Phenylketonuria is an inherited metabolic disorder that increases phenylalanine levels in the body

pku handbook

An overview of the disease

Pku can range from mild to severe

PKU ranges from mild to severe. The most severe form pku handbook is called classic PKU. Children with untreated classic PKU will develop permanent mental disability. Light skin and hair, seizures, developmental delays, behavioral problems, and mental illness are also common. The less severe forms, sometimes called "mild PKU," "variant PKU," and "non-PKU hyperphenylalaninemia," carry a smaller risk of brain damage. Mothers with PKU who no longer follow a phenylalanine-restricted diet are at increased risk of having children with intellectual disabilities because their children may be exposed to high levels of phenylalanine before birth.

In most of these cases, PKU is caused by the development of changes (pathogenic variants, also called variants) in the PAH gene. The disease is autosomal recessive teaching method to analyze heredity, because PKU can be detected with a simple blood system test technology at the same time and we can improve treatment, so PKU is part of newborn screening. Typically, the treatment of PKU requires a time-restricted phenylalanine diet and management with strict control and monitoring. The combination of phenylalanine and low-phenylalanine dietary education may be helpful for some children and adults with PKU themselves. The drug polyethylene glycol glutaraldehyde will be given to help treat the disease in adults with high levels of phenylalanine.

2. Physiological overview

The liver enzyme phenylalanine hydroxylase (PAH) catalyzes the conversion of the amino acid phenylalanine to tyrosine. In addition to molecular oxygen and iron, tetrahydrobiota (BH4) is also a cofactor required for PAH activity. This pathway accounts for the majority of catabolism and is responsible for processing approximately 75% of dietary phenylalanine, with the remainder for protein synthesis. PKU is caused by PAH deficiency. This results in increased blood and urine concentrations of phenylalanine and its metabolites, phenylacetic acid and phenylacetic acid. Tyrosine concentrations are usually within the normal range, but low concentrations are occasionally observed. Defects in BH4 metabolism account for approximately 2% of patients with elevated phenylalanine levels.

Complete enzyme deficiency results in classic PKU, in which untreated, newly diagnosed neonates have serum phenylalanine plasma concentrations exceeding 20 mg/dL (1200 micromol/L). The reasons for the residual enzymatic activity were moderate PKU (phenylalanine concentration 900-1200 μmol/L) and mild PKU (phenylalanine concentration 600-900 μmol/L). Mild hyperphenylalaninemia (HPA; phenylalanine concentration 360-600 μmol/L) and benign mild HPA (phenylalanine concentration 120-360 μmol/L) that usually does not require treatment.


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