Understanding Horse DNA Results

DNA, or deoxyribonucleic acid, is made up of genetic code. This genetic code will determine the physical appearance of a person or an animal, such as a horse. Advances in DNA testing technology has made it possible to determine DNA via a hair sample. DNA can be found on any body tissue, including easy-to-gather hair. As few as 30 hairs can be used for DNA testing, as long as the root of the hair is still intact.

  1. DNA Profile

    • An equine DNA profile is sometimes referred to as either genotyping or a DNA fingerprint. This profile is made up of a specific genetic code, unique to the individual horse being tested. The horse will have two sets of genes, one from each of their parents. The DNA profile of one horse is essentially a combination of the two DNA profiles that were inherited from each parent.

    Parentage

    • DNA profiles from both the sire-paternal contributor and the dam-maternal contributor (the father and the mother) will determine parentage of the horse. These profiles must be verified. Accuracy is as high as 99.9 percent with verified profiles. In hair testing, DNA is found in hair follicles, and the DNA is made up of all of the horse̵7;s chromosomes. There are 12 gene markers that need to be tested in order to profile the horse, and each of the markers contains one gene for each parent. Each of these genes are matched to the father and the mother to determine if they are, in fact, the horse̵7;s parents.

    Alleles

    • Portions of a horse̵7;s DNA are called alleles. When the different markers of a horse are analyzed by a genetic analyzer, the alleles are determined to be either homozygous or heterozygous. Alleles of the same size are homozygous, meaning that the horse has two identical alleles, one from each parent. Alleles of different sizes are heterozygous, meaning that the horse has two alleles of different sizes from each parent. Alleles are also referred to as bands and all alleles are categorized based on their individual sizes.

    Exclusion

    • When testing horses for parentage, the exclusion method is most often used. The horse̵7;s DNA profile, or genotype, is compared to the DNA profiles of both the mother and the father. Any alleles that are found in the horse but that are not found in the mother̵7;s DNA are assumed to be from the father̵7;s DNA profile.