Severe combined immunodeficiency / SCID (PRKDC-related) - Jack Russell Terrier

What does this test examine?

This genetic test analyses the PRKDC c.10879G>T variant in the Jack Russell Terrier. The condition is known as severe combined immunodeficiency, SCID and PRKDC-related SCID. The result shows whether the dog carries zero, one or two copies of the tested variant.

PRKDC is required for normal development of the adaptive immune system. When both gene copies carry the tested variant, puppies cannot build an effective immune response and become highly vulnerable to infection.

What does this condition mean?

SCID is a severe inherited immune disorder. Affected puppies can fail to thrive, lose weight, become lethargic, develop chronic or recurrent diarrhoea and be highly susceptible to bacterial, viral and fungal infections. In this condition, infections can quickly become severe or life-threatening.

Because SCID can appear early in life and carriers can look healthy, DNA testing is especially valuable before breeding decisions. The result identifies carrier animals and helps prevent at-risk matings.

Inheritance and result

The trait is inherited in an autosomal recessive way. A clear dog does not carry the variant. A carrier has one copy and is usually not affected, but can pass the variant to offspring. A dog with two copies has the genotype that causes this form of SCID.

• GG - no copy of the tested variant detected.
• GT - carrier: one copy of the tested variant detected.
• TT - affected genotype: two copies of the tested variant detected.

Practical value of this test

This test is important because carriers cannot be recognised by appearance. Breeders can use the result to select safe matings and prevent puppies with two copies of the variant.

For breed clubs and breeding programmes, the test helps actively reduce a severe, often life-limiting immune disorder while managing healthy carriers responsibly.