Succinic Semialdehyde Dehydrogenase Deficiency

Synonyms

• 4-Hydroxybutyric Aciduria
• SSADH Deficiency

Disorder Subdivisions

• None

General Discussion

Succinic semialdehyde dehydrogenase (SSADH) deficiency is a rare inborn error of metabolism that is inherited as an autosomal recessive trait. In individuals with the disorder, deficient activity of the SSADH enzyme disrupts the metabolism of gamma-aminobutyric acid (GABA). GABA is a natural chemical known as a "neurotransmitter" that serves to inhibit the electrical activities of nerve cells (inhibitory neurotransmitter). SSADH deficiency leads to abnormal accumulation of the compound succinic semialdehyde, which is reduced or converted to 4-hydroxybutyric acid, also known as GHB (gamma-hydroxybutyric acid). GHB is a natural compound that has a wide range of effects within the nervous system. The "hallmark" laboratory finding associated with SSADH deficiency is elevated levels of GHB in the urine (i.e., 4-hydroxybutyric or gamma-hydroxybutyric aciduria), the liquid portion of the blood (plasma), and the fluid that flows through the brain and spinal canal (cerebrospinal fluid [CSF]).



SSADH deficiency leads to various neurological and neuromuscular symptoms and findings. These abnormalities may be extremely variable from case to case, including among affected members of the same families (kindreds). However, most individuals with SSADH deficiency are affected by mild to severe mental retardation, delays in the acquisition of skills requiring the coordination of mental and physical activities (psychomotor retardation), and delays in language and speech development. In addition, in some cases, initial findings may include diminished muscle tone (hypotonia), an impaired ability to coordinate voluntary movements (ataxia), and/or episodes of uncontrolled electrical activity in the brain (seizures). Some affected individuals may also have additional abnormalities, such as decreased reflex reactions (hyporeflexia); involuntary, rapid, rhythmic eye movements (nystagmus); increased muscular activity (hyperkinesis); and/or behavioral abnormalities.

Resources

Children Living with Inherited Metabolic Diseases (CLIMB)

Climb Building

176 Nantwich Road

Crewe, Intl CW2 6BG

United Kingdom

Tel: 0845 241 2174

Tel: 800 652 3181

Email: info.svcs@climb.org.uk

Internet: http://www.CLIMB.org.uk



March of Dimes Birth Defects Foundation

1275 Mamaroneck Avenue

White Plains, NY 10605

Tel: (914)997-4488

Fax: (914)997-4763

Tel: (888)663-4637

Email: Askus@marchofdimes.com

Internet: http://www.marchofdimes.com



The Arc

1660 L Street, NW, Suite 301

Washington, DC 20036

Tel: (202)534-3700

Fax: (202)534-3731

Tel: (800)433-5255

TDD: (817)277-0553

Email: info@thearc.org

Internet: http://www.thearc.org



Epilepsy Foundation

8301 Professional Place

Landover, MD 20785

Tel: (301)459-3700

Fax: (301)577-2684

Tel: (800)332-1000

TDD: (800)332-2070

Email: info@efa.org

Internet: http://www.epilepsyfoundation.org



NIH/National Institute of Diabetes, Digestive & Kidney Diseases

Office of Communications & Public Liaison

Bldg 31, Rm 9A06

31 Center Drive, MSC 2560

Bethesda, MD 20892-2560

Tel: (301)496-3583

Email: NDDIC@info.niddk.nih.gov

Internet: http://www2.niddk.nih.gov/



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

TDD: (301)468-5981

Email: me20t@nih.gov

Internet: http://www.ninds.nih.gov/



NIH/National Institute of Child Health and Human Development

31 Center Dr

Building 31, Room 2A32

MSC2425

Bethesda, MD 20892

Fax: (866)760-5947

Tel: (800)370-2943

TDD: (888)320-6942

Email: NICHDInformationResourceCenter@mail.nih.gov

Internet: http://www.nichd.nih.gov/



Pediatric Neurotransmitter Disease Association

PO Box 180622

498 Lillian Court

Delafield, WI 53018

Tel: (603)733-8409

Fax: (516)937-0049

Email: pnd@pndassoc.org

Internet: http://www.pndassoc.org



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

TDD: (888)205-3223

Email: http://rarediseases.info.nih.gov/GARD/EmailForm.aspx

Internet: http://rarediseases.info.nih.gov/GARD



Madisons Foundation

PO Box 241956

Los Angeles, CA 90024

Tel: (310)264-0826

Fax: (310)264-4766

Email: getinfo@madisonsfoundation.org

Internet: http://www.madisonsfoundation.org

For a Complete Report

This is an abstract of a report from the National Organization for Rare Disorders, Inc. ® (NORD). A copy of the complete report can be obtained for a small fee by visiting the NORD website. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational treatments (if available), and references from medical literature. For a full-text version of this topic, see http://www.rarediseases.org/search/rdblist.html

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 orphan@rarediseases.org

Last Updated:  4/25/2008

Copyright  2000, 2002, 2003 National Organization for Rare Disorders, Inc.