Association analysis of KIT, MITF, and PAX3 variants with white markings in Spanish horses.

The research investigates the connection between specific gene variants (KIT, PAX3, and MITF) and the extent of white markings in Spanish horses. In particular, a distinct mutation in the KIT gene was found to influence the extent of white markings on the face and body of Menorca Purebred horses, while a variant in the MITF gene was associated with less white markings on forelimbs.

Research Context

• The research extends upon existing studies that have identified an association between variants in KIT, PAX3 and MITF genes and white markings in horses.
• In this study, they assessed eight different variants of these genes.
• The study sample included two breeds of Spanish horses: 70 Menorca Purebred (PRMe), which are primarily solid black, and 70 Spanish Purebred (PRE), which exist in a variety of coat colors.

Research Methods

• The researchers employed a maximum likelihood chi-square test, a logistic regression model and ridge regression analyses to examine the relationship between gene variants and the extent of white markings.
• The extent of white markings were scored on the selected horses.

Key Findings

• The research identified a particular missense mutation in the KIT gene associated with facial and total white markings on PRMe horses. The relative contribution of this mutation to white markings was estimated to be 47.6% for the head and 43.4% for the total score.
• The same KIT variant was also found to be associated with hindlimb white markings in PRE horses, with a relative contribution of 41.2%.
• A variant in the MITF gene (specifically, an intronic variant located downstream from the gene’s transcription start site) was found to be associated with a decreased presence of white markings on PRMe’s forelimbs. In these horses, this variant contributed 63.9% to the markings.
• In PRE horses, the same MITF gene variant was associated with white facial markings; again, with a relative contribution of 63.9%.
• No significant associations were identified for PAX3 gene variants in both horse breeds studied.

Implications and Conclusions

• The outcomes of this study reveal the important role of KIT and MITF gene variants in determining the white marking patterns in both PRMe and PRE horses.
• This discovery offers breeders new opportunities for leveraging genetic testing to help them breed horses with desired levels of white markings.