What does Dihydropteridine reductase do?

Dihydropteridine reductase (DHPR) is an enzyme essential for the regeneration of tetrahydrobiopterin, itself a co-factor necessary for the hydroxylation reactions in the brain leading to the synthesis of tyrosine, dopa, noradrenaline and 5-hydroxytryptophan (Fig. 1).

What is Dhpr deficiency?

Dihydropteridine reductase deficiency (DHPR) is a severe form of hyperphenylalaninemia (high levels of the amino acid phenylalanine in the blood) due to impaired renewal of a substance known as tetrahydrobiopterin (BH4).

What is malignant PKU?

A small percentage of children with elevated phenylalanine levels exhibit normal PAH levels but have a deficiency in synthesis or recycling of BH4 known as tetrahydrobiopterin deficiency. This condition is sometimes termed malignant PKU and can result from biallelic mutations in the GCH1, PCB1, PTS, or QDPR genes.

What causes dihydropteridine reductase deficiency ( DHPR )?

Dihydropteridine reductase deficiency (DHPR) is a severe form of hyperphenylalaninemia (high levels of the amino acid phenylalanine in the blood) due to impaired renewal of a substance known as tetrahydrobiopterin (BH4).

What kind of tests are done for PKU?

If your baby’s results were not normal, your health care provider will order more tests to confirm or rule out PKU. These tests may include more blood tests and/or urine tests. You and your baby may also get genetic tests, since PKU is an inherited condition.

How does dihydrobiopterin reductase convert phenylalanine to DOPA?

Phenylalanine is converted into dopa using tetrahydrobiopterin releasing dihydrobiopterin and water, which is then converted back into tetrahydrobiopterin using the NADPH-dependent enzyme dihydrobiopterin reductase. A deficiency of dihydrobiopterin reductase is one cause of tetrahydrobiopterin deficiency.

Do you have to pass down the PKU gene?

Genes are the basic units of heredity passed down from your mother and father. For a child to get the disorder, both the mother and father must pass down a mutated PKU gene. Although PKU is rare, all newborns in the United States are required to get a PKU test.