Explicit evidence for a missense mutation in exon 4 of SLC45A2 gene causing the pearl coat dilution in horses.

This research paper identifies a specific gene mutation responsible for the unique pearl coat color observed in certain horse breeds. The mutation occurs in the SLC45A2 gene and is believed to play a role in other cream-like coat colors as well. By identifying this mutation, breeders can better select and breed for this particular coat color.

Genetic Factors Behind Horse Coat Colors

• The study examines four known loci (Dun, Silver Dapple, Champagne, and Cream) involved in determining the color dilution of a horse’s coat.
• The ‘pearl’ color is a distinct coat variation observed mostly in the Iberian breeds: Purebred Spanish horse and Lusitano.
• It is also seen in breeds of Iberian origin, like Quarter Horses and Paint Horse. In these breeds, the color is referred to as the ‘Barlink Factor’.

The Autosomal Recessive Nature of Pearl Color

• The pearl phenotype follows an autosomal recessive pattern, meaning the trait can be expressed only when the horse inherits two copies of the pearl gene, one each from the sire and the dam.
• The pearl color resembles coat colors produced by the Champagne and Cream alleles, complicating phenotype differentiation.

The Role of SLC45A2 Gene

• Researchers have identified SLC45A2 as the prime candidate gene for the pearl phenotype due to the effect of compound heterozygous mutations on the Cream and pearl loci.
• The document provides evidence for a specific missense mutation—SLC45A2:c.985G>A; SLC45A2:p.(Ala329Thr)—as the cause of the pearl coat color.
• This mutation may also be involved in other horse phenotypes such as Cremello, Perlino, and Smoky Cream, which are associated with Cream-heterozygous genotypes.

Importance for Breeders

• The identification of this gene mutation allows breeders to identify carriers of this allele.
• Knowing the genetic basis for the pearl color can assist breeders in selecting and breeding for this specific trait.
• Such genetic knowledge meets various needs, including personal preferences for certain coat colors, market demands, studbook requirements, and verifying segregation within specific pedigrees.