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Startle Disease (SD) – Hyperekplexia Spanish Greyhound Type
| Acronym: | SDSG |
| Gene: | SLC6A5 |
| Mutation: | c.1379_1380delCT |
| Inheritance: | Autosomal recessive |
| Sample type: | CHS (Cheek Swab), WBE (Whole Blood EDTA) |
| Method: |
Genetics and characteristics
Hyperekplexia, also known as startle disease (SD), is a genetic neurological disorder that naturally occurs in a few domesticated species, including dogs, horses, and cattle. Hyperekplexia in dogs has been identified in Irish Wolfhound and Spanish greyhound dogs so far and it usually affects puppies as newborns or at a few months of age. Affected dogs have an excessive startle reaction that includes eye blinking or body spasms to sudden unexpected noise, movement, or touch. Apart from muscle stiffness, they do not show any other physical sign of the disease and seem normal, but the cessation of breathing that occurs during a startling episode is highly dangerous, as it can lead to brain damage and sudden infant death. The cause of startle disease is defective neurotransmission of inhibitory glycinergic signals due to the mutation in the gene that encodes presynaptic glycine transporter (SLC6A5). SLC6A5 is a glycine transporter critical for maintaining a presynaptic pool of neurotransmitters that are important for nerve signal transduction.
This severe neurological disorder found in Spanish Greyhound dogs is inherited as an autosomal recessive trait, requiring two copies of the mutated gene for the disease to develop. Dogs with only one copy of the mutated gene will not develop the disease but may act as carriers and pass the mutation to their offspring. Early detection by genetic testing can help breeders in selecting future mating pairs and help in preventing the development of the disease.
Results Reported As
Test Result |
Interpretation of test result |
CLEAR |
Tested mutation was not detected in animal with „clear“ result. Animal tested as clear has wild-type allele in homozygous state (i.e. two pairs of healthy alleles). It will not develop disease caused by tested mutation.* It will pass only wild-type allele to its offspring. |
CARRIER |
Tested mutation was detected in animal with „carrier“ result. Animal tested as carrier has one wild-type and one mutation allele, it is in heterozygous state. It will not develop disease caused by tested mutation.* It can pass wild-type or mutation allele to its offspring. |
AFFECTED |
Tested mutation was detected in animal with „affected“ result. Animal tested as affected has two copies of mutation alleles affecting the gene. It is likely the animal will experience a genetic disorder due to this mutation.** It will pass only mutation allele to its offspring. |
*Test excludes only tested mutation but not possible unknown mutations or factors that can lead to similar condition/symptoms.
** Potential unknown mutations or multiple other factors can possibly affect the likelihood of experiencing a genetic disorder.
References:
Murphy, S. C., Recio, A., de la Fuente, C., Guo, L. T., Shelton, G. D., Clark, L. A. (2019). A glycine transporter SLC6A5 frameshift mutation causes startle disease in Spanish greyhounds. Human genetics, 138(5), 509–513. https://doi.org/10.1007/s00439-019-01986-x