Equine Severe Combined Immune Deficiency
(Equine SCID)
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Description
Severe combined immunodeficiency disease (SCID) of horses is an autosomal, recessive hereditary disease occurring in 2-3% of Arab or cross-bred Arab foals. It is characterised by a complete absence of functional B and T lymphocytes and affected (homozygous) foals fail to produce antigen-specific immune responses.
Signalment
Only Arab or cross-bred Arabs are affected.
- Defect in DNA-dependent protein kinase gene
- Gene codes for a DNA repair enzyme involved in V(D)J recombination for antigen receptors of lymphocytes (e.g. Ig and TCR)
- No functional B cells or T cells
- Foals develop infections (usually around 8 weeks of age as maternal antibody in colostrum wanes around this time)
- Foals usually die from bronchopneumonia