Epsilon Archive for Student Projects

Abstract

The study investigates the prevalence and potential genetic basis of hypermobility disease among a family of Gotland ponies at Lojsta Hed on Gotland Island. It hypothesizes that this condition, inherited in an autosomal recessive manner, may be connected to a single mutation or structural variant. When sire 276 was selected to breed all the mares at Lojsta Hed, unhealthy foals were born, diagnosed with hydrocephalus and hyperflexible joints. There was a significant increase in the percentage of mares not giving birth (52%) compared to previous years with different sires (20%). This difference may be attributed to hypermobility disease, which is associated with abortion and stillbirths, similar to Warmblood Fragile Foal Syndrome (WFFS). The study compares the breeding outcomes of sire 276 at Lojsta Hed with his performance on other farms, revealing a huge contrast in foal birth percentages (52% vs. 16.2%). This suggests a potential inbreeding effect or environmental influence at Lojsta Hed. The samples included foals and their parents to identify carriers of the suspected recessive allele. After extracting the samples’ DNA from the blood, they were genotyped using the Axiom® Equine Genotyping Array containing 670,806 markers. To map the genomic loci, both association and linkage analyses were used. Linkage analysis was employed to find the location of disease genes by noticing that genes close together on the same chromosome tend to be inherited together during meiosis. An association analysis was also performed to study the relationship between genotypes and phenotypes in healthy (controls) and affected horses (cases). The analyses identified significant markers on chromosome 9, at positions between 17,8 and 18,5 cM. These markers are notably within the TRPA1 gene, linked to neurological and skeletal muscle conditions in humans and is hypothesized to be associated with the observed hypermobility in the foals. They showed a correlation with the recessive disease genotypes, suggesting a potential genetic basis for the disease. Further research with larger sample sizes and unrelated Gotland ponies is necessary to identify the causative gene in that region of hypermobility disease