succinic semialdehyde dehydrogenase deficiency
Findings
No curated finding names succinic semialdehyde dehydrogenase deficiency yet. Everything below is reference data from Mondo, HPO and GenCC, not evidence about what affects it.
Definition
Succinic semialdehyde dehydrogenase (SSADH) deficiency is a rare neurometabolic disorder of gamma-aminobutyric acid (GABA) metabolism with a nonspecific clinical presentation (ranging from mild to severe) with the most frequent symptoms being cognitive impairment with prominent deficit in expressive language, hypotonia, ataxia, epilepsy, and behavioral dysregulation.
Definition from the Mondo Disease Ontology (MONDO:0010083), read 2026-09-29. CC BY 4.0.
- Inheritance
- Autosomal recessive inheritance
- Onset and course
- Infantile onset · Juvenile onset · Young adult onset · Childhood onset
HPO, annotations 2026-09-02
Features
18 features
What the disease is reported to present with, and how often among people who have it — never how often a feature means the disease. HPO, annotations 2026-09-02.
- Delayed speech and language developmentHPOHP:0000750
- 50 of 62 reported patients
- Abnormality of metabolism/homeostasisHPOHP:0001939
- Very frequent (80% to 99% of cases)
- AtaxiaHPOHP:0001251
- 28 of 62 reported patients
- Very frequent (80% to 99% of cases)
- Global developmental delayHPOHP:0001263
- Very frequent (80% to 99% of cases)
- HypotoniaHPOHP:0001252
- Very frequent (80% to 99% of cases)
Genes
1 gene
Germline variants in the gene encoding each protein, as classified by GenCC submitters, each in their own words. Limited, disputed and refuted submissions are listed too.
- ALDH5A1HGNC:408
- Definitive · ClinGen · Autosomal recessive · 2021
- Definitive · G2P · Autosomal recessive · 2015
- Strong · Labcorp Genetics (formerly Invitae) · Autosomal recessive · 2020
- Strong · PanelApp Australia · Autosomal recessive · 2025
- Supportive · Orphanet · Autosomal recessive · 2021
Where it sits
Other names
3 names
Resolves to: succinic semialdehyde dehydrogenase deficiency
- Also called
- 4-hydroxybutyric aciduriagamma-hydroxybutyric aciduriaSSADH deficiency