Diseases & Conditions


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Succinic Semialdehyde Dehydrogenase Deficiency


Synonyms of Succinic Semialdehyde Dehydrogenase Deficiency
  • 4-Hydroxybutyric Aciduria
  • SSADH Deficiency

Disorder Subdivisions



    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.
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    Organizations related to Succinic Semialdehyde Dehydrogenase Deficiency
    • CLIMB (Children Living with Inherited Metabolic Diseases)
      Climb Building
      Crewe Intl CW2 6BG
      Phone #: +44- 87-0 7700 325
      800 #: --
      e-mail: info@climb.org.uk
      Home page: http://www.CLIMB.org.uk
    • Epilepsy Foundation
      4351 Garden City Drive
      Landover MD 20785
      Phone #: 301-459-3700
      800 #: 800-332-1000
      e-mail: postmaster@efa.org
      Home page: http://www.epilepsyfoundation.org
    • Madisons Foundation
      PO Box 241956
      Los Angeles CA 90024
      Phone #: 310-264-0826
      800 #: N/A
      e-mail: getinfo@madisonsfoundation.org
      Home page: http://www.madisonsfoundation.org
    • March of Dimes Birth Defects Foundation
      1275 Mamaroneck Avenue
      White Plains NY 10605
      Phone #: 914-428-7100
      800 #: 888-663-4637
      e-mail: Askus@marchofdimes.com
      Home page: http://www.marchofdimes.com
    • NIH/National Institute of Child Health & Human Development (Preg & Perinat)
      Pregnancy and Perinatology Branch
      Bethesda MD 20892-7510
      Phone #: 301-496-5575
      800 #: --
      e-mail: BOCKR@mail.nih.gov
      Home page: http://www.nichd.nih.gov
    • NIH/National Institute of Diabetes, Digestive & Kidney Diseases
      Endocrine Diseases Metabolic Diseases Branch
      Bethesda MD 20892-3570
      Phone #: 301-654-3810
      800 #: --
      e-mail: NDDIC@info.niddk.nih.gov
      Home page: http://www.niddk.nih.gov
    • National Institute of Neurological Disorders and Stroke (NINDS)
      31 Center Drive
      Bethesda MD 20892-2540
      Phone #: 301-496-5751
      800 #: 800-352-9424
      e-mail: braininfo@ninds.nih.gov
      Home page: http://www.ninds.nih.gov/
    • Pediatric Neurotransmitter Disease Association (PND Association)
      6 Nathan Drive
      Plainview NY 11803
      Phone #: 516-937-0049
      800 #: --
      e-mail: PND@PNDAssoc.org
      Home page: http://www.pndassoc.org
    • The Arc (a national organization on mental retardation)
      1010 Wayne Ave
      Silver Spring MD 20910
      Phone #: 301-565-3842
      800 #: 800-433-5255
      e-mail: info@thearc.org
      Home page: http://www.thearc.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