Sepiapterin Reductase Deficiency

National Organization for Rare Disorders, Inc.

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It is possible that the main title of the report Sepiapterin Reductase Deficiency is not the name you expected.

Disorder Subdivisions

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General Discussion

Sepiapterin reductase deficiency (SRD) is a rare genetic disorder that is characterized by abnormally low levels of certain neurotransmitters. Neurotransmitters are chemicals that modify, amplify or transmit nerve impulses from one nerve cell to another, enabling nerve cells to communicate. The severity of sepiapterin reductase deficiency can range from a mild movement disorder at one end to severe, progressive neurological disease at the other. Common symptoms include lack of muscle tone (hypotonia), drooling, loss of coordination, abnormal movements, delayed motor and language development (i.e. delays in reaching developmental milestones), and/or dystonia. Dystonia is a general term for a group of muscle disorders, generally characterized by involuntary muscle contractions that force the body into abnormal, sometimes painful, movements and positions (postures). The specific symptoms can vary dramatically from one person to another. Prompt diagnosis and treatment can reduce or potentially prevent severe, irreversible neurological damage. Children with sepiapterin reductase deficiency may show a dramatic response and sustained improvement when treated with levodopa. Levodopa is a chemical that is converted to dopamine, a brain chemical that serves as a neurotransmitter. Some individuals show benefit with treatment with addition of 5-HTP, a neurotransmitter precursor that is converted to serotonin. Sepiapterin reductase deficiency is caused by mutations in the SPR gene and is inherited as an autosomal recessive disorder.

Sepiapterin reductase deficiency can be classified as a form of dystonia, a pediatric neurotransmitter disorder or a disorder of tetrahydrobiopterin deficiency. The disorder is sometimes referred to as a form of dopa-responsive dystonia. However, dystonia is not always present in infancy and may not be a universal symptom so that term may not apply to all cases. The non-specific symptoms of this condition may be misdiagnosed as cerebral palsy.

Supporting Organizations

American Dystonia Society

17 Suffolk Lane
Suite 1
Princeton Junction, NJ 08550
Tel: 310-237-5478
Fax: 609-275-5663

CLIMB (Children Living with Inherited Metabolic Diseases)

Climb Building
176 Nantwich Road
Crewe, CW2 6BG
United Kingdom
Tel: 4408452412173
Fax: 4408452412174

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

Dystonia Society

89 Albert Embankment, 2nd Floor
London, SE1 7TP
United Kingdom
Tel: 8454586211
Fax: 8454586311
Tel: 8454586322

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

Pediatric Neurotransmitter Disease Association

28 Prescott Place
Old Bethpage, NY 11804
Tel: (603)733-8409

The Arc

1825 K Street NW, Suite 1200
Washington, DC 20006
Tel: (202)534-3700
Fax: (202)534-3731
Tel: (800)433-5255

For a Complete Report

This is an abstract of a report from the National Organization for Rare Disorders (NORD). For a full-text version of this report, go to and click on Rare Disease Database under "Rare Disease Information".

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Last Updated:  8/25/2015
Copyright  2015 National Organization for Rare Disorders, Inc.