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Genetic and Rare Diseases Information Center (GARD)

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Succinic semialdehyde dehydrogenase deficiency

Other Names for this Disease
  • 4-hydroxybutyric aciduria
  • GABA metabolic defect
  • Gamma-hydroxybutyricaciduria
  • SSADH deficiency
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Tests & Diagnosis

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How is succinic semialdehyde dehydrogenase deficiency diagnosed?

The diagnosis of succinic semialdehyde dehydrogenase (SSADH) deficiency is based upon a thorough clinical exam, the identification of features consistent with the condition, and a variety of specialized tests.[1] SSADH deficiency may first be suspected in late infancy or early childhood in individuals who have encephalopathy, a state in which brain function or structure is altered. The encephalopathy may be characterized by cognitive impairment; language deficit; poor muscle tone (hypotonia); seizures; decreased reflexes (hyporeflexia); and/or difficulty coordinating movements (ataxia). The diagnosis may be further suspected if urine organic acid analysis (a test that provides information about the substances the body discards through the urine) shows the presence of 4-hydroxybutyric acid. The diagnosis can be confirmed by an enzyme test showing deficiency of SSADH, or by genetic testing. ALDH5A1 is the only gene currently known to be associated with SSADH deficiency, and genetic testing can detect mutations in about 97% of affected individuals.[2]
Last updated: 9/25/2013

  1. Succinic Semialdehyde Dehydrogenase Deficiency. NORD. 2003; Accessed 9/25/2013.
  2. Pearl PL, Dorsey AM, Barrios ES, Gibson KM. Succinic Semialdehyde Dehydrogenase Deficiency. GeneReviews. September 19, 2013; Accessed 9/25/2013.