QDPR cDNA Clone – Quinoid Dihydropteridine Reductase (Human)

This gene encodes the enzyme dihydropteridine reductase, which catalyzes the NADH-mediated reduction of quinonoid dihydrobiopterin. This enzyme is an essential component of the pterin-dependent aromatic amino acid hydroxylating systems. Mutations in this gene resulting in QDPR deficiency include aberrant splicing, amino acid substitutions, insertions, or premature terminations. Dihydropteridine reductase deficiency presents as atypical phenylketonuria due to insufficient production of biopterin, a cofactor for phenylalanine hydroxylase. [provided by RefSeq, Jul 2008]

QDPR: The product of this enzyme, tetrahydrobiopterin (BH-4), is an essential cofactor for phenylalanine, tyrosine, and tryptophan hydroxylases. Defects in QDPR are the cause of BH4-deficient hyperphenylalaninemia type C (HPABH4C); also called dihydropteridine reductase deficiency (DHPR deficiency) or hyperphenylalaninemia tetrahydrobiopterin-deficient due to DHPR deficiency or quinoid dihydropteridine reductase deficiency (QDPR deficiency). HPABH4C is a rare autosomal recessive disorder characterized by hyperphenylalaninemia and severe neurologic symptoms (malignant hyperphenylalaninemia) including axial hypotonia and truncal hypertonia, abnormal thermogenesis, and microcephaly. These signs are attributable to depletion of the neurotransmitters dopamine and serotonin, whose syntheses are controlled by tryptophan and tyrosine hydroxylases that use BH-4 as cofactor. These patients do not respond to phenylalanine- restricted diet. HPABH4C is lethal if untreated. Belongs to the short-chain dehydrogenases/reductases (SDR) family.

Protein type: Cofactor and Vitamin Metabolism - folate biosynthesis; EC 1.5.1.34; Oxidoreductase

Chromosomal Location of Human Ortholog: 4p15.31

Cellular Component: cytoplasm; cytosol

Molecular Function: 6,7-dihydropteridine reductase activity; electron carrier activity

Biological Process: amino acid metabolic process; dihydrobiopterin metabolic process; L-phenylalanine catabolic process

Disease: Hyperphenylalaninemia, Bh4-deficient, C