GTR Home > Conditions/Phenotypes > Succinate-semialdehyde dehydrogenase deficiency

Disease characteristics

Excerpted from the GeneReview: Succinic Semialdehyde Dehydrogenase Deficiency
Succinic semialdehyde dehydrogenase (SSADH) deficiency is characterized by psychomotor retardation, childhood-onset hypotonia, and ataxia. Seizures occur in more than 50% of affected individuals. Hyperkinetic behavior, aggression, self-injurious behaviors, hallucinations, and sleep disturbances have been reported in nearly half of all patients, and are common in older individuals. Basal ganglia signs such as choreoathetosis, dystonia, and myoclonus have been reported in a few individuals with earlier-onset, more severe disease. Involvement beyond the central nervous system has not been described.

Available tests

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Associated genes

Clinical features

  • EEG abnormalities
  • Hyporeflexia
  • Intellectual disability
  • Cognitive impairment
  • Incoordination
  • Seizure
  • Anxiety
  • Hallucinations
  • Abnormality of eye movement
  • Psychosis
  • Autism
  • Aggressive behavior
  • Delayed speech and language development
  • Hyperactivity
  • Ataxia
  • Muscular hypotonia
  • Global developmental delay
  • Motor delay
  • Abnormality of metabolism/homeostasis
  • Generalized tonic-clonic seizures
  • Absence seizures
  • Generalized myoclonic seizures
  • Status epilepticus
  • Hyperkinesis
  • Self-injurious behavior
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