Tetrahydrobiopterin Deficiency: Symptoms & Signs

Medically Reviewed on 5/28/2021

Tetrahydrobiopterin deficiency is a very rare disorder that increases the levels of several substances, including phenylalanine, in the blood. Most cases of elevated levels of phenylalanine in the blood are caused by a different condition known as phenylketonuria. Tetrahydrobiopterin is a molecule that helps process several amino acids in the body, including phenylalanine.

Signs and symptoms of tetrahydrobiopterin deficiency include

Causes of tetrahydrobiopterin deficiency

Tetrahydrobiopterin deficiency can be caused by mutations in one of several genes, including GCH1, PCBD1, PTS, and QDPR. These mutations are inherited in an autosomal recessive manner, meaning an affected individual must receive one defective gene from each parent, and each parent is an unaffected carrier.

Other tetrahydrobiopterin deficiency symptoms and signs

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Jameson, J. Larry, et al. Harrison's Principles of Internal Medicine, 20th Ed. New York: McGraw-Hill Education, 2018.