Major histocompatibility locus in the Arabian horse

Area of Science:

• Immunogenetics
• Equine Health
• Veterinary Immunology

Background:

• Combined immunodeficiency disease (CID) is a severe genetic disorder affecting T and B lymphocyte production, leading to a compromised immune system.
• This autosomal recessive condition has been documented in humans and specifically in Arabian horses.
• Identifying carriers is crucial for managing and potentially eradicating CID within the breed.

Purpose of the Study:

• To develop and validate a serological method for identifying genetic specificities associated with Combined Immunodeficiency Disease in Arabian horses.
• To investigate the inheritance pattern of these specificities and their relationship to CID carrier status.

Main Methods:

• Microlymphocytotoxicity technique was employed to test Arabian horses for specificities.
• Computer chi-squared analysis was used to analyze serological data and determine genetic segregation.
• Family studies and population analysis were conducted to assess antigen frequencies.

Main Results:

• Six distinct serologically defined specificities were identified using computer chi-squared analysis.
• These specificities demonstrated codominant allelic behavior, segregating at a single genetic locus.
• No significant differences in antigen frequency were observed between known CID carriers and the general horse population.

Conclusions:

• The identified specificities are valuable genetic markers for studying Combined Immunodeficiency Disease in Arabian horses.
• The findings support a single-locus, codominant inheritance model for these specificities.
• Further research may refine diagnostic capabilities for CID carrier status in Arabian horses.