Citation: Lawlor, T.J., Van Raden, P.M., Null, D.J., Levisee, J., Dorhorst, B. 2014. Using haplotypes to unravel the inheritance of Holstein coat color for a larger audience. World Congress of Genetics Applied in Livestock Production. Vancouver, Canada, Aug. 17–22. 3 pp.
Technical Abstract: Haplotype testing identifies single-nucleotide polymorphisms that bracket a group of alleles from several different genes located on a specific chromosomal section of DNA. For a trait with a limited number of genotypes and phenotypes, the rules of inheritance can be determined by matching up certain haplotypes with observed phenotypes. Two genes controlling Holstein coat color were identified. A newly identified gene with 2 alleles was found on chromosome 3, with the dominant allele coding for red. Also identified was the well known MC1R gene located on chromosome 18. Four forms of the gene were identified, two causative alleles E_D and e, coding for eumelanin (black) and phaeomelanin (red), respectively; E_BR believed to be linked to a regulatory mutation causing the black/red phenotype; and E+, the ancestral form of the gene coding for a red phenotype. In the traditional gene, MC1R, the red alleles are recessive. The dominant red allele from the newly discovered gene on chromosome 3 is dominant to all of the alleles at the traditional recessive red gene. A key advantage to breeders is that they can obtain haplotype results easily and at little to no cost from their participation in a genomic selection program.