Abstract: Insect bite hypersensitivity is a common allergic disease in horse populations worldwide. Insect bite hypersensitivity is affected by both environmental and genetic factors. However, little is known about genes contributing to the genetic variance associated with insect bite hypersensitivity. Therefore, the aim of our study was to identify and quantify genomic associations with insect bite hypersensitivity in Shetland pony mares and Icelandic horses in the Netherlands. Methods: Data on 200 Shetland pony mares and 146 Icelandic horses were collected according to a matched case-control design. Cases and controls were matched on various factors (e.g. region, sire) to minimize effects of population stratification. Breed-specific genome-wide association studies were performed using 70 k single nucleotide polymorphisms genotypes. Bayesian variable selection method Bayes-C with a threshold model implemented in GenSel software was applied. A 1 Mb non-overlapping window approach that accumulated contributions of adjacent single nucleotide polymorphisms was used to identify associated genomic regions. Results: The percentage of variance explained by all single nucleotide polymorphisms was 13% in Shetland pony mares and 28% in Icelandic horses. The 20 non-overlapping windows explaining the largest percentages of genetic variance were found on nine chromosomes in Shetland pony mares and on 14 chromosomes in Icelandic horses. Overlap in identified associated genomic regions between breeds would suggest interesting candidate regions to follow-up on. Such regions common to both breeds (within 15 Mb) were found on chromosomes 3, 7, 11, 20 and 23. Positional candidate genes within 2 Mb from the associated windows were identified on chromosome 20 in both breeds. Candidate genes are within the equine lymphocyte antigen class II region, which evokes an immune response by recognizing many foreign molecules. Conclusions: The genome-wide association study identified several genomic regions associated with insect bite hypersensitivity in Shetland pony mares and Icelandic horses. On chromosome 20, associated genomic regions in both breeds were within 2 Mb from the equine lymphocyte antigen class II region. Increased knowledge on insect bite hypersensitivity associated genes will contribute to our understanding of its biology, enabling more efficient selection, therapy and prevention to decrease insect bite hypersensitivity prevalence.
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This research study aims to identify genomic associations with insect bite hypersensitivity in two horse populations, Shetland pony mares and Icelandic horses, in the Netherlands.
Objectives of the Study
The primary goal was to better understand the genetic factors contributing to insect bite hypersensitivity in horses, a common allergic condition.
The research hoped to uncover specific genes and genomic regions associated with this hypersensitivity.
By identifying these genes, the study aimed to enhance our understanding of the disease’s biology, thereby providing insights into more efficient selection, therapy, and prevention techniques.
Methods
The researchers collected data on 200 Shetland pony mares and 146 Icelandic horses.
They used a matched case-control design to account for potential effects of population stratification. This means cases and controls were deliberately matched on various factors like region and sire to ensure comparability.
The researchers performed breed-specific genome-wide association studies using 70,000 single nucleotide polymorphisms (SNPs) genotypes, genetic variations that could be associated with the hypersensitivity.
They applied the Bayesian variable selection method Bayes-C with a threshold model in GenSel software.
A non-overlapping window approach was used, which entails assessing the contributions of adjacent SNPs to identify associated genomic regions.
Results
All single nucleotide polymorphisms together explained 13% of the variance in Shetland pony mares and 28% in Icelandic horses, highlighting genetic contributions to the hypersensitivity.
The research identified the 20 non-overlapping windows that contributed the most to genetic variance on nine chromosomes in Shetland pony mares and 14 chromosomes in Icelandic horses.
Genomic regions associated with hypersensitivity were found on chromosomes 3, 7, 11, 20, and 23 in both breeds.
Specifically on chromosome 20 in both breeds, candidate genes were identified within 2 Megabases (Mb) of the associated windows, located within the equine lymphocyte antigen class II region, which plays a significant role in immune response.
Conclusion
The genome-wide association study identified several genomic regions associated with insect bite hypersensitivity in Shetland pony mares and Icelandic horses.
This understanding can provide a foundation for further genetic research on insect bite hypersensitivity and offers potential insights into treatments and prevention strategies.
Cite This Article
APA
Schurink A, Wolc A, Ducro BJ, Frankena K, Garrick DJ, Dekkers JC, van Arendonk JA.
(2012).
Genome-wide association study of insect bite hypersensitivity in two horse populations in the Netherlands.
Genet Sel Evol, 44(1), 31.
https://doi.org/10.1186/1297-9686-44-31
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