Severe Combined Immunodeficiency (Discovered in Russell Terriers)

Autosomal Recessive Severe Combined Immunodeficiency (ARSCID) is a severe immunodeficiency disorder discovered in Jack Russell Terriers, that leaves affected dogs prone to infection.

Key Signs

Immunodeficiency, Lymphopenia, Lymphoid hypoplasia

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 ARSCID

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 ARSCID

ARSCID causes severe immunodeficiency because of the low number of white blood cells (lymphopenia) involved in the body's immune defenses. There is a complete absence of the IgM antibodies. Affected puppies show incomplete development of the lymphoid tissue so they are highly susceptible to recurrent infections and usually die at a young age due to infection, after the maternal antibodies they received while nursing decline. Necropsy results show that all the lymphoid tissues fail to develop.

Therapy is targeted at treating the secondary infections and affected puppies should not be treated with modified-live vaccines. Humane euthanasia for affected puppies is often elected.

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 disease is autosomal recessive meaning that two copies of the mutation are needed for disease signs to be shown. A carrier dog with one copy of the ARSCID mutation can be safely bred with a clear dog with no copies of the ARSCID mutation. About half of the puppies will have one copy (carriers) and half will have no copies of the ARSCID mutation. 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 disease signs similar to the ones caused by the ARSCID mutation could develop due to a different genetic or clinical cause.

Technical Details

Gene	PRKDC
Variant	G>T
Chromosome	29
Coordinate	49,588

All coordinates reference CanFam3.1

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References & Credit

Credit to our scientific colleagues:

Bell, T. G., Butler, K. L., Sill, H. B., Stickle, J. E., Ramos-Vara, J. A., & Dark, M. J. (2002). Autosomal recessive severe combined immunodeficiency of Jack Russell Terriers. Journal of Veterinary Diagnostic Investigation, 14(3), 194–204. View the article

Ding, Q., Bramble, L., Yuzbasiyan-Gurkan, V., Bell, T., & Meek, K. (2002). DNA-PKcs mutations in dogs and horses: Allele frequency and association with neoplasia. Gene, 283(1–2), 263–269. View the article

Meek, K., Kienker, L., Dallas, C., Wang, W., Dark, M. J., Venta, P. J., … Bell, T. (2001). SCID in Jack Russell Terriers: A New Animal Model of DNA-PKcs Deficiency. The Journal of Immunology, 167(4), 2142–2150. View the article

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