Subsequent diagnostic procedures (called mutation analysis and genotype determination) can actually identify the specific types of PAH gene mutations inherited by PKU infants.
In more detail, PKU mutations can involve many different types of changes, such as deletions and insertions, in the DNA of the gene that codes for the PAH enzyme.
Phenylketonuria (PKU) is a rare metabolic disorder caused by a deficiency in the production of the hepatic (liver) enzyme phenylalanine hydroxylase (PAH).
A carrier does not display any symptoms of the disease because the carrier's liver produces normal quantities of the PAH enzyme.
Mutations in the PAH gene prevent the liver from producing adequate levels of the PAH enzyme needed to break down phenylalanine.
A lack of PAH results in the buildup of abnormally high phenylalanine concentrations (or levels) in the blood and brain.
PKU symptoms are caused by alterations or mutations in the genetic code for the PAH enzyme.
The PAH gene and its PKU mutations are found on chromosome 12 in the human genome.
PKU is caused by the liver's inability to produce a particular type of PAH enzyme.
The normal PAH gene is dominant to recessive PKU mutations.