de la Cruz, Felix Intellectual and Developmental Disabilities Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland.
- Related Primary Literature
- Additional Reading
An inborn error of metabolism in which affected individuals lack the liver enzyme phenylalanine hydroxylase (PAH), which is needed to metabolize phenylalanine, an amino acid essential for normal growth and development. If untreated, affected individuals may suffer from severe intellectual disability, become microcephalic, have behavioral problems, develop epilepsy, or show other signs of neurological impairment. Phenylketonuria (PKU) is inherited as an autosomal recessive trait and is found in all ethnic groups but most frequently in individuals of northern European descent. Its incidence is about 1 per 14,000 births in the United States. Classically, persons with phenylketonuria exhibit blood phenylalanine concentrations of 20 mg/deciliter or more (normal concentrations are about 1–2 mg/dl), normal blood tyrosine levels, and excessive phenylalanine metabolites in the urine while on a normal diet. Phenylketonuria variants have blood phenylalanine concentrations of 10–20 mg/dl, but may not have phenylalanine metabolites in their urine unless they have ingested excessive amounts of protein. See also: Amino acid; Enzyme; Intellectual disability; Metabolism
The content above is only an excerpt.
for your institution. Subscribe
To learn more about subscribing to AccessScience, or to request a no-risk trial of this award-winning scientific reference for your institution, fill in your information and a member of our Sales Team will contact you as soon as possible.
to your librarian. Recommend
Let your librarian know about the award-winning gateway to the most trustworthy and accurate scientific information.
AccessScience provides the most accurate and trustworthy scientific information available.
Recognized as an award-winning gateway to scientific knowledge, AccessScience is an amazing online resource that contains high-quality reference material written specifically for students. Contributors include more than 10,000 highly qualified scientists and 45 Nobel Prize winners.
MORE THAN 8700 articles covering all major scientific disciplines and encompassing the McGraw-Hill Encyclopedia of Science & Technology and McGraw-Hill Yearbook of Science & Technology
115,000-PLUS definitions from the McGraw-Hill Dictionary of Scientific and Technical Terms
3000 biographies of notable scientific figures
MORE THAN 19,000 downloadable images and animations illustrating key topics
ENGAGING VIDEOS highlighting the life and work of award-winning scientists
SUGGESTIONS FOR FURTHER STUDY and additional readings to guide students to deeper understanding and research
LINKS TO CITABLE LITERATURE help students expand their knowledge using primary sources of information