Genome-wide association study of insect bite hypersensitivity in Dutch Shetland pony mares.

This study discusses a genome-wide research conducted to identify the genetic factors associated with Insect Bite Hypersensitivity (IBH), a common allergic condition in horses, specifically in Dutch Shetland pony mares.

Objective of the Study

• The primary aim of the study is to identify and quantify the genomic regions that contribute to IBH in the Dutch Shetland pony population. Previous research has revealed that the disease is genetically controlled, but the knowledge about the associated genes is limited. The researchers hoped to augment the existing knowledge about IBH.

Methodology

• Researchers selected a total of 97 cases and 91 controls for the study. To minimize population stratification, these samples were matched based on characteristics such as withers height, coat color, and pedigree.
• They collected blood samples from all participating Dutch Shetland pony mares and scored their IBH phenotype. The owners were also requested to fill in a questionnaire.
• The collected data was then analysed for 40,021 Single Nucleotide Polymorphisms (SNPs) using a univariable logistic model that fits an additive effect. SNP is a variation at a single position in a DNA sequence.

Findings

• The analysis showed that there were zero effects from population stratification, proving that their selection and control approaches were effective.
• The researchers found associations with IBH for 24 SNPs, located on 12 chromosomes. The odds ratios of allele substitution effects for these SNPs ranged from 1.94 to 5.95.
• The most significant SNP was found on chromosome 27 with an odds ratio of 2.31. The unfavorable allele frequency for this SNP was 0.72 in cases and 0.53 in the controls.

Conclusion and Future Directions

• The significant associations between certain SNPs and IBH have been identified, which brings new understanding to the genetic factors that potentially cause IBH.
• However, associations identified in this study require validation through more genome-wide association studies on other horse populations. This could better identify the genes involved in causing IBH and could potentially lead to the development of genomic tools to decrease the prevalence of IBH in horse populations.