succinic semialdehyde dehydrogenase deficiency At least 35 mutations in the ALDH5A1 gene have been found to cause succinic semialdehyde dehydrogenase deficiency. Most of these mutations change one protein building block (amino acid) in the succinic semialdehyde dehydrogenase enzyme. Mutations in the ALDH5A1 gene lead to the production of an enzyme with little or no activity. A lack of functional succinic semialdehyde dehydrogenase disrupts the conversion of succinic semialdehyde to succinic acid. Instead, succinic semialdehyde is converted back into GABA or to a related molecule, gamma-hydroxybutyrate (GHB). It is unclear how increases in GHB and GABA cause developmental delay, seizures, and other features of succinic semialdehyde dehydrogenase deficiency.

     The ALDH5A1 gene provides instructions for producing the succinic semialdehyde dehydrogenase enzyme. This enzyme is found in the energy-producing centers of cells (mitochondria). Succinic semialdehyde dehydrogenase is involved in the breakdown of a chemical that transmits signals in the brain (neurotransmitter) called gamma-amino butyric acid (GABA). The primary role of GABA is to prevent the brain from being overloaded with too many signals. Once GABA molecules have been released from nerve cells, they are broken down by succinic semialdehyde dehydrogenase and other enzymes.

The following transcription factors affect gene expression:

• HNF-4alpha1
• HNF-4alpha2

Tissue specificity:

Brain, pancreas, heart, liver, skeletal muscle and kidney. Lower in placenta.

Enzyme Regulation:

Redox-regulated. Inhibited under oxydizing conditions. Inhibited by hydrogen peroxide H(2)O(2).

Molecular Function:

• Aldehyde Dehydrogenase (Nad) Activity
• Succinate-Semialdehyde Dehydrogenase (Nad+) Activity
• Succinate-Semialdehyde Dehydrogenase [Nad(P)+] Activity
• Carboxylic Acid Binding
• Protein Homodimerization Activity
• Nad Binding
• Aldehyde Dehydrogenase

Biological Processes:

• Glucose Metabolic Process
• Acetate Metabolic Process
• Succinate Metabolic Process
• Glutamate Metabolic Process
• Glutamine Metabolic Process
• Glycerophospholipid Metabolic Process
• Glucosylceramide Metabolic Process
• Galactosylceramide Metabolic Process
• Glutathione Metabolic Process
• Central Nervous System Development
• Gamma-Aminobutyric Acid Catabolic Process
• Post-Embryonic Development
• Respiratory Electron Transport Chain
• Neurotransmitter Catabolic Process
• Short-Chain Fatty Acid Metabolic Process
• Protein Homotetramerization

Drug Bank:

• Valproic Acid
• Chlormerodrin
• Succinic Acid