Dihydropteridine reductase deficiency DHPR

Regarding the dihydropteridine reductase deficiency (DHPR) and defect in biosynthesis of biopterin, further studies may be in order in most hyperphenyla-laninemic infants. 

A Fig. 6.1.7a- HPLC of pterins using a column-switching system a standard mixture b control urine c urine guanosine triphosphate cyclohydrolase I (GTPCH) deficiency d urine 6-pyru-voyl-tetrahydropterin synthase (PTPS) deficiency e urine pterin-4a-carbinolamine dehydratase (PCD) deficiency f urine dihydropteridine reductase (DHPR) deficiency g urine phenylketonuria 4-8 h after tetrahydrobiopterin (BH4) administration h-k see next page... 

CFD is further associated with the following inherited metabolic disorders 5,10-methylen-tetrahydrofolate reductase (MTHFR) deficiency [7], 3-phos-phoglycerate dehydrogenase (PGDH) deficiency [8], dihydropteridine reductase (DHPR) deficiency [9], as well as with Rett syndrome [10], and Aicardi-Gou res Syndrome [11]. Furthermore, folate deficiency may be associated with congenital folate malabsorption, severe malnutrition, and formiminotransferase deficiency. 

A. The patient, despite being put on a low-Phe diet, exhibits neurologic problems resulting from an inability to synthesize catecholamine and indoleamine neurotransmitters. This is caused by a deficiency in dihydropteridine reductase (DHPR). DHPR regenerates tetrahydro-biopterin (BH ), which is oxidized to dihydrobiopterin by phenylalanine hydroxylase, as well as tyrosine hydroxylase and tryptophan hydroxylase (tryptophan 5-monooxygenase). If phenylalanine hydroxylase were deficient, a diet low in Phe would alleviate the effects. Since the urinary biopterin concentration is elevated, a deficiency in GTP cyclohydrolase I is eliminated because that is an enzyme in the biosynthetic pathway of BH. Phe hydroxylase, Tyr hydroxylase, and Tip hydroxylase activities are low because of a lack of BH. ... 

Dihydropteridine reductase (DHPR) deficiency all tissues 4pl5.3 261630... 

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