Skip to content
Use your HSA or FSA funds

Condition report · Metabolic

Succinic Semialdehyde Dehydrogenase Deficiency (ALDH5A1)

Whole genome sequencing reads the ALDH5A1 gene for the changes in both copies that cause succinic semialdehyde dehydrogenase deficiency, a condition in which the brain cannot properly break down GABA.

A condition report looks for rare variants known to cause the conditions it covers.

Included in Premium and Premium + AI

Premium adds $99 per kit for the first year.

Order with Premium

About this condition

An inherited metabolic condition in which the brain cannot properly break down the signalling chemical GABA, causing developmental delay, low muscle tone and behavioural differences. It is caused by changes in both copies of ALDH5A1.

Succinic semialdehyde dehydrogenase deficiency is an inherited metabolic condition that affects the brain. Children usually have low muscle tone and delayed speech and motor development in the first two years of life, and intellectual disability is almost universal. Behavioural features such as hyperactivity, anxiety, obsessive-compulsive behaviour and sleep problems are common.

The condition is caused by changes in both copies of ALDH5A1, which makes the enzyme that breaks down succinic semialdehyde during the breakdown of GABA. GABA is a chemical that stops the brain from being overloaded with signals. When the enzyme does not work, GABA and gamma-hydroxybutyrate (GHB) build up, and raised GHB in the urine is a key test finding.

About half of people have seizures or ataxia, an unsteadiness of movement, and these tend to worsen around late childhood or early adolescence. It is inherited in an autosomal recessive way, so when both parents carry a change, each sibling of an affected child has a 25% chance of being affected. Carrier testing for relatives and genetic counselling are available.

The condition we analyse

Autosomal recessive

Caused by changes in both copies of ALDH5A1, which encodes the enzyme that breaks down succinic semialdehyde in GABA metabolism. GABA and gamma-hydroxybutyrate (GHB) build up, and raised GHB in urine is a key test finding.

Signs and symptoms

Developmental delay, especially of speech and language, intellectual disability and low muscle tone are typical. Behavioural differences such as hyperactivity, anxiety, obsessive-compulsive behaviour and sleep problems are common. About half of people have seizures or ataxia, and seizures and behavioural problems tend to worsen around late childhood or early adolescence.

What a diagnosis changes

Care is symptomatic, with developmental and behavioural support and seizure treatment; valproate is generally avoided. Carrier testing of relatives and genetic counselling are available.

Genes analysed

Also known as

4-hydroxybutyric aciduria; gamma-hydroxybutyric aciduria; gamma-hydroxybutyricaciduria; SSADH deficiency; SSADHD

MONDO:0010083OMIM 271980Orphanet 22MedGen 124340Sources: [1][2][3]

Why whole genome sequencing

Succinic semialdehyde dehydrogenase deficiency is recessive, and knowing the diagnosis shapes which seizure medicines are chosen.

Seizure medicines need care

Many anti-seizure medicines may help with seizures, but none has been shown to work specifically for this disorder. Valproate is generally avoided, and vigabatrin and tiagabine are not recommended because they can raise GABA levels.

Carrier testing for relatives

When both parents carry a change, each further child has a 1 in 4 chance of being affected, a 1 in 2 chance of being a carrier and a 1 in 4 chance of inheriting neither. Molecular carrier testing for at-risk relatives and prenatal or preimplantation testing are possible once the changes are known.

References

  1. Tokatly Latzer I, Pearl PL, Roullet JB, 2004. Succinic Semialdehyde Dehydrogenase Deficiency. GeneReviews
  2. Sergi C, Parayil Sankaran B, 2023. Succinic Semialdehyde Dehydrogenase Deficiency. GeneReviews
  3. Succinic semialdehyde dehydrogenase deficiency. MedlinePlus Genetics

Other metabolic conditions

All conditions →

One test. A lifetime of answers.

One kit, sent to your home. Your entire genome sequenced at the clinical standard used for diagnostic decisions. Physician-ready reports delivered to your Genome Manager in 6–8 weeks — permanent and updated as science advances.

From $449

Free shipping · Results in 6–8 weeks

Premium adds $99 per kit for the first year.

Order with Premium