with pre-treatment blood phenylalanine concentrations (n = 6,115) and tetrahydrobiopterin loading test results (n = 4,381), enabling prediction of both a genotype-based phenotype (88%) and tetrahydrobiopterin responsiveness (83%). This study shows that large genotype databases enable accurate phenotype prediction, allowing appropriate targeting of therapies to optimize clinical outcome.
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http://dx.doi.org/10.1016/j.ajhg.2020.06.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7413859PMC
August 2020

First 1.5 years of pegvaliase clinic: Experiences and outcomes.

Mol Genet Metab Rep 2020 Sep 25;24:100603. Epub 2020 May 25.

Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA, United States of America.

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) <360 μmol/L, with an average of a 68 ± 24% decrease in blood Phe from baseline. All patients experienced at least minor side effects, but in most, management of the side effects allowed for treatment to continue.
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http://dx.doi.org/10.1016/j.ymgmr.2020.100603DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7256053PMC
September 2020

Discontinuation of Pegvaliase therapy during maternal PKU pregnancy and postnatal breastfeeding: A case report.

Mol Genet Metab Rep 2020 Mar 10;22:100555. Epub 2020 Jan 10.

Boston Children's Hospital, 300 Longwood Ave, Boston, MA 02115, United States of America.

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http://dx.doi.org/10.1016/j.ymgmr.2019.100555DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6957825PMC
March 2020

5-year retrospective analysis of patients with phenylketonuria (PKU) and hyperphenylalaninemia treated at two specialized clinics.

Mol Genet Metab 2020 03 10;129(3):177-185. Epub 2019 Dec 10.

Division Medical Genetics, Department of Pediatrics, University of Pittsburgh School of Medicine, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA, USA. Electronic address:

Background: Phenylketonuria (PKU) is an autosomal recessive disease caused by mutations in the PAH gene, resulting in deficiency of phenylalanine hydroxylase (PAH), an enzyme that converts phenylalanine (Phe) to tyrosine (Tyr). The purpose of this study was to capture real-world data associated with managing PKU under current standard of care and to characterize a representative population for a planned gene therapy trial.

Methods: A retrospective chart review was conducted at two U.S. clinics for individuals 10-40 years old diagnosed with PKU-related hyperphenylalaninemia (HPA). Demographics, medical history, treatments and blood Phe data were collected from electronic medical records spanning a five-year period ending in November 2017.

Results: 152 patients were enrolled (65.8% had classical PKU). Although >95% of patients were prescribed a Phe-restricted diet, blood Phe concentrations remained substantially elevated, particularly in patients diagnosed with classical PKU. As the Phe threshold was lowered (Phe < 600, 360, 120 or 30 μmol/L), the number of patients with consecutive lab values below the threshold decreased, suggesting that many patients' Phe levels are inadequately controlled. 62.5% of patients were reported as having a history of at least one neuropsychiatric comorbidity, and adults were more likely than adolescents (69.5% vs. 54.3%). 92 of 98 PAH genotypes collected were distinct mutations; the 6 null-null genotypes were associated with classical PKU. Overall the demographics and clinical data were consistent across both sites.

Conclusion: Despite dietary restrictions, mean Phe concentrations were > 360 μmol/L (a level considered well-controlled based on current U.S. treatment guidelines) for mild, moderate, and classical PKU patients. There remains an unmet need for therapies to control Phe concentrations.
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http://dx.doi.org/10.1016/j.ymgme.2019.12.007DOI Listing
March 2020

Phenylalanine hydroxylase genotype-phenotype associations in the United States: A single center study.

Mol Genet Metab 2019 12 14;128(4):415-421. Epub 2019 Sep 14.

Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA, USA; Department of Pediatrics, Harvard Medical School, Boston, MA, USA. Electronic address:

Phenylketonuria (PKU) is an autosomal recessive inborn error of metabolism caused by pathogenic variants in the phenylalanine hydroxylase gene (PAH). The correlation between genotype and phenotype can be complex and sometimes variable but often very useful for categorizing and predicting dietary tolerance and potential outcome. We reviewed medical records for 367 patients diagnosed with PKU or persistent mild hyperphenylalaninemia (MHP) between 1950 and 2015 who had PAH genotyping. In 351 we had the full PAH genotype as well as phenotypic characteristics such as phenylalanine (Phe) concentrations (at newborn screening, confirmation, and highest known), and dietary Phe tolerance. On 716 mutant chromosomes, including 14 in genotypes with only one identified variant, we identified 114 different pathogenic variants. The most frequent, p.R408W, was present in 15.4% of the alleles; other frequent variants were c.1315 + 1G > A (6.1%), p.I65T (5.7%), and p.R261Q (5.7%). Three variants, c.142 T > G (p.L48 V), c.615G > C (p.E205D), and c.1342_1345delCTCC, were novel. We used the phenotypic parameters of variants paired with null alleles (functional hemizygotes) to assign the variants as classic PKU, moderate PKU, mild PKU, MHP-gray zone, or MHP. We also included the phenotype association(s) for all of the full genotypes. In 103 patients, we also could assign sapropterin dihydrochloride responsiveness, which is a synthetic form of the tetrahydrobiopterin (BH) PAH cofactor. This compilation from a single metabolic center provides further information on PAH variants in the United States and the correlations between genotype and phenotype.
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http://dx.doi.org/10.1016/j.ymgme.2019.09.004DOI Listing
December 2019

Can Newborn Screening for Vitamin B Deficiency be Incorporated into All Newborn Screening Programs?

J Pediatr 2020 01 12;216:9-11.e1. Epub 2019 Oct 12.

Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts. Electronic address:

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http://dx.doi.org/10.1016/j.jpeds.2019.08.061DOI Listing
January 2020

Phenotypic variability in deficiency of the α subunit of succinate-CoA ligase.

JIMD Rep 2019 Mar 14;46(1):63-69. Epub 2019 Mar 14.

Division of Genetics and Genomics, Manton Center for Orphan Disease Research Boston Children's Hospital, Harvard Medical School Boston Massachusetts.

Succinyl-CoA synthetase or succinate-CoA ligase deficiency can result from biallelic mutations in gene that encodes for the alpha subunit of the succinyl-CoA synthetase. Mutations in this gene were initially associated with fatal infantile lactic acidosis. We describe an individual with a novel biallelic pathogenic mutation in with a less severe phenotype dominated by behavioral problems. The mutation was identified to be c.512A>G corresponding to a p.Asn171Ser change in the protein. The liquid chromatography tandem mass spectrometry-based enzyme activity assay on cultured fibroblasts revealed a markedly reduced activity of succinyl-CoA synthetase enzyme when both ATP and GTP were substrates, affecting both ADP-forming and GDP-forming functions of the enzyme.
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http://dx.doi.org/10.1002/jmd2.12018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6498818PMC
March 2019

The ability of an LC-MS/MS-based erythrocyte GALT enzyme assay to predict the phenotype in subjects with GALT deficiency.

Mol Genet Metab 2019 04 22;126(4):368-376. Epub 2019 Jan 22.

Manton Center for Orphan Disease Research, Division of Genetics and Genomics, Boston Children's Hospital, Harvard Medical School, Boston, MA, United States. Electronic address:

Background: GALT deficiency is a rare genetic disorder of carbohydrate metabolism. Due to the decreased activity or absence of the enzyme galactose-1-phosphate uridylyltransferase (GALT), cells from affected individuals are unable to metabolize galactose normally. Lactose consumption in the newborn period could potentially lead to a lethal disease process with multi-organ involvement. In contrast to the newborn-stage disease, however, a galactose-restricted diet does not prevent long-term complications such as central nervous system (CNS) dysfunction with speech defects, learning disability and neurological disease in addition to hypergonadotropic hypogonadism or primary ovarian insufficiency (POI) in females. As the literature suggests an association between GALT enzyme activity and the long-term complications, it is of importance to have a highly sensitive assay to quantify the GALT enzyme activity. To that end, we had developed a sensitive and accurate LC-MS/MS method to measure GALT enzyme activity. Its ability to predict outcome is the subject of this report.

Materials And Methods: The GALT enzyme activity in erythrocytes from 160 individuals, in which 135 with classic, clinical variant or biochemical variant galactosemia, was quantified by LC-MS/MS. Individuals with GALT deficiency were evaluated for the long-term complications of speech defects, dysarthria, ataxia, dystonia, tremor, POI, as well as intellectual functioning (full scale IQ). The LC-MS/MS results were compared to a variety of assays: radioactive, [C]-galactose-1-phosphate, paper chromatography with scintillation counting, enzyme-coupled assays with spectrophotometric or fluorometric readout or high-pressure liquid chromatography with UV detection of UDP-galactose.

Results: The LC-MS/MS method measured GALT activity as low as 0.2%, whereas other methods showed no detectable activity. Largely due to GALT activities that were over 1%, the LC-MS/MS measurements were not significantly different than values obtained in other laboratories using other methodologies. Severe long-term complications were less frequently noted in subjects with >1% activity. Patients with a p.Q188R/p.Q188R genotype have no residual enzyme activity in erythrocytes.

Conclusion: Our LC-MS/MS assay may be necessary to accurately quantify residual GALT activities below 5%. The data suggest that patients with >1% residual activity are less likely to develop diet-independent long-term complications. However, much larger sample sizes are needed to properly assess the clinical phenotype in patients with residual enzyme activities between 0.1 and 5%.
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http://dx.doi.org/10.1016/j.ymgme.2019.01.016DOI Listing
April 2019

Revising the Psychiatric Phenotype of Homocystinuria.

Genet Med 2019 08 15;21(8):1827-1831. Epub 2019 Jan 15.

Division of Genetics and Genomics, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.

Purpose: Associations of psychiatric and psychological symptoms with homocystinuria (HCU) have been described in multiple reports. This retrospective study was undertaken to refine the psychological phenotype among HCU patients and identify biomedical markers that could be used for prediction of those psychiatric or psychological symptoms.

Methods: This study examines the prevalence of psychological symptoms within a sample of 25 patients with classical homocystinuria.

Results: Psychological symptoms were noted in 16 of the 25 patients in the sample (64%), including a high prevalence of both anxiety (32%) and depression (32%) and correlated with IQ < 85. There was no difference in the type or the number of psychological symptoms between those diagnosed from newborn screening and early treated and those treated after 2 years of age.

Conclusion: The results support the possible role of homocysteine as a risk factor for psychological and psychiatric problems and cognitive deficits and suggest that earlier diagnosis and treatment may reduce risk of their occurrences. Although early treatment clearly prevented serious medical complications, psychological and psychiatric symptoms were not associated with medical complications, highlighting the need for continued investigation.
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http://dx.doi.org/10.1038/s41436-018-0419-4DOI Listing
August 2019

Untargeted metabolomics identifies unique though benign biochemical changes in patients with pathogenic variants in .

Mol Genet Metab Rep 2019 Mar 29;18:14-18. Epub 2018 Dec 29.

Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.

Urocanic aciduria is caused by a deficiency in the enzyme urocanase (E.C. 4.2.1.49) encoded by the gene . In the past, deficiency of urocanase has been associated with intellectual disability in a few case studies with some suggestion that the enzyme deficiency was the causative etiology. Here, we describe two phenotypically normal siblings with compound heterozygous pathogenic variants in and characteristic biochemical evidence of urocanase deficiency collected utilizing untargeted metabolomic analysis. These findings suggest that urocanic aciduria may represent an otherwise benign biochemical phenotype and that those individuals with concurrent developmental delay should continue to be evaluated for other underlying causes for their symptoms.
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http://dx.doi.org/10.1016/j.ymgmr.2018.12.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6312870PMC
March 2019

Evidence- and consensus-based recommendations for the use of pegvaliase in adults with phenylketonuria.

Genet Med 2019 08 14;21(8):1851-1867. Epub 2018 Dec 14.

Departments of Molecular and Medical Genetics and Pediatrics, Oregon Health & Science University, Portland, OR, USA.

Purpose: Phenylketonuria (PKU) is a rare metabolic disorder that requires life-long management to reduce phenylalanine (Phe) concentrations within the recommended range. The availability of pegvaliase (PALYNZIQ™, an enzyme that can metabolize Phe) as a new therapy necessitates the provision of guidance for its use.

Methods: A Steering Committee comprising 17 health-care professionals with experience in using pegvaliase through the clinical development program drafted guidance statements during a series of face-to-face meetings. A modified Delphi methodology was used to demonstrate consensus among a wider group of health-care professionals with experience in using pegvaliase.

Results: Guidance statements were developed for four categories: (1) treatment goals and considerations prior to initiating therapy, (2) dosing considerations, (3) considerations for dietary management, and (4) best approaches to optimize medical management. A total of 34 guidance statements were included in the modified Delphi voting and consensus was reached on all after two rounds of voting.

Conclusion: Here we describe evidence- and consensus-based recommendations for the use of pegvaliase in adults with PKU. The manuscript was evaluated against the Appraisal of Guidelines for Research and Evaluation (AGREE II) instrument and is intended for use by health-care professionals who will prescribe pegvaliase and those who will treat patients receiving pegvaliase.
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http://dx.doi.org/10.1038/s41436-018-0403-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6752676PMC
August 2019

Prevalence of comorbid conditions among adult patients diagnosed with phenylketonuria.

Mol Genet Metab 2018 11 12;125(3):228-234. Epub 2018 Sep 12.

Boston Children's Hospital and Harvard Medical School, 1 Autumn St., Rm #526, Boston, MA 02115, United States.

Background: Phenylalanine hydroxylase (PAH) deficiency, otherwise known as phenylketonuria (PKU), is an inborn error of metabolism that requires treatment to be initiated in the newborn period and continued throughout life. Due to the challenges of treatment adherence and the resulting cumulative effects of high and labile blood phenylalanine, PKU exerts a significant burden of disease. Retrospective studies using large databases allow for unique perspectives on comorbidities associated with rare diseases. An evaluation of comorbidities across various organ systems is warranted to understand the disease burden in adult patients.

Objectives: The aim of this insurance claim-based observational study was to assess the prevalence of comorbid conditions across various organ systems (e.g. dermatological, renal, respiratory, gastrointestinal, hematological, and others) among adult PKU patients compared with matched controls from the general population.

Methods: This retrospective, case-controlled study selected patients from United States insurance claims databases from 1998 to 2014 using International Classification of Diseases, Ninth Revision (ICD-9) codes for diagnosis of PKU. The date of first diagnosis during the study period was index date and this was not necessarily the first time the patient was diagnosed with PKU. Cases were matched with a 1:5 ratio with general population (non-PKU controls) on age, sex, race, geographic location, duration of time in the database and insurance type. Prevalence and prevalence ratio (PR) calculations for comorbidities across various organ systems among adults (≥20 years old) with PKU were compared with the general population (non-PKU controls). The conditions were selected based on complications associated with PKU and feedback from clinicians treating PKU patients.

Results: A total of 3691 PKU patients and 18,455 matched, non-PKU controls were selected, with an average age of 35 years. The mean healthcare costs incurred by the PKU patients during baseline, were approximately 4 times that of the controls ($4141 vs $1283; p < .0001). The prevalence rates of comorbidities across various organ systems during the follow-up period were significantly higher for those with PKU than in the control group. After adjusting for baseline characteristics, the adjusted prevalence ratios (PR) of 15 conditions studied (asthma, alopecia, urticaria, gallbladder disease, rhinitis, esophageal disorders, anemia, overweight, GERD, eczema, renal insufficiency, osteoporosis, gastritis/esophagitis and kidney calculus) were all above PR = 1.24 and significantly higher for the PKU cohort (p ≤ .001). The highest adjusted PR were for renal insufficiency with hypertension (PR [95% CI]: 2.20 [1.60-3.00]; p < .0001) and overweight (PR [95%CI]: 2.06 [1.85-2.30]; p < .0001).

Conclusions: The prevalence of selected comorbidities across several organ systems is significantly higher among PKU patients than for general population controls. Regular screening for common co-morbidities may be warranted as part of PKU management.
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http://dx.doi.org/10.1016/j.ymgme.2018.09.006DOI Listing
November 2018

The BabySeq project: implementing genomic sequencing in newborns.

BMC Pediatr 2018 07 9;18(1):225. Epub 2018 Jul 9.

Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, MA, USA.

Background: The greatest opportunity for lifelong impact of genomic sequencing is during the newborn period. The "BabySeq Project" is a randomized trial that explores the medical, behavioral, and economic impacts of integrating genomic sequencing into the care of healthy and sick newborns.

Methods: Families of newborns are enrolled from Boston Children's Hospital and Brigham and Women's Hospital nurseries, and half are randomized to receive genomic sequencing and a report that includes monogenic disease variants, recessive carrier variants for childhood onset or actionable disorders, and pharmacogenomic variants. All families participate in a disclosure session, which includes the return of results for those in the sequencing arm. Outcomes are collected through review of medical records and surveys of parents and health care providers and include the rationale for choice of genes and variants to report; what genomic data adds to the medical management of sick and healthy babies; and the medical, behavioral, and economic impacts of integrating genomic sequencing into the care of healthy and sick newborns.

Discussion: The BabySeq Project will provide empirical data about the risks, benefits and costs of newborn genomic sequencing and will inform policy decisions related to universal genomic screening of newborns.

Trial Registration: The study is registered in ClinicalTrials.gov Identifier: NCT02422511 . Registration date: 10 April 2015.
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http://dx.doi.org/10.1186/s12887-018-1200-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6038274PMC
July 2018

Phenylalanine ammonia lyase (PAL): From discovery to enzyme substitution therapy for phenylketonuria.

Mol Genet Metab 2018 08 9;124(4):223-229. Epub 2018 Jun 9.

Department of Human Genetics, McGill University, Montreal, Quebec H3A 0C7, Canada. Electronic address:

Phenylketonuria (PKU) is a genetic inborn error in metabolism that impacts many people globally, with profound individual and societal consequences when left untreated. The journey of phenylalanine ammonia lyase (PAL) from plant enzyme to enzyme substitution therapy for PKU is a fascinating story that illustrates the importance of collaboration between basic scientists and industry in the drug development process. The story begins with the curiosity of plant physiologists about the origin of lignin, a polymer involved in maintaining the rigidity of plants. They learned that the critical element in this synthesis was an intermediary enzyme that deaminates phenylalanine to cinnamic acid and ammonia (later called phenylalanine ammonia lyase or PAL). Recognition of this ability to metabolize phenylalanine led to subsequent consideration of PAL as a treatment for PKU. This was initially attempted as enteral therapy with extracted enzyme, but that showed only minimal efficacy. Crucially, further development of PAL as a therapy for PKU required quantities of enzyme that could only be obtained after successfully cloning the gene, expressing the enzyme in vitro and modifying the protein via PEGylation to enable parenteral administration of this non-mammalian enzyme. Ultimately, PEGylated PAL was developed as an enzyme substitution therapy for PKU now approved under the name "Palynziq." The multidisciplinary academic-industrial partnership engaged throughout this process has been key to the successful pursuit of this therapeutic possibility and serves as a model for the development of future innovative therapies.
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http://dx.doi.org/10.1016/j.ymgme.2018.06.002DOI Listing
August 2018

Pegvaliase for the treatment of phenylketonuria: Results of a long-term phase 3 clinical trial program (PRISM).

Mol Genet Metab 2018 05 31;124(1):27-38. Epub 2018 Mar 31.

Department of Pediatrics, Division of Medical Genetics, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA. Electronic address:

Background: Phenylketonuria (PKU) is caused by phenylalanine hydroxylase (PAH) deficiency that results in phenylalanine (Phe) accumulation. Pegvaliase, PEGylated recombinant Anabaena variabilis phenylalanine ammonia lyase (PAL), converts Phe to trans-cinnamic acid and ammonia, and is a potential enzyme substitution therapy to lower blood Phe in adults with PKU.

Methods: Two Phase 3 studies, PRISM-1 and PRISM-2, evaluated the efficacy and safety of pegvaliase treatment using an induction, titration, and maintenance dosing regimen in adults with PKU. In PRISM-1, pegvaliase-naïve participants with blood Phe >600 μmol/L were randomized 1:1 to a maintenance dose of 20 mg/day or 40 mg/day of pegvaliase. Participants in PRISM-1 continued pegvaliase treatment in PRISM-2, a 4-part clinical trial that includes an ongoing, open-label, long-term extension study of pegvaliase doses of 5 mg/day to 60 mg/day.

Results: Of 261 participants who received pegvaliase treatment, 72.0% and 32.6% reached ≥12 months and ≥ 24 months of study treatment, respectively, and 65% are still actively receiving treatment. Mean (SD) blood Phe was 1232.7 (386.4) μmol/L at baseline, 564.5 (531.2) μmol/L at 12 months, and 311.4 (427) μmol/L at 24 months, a decrease from baseline of 51.1% and 68.7%, respectively. Within 24 months, 68.4% of participants achieved blood Phe ≤600 μmol/L, 60.7% of participants achieved blood Phe ≤360 μmol/L, below the upper limit recommended in the American College of Medical Genetics and Genomics PKU management guidelines, and 51.2% achieved blood Phe ≤120 μmol/L, below the upper limit of normal in the unaffected population. Improvements in neuropsychiatric outcomes were associated with reductions in blood Phe and were sustained with long-term pegvaliase treatment. Adverse events (AEs) were more frequent in the first 6 months of exposure (early treatment phase) than after 6 months of exposure (late treatment phase); 99% of AEs were mild or moderate in severity and 96% resolved without dose interruption or reduction. The most common AEs were arthralgia (70.5%), injection-site reaction (62.1%), injection-site erythema (47.9%), and headache (47.1%). Acute systemic hypersensitivity events consistent with clinical National Institute of Allergy and Infectious Diseases and the Food Allergy and Anaphylaxis Network anaphylaxis criteria were observed in 12 participants (17 events); of these, 6 participants remained on treatment. Acute systemic hypersensitivity events including potential events of anaphylaxis were not associated with immunoglobulin E, and all events resolved without sequelae.

Conclusion: Results from the PRISM Phase 3 program support the efficacy of pegvaliase for the treatment of adults with PKU, with a manageable safety profile in most participants. The PRISM-2 extension study will continue to assess the long-term effects of pegvaliase treatment.
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http://dx.doi.org/10.1016/j.ymgme.2018.03.006DOI Listing
May 2018

Metabolomic Markers of Essential Fatty Acids, Carnitine, and Cholesterol Metabolism in Adults and Adolescents with Phenylketonuria.

J Nutr 2018 02;148(2):194-201

Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, WI.

Background: Individuals with phenylketonuria (PKU) have a risk of cognitive impairment and inflammation. Many follow a low-phenylalanine (low-Phe) diet devoid of animal protein in combination with medical foods (MFs).

Objective: To assess lipid metabolism in participants with PKU consuming amino acid MFs (AA-MFs) or glycomacropeptide MFs (GMP-MFs), we conducted fatty acid and metabolomics analyses.

Methods: We used subsets of fasting plasma and urine samples from our randomized crossover trial in which participants with early-treated classical and variant (milder) PKU consumed a low-Phe diet combined with AA-MFs or GMP-MFs for 3 wk each. Fatty acid profiles of red blood cell (RBC) membranes were determined for 25 adults (aged 18-49 y) with PKU and 143 control participants. Metabolomics analyses of plasma and urine samples were conducted by Metabolon for 9-10 adolescent and adult participants with PKU and for 15 control participants.

Results: RBC fatty acid profiles were not significantly different with AA-MFs or GMP-MFs. PKU participants showed higher total n-6:n-3 (ω-6:ω-3) fatty acids (mean ± SD percentages of total fatty acids: AA-MF = 5.45% ± 1.07%; controls = 4.33%; P < 0.001) and lower docosahexaenoic acid (DHA; AA-MF = 3.21% ± 0.98%; controls = 3.70% ± 1.01%; P = 0.02) and eicosapentaenoic acid (AA-MF = 0.33% ± 0.12%; controls = 0.60% ± 0.43%; P < 0.001) in RBCs than did control participants. Despite higher carnitine intake from AA-MFs than GMP-MFs (mean ± SE intake: AA-MFs = 58.6 ± 5.3 mg/d; GMP-MFs = 0.3 ± 0.01 mg/d; P < 0.001), plasma concentrations of carnitine were similar and not different from those in the control group (AA-MF compared with GMP-MF, P = 0.73). AA-MFs resulted in higher urinary excretion of trimethylamine N-oxide (TMAO), which is synthesized by bacteria from carnitine, compared with GMP-MFs (mean ± SE scaled intensity-TMAO: AA-MFs = 1.2 ± 0.1, GMP-MFs = 0.9 ± 0.1; P = 0.005). Plasma deoxycarnitine was lower in PKU participants than in control participants, suggesting reduced carnitine biosynthesis in PKU (AA-MF = 0.9 ± 0.1; GMP-MF = 1.0 ± 0.1; controls = 1.3 ± 0.1; AA-MF compared with controls, P = 0.01; GMP-MF compared with controls, P = 0.04).

Conclusions: Supplementation with DHA is needed in PKU. Carnitine supplementation of AA-MFs shows reduced bioavailability due, in part, to bacterial degradation to TMAO, whereas the bioavailability of carnitine is greater with prebiotic GMP-MFs. This trial was registered at www.clinicaltrials.gov as NCT01428258.
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http://dx.doi.org/10.1093/jn/nxx039DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6251508PMC
February 2018

Metabolomic Insights into the Nutritional Status of Adults and Adolescents with Phenylketonuria Consuming a Low-Phenylalanine Diet in Combination with Amino Acid and Glycomacropeptide Medical Foods.

J Nutr Metab 2017 31;2017:6859820. Epub 2017 Dec 31.

Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.

Background: Nutrient status in phenylketonuria (PKU) requires surveillance due to the restrictive low-Phe diet in combination with amino acid medical foods (AA-MF) or glycomacropeptide medical foods (GMP-MF). Micronutrient profiles of medical foods are diverse, and optimal micronutrient supplementation in PKU has not been established.

Methods: In a crossover design, 30 participants with PKU were randomized to consume AA-MF and Glytactin™ GMP-MF in combination with a low-Phe diet for 3 weeks each. Fasting venipunctures, medical food logs, and 3-day food records were obtained. Metabolomic analyses were completed in plasma and urine by Metabolon, Inc.

Results: The low-Phe diets in combination with AA-MF and GMP-MF were generally adequate based on Dietary Reference Intakes, clinical measures, and metabolomics. Without micronutrient supplementation of medical foods, >70% of participants would have inadequate intakes for 11 micronutrients. Despite micronutrient supplementation of medical foods, inadequate intakes of potassium in 93% of participants and choline in >40% and excessive intakes of sodium in >63% of participants and folic acid in >27% were observed. Sugar intake was excessive and provided 27% of energy.

Conclusions: Nutrient status was similar with AA-MF and Glytactin GMP-MF. More research related to micronutrient supplementation of medical foods for the management of PKU is needed.
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http://dx.doi.org/10.1155/2017/6859820DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5804357PMC
December 2017

Acute Illness Protocol for Urea Cycle Disorders.

Pediatr Emerg Care 2018 Jun;34(6):e115-e119

Inborn errors of metabolism (IEMs) are genetic disorders that disrupt enzyme activity, cellular transport, or energy production. They are individually rare but collectively have an incidence of 1:1000. Most patients with IEMs are followed up by a physician with expertise in biochemical genetics (metabolism), but may present outside this setting. Because IEMs can present acutely with life-threatening crises that require specific interventions, it is critical for the emergency physician, internist, and critical care physician as well as the biochemical geneticist to have information on the initial assessment and management of patients with these disorders. Appropriate early care can be lifesaving. This protocol is not designed to replace the expert consultation of a biochemical geneticist, but rather to improve early care and increase the level of comfort of the acute care physician with initial management of urea cycle disorders until specialty consultation is obtained.
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http://dx.doi.org/10.1097/PEC.0000000000001298DOI Listing
June 2018

Acute Illness Protocol for Maple Syrup Urine Disease.

Pediatr Emerg Care 2018 Jan;34(1):64-67

Inborn errors of metabolism (IEMs) are genetic disorders that disrupt enzyme activity, cellular transport, or energy production. They are individually rare but collectively have an incidence of 1:1000. Most patients with IEMs are followed up by a physician with expertise in biochemical genetics (metabolism), but may present outside this setting. Because IEMs can present acutely with life-threatening crises that require specific interventions, it is critical for the emergency medicine physician, pediatrician, internist, and critical care physician as well as the biochemical geneticist to have information on the initial assessment and management of patients with these disorders. Appropriate early care can be lifesaving. This protocol is not designed to replace the expert consultation of a biochemical geneticist, but rather to improve early care and increase the level of comfort of the acute care physician with initial management of maple syrup urine disease until specialty consultation is obtained.
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http://dx.doi.org/10.1097/PEC.0000000000001299DOI Listing
January 2018

Dietary amino acid intakes associated with a low-phenylalanine diet combined with amino acid medical foods and glycomacropeptide medical foods and neuropsychological outcomes in subjects with phenylketonuria.

Data Brief 2017 Aug 7;13:377-384. Epub 2017 Jun 7.

Department of Nutritional Sciences, University of Wisconsin-Madison, WI, United States.

This article provides original data on median dietary intake of 18 amino acids from amino acid medical foods, glycomacropeptide medical foods, and natural foods based on 3-day food records obtained from subjects with phenylketonuria who consumed low-phenylalanine diets in combination with amino acid medical foods and glycomacropeptide medical foods for 3 weeks each in a crossover design. The sample size of 30 subjects included 20 subjects with classical phenylketonuria and 10 with a milder or variant form of phenylketonuria. Results are presented for the Delis-Kaplan Executive Function System and the Cambridge Neuropsychological Test Automated Battery; the tests were administered at the end of each 3-week dietary treatment with amino acid medical foods and glycomacropeptide medical foods. The data are supplemental to our clinical trial, entitled "Glycomacropetide for nutritional management of phenylketonuria: a randomized, controlled, crossover trial, 2016 (1) and "Metabolomic changes demonstrate reduced bioavailability of tyrosine and altered metabolism of tryptophan via the kynurenine pathway with ingestion of medical foods in phenylketonuria, 2017 (2). This data has been made public and has utility to clinicians and researchers due to the following: 1) This provides the first comprehensive report of typical intakes of 18 amino acids from natural foods, as well as amino acid and glycomacropeptide medical foods in adolescents and adults with phenylketonuria; and 2) This is the first evidence of similar standardized neuropsychological testing data in adolescents and adults with early-treated phenylketonuria who consumed amino acid and glycomacropeptide medical foods.
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http://dx.doi.org/10.1016/j.dib.2017.06.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5480823PMC
August 2017

Metabolomic changes demonstrate reduced bioavailability of tyrosine and altered metabolism of tryptophan via the kynurenine pathway with ingestion of medical foods in phenylketonuria.

Mol Genet Metab 2017 06 6;121(2):96-103. Epub 2017 Apr 6.

Division of Genetics and Genomics, Boston Children's Hospital, Harvard Medical School, Boston, MA, United States.

Background: Deficiencies of the monoamine neurotransmitters, such as dopamine synthesized from Tyr and serotonin synthesized from Trp, are of concern in PKU. Our objective was to utilize metabolomics analysis to assess monoamine metabolites in subjects with PKU consuming amino acid medical foods (AA-MF) and glycomacropeptide medical foods (GMP-MF).

Methods: Subjects with PKU consumed a low-Phe diet combined with AA-MF or GMP-MF for 3weeks each in a randomized, controlled, crossover study. Metabolomic analysis was conducted by Metabolon, Inc. on plasma (n=18) and urine (n=9) samples. Catecholamines and 6-sulfatoxymelatonin were measured in 24-h urine samples.

Results: Intake of Tyr and Trp was ~50% higher with AA-MF, and AA-MF were consumed in larger quantities, less frequently during the day compared with GMP-MF. Performance on neuropsychological tests and concentrations of neurotransmitters derived from Tyr and Trp were not significantly different with AA-MF or GMP-MF. Plasma serotonin levels of gut origin were higher in subjects with variant compared with classical PKU, and with GMP-MF compared with AA-MF in subjects with variant PKU. Metabolomics analysis identified higher levels of microbiome-derived compounds synthesized from Tyr, such as phenol sulfate, and higher levels of compounds synthesized from Trp in the kynurenine pathway, such as quinolinic acid, with ingestion of AA-MF compared with GMP-MF.

Conclusions: The Tyr from AA-MF is less bioavailable due, in part, to greater degradation by intestinal microbes compared with the Tyr from prebiotic GMP-MF. Research is needed to understand how metabolism of Trp via the kynurenine pathway and changes in the intestinal microbiota affect health for individuals with PKU. This trial is registered at www.clinicaltrials.gov as NCT01428258.
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http://dx.doi.org/10.1016/j.ymgme.2017.04.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5484416PMC
June 2017

Acute Illness Protocol for Fatty Acid Oxidation and Carnitine Disorders.

Pediatr Emerg Care 2017 Apr;33(4):296-301

From the *Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA; and †Department of Medicine, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia.

Inborn errors of metabolism (IEMs) are genetic disorders that disrupt enzyme activity, cellular transport, or energy production. They are individually rare but collectively have an incidence of 1:1000. Most patients with IEMs are followed by a physician with expertise in biochemical genetics (metabolism) but may present outside this setting. Because IEMs can present acutely with life-threatening crises that require specific interventions, it is critical for the emergency medicine physicians, pediatricians, internists, critical care physicians, and biochemical geneticists to be familiar with the initial assessment and management of patients with these disorders. Appropriate early care can be lifesaving. This protocol is not designed to replace the expert consultation of a biochemical geneticist but rather to improve early care and increase the level of comfort of the acute care physician with initial management of fatty acid oxidation and carnitine disorders until specialty consultation is obtained.
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http://dx.doi.org/10.1097/PEC.0000000000001093DOI Listing
April 2017

Acute Illness Protocol for Organic Acidemias: Methylmalonic Acidemia and Propionic Acidemia.

Pediatr Emerg Care 2017 Feb;33(2):142-146

*Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA; and †Department of Medicine, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia.

Inborn errors of metabolism (IEM) are genetic disorders that disrupt enzyme activity, cellular transport, or energy production. They are individually rare, but collectively have an incidence of 1:1000. Most patients with IEMs are followed by a physician with expertise in Biochemical Genetics (Metabolism), but may present outside of this setting. Because IEMs can present acutely with life-threatening crises that require specific interventions, it is critical for the emergency medicine physicians, pediatricians, internists, and critical care physicians as well as biochemical geneticists to be familiar with the initial assessment and management of patients with these disorders. Appropriate early care can be lifesaving. This protocol is not designed to replace the expert consultation of a biochemical geneticist but rather to improve early care and increase the level of comfort of the acute care physician with initial management of organic acidemias until specialty consultation is obtained.
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http://dx.doi.org/10.1097/PEC.0000000000001028DOI Listing
February 2017

Long-term outcome of expanded newborn screening at Boston children's hospital: benefits and challenges in defining true disease.

J Inherit Metab Dis 2017 03 4;40(2):209-218. Epub 2017 Jan 4.

Division of Genetics and Genomics, Boston Children's Hospital and Department of Pediatrics, Harvard Medical School, 1 Autumn Street, Rm 526.1, Boston, MA, 02115, USA.

Introduction: There is no universal consensus of the disorders included in newborn screening programs. Few studies so far, mostly short-term, have compared the outcome of disorders detected by expanded newborn screening (ENBS) to the outcome of the same disorders detected clinically.

Methods: We compared the clinical and neurodevelopmental outcomes in patients with metabolic disorders detected by ENBS, including biotinidase testing, with those detected clinically and followed at the Metabolism Clinic at Boston Children's Hospital.

Results: One hundred eighty-nine patients came to attention from ENBS and 142 were clinically diagnosed. 3-methylcrotonyl-CoA carboxylase, biotinidase, and carnitine deficiencies were exclusively identified by ENBS and medium chain acyl-CoA dehydrogenase (MCADD) and very long chain acyl-CoA dehydrogenase deficiencies (VLCADD) were predominantly identified by ENBS whereas the organic acid disorders more often came to attention clinically. Only 2% of the ENBS-detected cases had clinically severe outcomes compared to 42% of those clinically detected. The mean IQ score was 103 + 17 for the ENBS-detected cases and 77 + 24 for those clinically detected. Those newly included disorders that seem to derive the greatest benefit from ENBS include the fatty acid oxidation disorders, profound biotinidase deficiency, tyrosinemia type 1, and perhaps carnitine deficiency.

Conclusion: Although the NBS-identified and clinically-identified cohorts were not completely comparable, this long-term study shows likely substantial improvement overall in the outcome of these metabolic disorders in the NBS infants. Infants with mild disorders and benign variants may represent a significant number of infants identified by ENBS. The future challenge will be to unequivocally differentiate the disorders most benefitting from ENBS and adjust programs accordingly.
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http://dx.doi.org/10.1007/s10545-016-0004-4DOI Listing
March 2017

Confounding factors in identification of disease-resilient individuals.

Nat Biotechnol 2016 11;34(11):1103-1104

Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA.

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http://dx.doi.org/10.1038/nbt.3684DOI Listing
November 2016

Glycomacropeptide for nutritional management of phenylketonuria: a randomized, controlled, crossover trial.

Am J Clin Nutr 2016 Aug 13;104(2):334-45. Epub 2016 Jul 13.

Division of Genetics and Genomics, Boston Children's Hospital, Harvard Medical School, Boston, MA.

Background: To prevent cognitive impairment, phenylketonuria requires lifelong management of blood phenylalanine (Phe) concentration with a low-Phe diet. The diet restricts intake of Phe from natural proteins in combination with traditional amino acid medical foods (AA-MFs) or glycomacropeptide medical foods (GMP-MFs) that contain primarily intact protein and a small amount of Phe.

Objective: We investigated the efficacy and safety of a low-Phe diet combined with GMP-MFs or AA-MFs providing the same quantity of protein equivalents in free-living subjects with phenylketonuria.

Design: This 2-stage, randomized crossover trial included 30 early-treated phenylketonuria subjects (aged 15-49 y), 20 with classical and 10 with variant phenylketonuria. Subjects consumed, in random order for 3 wk each, their usual low-Phe diet combined with AA-MFs or GMP-MFs. The treatments were separated by a 3-wk washout with AA-MFs. Fasting plasma amino acid profiles, blood Phe concentrations, food records, and neuropsychological tests were obtained.

Results: The frequency of medical food intake was higher with GMP-MFs than with AA-MFs. Subjects rated GMP-MFs as more acceptable than AA-MFs and noted improved gastrointestinal symptoms and less hunger with GMP-MFs. ANCOVA indicated no significant mean ± SE increase in plasma Phe (62 ± 40 μmol/L, P = 0.136), despite a significant increase in Phe intake from GMP-MFs (88 ± 6 mg Phe/d, P = 0.026). AA-MFs decreased plasma Phe (-85 ± 40 μmol/L, P = 0.044) with stable Phe intake. Blood concentrations of Phe across time were not significantly different (AA-MFs = 444 ± 34 μmol/L, GMP-MFs = 497 ± 34 μmol/L), suggesting similar Phe control. Results of the Behavior Rating Inventory of Executive Function were not significantly different.

Conclusions: GMP-MFs provide a safe and acceptable option for the nutritional management of phenylketonuria. The greater acceptability and fewer side effects noted with GMP-MFs than with AA-MFs may enhance dietary adherence for individuals with phenylketonuria. This trial was registered at www.clinicaltrials.gov as NCT01428258.
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http://dx.doi.org/10.3945/ajcn.116.135293DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4962165PMC
August 2016