recessive genotype (ch/ch) are not affected by champagne. Champagne is now identifiable by DNA test. The Champagne locus is occupied by the Solute carrier family 36, member 1 (SLC36A1) gene, which encodes the Proton-coupled amino acid transporter 1 (PAT1) protein. This protein is one of many which is involved in active transport. The gene associated with the Cream coat colors is also a solute carrier, and orthologous genes in humans, mice, and other species are also linked to coat color phenotypes. The single nucleotide polymorphism responsible for the champagne phenotype is a missense mutation in exon 2, in which a C is replaced with a G, such that a threonine is replaced with arginine. This mutation was identified and described by an American research team in 2008. Champagne phenotypes ch/ch (N/N) wildtype, homozygous recessive. Visually, the horse may be any color other than the champagne shades. CH/ch (CH/N) heterozygous. The colors most commonly associated with this genotype are gold champagne, amber champagne, and classic champagne, though the exact phenotype depends on a variety of factors. At birth, the skin is bright pink and the eyes bright blue, darkening to freckled and light brown or green, respectively, with age. Both red and black pigment in the hair are also diluted. CH/CH homozygous champagne. Homozygotes, which will never produce non-champagne offspring, are indistinguishable from heterozygotes except that their freckling may be sparser, and their coats a shade lighter. Alleles and effects Notable color combinations See also Equine coat color Tiger eye Horse genome Horse breeding Ann T. Bowling References External links "Horse coat color tests" from the UC Davis Veterinary Genetics Lab "Introduction to Coat Color Genetics" from Veterinary Genetics Laboratory, School of Veterinary Medicine, University of California, Davis. Web Site accessed January 12, 2008 "Horse Color Calculator" From Animal Genetics Incorporated. This creates the possible coat coloring of the offspring from the imputed color of sire and dam. "Horse Genome Project" A quick summary of horse color genetics. Genetics Equine genetics