Mammalian Genome

, Volume 12, Issue 6, pp 450–455

Mutations in the agouti (ASIP), the extension (MC1R), and the brown (TYRP1) loci and their association to coat color phenotypes in horses (Equus caballus)

  • Stefan  Rieder
  • Sead  Taourit
  • Denis  Mariat
  • Bertrand  Langlois
  • Gérard  Guérin

DOI: 10.1007/s003350020017

Cite this article as:
Rieder, S., Taourit, S., Mariat, D. et al. (2001) 12: 450. doi:10.1007/s003350020017

Abstract.

Coat color genetics, when successfully adapted and applied to different mammalian species, provides a good demonstration of the powerful concept of comparative genetics. Using cross-species techniques, we have cloned, sequenced, and characterized equine melanocortin-1-receptor (MC1R) and agouti-signaling-protein (ASIP), and completed a partial sequence of tyrosinase-related protein 1 (TYRP1).

The coding sequences and parts of the flanking regions of those genes were systematically analyzed in 40 horses and mutations typed in a total of 120 horses. Our panel represented 22 different horse breeds, including 11 different coat colors of Equus caballus. The comparison of a 1721-bp genomic fragment of MC1R among the 11 coat color phenotypes revealed no sequence difference apart from the known chestnut allele (C901T). In particular, no dominant black (ED) mutation was found.

In a 4994-bp genomic fragment covering the three putative exons, two introns and parts of the 5′- and 3′-UTRs of ASIP, two intronic base substitutions (SNP-A845G and C2374A), a point mutation in the 3′-UTRs (A4734G), and an 11-bp deletion in exon 2 (ADEx2) were detected. The deletion was found to be homozygous and completely associated with horse recessive black coat color (Aa/Aa) in 24 black horses out of 9 different breeds from our panel. The frameshift initiated by ADEx2 is believed to alter the regular coding sequence, acting as a loss-of-function ASIP mutation. In TYRP1 a base substitution was detected in exon 2 (C189T), causing a threonine to methionine change of yet unknown function, and an SNP (A1188G) was found in intron 2.

Copyright information

© Springer-Verlag New York Inc. 2001

Authors and Affiliations

  • Stefan  Rieder
    • 1
  • Sead  Taourit
    • 1
  • Denis  Mariat
    • 1
  • Bertrand  Langlois
    • 2
  • Gérard  Guérin
    • 1
  1. 1.Laboratoire de Génétique biochimique et de Cytogénétique, Département de Génétique animale, INRA Centre de Recherche de Jouy, 78352 Jouy-en-Josas cedex, FranceFR
  2. 2.Station de Génétique quantitative et appliquée, Département de Génétique animale, INRA Centre de Recherche de Jouy, 78352 Jouy-en-Josas cedex, FranceFR