DNA testing::Tobiano


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DNA testing Tobiano occurs due to a chromosomal inversion on ECA3 where the gene order of a section spanning nearly one-third of the chromosome "flipped" during a genetic recombination event. It is thought to be a very ancient gene, about 3500 years old, and is widely distributed across many breeds in the world.<ref name=Bailey>{{#invoke:citation/CS1|citation |CitationClass=book }}</ref>

Genetic testing is available to help determine the presence of the Tobiano gene. Originally, there was no direct test for Tobiano, the early Tobiano tests utilized six genetic markers, including a marker on the KIT gene on horse chromosome 3, which were closely linked to Tobiano but could not be used to officially prove homozygosity.<ref>"Tobiano" from Veterinary Genetics Laboratory, School of Veterinary Medicine, University of California, Davis. Web Site accessed January 13, 2008</ref> After some years of research from the University of Kentucky, in 2008 the chromosomal inversion that affects regulatory regions of the KIT gene was discovered.<ref>"DNA Testing for Tobiano" from Animal Genetics Incorporated</ref> This inversion was finally mapped for genetic testing and is now offered by several laboratories.<ref name=Bailey/> Testing is most often intended to determine homozygosity, but is also useful in cases where a horse has greyed out, or if a horse has an unexplained loss of pigmentation.

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DNA testing
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