Fine mapping a quantitative trait locus on horse chromosome 2 associated with radiological signs of navicular disease in Hanoverian warmblood horses.

The study focuses on identifying a specific gene in Hanoverian warmblood horses that is associated with navicular disease, a common cause of progressive lameness. This research marks a step towards developing a genetic test for this disease in these horses.

Objective and Methodology

• The study aims to refine a quantitative trait locus (QTL), essentially a section of DNA that correlates with a particular trait, on horse chromosome 2. This trait is linked with radiological alterations in the shape of the navicular bone and is associated with navicular disease in Hanoverian warmblood horses.
• The research team conducted genotyping, identifying and comparing individual’s genes, in 192 Hanoverian warmblood horses. The horses were from 17 paternal half-sibling groups.
• The researchers increased their marker set to 58 informative microsatellites, including nine new ones. Microsatellites are short, repeating sections of DNA that can be useful for forensic or parentage testing.

Results and Findings

• The study managed to refine the location of the QTL for navicular disease to two areas on chromosome 2: one between 32.50-43.13 Megabases (Mb) and a newly identified one between 59.08-65.14 Mb.
• The researchers identified markers ABGe342 and ABGe343 as having the highest multipoint Z(mean) and LOD scores, essentially a high likelihood of being the cause at 34.42 and 35.23 Mb. The genome-wide error probabilities of these markers are P = 0.013 and P = 0.064 respectively, indicating a significant association.
• In addition to these main findings, associations of markers and specific gene combinations within the QTL were identified.

Conclusions and Implications

• The results of this study solidify the hypothesis that the QTL associated with navicular disease is located on horse chromosome 2.
• This research contributes to the ongoing efforts to develop a genetic test for navicular disease in Hanoverian warmblood horses.