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Succinic Semialdehyde Dehydrogenase Deficiency (Discovered in the Saluki)

Succinic Semialdehyde Dehydrogenase Deficiency (SSADHD) is a neurologic disorder characterized by seizures, uncoordinated movements, and abnormal behaviors, such as vocalization episodes. The associated genetic variant has been identified in the Saluki.

Key Signs

Epileptic seizures, Episodic vocalization, Uncoordinated movements, Overstepping front limb gait, Difficult to wake while sleeping

Age of Onset

0 to 2 yrs

Juvenile onset

Inheritance

Autosomal Recessive

For autosomal recessive disorders, dogs with two copies of the variant are at risk of developing the condition. Dogs with one copy of the variant are considered carriers and are usually not at risk of developing the disorder. However, carriers of some complex variants grouped in this category may be associated with a low risk of developing the disorder. Individuals with one or two copies may pass the disorder-associated variant to their puppies if bred.

Likelihood of the Condition

High likelihood

At risk dogs are highly likely to show signs of this disease in their lifetime.

What to Do

Here’s how to care for a dog with SSADHD

Partner with your veterinarian to make a plan regarding your dog’s well-being, including any insights provided through genetic testing. If your pet is at risk or is showing signs of this disorder, then the first step is to speak with your veterinarian.

For Veterinarians

Here’s what a vet needs to know about SSADHD

Succinic Semialdehyde Dehydrogenase Deficiency, formerly known as central nervous system status spongiosus in Saluki dogs (SSSD), is caused by deficiency of succinic semialdehyde dehydrogenase (SSADH) enzyme critical in the metabolism of gamma-aminobutyric acid (GABA) neurotransmitter. The enzyme deficiency leads to cerebral cortical atrophy with vacuolation (status spongiosus) predominantly affecting gray matter structures in the brain. SSADHD is characterized by generalized or focal epileptic seizures, difficulty being aroused from sleep, and altered behaviors, such as episodes of vocalization. While a physical exam can appear normal in affected dogs, a neurologic exam may reveal a mild generalized ataxia with thoracic limb hypermetria (overreaching steps), bilaterally absent menace reflex, and delayed proprioceptive positioning in all limbs. The initial neurological signs are usually seen in affected puppies between the ages of 6 to 10 weeks.

There is no effective treatment available for SSADH deficiency. Anti-seizure medications may help control seizures in affected dogs but will not address the underlying disorder. Upon initial observation of clinical signs, affected dogs should be closely monitored to assess welfare. Due to the early onset and severe nature of clinical signs, the prognosis is considered poor for affected puppies and humane euthanasia is often considered by 9 months of age.

For Breeders

Planning to breed a dog with this genetic variant?

There are many responsibilities to consider when breeding dogs. Regardless of test results it is important that your dog is in good general health and that you are in a position to care for the puppies if new responsible owners are not found. For first time or novice breeders, advice can be found at most kennel club websites.

This disorder is autosomal recessive, meaning two copies of the variant are needed for a dog to be at an elevated risk for being diagnosed with the condition. A carrier dog with one copy of the Succinic Semialdehyde Dehydrogenase Deficiency (Discovered in the Saluki) variant can be safely bred with a clear dog with no copies of the Succinic Semialdehyde Dehydrogenase Deficiency (Discovered in the Saluki) variant. About half of the puppies will have one copy (carriers) and half will have no copies of the variant. Puppies in a litter which is expected to contain carriers should be tested prior to breeding. Carrier to carrier matings are not advised as the resulting litter may contain affected puppies. Please note: It is possible that disorder signs similar to the ones associated with this Succinic Semialdehyde Dehydrogenase Deficiency variant could develop due to a different genetic or clinical cause.

Technical Details

Gene ALDH5A1
Variant G>A
Chromosome 35
Coordinate 22,572,768

All coordinates reference CanFam3.1

References & Credit

Credit to our scientific colleagues:

Vernau, K.M., Struys, E., Letko, A., Woolard, K.D., Aguilar, M., Brown, … Bannasch, D.L. (2020). A missense variant in ALDH5A1 associated with canine succinic semialdehyde dehydrogenase deficiency (SSADHD) in the Saluki dog. Genes (Basel), 11(9), 1033. View the article