Accumulating mutations in series of haplotypes at the KIT and MITF loci are major determinants of white markings in Franches-Montagnes horses

PLoS One. 2013 Sep 30;8(9):e75071. doi: 10.1371/journal.pone.0075071. eCollection 2013.


Coat color and pattern variations in domestic animals are frequently inherited as simple monogenic traits, but a number are known to have a complex genetic basis. While the analysis of complex trait data remains a challenge in all species, we can use the reduced haplotypic diversity in domestic animal populations to gain insight into the genomic interactions underlying complex phenotypes. White face and leg markings are examples of complex traits in horses where little is known of the underlying genetics. In this study, Franches-Montagnes (FM) horses were scored for the occurrence of white facial and leg markings using a standardized scoring system. A genome-wide association study (GWAS) was performed for several white patterning traits in 1,077 FM horses. Seven quantitative trait loci (QTL) affecting the white marking score with p-values p≤10(-4) were identified. Three loci, MC1R and the known white spotting genes, KIT and MITF, were identified as the major loci underlying the extent of white patterning in this breed. Together, the seven loci explain 54% of the genetic variance in total white marking score, while MITF and KIT alone account for 26%. Although MITF and KIT are the major loci controlling white patterning, their influence varies according to the basic coat color of the horse and the specific body location of the white patterning. Fine mapping across the MITF and KIT loci was used to characterize haplotypes present. Phylogenetic relationships among haplotypes were calculated to assess their selective and evolutionary influences on the extent of white patterning. This novel approach shows that KIT and MITF act in an additive manner and that accumulating mutations at these loci progressively increase the extent of white markings.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Genome-Wide Association Study
  • Genotype
  • Hair Color / genetics*
  • Hair Color / physiology
  • Horses / genetics*
  • Linkage Disequilibrium
  • Logistic Models
  • Microphthalmia-Associated Transcription Factor / genetics*
  • Mutation / genetics
  • Phenotype*
  • Phylogeny
  • Proto-Oncogene Proteins c-kit / genetics*
  • Quantitative Trait Loci / genetics*


  • Microphthalmia-Associated Transcription Factor
  • Proto-Oncogene Proteins c-kit

Grant support

This study was funded by the Swiss National Science Foundation grant no. 31003A_133034. The population wide SNP data of the Franches-Montagnes horse breed was generated with funds from the ALP-Haras Research Station. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.