X-Linked Severe Combined Immunodeficiency (Discovered in the Basset Hound)

X-linked Severe Combined Immunodeficiency (XSCID) is a severe dysfunction of the immune system, that leaves affected dogs prone to infection.

Key Signs

Immunodeficiency, Lymphopenia, Lack of lymph nodes, Vomiting, Diarrhea, Failure to thrive, Opportunistic infections

Age of Onset

At birth

Present at birth


X-linked Recessive

For X-linked recessive disorders, the genetic variant is found on the X chromosome. Female dogs must have two copies of the variant to be at risk of developing the condition, whereas male dogs only need one copy to be at risk. Males and females with any copies of the variant 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 XSCID

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 XSCID

X-SCID is a severe immunodeficiency, which results from abnormally low levels of lymphocytes (white blood cells) and their dysfunctionality. Lymphatic tissue of affected dogs is also underdeveloped. Affected dogs are extremely susceptible to opportunistic infections and typically die at a very young age.

Therapy is limited to symptomatic treatments for resulting infections and general supportive care. There is no cure.

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 X-linked recessive, meaning the genetic variant is found on the X chromosome. Given males only have one X chromosome, a single affected copy will increase the risk of being diagnosed with the disorder. Females typically require two copies to be at an elevated risk for full clinical signs but are not generally seen due to the poor prognosis for affected males. Use of dogs with one or two copies of the variant is not recommended for breeding as there is a risk that the resulting litter will contain affected puppies. Please note: It is possible that clinical signs similar to the ones caused by this variant could develop due to a different genetic or clinical cause.

Technical Details

Gene IL2RG
Variant Deletion
Chromosome X
Coordinate Start 55,484,660
Coordinate End 55,484,657

All coordinates reference CanFam3.1

References & Credit

Credit to our scientific colleagues:

Henthorn, P. S., Somberg, R. L., Patterson, D. F., Puck, J. M., & Felsburg, P. J. (1994). Il-2rγ gene microdeletion demonstrates that canine x-linked severe combined immunodeficiency is a homologue of the human disease. Genomics. View the article

Somberg, R. L., Pullen, R. P., Casal, M. L., Patterson, D. F., Felsburg, P. J., & Henthorn, P. S. (1995). A single nucleotide insertion in the canine interleukin-2 receptor gamma chain results in X-linked severe combined immunodeficiency disease. Veterinary Immunology and Immunopathology. View the article