Editing Appaloosa (section)

=== Color genetics ===

{{main|Leopard complex}}
{{see also|Equine coat color genetics}}
[[File:Stripedhooves.jpg|thumb|upright|Striped hooves are a characteristic trait.|alt=A brown and white striped horse hoof, with a dark colored leg partially visible]]

Any horse that shows Appaloosa core characteristics of coat pattern, mottled skin, striped hooves, and a visible white sclera, carries at least one [[allele]] of the dominant "leopard complex" (LP) [[gene]]. The use of the word "complex" is used to refer to the large group of visible patterns that may occur when LP is present.<ref name=APstudies>{{cite web|url=http://www.appaloosaproject.com/index.php?module=pagemaster&PAGE_user_op=view_page&PAGE_id=1&MMN_position=5:5 |author=Archer, Sheila |title=The Appaloosa Project: Studies Currently Underway |access-date=December 10, 2010 |publisher=The Appaloosa Project |url-status = dead|archive-url=https://web.archive.org/web/20110707152301/http://www.appaloosaproject.com/index.php?module=pagemaster&PAGE_user_op=view_page&PAGE_id=1&MMN_position=5%3A5 |archive-date=July 7, 2011 }}</ref> LP is an [[autosomal]] [[Dominance relationship#Incomplete and semi-dominance|incomplete dominant]] [[mutation]] in the [[TRPM1]] gene located at horse chromosome 1 (ECA 1).<ref name=Bellone2010/><ref name="Terry">{{cite journal |author=Terry, R. B. |author2=Archer, S. |author3=Brooks, S. |author4=Bernoco, D. |author5=Bailey, E. |year=2004 |title=Assignment of the appaloosa coat colour gene (LP) to equine chromosome 1 |journal=Animal Genetics |volume=35 |issue=2 |doi=10.1111/j.1365-2052.2004.01113.x |pages=134–137 |pmid=15025575}}</ref>  All horses with at least one copy of LP show leopard characteristics,<!--sometimes no spots, though--> and it is hypothesized that LP acts together with other patterning genes (PATN) that have not yet been identified to produce the different coat patterns.<ref name=APstudies/><ref>{{cite web|url= http://www.uky.edu/Ag/Horsemap/hgpcoatcolor.html |title= Applications of Genome Study&nbsp;– Coat Color |work=Horse Genome Project |publisher=University of Kentucky|access-date=July 3, 2008| archive-url= https://web.archive.org/web/20080724141007/http://www.uky.edu/Ag/Horsemap/hgpcoatcolor.html| archive-date= 24 July 2008 <!--DASHBot-->|url-status = live}}</ref> Horses that are [[heterozygous]] for LP tend to be darker than [[homozygous]] horses, but this is not consistent.{{sfn|Sponenberg, ''Equine Color Genetics''|p=93}}

Three [[single-nucleotide polymorphism]]s (SNPs) in the TRPM1 gene have been identified as closely associated with the LP mutation, although the mechanism by which the pattern is produced remains unclear.<ref name=APstudies/><ref name=Bellone2010/> A commercially available DNA based test is likely to be developed in the near future,<!--there's nothing that breeders can buy yet--> which breeders can use to determine if LP is present in horses that do not have visible Appaloosa characteristics.<ref name="APstudies" /><ref name=Bellone2010>{{cite journal|author=Bellone, R.|author2=Archer, S.|author3=Wade, C. M.|author4=Cuka-Lawson, C.|author5=Haase, B.|author6=Leeb, T.|author7=Forsyth, G.|author8=Sandmeyer, L.|author9= Grahn, B. |title=Association analysis of candidate SNPs in TRPM1 with leopard complex spotting (LP) and congenital stationary night blindness (CSNB) in horses|journal= Animal Genetics |volume=41|issue= Supplement s2| page=207| date=December 2010|doi= 10.1111/j.1365-2052.2010.02119.x|s2cid=84404747 }}</ref>

Not every Appaloosa exhibits visible coat spotting, but even apparently solid-colored horses that carry at least one dominant LP allele will exhibit characteristics such as vertically striped hooves, white [[sclera]] of the eye, and mottled skin around the eyes, lips, and genitalia.<ref>{{cite web|url= http://www.vgl.ucdavis.edu/services/coatcolor.php |title= Introduction to Coat Color Genetics |access-date=January 31, 2008 |publisher= Veterinary Genetics Laboratory, School of Veterinary Medicine, University of California-Davis| archive-url= https://web.archive.org/web/20080120014506/http://www.vgl.ucdavis.edu/services/coatcolor.php| archive-date= 20 January 2008 <!--DASHBot-->|url-status = live}}</ref>  Appaloosas may also exhibit [[sabino horse|sabino]] or [[pinto horse|pinto]] type markings; as pinto genes may cover or obscure Appaloosa patterns, pinto breeding is discouraged by the ApHC, which will deny registration to horses with excessive white markings.<ref name=Rule205>{{cite web|url= http://www.appaloosa.com/registration/handbook.htm|title= 2012 Appaloosa Horse Club Handbook|access-date= April 2, 2012|publisher= Appaloosa Horse Club|format= PDF|pages= Rule 205.C|archive-date= April 22, 2011|archive-url= https://web.archive.org/web/20110422185434/http://appaloosa.com/registration/handbook.htm|url-status= dead}}</ref> The genes that create these different patterns can be present in the same horse. The Appaloosa Project, a genetic study group, researchers the interactions of Appaloosa and pinto genes, and how they affect each other.<ref>{{cite web|url= http://www.appaloosaproject.info/index.php?module=pagemaster&PAGE_user_op=view_page&PAGE_id=1&MMN_position=5:5|title= What is the Appaloosa Project?|access-date= October 25, 2009|publisher= The Appaloosa Project|archive-url= https://web.archive.org/web/20080824213835/http://www.appaloosaproject.info/index.php?module=pagemaster&PAGE_user_op=view_page&PAGE_id=1&MMN_position=5:5|archive-date= August 24, 2008|url-status= dead}}</ref>