National Organization for Rare Disorders, Inc.
It is possible that the main title of the report Tetrahydrobiopterin Deficiency is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.
Tetrahydrobiopterin (BH4) deficiencies is a general term for a group of disorders characterized by abnormalities in the creation (biosynthesis) or regeneration of tetrahydrobiopterin, a naturally-occurring compound that acts as a cofactor. A cofactor is a non-protein substance in the body that enhances or is necessary for the proper function of certain enzymes. When tetrahydrobiopterin is deficient, the chemical balance within the body is upset. In most of these disorders, there are abnormally high levels of the amino acid phenylalanine (hyperphenylalaninemia). Amino acids such as phenylalanine are chemical building blocks of proteins and are essential for proper growth and development. Most of these disorders also cause abnormally low levels of neurotransmitters. Neurotransmitters are chemicals that modify, amplify or transmit nerve impulses from one nerve cell to another, enabling nerve cells to communicate. These chemical imbalances can ultimately cause a wide variety of symptoms and physical findings including progressive neurological abnormalities, lack of muscle tone (hypotonia), the overproduction of saliva (hypersalivation), loss of coordination, abnormal movements, and/or delayed motor development. The specific symptoms can vary dramatically from one person to another and can range from mild to severe in expression. Prompt diagnosis and treatment of these disorders can prevent potentially severe, irreversible neurological damage. Tetrahydrobiopterin deficiency is caused by mutations in specific genes that encode enzymes required for the biosynthesis or regeneration of tetrahydrobiopterin. Most of these mutations are inherited as autosomal recessive traits.
There are four main forms of tetrahydrobiopterin deficiency sometimes referred to as ‘classical' tetrahydrobiopterin deficiency. They are: guanosine triphosphate cyclohydrolase I (GTPCH) deficiency; 6-pyruvoyl tetrahydropterin synthase (PTPS) deficiency; pterin-4-alpha-carbinolamine dehydratase (PCD) deficiency; and dihydropteridine reductase (DHPR) deficiency. The first two disorders are defects in tetrahydrobiopterin creation and the latter two are defects in tetrahydrobiopterin regeneration. Sepiapterin reductase deficiency is a related disorder affecting the third step of tetrahydrobiopterin biosynthesis; it differs from the other disorders in that elevated levels of phenylalanine do not develop. GTPCH deficiency can be broken down in the autosomal dominant form, also known as Segawa syndrome or autosomal dominant dopa-responsive dystonia, or the autosomal recessive form, which is covered in this report. NORD has separate, individual reports on sepiapterin reductase deficiency and Segawa syndrome.
In the past, disorders of tetrahydrobiopterin deficiency were referred to as atypical phenylketonuria or malignant phenylketonuria because physicians believed they were forms of phenylketonuria that did not respond to the standard therapy for that disorder. These terms are now considered obsolete because disorders of tetrahydrobiopterin deficiency are now known to be distinct disorders that are treatable with different therapies.
American Dystonia Society
- 17 Suffolk Lane
- Suite 1
- Princeton Junction, NJ 08550
- Tel: 310-237-5478
- Fax: 609-275-5663
- Email: email@example.com
- Website: http://www.dystonia.us
CLIMB (Children Living with Inherited Metabolic Diseases)
- Climb Building
- 176 Nantwich Road
- Crewe, CW2 6BG
- United Kingdom
- Tel: 4408452412173
- Fax: 4408452412174
- Email: firstname.lastname@example.org
- Website: http://www.CLIMB.org.uk
Dystonia Medical Research Foundation
- 1 East Wacker Drive, Suite 2810 East Wacker Drive
- Suite 2810
- Chicago, IL 60601-1905
- United States
- Tel: (312)755-0198
- Fax: (312)803-0138
- Tel: (800)377-3978
- Email: email@example.com
- Website: http://www.dystonia-foundation.org
- 89 Albert Embankment, 2nd Floor
- London, SE1 7TP
- United Kingdom
- Tel: 8454586211
- Fax: 8454586311
- Tel: 8454586322
- Email: firstname.lastname@example.org
- Website: http://www.dystonia.org.uk
Genetic and Rare Diseases (GARD) Information Center
- PO Box 8126
- Gaithersburg, MD 20898-8126
- Tel: (301)251-4925
- Fax: (301)251-4911
- Tel: (888)205-2311
- Website: http://rarediseases.info.nih.gov/GARD/
NIH/National Institute of Neurological Disorders and Stroke
- P.O. Box 5801
- Bethesda, MD 20824
- Tel: (301)496-5751
- Fax: (301)402-2186
- Tel: (800)352-9424
- Website: http://www.ninds.nih.gov/
Pediatric Neurotransmitter Disease Association
- 28 Prescott Place
- Old Bethpage, NY 11804
- Tel: (603)733-8409
- Email: email@example.com
- Website: http://www.pndassoc.org
- 1825 K Street NW, Suite 1200
- Washington, DC 20006
- Tel: (202)534-3700
- Fax: (202)534-3731
- Tel: (800)433-5255
- Email: firstname.lastname@example.org
- Website: http://www.thearc.org
For a Complete Report
This is an abstract of a report from the National Organization for Rare Disorders (NORD). A copy of the complete report can be downloaded free from the NORD website for registered users. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational therapies (if available), and references from medical literature. For a full-text version of this topic, go to www.rarediseases.org and click on Rare Disease Database under "Rare Disease Information".
The information provided in this report is not intended for diagnostic purposes. It is provided for informational purposes only. NORD recommends that affected individuals seek the advice or counsel of their own personal physicians.
It is possible that the title of this topic is not the name you selected. Please check the Synonyms listing to find the alternate name(s) and Disorder Subdivision(s) covered by this report
This disease entry is based upon medical information available through the date at the end of the topic. Since NORD's resources are limited, it is not possible to keep every entry in the Rare Disease Database completely current and accurate. Please check with the agencies listed in the Resources section for the most current information about this disorder.
For additional information and assistance about rare disorders, please contact the National Organization for Rare Disorders at P.O. Box 1968, Danbury, CT 06813-1968; phone (203) 744-0100; web site www.rarediseases.org or email email@example.com
Last Updated: 1/13/1970
Copyright 2015 National Organization for Rare Disorders, Inc.
Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.