Related Experiment Video
Updated: Jul 30, 2026
09:28
One-step Metabolomics: Carbohydrates, Organic and Amino Acids Quantified in a Single Procedure
Published on: June 25, 2010
Phenylketonuria: contemporary screening and diagnosis
1Department of Pediatrics, University of Kentucky, Lexington 40536.
Annals of Clinical and Laboratory Science
|November 1, 1990
Summary
Newborn screening for phenylketonuria (PKU) detects high phenylalanine levels but faces challenges. Despite protocols, some infants are missed, leading to severe developmental issues.
Area of Science:
- Biochemistry
- Genetics
- Neonatal Medicine
Background:
- Newborn screening for phenylketonuria (PKU) is standard practice.
- Early detection relies on measuring elevated blood phenylalanine levels.
Purpose of the Study:
- To highlight the challenges and pitfalls in newborn screening for PKU.
- To discuss the different forms of hyperphenylalaninemia and their causes.
Main Methods:
- Review of current newborn screening protocols for PKU.
- Analysis of factors contributing to false positives and missed cases.
- Discussion of confirmatory testing and cofactor-related disorders.
Main Results:
- PKU screening identifies elevated phenylalanine, but numerous factors can affect results.
- Approximately 1% of screened infants are false positives.
- Two-thirds of persistent hyperphenylalaninemia cases are classic PKU.
- Other forms include non-classic PKU and tetrahydrobiopterin cofactor defects.
- Despite screening, about 1 in 70 affected infants are missed, leading to adverse outcomes.
Conclusions:
- Newborn screening for PKU is crucial but imperfect, with potential for false positives and missed diagnoses.
- Accurate diagnosis requires careful adherence to testing protocols and confirmatory tests.
- Understanding different forms of hyperphenylalaninemia, including cofactor defects, is essential for appropriate management.
Related Concept Videos
02:46Genetic Screens
Genetic screens are tools used to identify genes and mutations responsible for phenotypes of interest. Genetic screens help identify individuals or a group of people at risk of developing genetic diseases and help them with early intervention, targeted therapy, and reproductive options.
Forward genetic screens
Forward or “classical” genetic screens involve creating random mutations in an organism’s DNA using radiation, mutagens, or insertion of additional bases, which result in visible changes...
Forward genetic screens
Forward or “classical” genetic screens involve creating random mutations in an organism’s DNA using radiation, mutagens, or insertion of additional bases, which result in visible changes...
01:21Overview of Protein Metabolism
Proteins are broken down into amino acids during digestion. Unlike fats and carbohydrates, which are stored for later use, proteins are not. Instead, amino acids are either used to produce ATP through oxidation or contribute to the creation of new proteins for the growth and repair of the body. Any surplus amino acids from the diet are converted into glucose or triglycerides rather than excreted.
Amino acids play various roles in the body once they are absorbed into cells. They are restructured...
Amino acids play various roles in the body once they are absorbed into cells. They are restructured...
01:20Inborn Errors of Metabolism
Phenylketonuria (PKU) is a protein metabolism disorder characterized by high blood levels of the amino acid phenylalanine. This results from a mutation in the gene responsible for phenylalanine hydroxylase, an enzyme that converts phenylalanine into tyrosine. When this enzyme is deficient, phenylalanine builds up in the blood, leading to symptoms such as vomiting, rashes, seizures, growth deficiency, and severe mental retardation. An early diagnosis and a diet restricting phenylalanine intake...
01:27Pharmacogenetics of Phase II Enzymes: N-acetyltransferase, Thiopurine S-methyltransferase, UDP-glucuronosyltransferase
Phase II biotransformation reactions are essential for detoxifying and eliminating xenobiotics, including many pharmaceutical compounds. These reactions typically involve conjugation, the covalent attachment of polar endogenous groups such as glucuronic acid, sulfate, methyl, or acetyl moieties to functional groups introduced during Phase I metabolism. The resulting conjugates are more water-soluble, enabling efficient renal or biliary excretion.The major classes of Phase II enzymes include...
01:26Nephrotic Syndrome II : Assessment and Medical Management
IntroductionNephrotic syndrome is a kidney disorder marked by excessive protein loss in the urine, leading to various systemic complications. This condition often results from damage to the glomeruli—the kidney's filtering units—causing proteinuria, low blood protein levels, and fluid retention. Understanding the assessment, diagnosis, and management of nephrotic syndrome is essential for effective treatment and prevention of further kidney damage.AssessmentPatient History: Document any history...
01:25Type II Diabetes Mellitus III: Clinical Manifestations and Diagnosis
Type 2 diabetes mellitus develops gradually and is often asymptomatic in early stages.Clinical ManifestationsWhen symptoms appear, they include fatigue, blurred vision, pruritus, delayed wound healing, and recurrent infections, particularly candidal infections. Peripheral neuropathy may present as numbness or tingling in the extremities. Classic hyperglycemia symptoms—polyuria, polydipsia, and polyphagia—are less common. Most patients are overweight and frequently have associated hypertension...