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Pathway Description
Hyperphenylalaninemia Due to DHPR-Deficiency
Homo sapiens
Disease Pathway
Hyperphenylalaninemia due to dihydropteridine reductase deficiency (DHPR) is the high presence of phenylalanine in the system/blood caused by a genetic mutation. More specificially, mutations in the QDPR gene are the root cause of the condition. One observes that such a mutation results in an error encoding a reductase enzyme, and from there a chain reaction of effects lead to the observed effects of the disease. The mutation is autosomal recessive.
When tetrahydrobiopterin levels drop, the breakdown of many several amino acids, such as phenylalanine, is reduced and as a result their levels in the blood augment.
Symptoms of hyperphenylalaninemia due to dihydropteridine reductase deficiency include: dysphagia, global development delay, microcephaly, and intellectual disability (among others). Treatment consists of BH4 supplements as well as other medical treatments.
References
Hyperphenylalaninemia Due to DHPR-Deficiency References
[Metagen: HYPERPHENYLALANINEMIA DUE TO DHPR-DEFICIENCY](http://metagene.de/program/d.prg?id_d=133)
[OMIM: 261630](http://omim.org/entry/261630})
Dianzani I, de Sanctis L, Smooker PM, Gough TJ, Alliaudi C, Brusco A, Spada M, Blau N, Dobos M, Zhang HP, Yang N, Ponzone A, Armarego WL, Cotton RG: Dihydropteridine reductase deficiency: physical structure of the QDPR gene, identification of two new mutations and genotype-phenotype correlations. Hum Mutat. 1998;12(4):267-73. doi: 10.1002/(SICI)1098-1004(1998)12:4<267::AID-HUMU8>3.0.CO;2-C.
Pubmed: 9744478
Arai N, Narisawa K, Hayakawa H, Tada K: Hyperphenylalaninemia due to dihydropteridine reductase deficiency: diagnosis by enzyme assays on dried blood spots. Pediatrics. 1982 Sep;70(3):426-30.
Pubmed: 7110817
Pterine Biosynthesis References
Lehninger, A.L. Lehninger principles of biochemistry (4th ed.) (2005). New York: W.H Freeman.
Salway, J.G. Metabolism at a glance (3rd ed.) (2004). Alden, Mass.: Blackwell Pub.
Thony B, Auerbach G, Blau N: Tetrahydrobiopterin biosynthesis, regeneration and functions. Biochem J. 2000 Apr 1;347 Pt 1:1-16.
Pubmed: 10727395
Longo N: Disorders of biopterin metabolism. J Inherit Metab Dis. 2009 Jun;32(3):333-42. doi: 10.1007/s10545-009-1067-2. Epub 2009 Feb 9.
Pubmed: 19234759
Crabtree MJ, Channon KM: Synthesis and recycling of tetrahydrobiopterin in endothelial function and vascular disease. Nitric Oxide. 2011 Aug 1;25(2):81-8. doi: 10.1016/j.niox.2011.04.004. Epub 2011 Apr 22.
Pubmed: 21550412
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