Related Experiment Video
Updated: Aug 2, 2026
07:35
Use of Ultra-high Field MRI in Small Rodent Models of Polycystic Kidney Disease for In Vivo Phenotyping and Drug Monitoring
Published on: June 23, 2015
["Transitory" phenylketonuria. A permanent deficit]
Archives Francaises De Pediatrie
|November 1, 1979
Summary
This study introduces "transitory" phenylketonuria, a condition where infants initially show high phenylalanine levels but later tolerate normal protein intake. This highlights a potentially distinct metabolic disorder in newborns.
Area of Science:
- Biochemistry
- Genetics
- Neonatal Medicine
Background:
- Hyperphenylalaninemia in neonates requires careful management to prevent neurological damage.
- Understanding the diverse causes and prognoses of elevated phenylalanine is crucial for early intervention.
Observation:
- Three neonates presented with hyperphenylalaninemia (>1.8 µmol/ml) but normalized with a standard diet (3g/kg protein).
- Atypical (zero-order) phenylalanine clearance kinetics were observed at one year, with persistence noted at five years in two cases.
- Parental screening revealed normal phenylalanine levels and phenylalanine/tyrosine ratios.
Findings:
- The study proposes a new entity: "transitory" phenylketonuria, characterized by transient hyperphenylalaninemia.
- This condition may not be homogenous, as one case showed a partial defect in biopterin synthesis.
- The underlying mechanism remains unclear in two of the reported cases.
Implications:
- Recognition of "transitory" phenylketonuria could refine diagnostic and treatment approaches for neonatal hyperphenylalaninemia.
- Further research is needed to elucidate the specific genetic and biochemical pathways involved.
- Distinguishing this entity from classic phenylketonuria is vital for appropriate patient management and prognosis.
More Related Videos
Related Concept Videos
01:27Glucose Transporters
Glucose transporters facilitate the transport of glucose across the cell membrane. In addition to glucose, some glucose transporters can also aid the movement of other hexoses such as fructose, mannose, and galactose.
Facilitated diffusion-glucose transporters (GLUTs) are encoded by the solute-linked carrier (SLC) family 2, subfamily A gene family, or SLC2A. The 14 GLUT protein members are distributed into three classes:
Facilitated diffusion-glucose transporters (GLUTs) are encoded by the solute-linked carrier (SLC) family 2, subfamily A gene family, or SLC2A. The 14 GLUT protein members are distributed into three classes:
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...
01:23Pharmacokinetics in Pediatric Patients: Overview and Drug Absorption
Understanding the physiological differences in the pediatric population is crucial for effective pharmacotherapy. Neonates, infants, and children exhibit significant variations in gastric pH, gastric emptying time, intestinal transit time, and biliary function. These variations profoundly affect oral drug absorption, necessitating a nuanced approach to pediatric dosing.Neonates present with a unique physiological profile, having a gastric pH greater than 4 and faster and more irregular gastric...
01:24Pharmacokinetics in Pediatric Patients: Drug Metabolism
In pediatric care, understanding the nuances of hepatic drug metabolism is crucial, as it significantly differs from that of adults. This divergence is primarily due to the developmental stage of drug-metabolizing enzymes, which affects how medications are processed in the body. In neonates, for instance, the activity of Phase I enzymes—critical for the initial breakdown of drugs—is markedly reduced, functioning at just 20–40% of the levels seen in adults. This reduction poses a challenge in...
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...