Dr. Levy directs a clinical research group that is studying the effect of innovative therapies for phenylketonuria (PKU). His group has examined the role of cofactor therapy for stimulating phenylalanine hydroxylase (PAH) and is currently a major site for a clinical trial of alternative enzyme therapy of PKU. Dr. Levy is also an investigator for the national study of the natural history and treatment of urea cycle disorders, a study examining brain imagining in PKU, and a study to determine the feasibility of next generation sequencing in newborn screening.

Laboratory Projects

  1. Cofactor Therapy for PKU: Dietary therapy has been enormously successful in PKU, converting a disease that produced intellectual disability into a disorder that can result in normal growth and development. However, the diet is extremely difficult and because of this most adults and many adolescents do not follow the diet as required, resulting in long-term problems. Some individuals with PKU respond to megadoses of sapropterin dihydrochloride, a synthetic form of tetrahydrobiopterin (BH4), with increased activity of PAH, the defective enzyme in PKU. This results in a lower phenylalanine level and greater tolerance of natural foods, alleviating some of the difficulties of the diet. Our ongoing work is in examining the benefits and long-term results of cofactor treatment in PKU.

  2. Alternative Enzyme Therapy for PKU:Phenylalanine ammonia lyase (PAL) is an enzyme that has been found to metabolize phenylalanine in a different direction from the natural pathway that is blocked in PKU. Consequently, this enzyme reduces the blood phenylalanine level in those with PKU and may serve as therapy for PKU, perhaps substituting for the difficult diet. Ongoing studies are examining this therapy to determine if it is safe and offers long-term treatment for PKU.


Dr. Levy obtained his M.D. degree from the Medical College of Georgia. Following residences in Pediatrics and Pediatric Pathology at Boston City Hospital, Columbia- Presbyterian Medical Center in New York, and Johns Hopkins Hospital in Baltimore, he served a fellowship in Metabolism under Drs. Mary Efron and Hugo Moser at the Massachusetts General Hospital. Subsequently, Dr. Levy was on the faculty at the Massachusetts General Hospital and also served as Consultant and then Director of the Massachusetts Metabolic Disorders Program. When the New England Newborn Screening Program was established, Dr. Levy became the Chief of Biochemical Genetics.

In 1978, Dr. Levy moved to Boston Children’s Hospital as Director of the Metabolic Program where he expanded the program from a PKU clinic to inborn errors of metabolism, and at the same time directed the New England Maternal PKU Program. Dr. Levy has served as Chair of the Workgroup on Newborn Screening and Follow-Up and Chair of the Newborn Screening Translational Research Network for the American College of Medical Genetics. He is a reviewer for many leading medical journals, is on the Editorial Board of the International Journal of Neonatal Screening, has served on several research advisory boards, is a consultant for several laboratories that are developing new metabolic treatments, has published over 450 peer-reviewed articles on metabolic disorders, and has received a number of national and international awards and honors for research in newborn screening and biochemical genetics.

Selected Publications

  1. S.E. Waisbren, F. Rohr, V. Anastasoaie, M. Brown, D. Harris, A. Ozonoff, S. Petrides, A. Wessel, H.L. Levy. Maternal Phenylketonuria: Long-term Outcomes in Offspring and Post-pregnancy Maternal Characteristics. JIMD Rep. 2015;21:23-33. doi: 10.1007/8904_2014_365. Epub 2015 Feb 25.
  2. Landau YE, Lichter-Konecki U, Levy HL. Genomics in newborn screening. J Pediatr, 2014;164:14-9.
  3. Levy HL, Milanowski A, Chakrapani A, Cleary M, Lee P, Trefz F, Whitely C, Feillet F, Feigenbaum A, Bebchuk J, Christ-Schmidt H, Dorenbaum A, for the Sapropterin Research Group. A Phase-III randomized placebo-controlled study of the efficacy of sapropterin dihydrochloride (tetrahydrobiopterin, 6-BH4) in reducing phenylalanine levels in subjects with phenylketonuria. Lancet, 2007; 370:504-10.
  4. Levy HL, Burton B, Cederbaum S, Scriver C. Recommendations for evaluation of responsiveness to tetrahydrobiopterin (BH4) in phenylketonuria and its use in treatment. Molec Genet Metab, 2007;92:287-91.


Publications powered by Harvard Catalyst Profiles

  1. Pancreatic involvement in patients with inborn errors of metabolism. Orphanet J Rare Dis. 2021 01 20; 16(1):37. View abstract
  2. Robert Guthrie and the Trials and Tribulations of Newborn Screening. Int J Neonatal Screen. 2021 Jan 19; 7(1). View abstract
  3. Ethical and Psychosocial Implications of Genomic Newborn Screening. Int J Neonatal Screen. 2021 Jan 09; 7(1). View abstract
  4. The Genetic Landscape and Epidemiology of Phenylketonuria. Am J Hum Genet. 2020 08 06; 107(2):234-250. View abstract
  5. Discontinuation of Pegvaliase therapy during maternal PKU pregnancy and postnatal breastfeeding: A case report. Mol Genet Metab Rep. 2020 Mar; 22:100555. View abstract
  6. Can Newborn Screening for Vitamin B12 Deficiency be Incorporated into All Newborn Screening Programs? J Pediatr. 2020 01; 216:9-11.e1. View abstract
  7. Phenylalanine hydroxylase genotype-phenotype associations in the United States: A single center study. Mol Genet Metab. 2019 12; 128(4):415-421. View abstract
  8. Phenotypic variability in deficiency of the a subunit of succinate-CoA ligase. JIMD Rep. 2019 Mar; 46(1):63-69. View abstract
  9. 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; 126(4):368-376. View abstract
  10. Revising the Psychiatric Phenotype of Homocystinuria. Genet Med. 2019 08; 21(8):1827-1831. View abstract
  11. Untargeted metabolomics identifies unique though benign biochemical changes in patients with pathogenic variants in UROC1. Mol Genet Metab Rep. 2019 Mar; 18:14-18. View abstract
  12. The BabySeq project: implementing genomic sequencing in newborns. BMC Pediatr. 2018 07 09; 18(1):225. View abstract
  13. Phenylalanine ammonia lyase (PAL): From discovery to enzyme substitution therapy for phenylketonuria. Mol Genet Metab. 2018 08; 124(4):223-229. View abstract
  14. Acute Illness Protocol for Urea Cycle Disorders. Pediatr Emerg Care. 2018 Jun; 34(6):e115-e119. View abstract
  15. Metabolomic Markers of Essential Fatty Acids, Carnitine, and Cholesterol Metabolism in Adults and Adolescents with Phenylketonuria. J Nutr. 2018 02 01; 148(2):194-201. View abstract
  16. Acute Illness Protocol for Maple Syrup Urine Disease. Pediatr Emerg Care. 2018 Jan; 34(1):64-67. View abstract
  17. 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; 2017:6859820. View abstract
  18. 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; 13:377-384. View abstract
  19. 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; 121(2):96-103. View abstract
  20. Acute Illness Protocol for Fatty Acid Oxidation and Carnitine Disorders. Pediatr Emerg Care. 2017 Apr; 33(4):296-301. View abstract
  21. Acute Illness Protocol for Organic Acidemias: Methylmalonic Acidemia and Propionic Acidemia. Pediatr Emerg Care. 2017 Feb; 33(2):142-146. View abstract
  22. 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; 40(2):209-218. View abstract
  23. Confounding factors in identification of disease-resilient individuals. Nat Biotechnol. 2016 11 08; 34(11):1103-1104. View abstract
  24. Glycomacropeptide for nutritional management of phenylketonuria: a randomized, controlled, crossover trial. Am J Clin Nutr. 2016 Aug; 104(2):334-45. View abstract
  25. The remarkable S. Harvey Mudd - A reminiscence. Mol Genet Metab. 2016 07; 118(3):143-144. View abstract
  26. Hyperphenylalaninemia and the genomic revolution. Mol Genet Metab. 2015 Mar; 114(3):380-1. View abstract
  27. Adherence to tetrahydrobiopterin therapy in patients with phenylketonuria. Mol Genet Metab. 2015 Jan; 114(1):25-8. View abstract
  28. The complexity of newborn screening follow-up in phenylketonuria. JIMD Rep. 2014; 17:37-9. View abstract
  29. Management of a Woman With Maple Syrup Urine Disease During Pregnancy, Delivery, and Lactation. JPEN J Parenter Enteral Nutr. 2015 Sep; 39(7):875-9. View abstract
  30. Phenylketonuria Scientific Review Conference: state of the science and future research needs. Mol Genet Metab. 2014 Jun; 112(2):87-122. View abstract
  31. Newborn screening: the genomic challenge. Mol Genet Genomic Med. 2014 Mar; 2(2):81-4. View abstract
  32. Genomics in newborn screening. J Pediatr. 2014 Jan; 164(1):14-9. View abstract
  33. Is melatonin synthesis a new biomarker for the pathogenesis and treatment of phenylketonuria? J Pediatr. 2013 May; 162(5):893-4. View abstract
  34. Congenital heart disease in maternal PKU. Mol Genet Metab. 2012 Dec; 107(4):648-9. View abstract
  35. A germline or de novo mutation in two families with Gaucher disease: implications for recessive disorders. Eur J Hum Genet. 2013 Jan; 21(1):115-7. View abstract
  36. The adult galactosemic phenotype. J Inherit Metab Dis. 2012 Mar; 35(2):279-86. View abstract
  37. Newborn screening conditions: What we know, what we do not know, and how we will know it. Genet Med. 2010 Dec; 12(12 Suppl):S213-4. View abstract
  38. Phenylketonuria. Lancet. 2010 Oct 23; 376(9750):1417-27. View abstract
  39. Sudden death in medium chain acyl-coenzyme a dehydrogenase deficiency (MCADD) despite newborn screening. Mol Genet Metab. 2010 Sep; 101(1):33-9. View abstract
  40. Newborn screening of lysosomal storage disorders. Clin Chem. 2010 Jul; 56(7):1071-9. View abstract
  41. Recommendations for evaluation of responsiveness to tetrahydrobiopterin (BH(4)) in phenylketonuria and its use in treatment. Mol Genet Metab. 2007 Dec; 92(4):287-91. View abstract
  42. Efficacy of sapropterin dihydrochloride (tetrahydrobiopterin, 6R-BH4) for reduction of phenylalanine concentration in patients with phenylketonuria: a phase III randomised placebo-controlled study. Lancet. 2007 Aug 11; 370(9586):504-10. View abstract
  43. Phenylalanine blood levels and clinical outcomes in phenylketonuria: a systematic literature review and meta-analysis. Mol Genet Metab. 2007 Sep-Oct; 92(1-2):63-70. View abstract
  44. Mutations in the phenylalanine hydroxylase gene identified in 95 patients with phenylketonuria using novel systems of mutation scanning and specific genotyping based upon thermal melt profiles. Mol Genet Metab. 2007 Jul; 91(3):218-27. View abstract
  45. Pericardial effusion in primary systemic carnitine deficiency. J Inherit Metab Dis. 2006 Aug; 29(4):589. View abstract
  46. Newborn screening for metabolic disorders. J Pediatr. 2006 May; 148(5):577-584. View abstract
  47. Subacute combined degeneration of the spinal cord in cblC disorder despite treatment with B12. Mol Genet Metab. 2006 Jun; 88(2):138-45. View abstract
  48. The use of betaine in the treatment of elevated homocysteine. Mol Genet Metab. 2006 Jul; 88(3):201-7. View abstract
  49. The clinical aspects of newborn screening: importance of newborn screening follow-up. Ment Retard Dev Disabil Res Rev. 2006; 12(4):246-54. View abstract
  50. Fetal fatty acid oxidation defects and maternal liver disease in pregnancy. Obstet Gynecol. 2006 Jan; 107(1):115-20. View abstract
  51. Metabolic disorders in the center of genetic medicine. N Engl J Med. 2005 Nov 03; 353(18):1968-70. View abstract
  52. Krabbe disease: severe neonatal presentation with a family history of multiple sclerosis. J Child Neurol. 2005 Oct; 20(10):826-8. View abstract
  53. Brief report: Predictors of parenting stress among parents of children with biochemical genetic disorders. J Pediatr Psychol. 2004 Oct; 29(7):565-70. View abstract
  54. Expanded screening of newborns for genetic disorders. JAMA. 2004 Feb 18; 291(7):820-1; author reply 821. View abstract
  55. Research design, organization, and sample characteristics of the Maternal PKU Collaborative Study. Pediatrics. 2003 Dec; 112(6 Pt 2):1519-22. View abstract
  56. Historical background for the maternal PKU syndrome. Pediatrics. 2003 Dec; 112(6 Pt 2):1516-8. View abstract
  57. Pregnancy experiences in the woman with mild hyperphenylalaninemia. Pediatrics. 2003 Dec; 112(6 Pt 2):1548-52. View abstract
  58. The Maternal Phenylketonuria International Study: 1984-2002. Pediatrics. 2003 Dec; 112(6 Pt 2):1523-9. View abstract
  59. Impact of the phenylalanine hydroxylase gene on maternal phenylketonuria outcome. Pediatrics. 2003 Dec; 112(6 Pt 2):1530-3. View abstract
  60. Effect of expanded newborn screening for biochemical genetic disorders on child outcomes and parental stress. JAMA. 2003 Nov 19; 290(19):2564-72. View abstract
  61. Lessons from the past--looking to the future. Newborn screening. Pediatr Ann. 2003 Aug; 32(8):505-8. View abstract
  62. Molecular genetic and potential biochemical characteristics of patients with T-protein deficiency as a cause of glycine encephalopathy (NKH). Mol Genet Metab. 2003 Aug; 79(4):272-80. View abstract
  63. Infantile hypermethioninemia and hyperhomocysteinemia due to high methionine intake: a diagnostic trap. Mol Genet Metab. 2003 May; 79(1):6-16. View abstract
  64. Arginase deficiency with lethal neonatal expression: evidence for the glutamine hypothesis of cerebral edema. J Pediatr. 2003 Mar; 142(3):349-52. View abstract
  65. Expanded newborn screening using tandem mass spectrometry. Adv Pediatr. 2003; 50:81-111. View abstract
  66. Neonatal screening for medium--chain acyl-CoA dehydrogenase deficiency. Lancet. 2002 Feb 16; 359(9306):628. View abstract