Skip to content

    Children's Health

    Font Size
    A
    A
    A

    Phenylketonuria

    Important
    It is possible that the main title of the report Phenylketonuria is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.

    Synonyms

    Disorder Subdivisions

    • None

    General Discussion

    Phenylketonuria (PKU) is an inborn error of metabolism that is detectable during the first days of life with appropriate blood testing (e.g., during routine neonatal screening). PKU is characterized by absence or deficiency of an enzyme (phenylalanine hydroxylase) that is responsible for processing the essential amino acid phenylalanine. (Amino acids, the chemical building blocks of proteins, are essential for proper growth and development.) With normal enzymatic activity, phenylalanine is converted to another amino acid (tyrosine), which is then utilized by the body. However, when the phenylalanine hydroxylase enzyme is absent or deficient, phenylalanine abnormally accumulates in the blood and is toxic to brain tissue.

    Symptoms associated with PKU are typically absent in newborns. Affected infants may be abnormally drowsy and listless (lethargic) and have difficulties feeding. In addition, untreated infants with PKU tend to have unusually light eyes, skin, and hair (light pigmentation) and may develop a rash that appears similar to eczema, an inflammatory skin condition that may be characterized by itching, redness, and blistering in affected areas.

    Without treatment, most infants with PKU develop mental retardation that is typically severe. Those with untreated PKU may also develop additional neurologic symptoms, such as episodes of uncontrolled electrical activity in the brain (seizures), abnormally increased activity (hyperactivity), poor coordination and a clumsy manner of walking (gait), abnormal posturing, aggressive behavior, or psychiatric disturbances. Additional symptoms and findings may include nausea, vomiting, and a musty or "mousy" body odor due to the presence of a by-product of phenylalanine (phenylacetic acid) in the urine and sweat.

    To prevent mental retardation, treatment consists of a carefully controlled, phenylalanine-restricted diet beginning during the first days or weeks of life. Most experts suggest that a phenylalanine-restricted diet should be life-long in persons with classical PKU. Classical PKU refers to persons with 2 severe mutations of the phenylalanine hydroxylase gene.

    Resources

    March of Dimes Birth Defects Foundation
    1275 Mamaroneck Avenue
    White Plains, NY 10605
    Tel: (914)997-4488
    Fax: (914)997-4763
    Tel: (888)663-4637
    Email: Askus@marchofdimes.com
    Internet: http://www.marchofdimes.com

    National PKU News
    6869 Woodlawn Avenue NE #116
    Seattle, WA 98115-5469
    Tel: (206)525-8140
    Fax: (206)525-5023
    Email: schuett@pkunews.org
    Internet: http://www.pkunews.org

    Children's PKU Network
    3306 Bumann Rd
    Encinitas, CA 92024
    United States
    Tel: (858)756-0079
    Fax: (858)756-1059
    Tel: (800)377-6677
    Email: pkunetwork@aol.com
    Internet: http://www.pkunetwork.org/

    Phenylalanine Hydroxylase Locus Knowledgebase
    McGill Univeristy Health Center
    Montreal Children's Hospital
    DeBelle Laboratory, Room A717
    2300 Tupper Street
    Monteral, Quebec, H3H 1P3
    Canada
    Tel: 5144124400
    Fax: 5144124400
    Email: pahdb@debelle.mcgill.ca
    Internet: http://www.pahdb.mcgill.ca/

    NIH/National Institute of Child Health and Human Development
    31 Center Dr
    Building 31, Room 2A32
    MSC2425
    Bethesda, MD 20892
    Fax: (866)760-5947
    Tel: (800)370-2943
    TDD: (888)320-6942
    Email: NICHDInformationResourceCenter@mail.nih.gov
    Internet: http://www.nichd.nih.gov/

    Cochrane Cystic Fibrosis and Genetic Disorders Group
    Institute of Child Health, University of Liverpool
    Alder Hey Children's NHS Foundation Trust
    Liverpool, L12 2 AP
    United Kingdom
    Tel: 441512525696
    Email: nikkij@liverpool.ac.uk
    Internet: http://cfgd.cochrane.org

    Belgian Association for Metabolic Diseases
    Alice Nahonlann 7
    Melsele, 9120
    Belgium
    Tel: 0498701503
    Fax: 037754839
    Email: info@boks.be
    Internet: http://www.boks.be/site/index.php/

    Genetic and Rare Diseases (GARD) Information Center
    PO Box 8126
    Gaithersburg, MD 20898-8126
    Tel: (301)251-4925
    Fax: (301)251-4911
    Tel: (888)205-2311
    TDD: (888)205-3223
    Internet: http://rarediseases.info.nih.gov/GARD/

    Mid-Atlantic Connection for PKU and Allied Disorders, Inc.
    PO Box 6086
    Lancaster, PA 17607-6086
    Tel: (717)872-7546
    Fax: (717)872-7546
    Email: info@macpad.org
    Internet: http://www.macpad.org

    Madisons Foundation
    PO Box 241956
    Los Angeles, CA 90024
    Tel: (310)264-0826
    Fax: (310)264-4766
    Email: getinfo@madisonsfoundation.org
    Internet: http://www.madisonsfoundation.org

    Cook for Love, Inc.
    30 Seneca Street
    Dobbs Ferry, NY 10522
    Tel: (914)674-1025
    Email: info@cookforlove.org
    Internet: http://www.cookforlove.org

    National PKU Alliance
    P.O. Box 501
    Tomahawk, WI 54487-0501
    USA
    Tel: (715)437-0477
    Fax: (715)453-7670
    Email: christine.brown@npkua.org
    Internet: http://www.npkua.org

    PKU Challenge
    P.O. Box 896
    East Longmeadow, MA 01028
    Tel: (413)525-0204
    Email: Chris@ThePKUChallenge.com
    Internet: http://www.ThePKUChallenge.com

    Medical Home Portal
    Dept. of Pediatrics
    University of Utah
    P.O. Box 581289
    Salt Lake City, UT 84158
    Tel: (801)587-9978
    Fax: (801)581-3899
    Email: mindy.tueller@utah.edu
    Internet: http://www.medicalhomeportal.org

    For a Complete Report:

    This is an abstract of a report from the National Organization for Rare Disorders (NORD). A copy of the complete report can be downloaded free from the NORD website for registered users. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational therapies (if available), and references from medical literature. For a full-text version of this topic, go to www.rarediseases.org and click on Rare Disease Database under "Rare Disease Information".

    The information provided in this report is not intended for diagnostic purposes. It is provided for informational purposes only. NORD recommends that affected individuals seek the advice or counsel of their own personal physicians.

    It is possible that the title of this topic is not the name you selected. Please check the Synonyms listing to find the alternate name(s) and Disorder Subdivision(s) covered by this report

    This disease entry is based upon medical information available through the date at the end of the topic. Since NORD's resources are limited, it is not possible to keep every entry in the Rare Disease Database completely current and accurate. Please check with the agencies listed in the Resources section for the most current information about this disorder.

    For additional information and assistance about rare disorders, please contact the National Organization for Rare Disorders at P.O. Box 1968, Danbury, CT 06813-1968; phone (203) 744-0100; web site www.rarediseases.org or email orphan@rarediseases.org

    Last Updated: 5/1/2007
    Copyright 1986, 1989, 1990, 1993, 1996, 1997, 1998, 1999, 2000, 2002, 2003, 2004, 2006 National Organization for Rare Disorders, Inc.

    WebMD Medical Reference from the National Organization for Rare Disorders

    Last Updated: May 28, 2015
    This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

    Today on WebMD

    child with red rash on cheeks
    What’s that rash?
    plate of fruit and veggies
    How healthy is your child’s diet?
     
    smiling baby
    Treating diarrhea, fever and more.
    Middle school band practice
    Understanding your child’s changing body.
     

    worried kid
    fitArticle
    jennifer aniston
    Slideshow
     
    Measles virus
    Article
    sick child
    Slideshow
     

    babyapp
    New
    Child with adhd
    Slideshow
     
    rl with friends
    fitSlideshow
    Child Coughing or Sneezing into Elbow
    Article