Phenylketonuria

National Organization for Rare Disorders, Inc.

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

  • Classical Phenylketonuria
  • Hyperphenylalanemia
  • Phenylalanine Hydroxylase Deficiency
  • Phenylalaninemia
  • PKU

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 lifelong in persons with classical PKU. Classical PKU refers to persons with 2 severe mutations of the phenylalanine hydroxylase gene.
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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
3790 Via De La Valle, Ste 120
Del Mar, CA 92014
United States
Tel: (858)509-0767
Fax: (858)509-0768
Tel: (800)377-6677
Email: pkunetwork@aol.com
Internet: http://www.pkunetwork.org/

National Institute of Mental Retardation
York University
Kinsmen NIMR Building
4700 Keele Street
North York, Toronto
Ontario, M3J 1P3
Canada
Tel: 4166619611

Phenylalanine Hydroxylase Locus Knowledgebase (PAHdb)
McGill Univeristy Health Center
Montreal Children's Hospital
DeBelle Laboratory, Room A717
2300 Tupper St.
Monteral, Quebec, H3H 1P3
Canada
Tel: 5144124417
Fax: 5144124329
Email: pahdb@debelle.mcgill.ca
Internet: http://www.pahde.mcgill.ca

NIH/National Institute of Child Health and Human Development
31 Center Dr
Building 31, Room 2A32
MSC2425
Bethesda, MD 20892
Tel: (301)496-5133
Fax: (301)496-7101
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: +44 (0) 151 252 5696
Fax: +44 (0) 151 252 5456
Email: nikkij@liverpool.ac.uk
Internet: http://www.cfgd.cochrane.org/en/index.html

MUMS National Parent-to-Parent Network
150 Custer Court
Green Bay, WI 54301-1243
USA
Tel: (920)336-5333
Fax: (920)339-0995
Tel: (877)336-5333
Email: mums@netnet.net
Internet: http://www.netnet.net/mums/

Belgian Association for Metabolic Diseases (BOKS)
Alice Nahonlann 7
Melsele, 9120
Belgium
Tel: 3237754839
Email: info@boks.be
Internet: http://www.boks.be

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
Email: ordr@od.nih.gov
Internet: http://rarediseases.info.nih.gov/Default.aspx

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

For a Complete Report

For a Complete Report

This is an abstract of a report from the National Organization for Rare Disorders, Inc. ® (NORD). A copy of the complete report can be obtained for a small fee by visiting the NORD website. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational treatments (if available), and references from medical literature. For a full-text version of this topic, see http://www.rarediseases.org/search/rdblist.html

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